Merge rsync://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

Conflicts:

	include/linux/kernel.h

27 files changed, 2534 insertions, 3596 deletions

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index ac25a48362a..bf869ed03ee 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -90,7 +90,7 @@ config MD_RAID10
 	depends on BLK_DEV_MD && EXPERIMENTAL
 	---help---
 	  RAID-10 provides a combination of striping (RAID-0) and
-	  mirroring (RAID-1) with easier configuration and more flexable
+	  mirroring (RAID-1) with easier configuration and more flexible
 	  layout.
 	  Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
 	  be the same size (or at least, only as much as the smallest device
@@ -104,8 +104,8 @@ config MD_RAID10
 
 	  If unsure, say Y.
 
-config MD_RAID5
-	tristate "RAID-4/RAID-5 mode"
+config MD_RAID456
+	tristate "RAID-4/RAID-5/RAID-6 mode"
 	depends on BLK_DEV_MD
 	---help---
 	  A RAID-5 set of N drives with a capacity of C MB per drive provides
@@ -116,20 +116,28 @@ config MD_RAID5
 	  while a RAID-5 set distributes the parity across the drives in one
 	  of the available parity distribution methods.
 
+	  A RAID-6 set of N drives with a capacity of C MB per drive
+	  provides the capacity of C * (N - 2) MB, and protects
+	  against a failure of any two drives. For a given sector
+	  (row) number, (N - 2) drives contain data sectors, and two
+	  drives contains two independent redundancy syndromes.  Like
+	  RAID-5, RAID-6 distributes the syndromes across the drives
+	  in one of the available parity distribution methods.
+
 	  Information about Software RAID on Linux is contained in the
 	  Software-RAID mini-HOWTO, available from
 	  <http://www.tldp.org/docs.html#howto>. There you will also
 	  learn where to get the supporting user space utilities raidtools.
 
-	  If you want to use such a RAID-4/RAID-5 set, say Y.  To
+	  If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y.  To
 	  compile this code as a module, choose M here: the module
-	  will be called raid5.
+	  will be called raid456.
 
 	  If unsure, say Y.
 
 config MD_RAID5_RESHAPE
 	bool "Support adding drives to a raid-5 array (experimental)"
-	depends on MD_RAID5 && EXPERIMENTAL
+	depends on MD_RAID456 && EXPERIMENTAL
 	---help---
 	  A RAID-5 set can be expanded by adding extra drives. This
 	  requires "restriping" the array which means (almost) every
@@ -139,7 +147,7 @@ config MD_RAID5_RESHAPE
 	  is online.  However it is still EXPERIMENTAL code.  It should
 	  work, but please be sure that you have backups.
 
-	  You will need mdadm verion 2.4.1 or later to use this
+	  You will need mdadm version 2.4.1 or later to use this
 	  feature safely.  During the early stage of reshape there is
 	  a critical section where live data is being over-written.  A
 	  crash during this time needs extra care for recovery.  The
@@ -154,28 +162,6 @@ config MD_RAID5_RESHAPE
 	  There should be enough spares already present to make the new
 	  array workable.
 
-config MD_RAID6
-	tristate "RAID-6 mode"
-	depends on BLK_DEV_MD
-	---help---
-	  A RAID-6 set of N drives with a capacity of C MB per drive
-	  provides the capacity of C * (N - 2) MB, and protects
-	  against a failure of any two drives. For a given sector
-	  (row) number, (N - 2) drives contain data sectors, and two
-	  drives contains two independent redundancy syndromes.  Like
-	  RAID-5, RAID-6 distributes the syndromes across the drives
-	  in one of the available parity distribution methods.
-
-	  RAID-6 requires mdadm-1.5.0 or later, available at:
-
-	  ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
-
-	  If you want to use such a RAID-6 set, say Y.  To compile
-	  this code as a module, choose M here: the module will be
-	  called raid6.
-
-	  If unsure, say Y.
-
 config MD_MULTIPATH
 	tristate "Multipath I/O support"
 	depends on BLK_DEV_MD
@@ -235,7 +221,7 @@ config DM_SNAPSHOT
        tristate "Snapshot target (EXPERIMENTAL)"
        depends on BLK_DEV_DM && EXPERIMENTAL
        ---help---
-         Allow volume managers to take writeable snapshots of a device.
+         Allow volume managers to take writable snapshots of a device.
 
 config DM_MIRROR
        tristate "Mirror target (EXPERIMENTAL)"
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index d3efedf6a6a..34957a68d92 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -8,7 +8,7 @@ dm-multipath-objs := dm-hw-handler.o dm-path-selector.o dm-mpath.o
 dm-snapshot-objs := dm-snap.o dm-exception-store.o
 dm-mirror-objs	:= dm-log.o dm-raid1.o
 md-mod-objs     := md.o bitmap.o
-raid6-objs	:= raid6main.o raid6algos.o raid6recov.o raid6tables.o \
+raid456-objs	:= raid5.o raid6algos.o raid6recov.o raid6tables.o \
 		   raid6int1.o raid6int2.o raid6int4.o \
 		   raid6int8.o raid6int16.o raid6int32.o \
 		   raid6altivec1.o raid6altivec2.o raid6altivec4.o \
@@ -25,8 +25,7 @@ obj-$(CONFIG_MD_LINEAR)		+= linear.o
 obj-$(CONFIG_MD_RAID0)		+= raid0.o
 obj-$(CONFIG_MD_RAID1)		+= raid1.o
 obj-$(CONFIG_MD_RAID10)		+= raid10.o
-obj-$(CONFIG_MD_RAID5)		+= raid5.o xor.o
-obj-$(CONFIG_MD_RAID6)		+= raid6.o xor.o
+obj-$(CONFIG_MD_RAID456)	+= raid456.o xor.o
 obj-$(CONFIG_MD_MULTIPATH)	+= multipath.o
 obj-$(CONFIG_MD_FAULTY)		+= faulty.o
 obj-$(CONFIG_BLK_DEV_MD)	+= md-mod.o
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index f8ffaee20ff..ecc56765d94 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -7,7 +7,6 @@
  * additions, Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.:
  * - added disk storage for bitmap
  * - changes to allow various bitmap chunk sizes
- * - added bitmap daemon (to asynchronously clear bitmap bits from disk)
  */
 
 /*
@@ -15,16 +14,12 @@
  *
  * flush after percent set rather than just time based. (maybe both).
  * wait if count gets too high, wake when it drops to half.
- * allow bitmap to be mirrored with superblock (before or after...)
- * allow hot-add to re-instate a current device.
- * allow hot-add of bitmap after quiessing device
  */
 
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
 #include <linux/init.h>
-#include <linux/config.h>
 #include <linux/timer.h>
 #include <linux/sched.h>
 #include <linux/list.h>
@@ -73,24 +68,6 @@ static inline char * bmname(struct bitmap *bitmap)
 
 
 /*
- * test if the bitmap is active
- */
-int bitmap_active(struct bitmap *bitmap)
-{
-	unsigned long flags;
-	int res = 0;
-
-	if (!bitmap)
-		return res;
-	spin_lock_irqsave(&bitmap->lock, flags);
-	res = bitmap->flags & BITMAP_ACTIVE;
-	spin_unlock_irqrestore(&bitmap->lock, flags);
-	return res;
-}
-
-#define WRITE_POOL_SIZE 256
-
-/*
  * just a placeholder - calls kmalloc for bitmap pages
  */
 static unsigned char *bitmap_alloc_page(struct bitmap *bitmap)
@@ -269,6 +246,8 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde
 
 		if (sync_page_io(rdev->bdev, target, PAGE_SIZE, page, READ)) {
 			page->index = index;
+			attach_page_buffers(page, NULL); /* so that free_buffer will
+							  * quietly no-op */
 			return page;
 		}
 	}
@@ -300,77 +279,132 @@ static int write_sb_page(mddev_t *mddev, long offset, struct page *page, int wai
  */
 static int write_page(struct bitmap *bitmap, struct page *page, int wait)
 {
-	int ret = -ENOMEM;
+	struct buffer_head *bh;
 
 	if (bitmap->file == NULL)
 		return write_sb_page(bitmap->mddev, bitmap->offset, page, wait);
 
-	flush_dcache_page(page); /* make sure visible to anyone reading the file */
+	bh = page_buffers(page);
 
-	if (wait)
-		lock_page(page);
-	else {
-		if (TestSetPageLocked(page))
-			return -EAGAIN; /* already locked */
-		if (PageWriteback(page)) {
-			unlock_page(page);
-			return -EAGAIN;
-		}
+	while (bh && bh->b_blocknr) {
+		atomic_inc(&bitmap->pending_writes);
+		set_buffer_locked(bh);
+		set_buffer_mapped(bh);
+		submit_bh(WRITE, bh);
+		bh = bh->b_this_page;
 	}
 
-	ret = page->mapping->a_ops->prepare_write(bitmap->file, page, 0, PAGE_SIZE);
-	if (!ret)
-		ret = page->mapping->a_ops->commit_write(bitmap->file, page, 0,
-			PAGE_SIZE);
-	if (ret) {
-		unlock_page(page);
-		return ret;
+	if (wait) {
+		wait_event(bitmap->write_wait,
+			   atomic_read(&bitmap->pending_writes)==0);
+		return (bitmap->flags & BITMAP_WRITE_ERROR) ? -EIO : 0;
 	}
+	return 0;
+}
 
-	set_page_dirty(page); /* force it to be written out */
-
-	if (!wait) {
-		/* add to list to be waited for by daemon */
-		struct page_list *item = mempool_alloc(bitmap->write_pool, GFP_NOIO);
-		item->page = page;
-		get_page(page);
-		spin_lock(&bitmap->write_lock);
-		list_add(&item->list, &bitmap->complete_pages);
-		spin_unlock(&bitmap->write_lock);
-		md_wakeup_thread(bitmap->writeback_daemon);
+static void end_bitmap_write(struct buffer_head *bh, int uptodate)
+{
+	struct bitmap *bitmap = bh->b_private;
+	unsigned long flags;
+
+	if (!uptodate) {
+		spin_lock_irqsave(&bitmap->lock, flags);
+		bitmap->flags |= BITMAP_WRITE_ERROR;
+		spin_unlock_irqrestore(&bitmap->lock, flags);
+	}
+	if (atomic_dec_and_test(&bitmap->pending_writes))
+		wake_up(&bitmap->write_wait);
+}
+
+/* copied from buffer.c */
+static void
+__clear_page_buffers(struct page *page)
+{
+	ClearPagePrivate(page);
+	set_page_private(page, 0);
+	page_cache_release(page);
+}
+static void free_buffers(struct page *page)
+{
+	struct buffer_head *bh = page_buffers(page);
+
+	while (bh) {
+		struct buffer_head *next = bh->b_this_page;
+		free_buffer_head(bh);
+		bh = next;
 	}
-	return write_one_page(page, wait);
+	__clear_page_buffers(page);
+	put_page(page);
 }
 
-/* read a page from a file, pinning it into cache, and return bytes_read */
+/* read a page from a file.
+ * We both read the page, and attach buffers to the page to record the
+ * address of each block (using bmap).  These addresses will be used
+ * to write the block later, completely bypassing the filesystem.
+ * This usage is similar to how swap files are handled, and allows us
+ * to write to a file with no concerns of memory allocation failing.
+ */
 static struct page *read_page(struct file *file, unsigned long index,
-					unsigned long *bytes_read)
+			      struct bitmap *bitmap,
+			      unsigned long count)
 {
-	struct inode *inode = file->f_mapping->host;
 	struct page *page = NULL;
-	loff_t isize = i_size_read(inode);
-	unsigned long end_index = isize >> PAGE_SHIFT;
+	struct inode *inode = file->f_dentry->d_inode;
+	struct buffer_head *bh;
+	sector_t block;
 
 	PRINTK("read bitmap file (%dB @ %Lu)\n", (int)PAGE_SIZE,
 			(unsigned long long)index << PAGE_SHIFT);
 
-	page = read_cache_page(inode->i_mapping, index,
-			(filler_t *)inode->i_mapping->a_ops->readpage, file);
+	page = alloc_page(GFP_KERNEL);
+	if (!page)
+		page = ERR_PTR(-ENOMEM);
 	if (IS_ERR(page))
 		goto out;
-	wait_on_page_locked(page);
-	if (!PageUptodate(page) || PageError(page)) {
+
+	bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
+	if (!bh) {
 		put_page(page);
-		page = ERR_PTR(-EIO);
+		page = ERR_PTR(-ENOMEM);
 		goto out;
 	}
+	attach_page_buffers(page, bh);
+	block = index << (PAGE_SHIFT - inode->i_blkbits);
+	while (bh) {
+		if (count == 0)
+			bh->b_blocknr = 0;
+		else {
+			bh->b_blocknr = bmap(inode, block);
+			if (bh->b_blocknr == 0) {
+				/* Cannot use this file! */
+				free_buffers(page);
+				page = ERR_PTR(-EINVAL);
+				goto out;
+			}
+			bh->b_bdev = inode->i_sb->s_bdev;
+			if (count < (1<<inode->i_blkbits))
+				count = 0;
+			else
+				count -= (1<<inode->i_blkbits);
+
+			bh->b_end_io = end_bitmap_write;
+			bh->b_private = bitmap;
+			atomic_inc(&bitmap->pending_writes);
+			set_buffer_locked(bh);
+			set_buffer_mapped(bh);
+			submit_bh(READ, bh);
+		}
+		block++;
+		bh = bh->b_this_page;
+	}
+	page->index = index;
 
-	if (index > end_index) /* we have read beyond EOF */
-		*bytes_read = 0;
-	else if (index == end_index) /* possible short read */
-		*bytes_read = isize & ~PAGE_MASK;
-	else
-		*bytes_read = PAGE_SIZE; /* got a full page */
+	wait_event(bitmap->write_wait,
+		   atomic_read(&bitmap->pending_writes)==0);
+	if (bitmap->flags & BITMAP_WRITE_ERROR) {
+		free_buffers(page);
+		page = ERR_PTR(-EIO);
+	}
 out:
 	if (IS_ERR(page))
 		printk(KERN_ALERT "md: bitmap read error: (%dB @ %Lu): %ld\n",
@@ -441,16 +475,14 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 	char *reason = NULL;
 	bitmap_super_t *sb;
 	unsigned long chunksize, daemon_sleep, write_behind;
-	unsigned long bytes_read;
 	unsigned long long events;
 	int err = -EINVAL;
 
 	/* page 0 is the superblock, read it... */
 	if (bitmap->file)
-		bitmap->sb_page = read_page(bitmap->file, 0, &bytes_read);
+		bitmap->sb_page = read_page(bitmap->file, 0, bitmap, PAGE_SIZE);
 	else {
 		bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset, 0);
-		bytes_read = PAGE_SIZE;
 	}
 	if (IS_ERR(bitmap->sb_page)) {
 		err = PTR_ERR(bitmap->sb_page);
@@ -460,13 +492,6 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 
 	sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
 
-	if (bytes_read < sizeof(*sb)) { /* short read */
-		printk(KERN_INFO "%s: bitmap file superblock truncated\n",
-			bmname(bitmap));
-		err = -ENOSPC;
-		goto out;
-	}
-
 	chunksize = le32_to_cpu(sb->chunksize);
 	daemon_sleep = le32_to_cpu(sb->daemon_sleep);
 	write_behind = le32_to_cpu(sb->write_behind);
@@ -550,7 +575,6 @@ static void bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
 		spin_unlock_irqrestore(&bitmap->lock, flags);
 		return;
 	}
-	get_page(bitmap->sb_page);
 	spin_unlock_irqrestore(&bitmap->lock, flags);
 	sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
 	switch (op) {
@@ -561,7 +585,6 @@ static void bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
 		default: BUG();
 	}
 	kunmap_atomic(sb, KM_USER0);
-	put_page(bitmap->sb_page);
 }
 
 /*
@@ -614,48 +637,17 @@ static void bitmap_file_unmap(struct bitmap *bitmap)
 
 	while (pages--)
 		if (map[pages]->index != 0) /* 0 is sb_page, release it below */
-			put_page(map[pages]);
+			free_buffers(map[pages]);
 	kfree(map);
 	kfree(attr);
 
-	safe_put_page(sb_page);
-}
-
-static void bitmap_stop_daemon(struct bitmap *bitmap);
-
-/* dequeue the next item in a page list -- don't call from irq context */
-static struct page_list *dequeue_page(struct bitmap *bitmap)
-{
-	struct page_list *item = NULL;
-	struct list_head *head = &bitmap->complete_pages;
-
-	spin_lock(&bitmap->write_lock);
-	if (list_empty(head))
-		goto out;
-	item = list_entry(head->prev, struct page_list, list);
-	list_del(head->prev);
-out:
-	spin_unlock(&bitmap->write_lock);
-	return item;
-}
-
-static void drain_write_queues(struct bitmap *bitmap)
-{
-	struct page_list *item;
-
-	while ((item = dequeue_page(bitmap))) {
-		/* don't bother to wait */
-		put_page(item->page);
-		mempool_free(item, bitmap->write_pool);
-	}
-
-	wake_up(&bitmap->write_wait);
+	if (sb_page)
+		free_buffers(sb_page);
 }
 
 static void bitmap_file_put(struct bitmap *bitmap)
 {
 	struct file *file;
-	struct inode *inode;
 	unsigned long flags;
 
 	spin_lock_irqsave(&bitmap->lock, flags);
@@ -663,17 +655,14 @@ static void bitmap_file_put(struct bitmap *bitmap)
 	bitmap->file = NULL;
 	spin_unlock_irqrestore(&bitmap->lock, flags);
 
-	bitmap_stop_daemon(bitmap);
-
-	drain_write_queues(bitmap);
-
+	if (file)
+		wait_event(bitmap->write_wait,
+			   atomic_read(&bitmap->pending_writes)==0);
 	bitmap_file_unmap(bitmap);
 
 	if (file) {
-		inode = file->f_mapping->host;
-		spin_lock(&inode->i_lock);
-		atomic_set(&inode->i_writecount, 1); /* allow writes again */
-		spin_unlock(&inode->i_lock);
+		struct inode *inode = file->f_dentry->d_inode;
+		invalidate_inode_pages(inode->i_mapping);
 		fput(file);
 	}
 }
@@ -708,26 +697,27 @@ static void bitmap_file_kick(struct bitmap *bitmap)
 }
 
 enum bitmap_page_attr {
-	BITMAP_PAGE_DIRTY = 1, // there are set bits that need to be synced
-	BITMAP_PAGE_CLEAN = 2, // there are bits that might need to be cleared
-	BITMAP_PAGE_NEEDWRITE=4, // there are cleared bits that need to be synced
+	BITMAP_PAGE_DIRTY = 0, // there are set bits that need to be synced
+	BITMAP_PAGE_CLEAN = 1, // there are bits that might need to be cleared
+	BITMAP_PAGE_NEEDWRITE=2, // there are cleared bits that need to be synced
 };
 
 static inline void set_page_attr(struct bitmap *bitmap, struct page *page,
 				enum bitmap_page_attr attr)
 {
-	bitmap->filemap_attr[page->index] |= attr;
+	__set_bit((page->index<<2) + attr, bitmap->filemap_attr);
 }
 
 static inline void clear_page_attr(struct bitmap *bitmap, struct page *page,
 				enum bitmap_page_attr attr)
 {
-	bitmap->filemap_attr[page->index] &= ~attr;
+	__clear_bit((page->index<<2) + attr, bitmap->filemap_attr);
 }
 
-static inline unsigned long get_page_attr(struct bitmap *bitmap, struct page *page)
+static inline unsigned long test_page_attr(struct bitmap *bitmap, struct page *page,
+					   enum bitmap_page_attr attr)
 {
-	return bitmap->filemap_attr[page->index];
+	return test_bit((page->index<<2) + attr, bitmap->filemap_attr);
 }
 
 /*
@@ -751,11 +741,6 @@ static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
 	page = filemap_get_page(bitmap, chunk);
 	bit = file_page_offset(chunk);
 
-
-	/* make sure the page stays cached until it gets written out */
-	if (! (get_page_attr(bitmap, page) & BITMAP_PAGE_DIRTY))
-		get_page(page);
-
  	/* set the bit */
 	kaddr = kmap_atomic(page, KM_USER0);
 	if (bitmap->flags & BITMAP_HOSTENDIAN)
@@ -775,7 +760,8 @@ static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
  * sync the dirty pages of the bitmap file to disk */
 int bitmap_unplug(struct bitmap *bitmap)
 {
-	unsigned long i, attr, flags;
+	unsigned long i, flags;
+	int dirty, need_write;
 	struct page *page;
 	int wait = 0;
 	int err;
@@ -792,35 +778,26 @@ int bitmap_unplug(struct bitmap *bitmap)
 			return 0;
 		}
 		page = bitmap->filemap[i];
-		attr = get_page_attr(bitmap, page);
+		dirty = test_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
+		need_write = test_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
 		clear_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
 		clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
-		if ((attr & BITMAP_PAGE_DIRTY))
+		if (dirty)
 			wait = 1;
 		spin_unlock_irqrestore(&bitmap->lock, flags);
 
-		if (attr & (BITMAP_PAGE_DIRTY | BITMAP_PAGE_NEEDWRITE)) {
+		if (dirty | need_write)
 			err = write_page(bitmap, page, 0);
-			if (err == -EAGAIN) {
-				if (attr & BITMAP_PAGE_DIRTY)
-					err = write_page(bitmap, page, 1);
-				else
-					err = 0;
-			}
-			if (err)
-				return 1;
-		}
 	}
 	if (wait) { /* if any writes were performed, we need to wait on them */
-		if (bitmap->file) {
-			spin_lock_irq(&bitmap->write_lock);
-			wait_event_lock_irq(bitmap->write_wait,
-					    list_empty(&bitmap->complete_pages), bitmap->write_lock,
-					    wake_up_process(bitmap->writeback_daemon->tsk));
-			spin_unlock_irq(&bitmap->write_lock);
-		} else
+		if (bitmap->file)
+			wait_event(bitmap->write_wait,
+				   atomic_read(&bitmap->pending_writes)==0);
+		else
 			md_super_wait(bitmap->mddev);
 	}
+	if (bitmap->flags & BITMAP_WRITE_ERROR)
+		bitmap_file_kick(bitmap);
 	return 0;
 }
 
@@ -842,7 +819,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 	struct page *page = NULL, *oldpage = NULL;
 	unsigned long num_pages, bit_cnt = 0;
 	struct file *file;
-	unsigned long bytes, offset, dummy;
+	unsigned long bytes, offset;
 	int outofdate;
 	int ret = -ENOSPC;
 	void *paddr;
@@ -879,7 +856,12 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 	if (!bitmap->filemap)
 		goto out;
 
-	bitmap->filemap_attr = kzalloc(sizeof(long) * num_pages, GFP_KERNEL);
+	/* We need 4 bits per page, rounded up to a multiple of sizeof(unsigned long) */
+	bitmap->filemap_attr = kzalloc(
+		(((num_pages*4/8)+sizeof(unsigned long)-1)
+		 /sizeof(unsigned long))
+		*sizeof(unsigned long),
+		GFP_KERNEL);
 	if (!bitmap->filemap_attr)
 		goto out;
 
@@ -890,7 +872,12 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 		index = file_page_index(i);
 		bit = file_page_offset(i);
 		if (index != oldindex) { /* this is a new page, read it in */
+			int count;
 			/* unmap the old page, we're done with it */
+			if (index == num_pages-1)
+				count = bytes - index * PAGE_SIZE;
+			else
+				count = PAGE_SIZE;
 			if (index == 0) {
 				/*
 				 * if we're here then the superblock page
@@ -900,7 +887,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 				page = bitmap->sb_page;
 				offset = sizeof(bitmap_super_t);
 			} else if (file) {
-				page = read_page(file, index, &dummy);
+				page = read_page(file, index, bitmap, count);
 				offset = 0;
 			} else {
 				page = read_sb_page(bitmap->mddev, bitmap->offset, index);
@@ -971,12 +958,11 @@ void bitmap_write_all(struct bitmap *bitmap)
 	/* We don't actually write all bitmap blocks here,
 	 * just flag them as needing to be written
 	 */
+	int i;
 
-	unsigned long chunks = bitmap->chunks;
-	unsigned long bytes = (chunks+7)/8 + sizeof(bitmap_super_t);
-	unsigned long num_pages = (bytes + PAGE_SIZE-1) / PAGE_SIZE;
-	while (num_pages--)
-		bitmap->filemap_attr[num_pages] |= BITMAP_PAGE_NEEDWRITE;
+	for (i=0; i < bitmap->file_pages; i++)
+		set_page_attr(bitmap, bitmap->filemap[i],
+			      BITMAP_PAGE_NEEDWRITE);
 }
 
 
@@ -1007,7 +993,6 @@ int bitmap_daemon_work(struct bitmap *bitmap)
 	struct page *page = NULL, *lastpage = NULL;
 	int err = 0;
 	int blocks;
-	int attr;
 	void *paddr;
 
 	if (bitmap == NULL)
@@ -1029,43 +1014,34 @@ int bitmap_daemon_work(struct bitmap *bitmap)
 
 		if (page != lastpage) {
 			/* skip this page unless it's marked as needing cleaning */
-			if (!((attr=get_page_attr(bitmap, page)) & BITMAP_PAGE_CLEAN)) {
-				if (attr & BITMAP_PAGE_NEEDWRITE) {
-					get_page(page);
+			if (!test_page_attr(bitmap, page, BITMAP_PAGE_CLEAN)) {
+				int need_write = test_page_attr(bitmap, page,
+								BITMAP_PAGE_NEEDWRITE);
+				if (need_write)
 					clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
-				}
+
 				spin_unlock_irqrestore(&bitmap->lock, flags);
-				if (attr & BITMAP_PAGE_NEEDWRITE) {
+				if (need_write) {
 					switch (write_page(bitmap, page, 0)) {
-					case -EAGAIN:
-						set_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
-						break;
 					case 0:
 						break;
 					default:
 						bitmap_file_kick(bitmap);
 					}
-					put_page(page);
 				}
 				continue;
 			}
 
 			/* grab the new page, sync and release the old */
-			get_page(page);
 			if (lastpage != NULL) {
-				if (get_page_attr(bitmap, lastpage) & BITMAP_PAGE_NEEDWRITE) {
+				if (test_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE)) {
 					clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
 					spin_unlock_irqrestore(&bitmap->lock, flags);
 					err = write_page(bitmap, lastpage, 0);
-					if (err == -EAGAIN) {
-						err = 0;
-						set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
-					}
 				} else {
 					set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
 					spin_unlock_irqrestore(&bitmap->lock, flags);
 				}
-				put_page(lastpage);
 				if (err)
 					bitmap_file_kick(bitmap);
 			} else
@@ -1107,131 +1083,19 @@ int bitmap_daemon_work(struct bitmap *bitmap)
 	/* now sync the final page */
 	if (lastpage != NULL) {
 		spin_lock_irqsave(&bitmap->lock, flags);
-		if (get_page_attr(bitmap, lastpage) &BITMAP_PAGE_NEEDWRITE) {
+		if (test_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE)) {
 			clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
 			spin_unlock_irqrestore(&bitmap->lock, flags);
 			err = write_page(bitmap, lastpage, 0);
-			if (err == -EAGAIN) {
-				set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
-				err = 0;
-			}
 		} else {
 			set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
 			spin_unlock_irqrestore(&bitmap->lock, flags);
 		}
-
-		put_page(lastpage);
 	}
 
 	return err;
 }
 
-static void daemon_exit(struct bitmap *bitmap, mdk_thread_t **daemon)
-{
-	mdk_thread_t *dmn;
-	unsigned long flags;
-
-	/* if no one is waiting on us, we'll free the md thread struct
-	 * and exit, otherwise we let the waiter clean things up */
-	spin_lock_irqsave(&bitmap->lock, flags);
-	if ((dmn = *daemon)) { /* no one is waiting, cleanup and exit */
-		*daemon = NULL;
-		spin_unlock_irqrestore(&bitmap->lock, flags);
-		kfree(dmn);
-		complete_and_exit(NULL, 0); /* do_exit not exported */
-	}
-	spin_unlock_irqrestore(&bitmap->lock, flags);
-}
-
-static void bitmap_writeback_daemon(mddev_t *mddev)
-{
-	struct bitmap *bitmap = mddev->bitmap;
-	struct page *page;
-	struct page_list *item;
-	int err = 0;
-
-	if (signal_pending(current)) {
-		printk(KERN_INFO
-		       "%s: bitmap writeback daemon got signal, exiting...\n",
-		       bmname(bitmap));
-		err = -EINTR;
-		goto out;
-	}
-	if (bitmap == NULL)
-		/* about to be stopped. */
-		return;
-
-	PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap));
-	/* wait on bitmap page writebacks */
-	while ((item = dequeue_page(bitmap))) {
-		page = item->page;
-		mempool_free(item, bitmap->write_pool);
-		PRINTK("wait on page writeback: %p\n", page);
-		wait_on_page_writeback(page);
-		PRINTK("finished page writeback: %p\n", page);
-
-		err = PageError(page);
-		put_page(page);
-		if (err) {
-			printk(KERN_WARNING "%s: bitmap file writeback "
-			       "failed (page %lu): %d\n",
-			       bmname(bitmap), page->index, err);
-			bitmap_file_kick(bitmap);
-			goto out;
-		}
-	}
- out:
-	wake_up(&bitmap->write_wait);
-	if (err) {
-		printk(KERN_INFO "%s: bitmap writeback daemon exiting (%d)\n",
-		       bmname(bitmap), err);
-		daemon_exit(bitmap, &bitmap->writeback_daemon);
-	}
-}
-
-static mdk_thread_t *bitmap_start_daemon(struct bitmap *bitmap,
-				void (*func)(mddev_t *), char *name)
-{
-	mdk_thread_t *daemon;
-	char namebuf[32];
-
-#ifdef INJECT_FATAL_FAULT_2
-	daemon = NULL;
-#else
-	sprintf(namebuf, "%%s_%s", name);
-	daemon = md_register_thread(func, bitmap->mddev, namebuf);
-#endif
-	if (!daemon) {
-		printk(KERN_ERR "%s: failed to start bitmap daemon\n",
-			bmname(bitmap));
-		return ERR_PTR(-ECHILD);
-	}
-
-	md_wakeup_thread(daemon); /* start it running */
-
-	PRINTK("%s: %s daemon (pid %d) started...\n",
-		bmname(bitmap), name, daemon->tsk->pid);
-
-	return daemon;
-}
-
-static void bitmap_stop_daemon(struct bitmap *bitmap)
-{
-	/* the daemon can't stop itself... it'll just exit instead... */
-	if (bitmap->writeback_daemon && ! IS_ERR(bitmap->writeback_daemon) &&
-	    current->pid != bitmap->writeback_daemon->tsk->pid) {
-		mdk_thread_t *daemon;
-		unsigned long flags;
-
-		spin_lock_irqsave(&bitmap->lock, flags);
-		daemon = bitmap->writeback_daemon;
-		bitmap->writeback_daemon = NULL;
-		spin_unlock_irqrestore(&bitmap->lock, flags);
-		if (daemon && ! IS_ERR(daemon))
-			md_unregister_thread(daemon); /* destroy the thread */
-	}
-}
-
 static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
 					    sector_t offset, int *blocks,
 					    int create)
@@ -1500,8 +1364,6 @@ static void bitmap_free(struct bitmap *bitmap)
 
 	/* free all allocated memory */
 
-	mempool_destroy(bitmap->write_pool);
-
 	if (bp) /* deallocate the page memory */
 		for (k = 0; k < pages; k++)
 			if (bp[k].map && !bp[k].hijacked)
@@ -1549,20 +1411,20 @@ int bitmap_create(mddev_t *mddev)
 		return -ENOMEM;
 
 	spin_lock_init(&bitmap->lock);
-	bitmap->mddev = mddev;
-
-	spin_lock_init(&bitmap->write_lock);
-	INIT_LIST_HEAD(&bitmap->complete_pages);
+	atomic_set(&bitmap->pending_writes, 0);
 	init_waitqueue_head(&bitmap->write_wait);
-	bitmap->write_pool = mempool_create_kmalloc_pool(WRITE_POOL_SIZE,
-						sizeof(struct page_list));
-	err = -ENOMEM;
-	if (!bitmap->write_pool)
-		goto error;
+
+	bitmap->mddev = mddev;
 
 	bitmap->file = file;
 	bitmap->offset = mddev->bitmap_offset;
-	if (file) get_file(file);
+	if (file) {
+		get_file(file);
+		do_sync_file_range(file, 0, LLONG_MAX,
+				   SYNC_FILE_RANGE_WAIT_BEFORE |
+				   SYNC_FILE_RANGE_WRITE |
+				   SYNC_FILE_RANGE_WAIT_AFTER);
+	}
 	/* read superblock from bitmap file (this sets bitmap->chunksize) */
 	err = bitmap_read_sb(bitmap);
 	if (err)
@@ -1594,8 +1456,6 @@ int bitmap_create(mddev_t *mddev)
 	if (!bitmap->bp)
 		goto error;
 
-	bitmap->flags |= BITMAP_ACTIVE;
-
 	/* now that we have some pages available, initialize the in-memory
 	 * bitmap from the on-disk bitmap */
 	start = 0;
@@ -1613,15 +1473,6 @@ int bitmap_create(mddev_t *mddev)
 
 	mddev->bitmap = bitmap;
 
-	if (file)
-		/* kick off the bitmap writeback daemon */
-		bitmap->writeback_daemon =
-			bitmap_start_daemon(bitmap,
-					    bitmap_writeback_daemon,
-					    "bitmap_wb");
-
-	if (IS_ERR(bitmap->writeback_daemon))
-		return PTR_ERR(bitmap->writeback_daemon);
 	mddev->thread->timeout = bitmap->daemon_sleep * HZ;
 
 	return bitmap_update_sb(bitmap);
@@ -1638,4 +1489,3 @@ EXPORT_SYMBOL(bitmap_start_sync);
 EXPORT_SYMBOL(bitmap_end_sync);
 EXPORT_SYMBOL(bitmap_unplug);
 EXPORT_SYMBOL(bitmap_close_sync);
-EXPORT_SYMBOL(bitmap_daemon_work);
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 61a590bb624..6022ed12a79 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -20,7 +20,7 @@
 
 #include "dm.h"
 
-#define PFX	"crypt: "
+#define DM_MSG_PREFIX "crypt"
 
 /*
  * per bio private data
@@ -125,19 +125,19 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 	u8 *salt;
 
 	if (opts == NULL) {
-		ti->error = PFX "Digest algorithm missing for ESSIV mode";
+		ti->error = "Digest algorithm missing for ESSIV mode";
 		return -EINVAL;
 	}
 
 	/* Hash the cipher key with the given hash algorithm */
 	hash_tfm = crypto_alloc_tfm(opts, CRYPTO_TFM_REQ_MAY_SLEEP);
 	if (hash_tfm == NULL) {
-		ti->error = PFX "Error initializing ESSIV hash";
+		ti->error = "Error initializing ESSIV hash";
 		return -EINVAL;
 	}
 
 	if (crypto_tfm_alg_type(hash_tfm) != CRYPTO_ALG_TYPE_DIGEST) {
-		ti->error = PFX "Expected digest algorithm for ESSIV hash";
+		ti->error = "Expected digest algorithm for ESSIV hash";
 		crypto_free_tfm(hash_tfm);
 		return -EINVAL;
 	}
@@ -145,7 +145,7 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 	saltsize = crypto_tfm_alg_digestsize(hash_tfm);
 	salt = kmalloc(saltsize, GFP_KERNEL);
 	if (salt == NULL) {
-		ti->error = PFX "Error kmallocing salt storage in ESSIV";
+		ti->error = "Error kmallocing salt storage in ESSIV";
 		crypto_free_tfm(hash_tfm);
 		return -ENOMEM;
 	}
@@ -159,20 +159,20 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 	                             CRYPTO_TFM_MODE_ECB |
 	                             CRYPTO_TFM_REQ_MAY_SLEEP);
 	if (essiv_tfm == NULL) {
-		ti->error = PFX "Error allocating crypto tfm for ESSIV";
+		ti->error = "Error allocating crypto tfm for ESSIV";
 		kfree(salt);
 		return -EINVAL;
 	}
 	if (crypto_tfm_alg_blocksize(essiv_tfm)
 	    != crypto_tfm_alg_ivsize(cc->tfm)) {
-		ti->error = PFX "Block size of ESSIV cipher does "
+		ti->error = "Block size of ESSIV cipher does "
 			        "not match IV size of block cipher";
 		crypto_free_tfm(essiv_tfm);
 		kfree(salt);
 		return -EINVAL;
 	}
 	if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) {
-		ti->error = PFX "Failed to set key for ESSIV cipher";
+		ti->error = "Failed to set key for ESSIV cipher";
 		crypto_free_tfm(essiv_tfm);
 		kfree(salt);
 		return -EINVAL;
@@ -521,7 +521,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	unsigned long long tmpll;
 
 	if (argc != 5) {
-		ti->error = PFX "Not enough arguments";
+		ti->error = "Not enough arguments";
 		return -EINVAL;
 	}
 
@@ -532,21 +532,21 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ivmode = strsep(&ivopts, ":");
 
 	if (tmp)
-		DMWARN(PFX "Unexpected additional cipher options");
+		DMWARN("Unexpected additional cipher options");
 
 	key_size = strlen(argv[1]) >> 1;
 
 	cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 	if (cc == NULL) {
 		ti->error =
-			PFX "Cannot allocate transparent encryption context";
+			"Cannot allocate transparent encryption context";
 		return -ENOMEM;
 	}
 
 	cc->key_size = key_size;
 	if ((!key_size && strcmp(argv[1], "-") != 0) ||
 	    (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) {
-		ti->error = PFX "Error decoding key";
+		ti->error = "Error decoding key";
 		goto bad1;
 	}
 
@@ -562,22 +562,22 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	else if (strcmp(chainmode, "ecb") == 0)
 		crypto_flags = CRYPTO_TFM_MODE_ECB;
 	else {
-		ti->error = PFX "Unknown chaining mode";
+		ti->error = "Unknown chaining mode";
 		goto bad1;
 	}
 
 	if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) {
-		ti->error = PFX "This chaining mode requires an IV mechanism";
+		ti->error = "This chaining mode requires an IV mechanism";
 		goto bad1;
 	}
 
 	tfm = crypto_alloc_tfm(cipher, crypto_flags | CRYPTO_TFM_REQ_MAY_SLEEP);
 	if (!tfm) {
-		ti->error = PFX "Error allocating crypto tfm";
+		ti->error = "Error allocating crypto tfm";
 		goto bad1;
 	}
 	if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) {
-		ti->error = PFX "Expected cipher algorithm";
+		ti->error = "Expected cipher algorithm";
 		goto bad2;
 	}
 
@@ -595,7 +595,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	else if (strcmp(ivmode, "essiv") == 0)
 		cc->iv_gen_ops = &crypt_iv_essiv_ops;
 	else {
-		ti->error = PFX "Invalid IV mode";
+		ti->error = "Invalid IV mode";
 		goto bad2;
 	}
 
@@ -610,7 +610,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	else {
 		cc->iv_size = 0;
 		if (cc->iv_gen_ops) {
-			DMWARN(PFX "Selected cipher does not support IVs");
+			DMWARN("Selected cipher does not support IVs");
 			if (cc->iv_gen_ops->dtr)
 				cc->iv_gen_ops->dtr(cc);
 			cc->iv_gen_ops = NULL;
@@ -619,36 +619,36 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
 	if (!cc->io_pool) {
-		ti->error = PFX "Cannot allocate crypt io mempool";
+		ti->error = "Cannot allocate crypt io mempool";
 		goto bad3;
 	}
 
 	cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
 	if (!cc->page_pool) {
-		ti->error = PFX "Cannot allocate page mempool";
+		ti->error = "Cannot allocate page mempool";
 		goto bad4;
 	}
 
 	if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) {
-		ti->error = PFX "Error setting key";
+		ti->error = "Error setting key";
 		goto bad5;
 	}
 
 	if (sscanf(argv[2], "%llu", &tmpll) != 1) {
-		ti->error = PFX "Invalid iv_offset sector";
+		ti->error = "Invalid iv_offset sector";
 		goto bad5;
 	}
 	cc->iv_offset = tmpll;
 
 	if (sscanf(argv[4], "%llu", &tmpll) != 1) {
-		ti->error = PFX "Invalid device sector";
+		ti->error = "Invalid device sector";
 		goto bad5;
 	}
 	cc->start = tmpll;
 
 	if (dm_get_device(ti, argv[3], cc->start, ti->len,
 	                  dm_table_get_mode(ti->table), &cc->dev)) {
-		ti->error = PFX "Device lookup failed";
+		ti->error = "Device lookup failed";
 		goto bad5;
 	}
 
@@ -657,7 +657,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 			*(ivopts - 1) = ':';
 		cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
 		if (!cc->iv_mode) {
-			ti->error = PFX "Error kmallocing iv_mode string";
+			ti->error = "Error kmallocing iv_mode string";
 			goto bad5;
 		}
 		strcpy(cc->iv_mode, ivmode);
@@ -918,13 +918,13 @@ static int __init dm_crypt_init(void)
 	_kcryptd_workqueue = create_workqueue("kcryptd");
 	if (!_kcryptd_workqueue) {
 		r = -ENOMEM;
-		DMERR(PFX "couldn't create kcryptd");
+		DMERR("couldn't create kcryptd");
 		goto bad1;
 	}
 
 	r = dm_register_target(&crypt_target);
 	if (r < 0) {
-		DMERR(PFX "register failed %d", r);
+		DMERR("register failed %d", r);
 		goto bad2;
 	}
 
@@ -942,7 +942,7 @@ static void __exit dm_crypt_exit(void)
 	int r = dm_unregister_target(&crypt_target);
 
 	if (r < 0)
-		DMERR(PFX "unregister failed %d", r);
+		DMERR("unregister failed %d", r);
 
 	destroy_workqueue(_kcryptd_workqueue);
 	kmem_cache_destroy(_crypt_io_pool);
diff --git a/drivers/md/dm-emc.c b/drivers/md/dm-emc.c
index c7067674dcb..2a374ccb30d 100644
--- a/drivers/md/dm-emc.c
+++ b/drivers/md/dm-emc.c
@@ -12,6 +12,8 @@
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
 
+#define DM_MSG_PREFIX "multipath emc"
+
 struct emc_handler {
 	spinlock_t lock;
 
@@ -66,7 +68,7 @@ static struct bio *get_failover_bio(struct path *path, unsigned data_size)
 
 	bio = bio_alloc(GFP_ATOMIC, 1);
 	if (!bio) {
-		DMERR("dm-emc: get_failover_bio: bio_alloc() failed.");
+		DMERR("get_failover_bio: bio_alloc() failed.");
 		return NULL;
 	}
 
@@ -78,13 +80,13 @@ static struct bio *get_failover_bio(struct path *path, unsigned data_size)
 
 	page = alloc_page(GFP_ATOMIC);
 	if (!page) {
-		DMERR("dm-emc: get_failover_bio: alloc_page() failed.");
+		DMERR("get_failover_bio: alloc_page() failed.");
 		bio_put(bio);
 		return NULL;
 	}
 
 	if (bio_add_page(bio, page, data_size, 0) != data_size) {
-		DMERR("dm-emc: get_failover_bio: alloc_page() failed.");
+		DMERR("get_failover_bio: alloc_page() failed.");
 		__free_page(page);
 		bio_put(bio);
 		return NULL;
@@ -103,7 +105,7 @@ static struct request *get_failover_req(struct emc_handler *h,
 	/* FIXME: Figure out why it fails with GFP_ATOMIC. */
 	rq = blk_get_request(q, WRITE, __GFP_WAIT);
 	if (!rq) {
-		DMERR("dm-emc: get_failover_req: blk_get_request failed");
+		DMERR("get_failover_req: blk_get_request failed");
 		return NULL;
 	}
 
@@ -160,7 +162,7 @@ static struct request *emc_trespass_get(struct emc_handler *h,
 
 	bio = get_failover_bio(path, data_size);
 	if (!bio) {
-		DMERR("dm-emc: emc_trespass_get: no bio");
+		DMERR("emc_trespass_get: no bio");
 		return NULL;
 	}
 
@@ -173,7 +175,7 @@ static struct request *emc_trespass_get(struct emc_handler *h,
 	/* get request for block layer packet command */
 	rq = get_failover_req(h, bio, path);
 	if (!rq) {
-		DMERR("dm-emc: emc_trespass_get: no rq");
+		DMERR("emc_trespass_get: no rq");
 		free_bio(bio);
 		return NULL;
 	}
@@ -200,18 +202,18 @@ static void emc_pg_init(struct hw_handler *hwh, unsigned bypassed,
 	 * initial state passed into us and then get an update here.
 	 */
 	if (!q) {
-		DMINFO("dm-emc: emc_pg_init: no queue");
+		DMINFO("emc_pg_init: no queue");
 		goto fail_path;
 	}
 
 	/* FIXME: The request should be pre-allocated. */
 	rq = emc_trespass_get(hwh->context, path);
 	if (!rq) {
-		DMERR("dm-emc: emc_pg_init: no rq");
+		DMERR("emc_pg_init: no rq");
 		goto fail_path;
 	}
 
-	DMINFO("dm-emc: emc_pg_init: sending switch-over command");
+	DMINFO("emc_pg_init: sending switch-over command");
 	elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 1);
 	return;
 
@@ -241,18 +243,18 @@ static int emc_create(struct hw_handler *hwh, unsigned argc, char **argv)
 		hr = 0;
 		short_trespass = 0;
 	} else if (argc != 2) {
-		DMWARN("dm-emc hwhandler: incorrect number of arguments");
+		DMWARN("incorrect number of arguments");
 		return -EINVAL;
 	} else {
 		if ((sscanf(argv[0], "%u", &short_trespass) != 1)
 			|| (short_trespass > 1)) {
-			DMWARN("dm-emc: invalid trespass mode selected");
+			DMWARN("invalid trespass mode selected");
 			return -EINVAL;
 		}
 
 		if ((sscanf(argv[1], "%u", &hr) != 1)
 			|| (hr > 1)) {
-			DMWARN("dm-emc: invalid honor reservation flag selected");
+			DMWARN("invalid honor reservation flag selected");
 			return -EINVAL;
 		}
 	}
@@ -264,14 +266,14 @@ static int emc_create(struct hw_handler *hwh, unsigned argc, char **argv)
 	hwh->context = h;
 
 	if ((h->short_trespass = short_trespass))
-		DMWARN("dm-emc: short trespass command will be send");
+		DMWARN("short trespass command will be send");
 	else
-		DMWARN("dm-emc: long trespass command will be send");
+		DMWARN("long trespass command will be send");
 
 	if ((h->hr = hr))
-		DMWARN("dm-emc: honor reservation bit will be set");
+		DMWARN("honor reservation bit will be set");
 	else
-		DMWARN("dm-emc: honor reservation bit will not be set (default)");
+		DMWARN("honor reservation bit will not be set (default)");
 
 	return 0;
 }
@@ -336,9 +338,9 @@ static int __init dm_emc_init(void)
 	int r = dm_register_hw_handler(&emc_hwh);
 
 	if (r < 0)
-		DMERR("emc: register failed %d", r);
+		DMERR("register failed %d", r);
 
-	DMINFO("dm-emc version 0.0.3 loaded");
+	DMINFO("version 0.0.3 loaded");
 
 	return r;
 }
@@ -348,7 +350,7 @@ static void __exit dm_emc_exit(void)
 	int r = dm_unregister_hw_handler(&emc_hwh);
 
 	if (r < 0)
-		DMERR("emc: unregister failed %d", r);
+		DMERR("unregister failed %d", r);
 }
 
 module_init(dm_emc_init);
diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index cc07bbebbb1..d12379b5cdb 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -16,6 +16,8 @@
 #include <linux/vmalloc.h>
 #include <linux/slab.h>
 
+#define DM_MSG_PREFIX "snapshots"
+
 /*-----------------------------------------------------------------
  * Persistent snapshots, by persistent we mean that the snapshot
  * will survive a reboot.
@@ -91,7 +93,6 @@ struct pstore {
 	struct dm_snapshot *snap;	/* up pointer to my snapshot */
 	int version;
 	int valid;
-	uint32_t chunk_size;
 	uint32_t exceptions_per_area;
 
 	/*
@@ -133,7 +134,7 @@ static int alloc_area(struct pstore *ps)
 	int r = -ENOMEM;
 	size_t len;
 
-	len = ps->chunk_size << SECTOR_SHIFT;
+	len = ps->snap->chunk_size << SECTOR_SHIFT;
 
 	/*
 	 * Allocate the chunk_size block of memory that will hold
@@ -160,8 +161,8 @@ static int chunk_io(struct pstore *ps, uint32_t chunk, int rw)
 	unsigned long bits;
 
 	where.bdev = ps->snap->cow->bdev;
-	where.sector = ps->chunk_size * chunk;
-	where.count = ps->chunk_size;
+	where.sector = ps->snap->chunk_size * chunk;
+	where.count = ps->snap->chunk_size;
 
 	return dm_io_sync_vm(1, &where, rw, ps->area, &bits);
 }
@@ -188,7 +189,7 @@ static int area_io(struct pstore *ps, uint32_t area, int rw)
 
 static int zero_area(struct pstore *ps, uint32_t area)
 {
-	memset(ps->area, 0, ps->chunk_size << SECTOR_SHIFT);
+	memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT);
 	return area_io(ps, area, WRITE);
 }
 
@@ -196,6 +197,7 @@ static int read_header(struct pstore *ps, int *new_snapshot)
 {
 	int r;
 	struct disk_header *dh;
+	chunk_t chunk_size;
 
 	r = chunk_io(ps, 0, READ);
 	if (r)
@@ -210,8 +212,29 @@ static int read_header(struct pstore *ps, int *new_snapshot)
 		*new_snapshot = 0;
 		ps->valid = le32_to_cpu(dh->valid);
 		ps->version = le32_to_cpu(dh->version);
-		ps->chunk_size = le32_to_cpu(dh->chunk_size);
-
+		chunk_size = le32_to_cpu(dh->chunk_size);
+		if (ps->snap->chunk_size != chunk_size) {
+			DMWARN("chunk size %llu in device metadata overrides "
+			       "table chunk size of %llu.",
+			       (unsigned long long)chunk_size,
+			       (unsigned long long)ps->snap->chunk_size);
+
+			/* We had a bogus chunk_size. Fix stuff up. */
+			dm_io_put(sectors_to_pages(ps->snap->chunk_size));
+			free_area(ps);
+
+			ps->snap->chunk_size = chunk_size;
+			ps->snap->chunk_mask = chunk_size - 1;
+			ps->snap->chunk_shift = ffs(chunk_size) - 1;
+
+			r = alloc_area(ps);
+			if (r)
+				return r;
+
+			r = dm_io_get(sectors_to_pages(chunk_size));
+			if (r)
+				return r;
+		}
 	} else {
 		DMWARN("Invalid/corrupt snapshot");
 		r = -ENXIO;
@@ -224,13 +247,13 @@ static int write_header(struct pstore *ps)
 {
 	struct disk_header *dh;
 
-	memset(ps->area, 0, ps->chunk_size << SECTOR_SHIFT);
+	memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT);
 
 	dh = (struct disk_header *) ps->area;
 	dh->magic = cpu_to_le32(SNAP_MAGIC);
 	dh->valid = cpu_to_le32(ps->valid);
 	dh->version = cpu_to_le32(ps->version);
-	dh->chunk_size = cpu_to_le32(ps->chunk_size);
+	dh->chunk_size = cpu_to_le32(ps->snap->chunk_size);
 
 	return chunk_io(ps, 0, WRITE);
 }
@@ -365,7 +388,7 @@ static void persistent_destroy(struct exception_store *store)
 {
 	struct pstore *ps = get_info(store);
 
-	dm_io_put(sectors_to_pages(ps->chunk_size));
+	dm_io_put(sectors_to_pages(ps->snap->chunk_size));
 	vfree(ps->callbacks);
 	free_area(ps);
 	kfree(ps);
@@ -384,6 +407,16 @@ static int persistent_read_metadata(struct exception_store *store)
 		return r;
 
 	/*
+	 * Now we know correct chunk_size, complete the initialisation.
+	 */
+	ps->exceptions_per_area = (ps->snap->chunk_size << SECTOR_SHIFT) /
+				  sizeof(struct disk_exception);
+	ps->callbacks = dm_vcalloc(ps->exceptions_per_area,
+			sizeof(*ps->callbacks));
+	if (!ps->callbacks)
+		return -ENOMEM;
+
+	/*
 	 * Do we need to setup a new snapshot ?
 	 */
 	if (new_snapshot) {
@@ -533,9 +566,6 @@ int dm_create_persistent(struct exception_store *store, uint32_t chunk_size)
 	ps->snap = store->snap;
 	ps->valid = 1;
 	ps->version = SNAPSHOT_DISK_VERSION;
-	ps->chunk_size = chunk_size;
-	ps->exceptions_per_area = (chunk_size << SECTOR_SHIFT) /
-	    sizeof(struct disk_exception);
 	ps->next_free = 2;	/* skipping the header and first area */
 	ps->current_committed = 0;
 
@@ -543,18 +573,9 @@ int dm_create_persistent(struct exception_store *store, uint32_t chunk_size)
 	if (r)
 		goto bad;
 
-	/*
-	 * Allocate space for all the callbacks.
-	 */
 	ps->callback_count = 0;
 	atomic_set(&ps->pending_count, 0);
-	ps->callbacks = dm_vcalloc(ps->exceptions_per_area,
-				   sizeof(*ps->callbacks));
-
-	if (!ps->callbacks) {
-		r = -ENOMEM;
-		goto bad;
-	}
+	ps->callbacks = NULL;
 
 	store->destroy = persistent_destroy;
 	store->read_metadata = persistent_read_metadata;
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 8edd6435414..d13bb15a8a0 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
- * Copyright (C) 2004 - 2005 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004 - 2006 Red Hat, Inc. All rights reserved.
  *
  * This file is released under the GPL.
  */
@@ -13,12 +13,12 @@
 #include <linux/init.h>
 #include <linux/wait.h>
 #include <linux/slab.h>
-#include <linux/devfs_fs_kernel.h>
 #include <linux/dm-ioctl.h>
 #include <linux/hdreg.h>
 
 #include <asm/uaccess.h>
 
+#define DM_MSG_PREFIX "ioctl"
 #define DM_DRIVER_EMAIL "dm-devel@redhat.com"
 
 /*-----------------------------------------------------------------
@@ -48,7 +48,7 @@ struct vers_iter {
 static struct list_head _name_buckets[NUM_BUCKETS];
 static struct list_head _uuid_buckets[NUM_BUCKETS];
 
-static void dm_hash_remove_all(void);
+static void dm_hash_remove_all(int keep_open_devices);
 
 /*
  * Guards access to both hash tables.
@@ -67,14 +67,12 @@ static int dm_hash_init(void)
 {
 	init_buckets(_name_buckets);
 	init_buckets(_uuid_buckets);
-	devfs_mk_dir(DM_DIR);
 	return 0;
 }
 
 static void dm_hash_exit(void)
 {
-	dm_hash_remove_all();
-	devfs_remove(DM_DIR);
+	dm_hash_remove_all(0);
 }
 
 /*-----------------------------------------------------------------
@@ -102,8 +100,10 @@ static struct hash_cell *__get_name_cell(const char *str)
 	unsigned int h = hash_str(str);
 
 	list_for_each_entry (hc, _name_buckets + h, name_list)
-		if (!strcmp(hc->name, str))
+		if (!strcmp(hc->name, str)) {
+			dm_get(hc->md);
 			return hc;
+		}
 
 	return NULL;
 }
@@ -114,8 +114,10 @@ static struct hash_cell *__get_uuid_cell(const char *str)
 	unsigned int h = hash_str(str);
 
 	list_for_each_entry (hc, _uuid_buckets + h, uuid_list)
-		if (!strcmp(hc->uuid, str))
+		if (!strcmp(hc->uuid, str)) {
+			dm_get(hc->md);
 			return hc;
+		}
 
 	return NULL;
 }
@@ -167,31 +169,12 @@ static void free_cell(struct hash_cell *hc)
 }
 
 /*
- * devfs stuff.
- */
-static int register_with_devfs(struct hash_cell *hc)
-{
-	struct gendisk *disk = dm_disk(hc->md);
-
-	devfs_mk_bdev(MKDEV(disk->major, disk->first_minor),
-		      S_IFBLK | S_IRUSR | S_IWUSR | S_IRGRP,
-		      DM_DIR "/%s", hc->name);
-	return 0;
-}
-
-static int unregister_with_devfs(struct hash_cell *hc)
-{
-	devfs_remove(DM_DIR"/%s", hc->name);
-	return 0;
-}
-
-/*
  * The kdev_t and uuid of a device can never change once it is
  * initially inserted.
  */
 static int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md)
 {
-	struct hash_cell *cell;
+	struct hash_cell *cell, *hc;
 
 	/*
 	 * Allocate the new cells.
@@ -204,19 +187,23 @@ static int dm_hash_insert(const char *name, const char *uuid, struct mapped_devi
 	 * Insert the cell into both hash tables.
 	 */
 	down_write(&_hash_lock);
-	if (__get_name_cell(name))
+	hc = __get_name_cell(name);
+	if (hc) {
+		dm_put(hc->md);
 		goto bad;
+	}
 
 	list_add(&cell->name_list, _name_buckets + hash_str(name));
 
 	if (uuid) {
-		if (__get_uuid_cell(uuid)) {
+		hc = __get_uuid_cell(uuid);
+		if (hc) {
 			list_del(&cell->name_list);
+			dm_put(hc->md);
 			goto bad;
 		}
 		list_add(&cell->uuid_list, _uuid_buckets + hash_str(uuid));
 	}
-	register_with_devfs(cell);
 	dm_get(md);
 	dm_set_mdptr(md, cell);
 	up_write(&_hash_lock);
@@ -236,7 +223,6 @@ static void __hash_remove(struct hash_cell *hc)
 	/* remove from the dev hash */
 	list_del(&hc->uuid_list);
 	list_del(&hc->name_list);
-	unregister_with_devfs(hc);
 	dm_set_mdptr(hc->md, NULL);
 
 	table = dm_get_table(hc->md);
@@ -251,19 +237,41 @@ static void __hash_remove(struct hash_cell *hc)
 	free_cell(hc);
 }
 
-static void dm_hash_remove_all(void)
+static void dm_hash_remove_all(int keep_open_devices)
 {
-	int i;
+	int i, dev_skipped, dev_removed;
 	struct hash_cell *hc;
 	struct list_head *tmp, *n;
 
 	down_write(&_hash_lock);
+
+retry:
+	dev_skipped = dev_removed = 0;
 	for (i = 0; i < NUM_BUCKETS; i++) {
 		list_for_each_safe (tmp, n, _name_buckets + i) {
 			hc = list_entry(tmp, struct hash_cell, name_list);
+
+			if (keep_open_devices &&
+			    dm_lock_for_deletion(hc->md)) {
+				dev_skipped++;
+				continue;
+			}
 			__hash_remove(hc);
+			dev_removed = 1;
 		}
 	}
+
+	/*
+	 * Some mapped devices may be using other mapped devices, so if any
+	 * still exist, repeat until we make no further progress.
+	 */
+	if (dev_skipped) {
+		if (dev_removed)
+			goto retry;
+
+		DMWARN("remove_all left %d open device(s)", dev_skipped);
+	}
+
 	up_write(&_hash_lock);
 }
 
@@ -289,6 +297,7 @@ static int dm_hash_rename(const char *old, const char *new)
 	if (hc) {
 		DMWARN("asked to rename to an already existing name %s -> %s",
 		       old, new);
+		dm_put(hc->md);
 		up_write(&_hash_lock);
 		kfree(new_name);
 		return -EBUSY;
@@ -309,16 +318,11 @@ static int dm_hash_rename(const char *old, const char *new)
 	/*
 	 * rename and move the name cell.
 	 */
-	unregister_with_devfs(hc);
-
 	list_del(&hc->name_list);
 	old_name = hc->name;
 	hc->name = new_name;
 	list_add(&hc->name_list, _name_buckets + hash_str(new_name));
 
-	/* rename the device node in devfs */
-	register_with_devfs(hc);
-
 	/*
 	 * Wake up any dm event waiters.
 	 */
@@ -328,6 +332,7 @@ static int dm_hash_rename(const char *old, const char *new)
 		dm_table_put(table);
 	}
 
+	dm_put(hc->md);
 	up_write(&_hash_lock);
 	kfree(old_name);
 	return 0;
@@ -344,7 +349,7 @@ typedef int (*ioctl_fn)(struct dm_ioctl *param, size_t param_size);
 
 static int remove_all(struct dm_ioctl *param, size_t param_size)
 {
-	dm_hash_remove_all();
+	dm_hash_remove_all(1);
 	param->data_size = 0;
 	return 0;
 }
@@ -524,7 +529,6 @@ static int __dev_status(struct mapped_device *md, struct dm_ioctl *param)
 {
 	struct gendisk *disk = dm_disk(md);
 	struct dm_table *table;
-	struct block_device *bdev;
 
 	param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
 			  DM_ACTIVE_PRESENT_FLAG);
@@ -534,20 +538,12 @@ static int __dev_status(struct mapped_device *md, struct dm_ioctl *param)
 
 	param->dev = huge_encode_dev(MKDEV(disk->major, disk->first_minor));
 
-	if (!(param->flags & DM_SKIP_BDGET_FLAG)) {
-		bdev = bdget_disk(disk, 0);
-		if (!bdev)
-			return -ENXIO;
-
-		/*
-		 * Yes, this will be out of date by the time it gets back
-		 * to userland, but it is still very useful for
-		 * debugging.
-		 */
-		param->open_count = bdev->bd_openers;
-		bdput(bdev);
-	} else
-		param->open_count = -1;
+	/*
+	 * Yes, this will be out of date by the time it gets back
+	 * to userland, but it is still very useful for
+	 * debugging.
+	 */
+	param->open_count = dm_open_count(md);
 
 	if (disk->policy)
 		param->flags |= DM_READONLY_FLAG;
@@ -567,7 +563,7 @@ static int __dev_status(struct mapped_device *md, struct dm_ioctl *param)
 
 static int dev_create(struct dm_ioctl *param, size_t param_size)
 {
-	int r;
+	int r, m = DM_ANY_MINOR;
 	struct mapped_device *md;
 
 	r = check_name(param->name);
@@ -575,10 +571,9 @@ static int dev_create(struct dm_ioctl *param, size_t param_size)
 		return r;
 
 	if (param->flags & DM_PERSISTENT_DEV_FLAG)
-		r = dm_create_with_minor(MINOR(huge_decode_dev(param->dev)), &md);
-	else
-		r = dm_create(&md);
+		m = MINOR(huge_decode_dev(param->dev));
 
+	r = dm_create(m, &md);
 	if (r)
 		return r;
 
@@ -611,10 +606,8 @@ static struct hash_cell *__find_device_hash_cell(struct dm_ioctl *param)
 		return __get_name_cell(param->name);
 
 	md = dm_get_md(huge_decode_dev(param->dev));
-	if (md) {
+	if (md)
 		mdptr = dm_get_mdptr(md);
-		dm_put(md);
-	}
 
 	return mdptr;
 }
@@ -628,7 +621,6 @@ static struct mapped_device *find_device(struct dm_ioctl *param)
 	hc = __find_device_hash_cell(param);
 	if (hc) {
 		md = hc->md;
-		dm_get(md);
 
 		/*
 		 * Sneakily write in both the name and the uuid
@@ -653,6 +645,8 @@ static struct mapped_device *find_device(struct dm_ioctl *param)
 static int dev_remove(struct dm_ioctl *param, size_t param_size)
 {
 	struct hash_cell *hc;
+	struct mapped_device *md;
+	int r;
 
 	down_write(&_hash_lock);
 	hc = __find_device_hash_cell(param);
@@ -663,8 +657,22 @@ static int dev_remove(struct dm_ioctl *param, size_t param_size)
 		return -ENXIO;
 	}
 
+	md = hc->md;
+
+	/*
+	 * Ensure the device is not open and nothing further can open it.
+	 */
+	r = dm_lock_for_deletion(md);
+	if (r) {
+		DMWARN("unable to remove open device %s", hc->name);
+		up_write(&_hash_lock);
+		dm_put(md);
+		return r;
+	}
+
 	__hash_remove(hc);
 	up_write(&_hash_lock);
+	dm_put(md);
 	param->data_size = 0;
 	return 0;
 }
@@ -790,7 +798,6 @@ static int do_resume(struct dm_ioctl *param)
 	}
 
 	md = hc->md;
-	dm_get(md);
 
 	new_map = hc->new_map;
 	hc->new_map = NULL;
@@ -1078,6 +1085,7 @@ static int table_clear(struct dm_ioctl *param, size_t param_size)
 {
 	int r;
 	struct hash_cell *hc;
+	struct mapped_device *md;
 
 	down_write(&_hash_lock);
 
@@ -1096,7 +1104,9 @@ static int table_clear(struct dm_ioctl *param, size_t param_size)
 	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
 
 	r = __dev_status(hc->md, param);
+	md = hc->md;
 	up_write(&_hash_lock);
+	dm_put(md);
 	return r;
 }
 
@@ -1462,7 +1472,6 @@ static struct file_operations _ctl_fops = {
 static struct miscdevice _dm_misc = {
 	.minor 		= MISC_DYNAMIC_MINOR,
 	.name  		= DM_NAME,
-	.devfs_name 	= "mapper/control",
 	.fops  		= &_ctl_fops
 };
 
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index daf586c0898..47b3c62bbdb 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -12,6 +12,8 @@
 #include <linux/bio.h>
 #include <linux/slab.h>
 
+#define DM_MSG_PREFIX "linear"
+
 /*
  * Linear: maps a linear range of a device.
  */
@@ -29,7 +31,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	unsigned long long tmp;
 
 	if (argc != 2) {
-		ti->error = "dm-linear: Invalid argument count";
+		ti->error = "Invalid argument count";
 		return -EINVAL;
 	}
 
@@ -111,7 +113,7 @@ int __init dm_linear_init(void)
 	int r = dm_register_target(&linear_target);
 
 	if (r < 0)
-		DMERR("linear: register failed %d", r);
+		DMERR("register failed %d", r);
 
 	return r;
 }
@@ -121,5 +123,5 @@ void dm_linear_exit(void)
 	int r = dm_unregister_target(&linear_target);
 
 	if (r < 0)
-		DMERR("linear: unregister failed %d", r);
+		DMERR("unregister failed %d", r);
 }
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index d73779a4241..64b764bd02c 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -12,6 +12,8 @@
 #include "dm-log.h"
 #include "dm-io.h"
 
+#define DM_MSG_PREFIX "mirror log"
+
 static LIST_HEAD(_log_types);
 static DEFINE_SPINLOCK(_lock);
 
@@ -155,8 +157,6 @@ struct log_c {
 
 	struct io_region header_location;
 	struct log_header *disk_header;
-
-	struct io_region bits_location;
 };
 
 /*
@@ -241,43 +241,21 @@ static inline int write_header(struct log_c *log)
 }
 
 /*----------------------------------------------------------------
- * Bits IO
- *--------------------------------------------------------------*/
-static int read_bits(struct log_c *log)
-{
-	int r;
-	unsigned long ebits;
-
-	r = dm_io_sync_vm(1, &log->bits_location, READ,
-			  log->clean_bits, &ebits);
-	if (r)
-		return r;
-
-	return 0;
-}
-
-static int write_bits(struct log_c *log)
-{
-	unsigned long ebits;
-	return dm_io_sync_vm(1, &log->bits_location, WRITE,
-			     log->clean_bits, &ebits);
-}
-
-/*----------------------------------------------------------------
  * core log constructor/destructor
  *
  * argv contains region_size followed optionally by [no]sync
  *--------------------------------------------------------------*/
 #define BYTE_SHIFT 3
-static int core_ctr(struct dirty_log *log, struct dm_target *ti,
-		    unsigned int argc, char **argv)
+static int create_log_context(struct dirty_log *log, struct dm_target *ti,
+			      unsigned int argc, char **argv,
+			      struct dm_dev *dev)
 {
 	enum sync sync = DEFAULTSYNC;
 
 	struct log_c *lc;
 	uint32_t region_size;
 	unsigned int region_count;
-	size_t bitset_size;
+	size_t bitset_size, buf_size;
 
 	if (argc < 1 || argc > 2) {
 		DMWARN("wrong number of arguments to mirror log");
@@ -319,22 +297,53 @@ static int core_ctr(struct dirty_log *log, struct dm_target *ti,
 	 * Work out how many "unsigned long"s we need to hold the bitset.
 	 */
 	bitset_size = dm_round_up(region_count,
-				  sizeof(unsigned long) << BYTE_SHIFT);
+				  sizeof(*lc->clean_bits) << BYTE_SHIFT);
 	bitset_size >>= BYTE_SHIFT;
 
-	lc->bitset_uint32_count = bitset_size / 4;
-	lc->clean_bits = vmalloc(bitset_size);
-	if (!lc->clean_bits) {
-		DMWARN("couldn't allocate clean bitset");
-		kfree(lc);
-		return -ENOMEM;
+	lc->bitset_uint32_count = bitset_size / sizeof(*lc->clean_bits);
+
+	/*
+	 * Disk log?
+	 */
+	if (!dev) {
+		lc->clean_bits = vmalloc(bitset_size);
+		if (!lc->clean_bits) {
+			DMWARN("couldn't allocate clean bitset");
+			kfree(lc);
+			return -ENOMEM;
+		}
+		lc->disk_header = NULL;
+	} else {
+		lc->log_dev = dev;
+		lc->header_location.bdev = lc->log_dev->bdev;
+		lc->header_location.sector = 0;
+
+		/*
+		 * Buffer holds both header and bitset.
+		 */
+		buf_size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) +
+				       bitset_size, ti->limits.hardsect_size);
+		lc->header_location.count = buf_size >> SECTOR_SHIFT;
+
+		lc->disk_header = vmalloc(buf_size);
+		if (!lc->disk_header) {
+			DMWARN("couldn't allocate disk log buffer");
+			kfree(lc);
+			return -ENOMEM;
+		}
+
+		lc->clean_bits = (void *)lc->disk_header +
+				 (LOG_OFFSET << SECTOR_SHIFT);
 	}
+
 	memset(lc->clean_bits, -1, bitset_size);
 
 	lc->sync_bits = vmalloc(bitset_size);
 	if (!lc->sync_bits) {
 		DMWARN("couldn't allocate sync bitset");
-		vfree(lc->clean_bits);
+		if (!dev)
+			vfree(lc->clean_bits);
+		vfree(lc->disk_header);
 		kfree(lc);
 		return -ENOMEM;
 	}
@@ -345,25 +354,40 @@ static int core_ctr(struct dirty_log *log, struct dm_target *ti,
 	if (!lc->recovering_bits) {
 		DMWARN("couldn't allocate sync bitset");
 		vfree(lc->sync_bits);
-		vfree(lc->clean_bits);
+		if (!dev)
+			vfree(lc->clean_bits);
+		vfree(lc->disk_header);
 		kfree(lc);
 		return -ENOMEM;
 	}
 	memset(lc->recovering_bits, 0, bitset_size);
 	lc->sync_search = 0;
 	log->context = lc;
+
 	return 0;
 }
 
-static void core_dtr(struct dirty_log *log)
+static int core_ctr(struct dirty_log *log, struct dm_target *ti,
+		    unsigned int argc, char **argv)
+{
+	return create_log_context(log, ti, argc, argv, NULL);
+}
+
+static void destroy_log_context(struct log_c *lc)
 {
-	struct log_c *lc = (struct log_c *) log->context;
-	vfree(lc->clean_bits);
 	vfree(lc->sync_bits);
 	vfree(lc->recovering_bits);
 	kfree(lc);
 }
 
+static void core_dtr(struct dirty_log *log)
+{
+	struct log_c *lc = (struct log_c *) log->context;
+
+	vfree(lc->clean_bits);
+	destroy_log_context(lc);
+}
+
 /*----------------------------------------------------------------
  * disk log constructor/destructor
  *
@@ -373,8 +397,6 @@ static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
 		    unsigned int argc, char **argv)
 {
 	int r;
-	size_t size;
-	struct log_c *lc;
 	struct dm_dev *dev;
 
 	if (argc < 2 || argc > 3) {
@@ -387,49 +409,22 @@ static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
 	if (r)
 		return r;
 
-	r = core_ctr(log, ti, argc - 1, argv + 1);
+	r = create_log_context(log, ti, argc - 1, argv + 1, dev);
 	if (r) {
 		dm_put_device(ti, dev);
 		return r;
 	}
 
-	lc = (struct log_c *) log->context;
-	lc->log_dev = dev;
-
-	/* setup the disk header fields */
-	lc->header_location.bdev = lc->log_dev->bdev;
-	lc->header_location.sector = 0;
-	lc->header_location.count = 1;
-
-	/*
-	 * We can't read less than this amount, even though we'll
-	 * not be using most of this space.
-	 */
-	lc->disk_header = vmalloc(1 << SECTOR_SHIFT);
-	if (!lc->disk_header)
-		goto bad;
-
-	/* setup the disk bitset fields */
-	lc->bits_location.bdev = lc->log_dev->bdev;
-	lc->bits_location.sector = LOG_OFFSET;
-
-	size = dm_round_up(lc->bitset_uint32_count * sizeof(uint32_t),
-			   1 << SECTOR_SHIFT);
-	lc->bits_location.count = size >> SECTOR_SHIFT;
 	return 0;
-
- bad:
-	dm_put_device(ti, lc->log_dev);
-	core_dtr(log);
-	return -ENOMEM;
 }
 
 static void disk_dtr(struct dirty_log *log)
 {
 	struct log_c *lc = (struct log_c *) log->context;
+
 	dm_put_device(lc->ti, lc->log_dev);
 	vfree(lc->disk_header);
-	core_dtr(log);
+	destroy_log_context(lc);
 }
 
 static int count_bits32(uint32_t *addr, unsigned size)
@@ -454,12 +449,7 @@ static int disk_resume(struct dirty_log *log)
 	if (r)
 		return r;
 
-	/* read the bits */
-	r = read_bits(lc);
-	if (r)
-		return r;
-
-	/* set or clear any new bits */
+	/* set or clear any new bits -- device has grown */
 	if (lc->sync == NOSYNC)
 		for (i = lc->header.nr_regions; i < lc->region_count; i++)
 			/* FIXME: amazingly inefficient */
@@ -469,15 +459,14 @@ static int disk_resume(struct dirty_log *log)
 			/* FIXME: amazingly inefficient */
 			log_clear_bit(lc, lc->clean_bits, i);
 
+	/* clear any old bits -- device has shrunk */
+	for (i = lc->region_count; i % (sizeof(*lc->clean_bits) << BYTE_SHIFT); i++)
+		log_clear_bit(lc, lc->clean_bits, i);
+
 	/* copy clean across to sync */
 	memcpy(lc->sync_bits, lc->clean_bits, size);
 	lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
 
-	/* write the bits */
-	r = write_bits(lc);
-	if (r)
-		return r;
-
 	/* set the correct number of regions in the header */
 	lc->header.nr_regions = lc->region_count;
 
@@ -518,7 +507,7 @@ static int disk_flush(struct dirty_log *log)
 	if (!lc->touched)
 		return 0;
 
-	r = write_bits(lc);
+	r = write_header(lc);
 	if (!r)
 		lc->touched = 0;
 
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 1816f30678e..217615b3322 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -21,6 +21,7 @@
 #include <linux/workqueue.h>
 #include <asm/atomic.h>
 
+#define DM_MSG_PREFIX "multipath"
 #define MESG_STR(x) x, sizeof(x)
 
 /* Path properties */
@@ -446,8 +447,6 @@ struct param {
 	char *error;
 };
 
-#define ESTR(s) ("dm-multipath: " s)
-
 static int read_param(struct param *param, char *str, unsigned *v, char **error)
 {
 	if (!str ||
@@ -495,12 +494,12 @@ static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
 	unsigned ps_argc;
 
 	static struct param _params[] = {
-		{0, 1024, ESTR("invalid number of path selector args")},
+		{0, 1024, "invalid number of path selector args"},
 	};
 
 	pst = dm_get_path_selector(shift(as));
 	if (!pst) {
-		ti->error = ESTR("unknown path selector type");
+		ti->error = "unknown path selector type";
 		return -EINVAL;
 	}
 
@@ -511,7 +510,7 @@ static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
 	r = pst->create(&pg->ps, ps_argc, as->argv);
 	if (r) {
 		dm_put_path_selector(pst);
-		ti->error = ESTR("path selector constructor failed");
+		ti->error = "path selector constructor failed";
 		return r;
 	}
 
@@ -529,7 +528,7 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
 
 	/* we need at least a path arg */
 	if (as->argc < 1) {
-		ti->error = ESTR("no device given");
+		ti->error = "no device given";
 		return NULL;
 	}
 
@@ -540,7 +539,7 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
 	r = dm_get_device(ti, shift(as), ti->begin, ti->len,
 			  dm_table_get_mode(ti->table), &p->path.dev);
 	if (r) {
-		ti->error = ESTR("error getting device");
+		ti->error = "error getting device";
 		goto bad;
 	}
 
@@ -562,8 +561,8 @@ static struct priority_group *parse_priority_group(struct arg_set *as,
 						   struct dm_target *ti)
 {
 	static struct param _params[] = {
-		{1, 1024, ESTR("invalid number of paths")},
-		{0, 1024, ESTR("invalid number of selector args")}
+		{1, 1024, "invalid number of paths"},
+		{0, 1024, "invalid number of selector args"}
 	};
 
 	int r;
@@ -572,13 +571,13 @@ static struct priority_group *parse_priority_group(struct arg_set *as,
 
 	if (as->argc < 2) {
 		as->argc = 0;
-		ti->error = ESTR("not enough priority group aruments");
+		ti->error = "not enough priority group aruments";
 		return NULL;
 	}
 
 	pg = alloc_priority_group();
 	if (!pg) {
-		ti->error = ESTR("couldn't allocate priority group");
+		ti->error = "couldn't allocate priority group";
 		return NULL;
 	}
 	pg->m = m;
@@ -633,7 +632,7 @@ static int parse_hw_handler(struct arg_set *as, struct multipath *m,
 	unsigned hw_argc;
 
 	static struct param _params[] = {
-		{0, 1024, ESTR("invalid number of hardware handler args")},
+		{0, 1024, "invalid number of hardware handler args"},
 	};
 
 	r = read_param(_params, shift(as), &hw_argc, &ti->error);
@@ -645,14 +644,14 @@ static int parse_hw_handler(struct arg_set *as, struct multipath *m,
 
 	hwht = dm_get_hw_handler(shift(as));
 	if (!hwht) {
-		ti->error = ESTR("unknown hardware handler type");
+		ti->error = "unknown hardware handler type";
 		return -EINVAL;
 	}
 
 	r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv);
 	if (r) {
 		dm_put_hw_handler(hwht);
-		ti->error = ESTR("hardware handler constructor failed");
+		ti->error = "hardware handler constructor failed";
 		return r;
 	}
 
@@ -669,7 +668,7 @@ static int parse_features(struct arg_set *as, struct multipath *m,
 	unsigned argc;
 
 	static struct param _params[] = {
-		{0, 1, ESTR("invalid number of feature args")},
+		{0, 1, "invalid number of feature args"},
 	};
 
 	r = read_param(_params, shift(as), &argc, &ti->error);
@@ -692,8 +691,8 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
 {
 	/* target parameters */
 	static struct param _params[] = {
-		{1, 1024, ESTR("invalid number of priority groups")},
-		{1, 1024, ESTR("invalid initial priority group number")},
+		{1, 1024, "invalid number of priority groups"},
+		{1, 1024, "invalid initial priority group number"},
 	};
 
 	int r;
@@ -707,7 +706,7 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
 
 	m = alloc_multipath();
 	if (!m) {
-		ti->error = ESTR("can't allocate multipath");
+		ti->error = "can't allocate multipath";
 		return -EINVAL;
 	}
 
@@ -746,7 +745,7 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
 	}
 
 	if (pg_count != m->nr_priority_groups) {
-		ti->error = ESTR("priority group count mismatch");
+		ti->error = "priority group count mismatch";
 		r = -EINVAL;
 		goto bad;
 	}
@@ -807,7 +806,7 @@ static int fail_path(struct pgpath *pgpath)
 	if (!pgpath->path.is_active)
 		goto out;
 
-	DMWARN("dm-multipath: Failing path %s.", pgpath->path.dev->name);
+	DMWARN("Failing path %s.", pgpath->path.dev->name);
 
 	pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
 	pgpath->path.is_active = 0;
@@ -1250,7 +1249,7 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
 	r = dm_get_device(ti, argv[1], ti->begin, ti->len,
 			  dm_table_get_mode(ti->table), &dev);
 	if (r) {
-		DMWARN("dm-multipath message: error getting device %s",
+		DMWARN("message: error getting device %s",
 		       argv[1]);
 		return -EINVAL;
 	}
@@ -1309,7 +1308,7 @@ static int __init dm_multipath_init(void)
 		return -ENOMEM;
 	}
 
-	DMINFO("dm-multipath version %u.%u.%u loaded",
+	DMINFO("version %u.%u.%u loaded",
 	       multipath_target.version[0], multipath_target.version[1],
 	       multipath_target.version[2]);
 
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index d12cf3e5e07..be48cedf986 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -20,6 +20,8 @@
 #include <linux/vmalloc.h>
 #include <linux/workqueue.h>
 
+#define DM_MSG_PREFIX "raid1"
+
 static struct workqueue_struct *_kmirrord_wq;
 static struct work_struct _kmirrord_work;
 
@@ -106,12 +108,42 @@ struct region {
 	struct bio_list delayed_bios;
 };
 
+
+/*-----------------------------------------------------------------
+ * Mirror set structures.
+ *---------------------------------------------------------------*/
+struct mirror {
+	atomic_t error_count;
+	struct dm_dev *dev;
+	sector_t offset;
+};
+
+struct mirror_set {
+	struct dm_target *ti;
+	struct list_head list;
+	struct region_hash rh;
+	struct kcopyd_client *kcopyd_client;
+
+	spinlock_t lock;	/* protects the next two lists */
+	struct bio_list reads;
+	struct bio_list writes;
+
+	/* recovery */
+	region_t nr_regions;
+	int in_sync;
+
+	struct mirror *default_mirror;	/* Default mirror */
+
+	unsigned int nr_mirrors;
+	struct mirror mirror[0];
+};
+
 /*
  * Conversion fns
  */
 static inline region_t bio_to_region(struct region_hash *rh, struct bio *bio)
 {
-	return bio->bi_sector >> rh->region_shift;
+	return (bio->bi_sector - rh->ms->ti->begin) >> rh->region_shift;
 }
 
 static inline sector_t region_to_sector(struct region_hash *rh, region_t region)
@@ -458,11 +490,9 @@ static int __rh_recovery_prepare(struct region_hash *rh)
 	/* Already quiesced ? */
 	if (atomic_read(&reg->pending))
 		list_del_init(&reg->list);
+	else
+		list_move(&reg->list, &rh->quiesced_regions);
 
-	else {
-		list_del_init(&reg->list);
-		list_add(&reg->list, &rh->quiesced_regions);
-	}
 	spin_unlock_irq(&rh->region_lock);
 
 	return 1;
@@ -541,35 +571,6 @@ static void rh_start_recovery(struct region_hash *rh)
 	wake();
 }
 
-/*-----------------------------------------------------------------
- * Mirror set structures.
- *---------------------------------------------------------------*/
-struct mirror {
-	atomic_t error_count;
-	struct dm_dev *dev;
-	sector_t offset;
-};
-
-struct mirror_set {
-	struct dm_target *ti;
-	struct list_head list;
-	struct region_hash rh;
-	struct kcopyd_client *kcopyd_client;
-
-	spinlock_t lock;	/* protects the next two lists */
-	struct bio_list reads;
-	struct bio_list writes;
-
-	/* recovery */
-	region_t nr_regions;
-	int in_sync;
-
-	struct mirror *default_mirror;	/* Default mirror */
-
-	unsigned int nr_mirrors;
-	struct mirror mirror[0];
-};
-
 /*
  * Every mirror should look like this one.
  */
@@ -603,7 +604,7 @@ static void recovery_complete(int read_err, unsigned int write_err,
 	struct region *reg = (struct region *) context;
 
 	/* FIXME: better error handling */
-	rh_recovery_end(reg, read_err || write_err);
+	rh_recovery_end(reg, !(read_err || write_err));
 }
 
 static int recover(struct mirror_set *ms, struct region *reg)
@@ -893,7 +894,7 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
 
 	ms = kmalloc(len, GFP_KERNEL);
 	if (!ms) {
-		ti->error = "dm-mirror: Cannot allocate mirror context";
+		ti->error = "Cannot allocate mirror context";
 		return NULL;
 	}
 
@@ -907,7 +908,7 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
 	ms->default_mirror = &ms->mirror[DEFAULT_MIRROR];
 
 	if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) {
-		ti->error = "dm-mirror: Error creating dirty region hash";
+		ti->error = "Error creating dirty region hash";
 		kfree(ms);
 		return NULL;
 	}
@@ -937,14 +938,14 @@ static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
 	unsigned long long offset;
 
 	if (sscanf(argv[1], "%llu", &offset) != 1) {
-		ti->error = "dm-mirror: Invalid offset";
+		ti->error = "Invalid offset";
 		return -EINVAL;
 	}
 
 	if (dm_get_device(ti, argv[0], offset, ti->len,
 			  dm_table_get_mode(ti->table),
 			  &ms->mirror[mirror].dev)) {
-		ti->error = "dm-mirror: Device lookup failure";
+		ti->error = "Device lookup failure";
 		return -ENXIO;
 	}
 
@@ -981,30 +982,30 @@ static struct dirty_log *create_dirty_log(struct dm_target *ti,
 	struct dirty_log *dl;
 
 	if (argc < 2) {
-		ti->error = "dm-mirror: Insufficient mirror log arguments";
+		ti->error = "Insufficient mirror log arguments";
 		return NULL;
 	}
 
 	if (sscanf(argv[1], "%u", &param_count) != 1) {
-		ti->error = "dm-mirror: Invalid mirror log argument count";
+		ti->error = "Invalid mirror log argument count";
 		return NULL;
 	}
 
 	*args_used = 2 + param_count;
 
 	if (argc < *args_used) {
-		ti->error = "dm-mirror: Insufficient mirror log arguments";
+		ti->error = "Insufficient mirror log arguments";
 		return NULL;
 	}
 
 	dl = dm_create_dirty_log(argv[0], ti, param_count, argv + 2);
 	if (!dl) {
-		ti->error = "dm-mirror: Error creating mirror dirty log";
+		ti->error = "Error creating mirror dirty log";
 		return NULL;
 	}
 
 	if (!_check_region_size(ti, dl->type->get_region_size(dl))) {
-		ti->error = "dm-mirror: Invalid region size";
+		ti->error = "Invalid region size";
 		dm_destroy_dirty_log(dl);
 		return NULL;
 	}
@@ -1038,7 +1039,7 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	if (!argc || sscanf(argv[0], "%u", &nr_mirrors) != 1 ||
 	    nr_mirrors < 2 || nr_mirrors > KCOPYD_MAX_REGIONS + 1) {
-		ti->error = "dm-mirror: Invalid number of mirrors";
+		ti->error = "Invalid number of mirrors";
 		dm_destroy_dirty_log(dl);
 		return -EINVAL;
 	}
@@ -1046,7 +1047,7 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	argv++, argc--;
 
 	if (argc != nr_mirrors * 2) {
-		ti->error = "dm-mirror: Wrong number of mirror arguments";
+		ti->error = "Wrong number of mirror arguments";
 		dm_destroy_dirty_log(dl);
 		return -EINVAL;
 	}
@@ -1115,7 +1116,7 @@ static int mirror_map(struct dm_target *ti, struct bio *bio,
 	struct mirror *m;
 	struct mirror_set *ms = ti->private;
 
-	map_context->ll = bio->bi_sector >> ms->rh.region_shift;
+	map_context->ll = bio_to_region(&ms->rh, bio);
 
 	if (rw == WRITE) {
 		queue_bio(ms, bio, rw);
@@ -1221,7 +1222,7 @@ static int mirror_status(struct dm_target *ti, status_type_t type,
 
 static struct target_type mirror_target = {
 	.name	 = "mirror",
-	.version = {1, 0, 1},
+	.version = {1, 0, 2},
 	.module	 = THIS_MODULE,
 	.ctr	 = mirror_ctr,
 	.dtr	 = mirror_dtr,
diff --git a/drivers/md/dm-round-robin.c b/drivers/md/dm-round-robin.c
index d0024865a78..c5a16c55012 100644
--- a/drivers/md/dm-round-robin.c
+++ b/drivers/md/dm-round-robin.c
@@ -14,6 +14,8 @@
 
 #include <linux/slab.h>
 
+#define DM_MSG_PREFIX "multipath round-robin"
+
 /*-----------------------------------------------------------------
  * Path-handling code, paths are held in lists
  *---------------------------------------------------------------*/
@@ -191,9 +193,9 @@ static int __init dm_rr_init(void)
 	int r = dm_register_path_selector(&rr_ps);
 
 	if (r < 0)
-		DMERR("round-robin: register failed %d", r);
+		DMERR("register failed %d", r);
 
-	DMINFO("dm-round-robin version 1.0.0 loaded");
+	DMINFO("version 1.0.0 loaded");
 
 	return r;
 }
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 08312b46463..1d0fafda0f7 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -7,7 +7,6 @@
  */
 
 #include <linux/blkdev.h>
-#include <linux/config.h>
 #include <linux/ctype.h>
 #include <linux/device-mapper.h>
 #include <linux/fs.h>
@@ -23,6 +22,8 @@
 #include "dm-bio-list.h"
 #include "kcopyd.h"
 
+#define DM_MSG_PREFIX "snapshots"
+
 /*
  * The percentage increment we will wake up users at
  */
@@ -117,7 +118,7 @@ static int init_origin_hash(void)
 	_origins = kmalloc(ORIGIN_HASH_SIZE * sizeof(struct list_head),
 			   GFP_KERNEL);
 	if (!_origins) {
-		DMERR("Device mapper: Snapshot: unable to allocate memory");
+		DMERR("unable to allocate memory");
 		return -ENOMEM;
 	}
 
@@ -412,7 +413,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	int blocksize;
 
 	if (argc < 4) {
-		ti->error = "dm-snapshot: requires exactly 4 arguments";
+		ti->error = "requires exactly 4 arguments";
 		r = -EINVAL;
 		goto bad1;
 	}
@@ -530,7 +531,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	}
 
 	ti->private = s;
-	ti->split_io = chunk_size;
+	ti->split_io = s->chunk_size;
 
 	return 0;
 
@@ -1127,7 +1128,7 @@ static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	struct dm_dev *dev;
 
 	if (argc != 1) {
-		ti->error = "dm-origin: incorrect number of arguments";
+		ti->error = "origin: incorrect number of arguments";
 		return -EINVAL;
 	}
 
@@ -1204,7 +1205,7 @@ static int origin_status(struct dm_target *ti, status_type_t type, char *result,
 
 static struct target_type origin_target = {
 	.name    = "snapshot-origin",
-	.version = {1, 1, 0},
+	.version = {1, 4, 0},
 	.module  = THIS_MODULE,
 	.ctr     = origin_ctr,
 	.dtr     = origin_dtr,
@@ -1215,7 +1216,7 @@ static struct target_type origin_target = {
 
 static struct target_type snapshot_target = {
 	.name    = "snapshot",
-	.version = {1, 1, 0},
+	.version = {1, 4, 0},
 	.module  = THIS_MODULE,
 	.ctr     = snapshot_ctr,
 	.dtr     = snapshot_dtr,
@@ -1236,7 +1237,7 @@ static int __init dm_snapshot_init(void)
 
 	r = dm_register_target(&origin_target);
 	if (r < 0) {
-		DMERR("Device mapper: Origin: register failed %d\n", r);
+		DMERR("Origin target register failed %d", r);
 		goto bad1;
 	}
 
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 08328a8f5a3..6c29fcecd89 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -12,6 +12,8 @@
 #include <linux/bio.h>
 #include <linux/slab.h>
 
+#define DM_MSG_PREFIX "striped"
+
 struct stripe {
 	struct dm_dev *dev;
 	sector_t physical_start;
@@ -78,19 +80,19 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	unsigned int i;
 
 	if (argc < 2) {
-		ti->error = "dm-stripe: Not enough arguments";
+		ti->error = "Not enough arguments";
 		return -EINVAL;
 	}
 
 	stripes = simple_strtoul(argv[0], &end, 10);
 	if (*end) {
-		ti->error = "dm-stripe: Invalid stripe count";
+		ti->error = "Invalid stripe count";
 		return -EINVAL;
 	}
 
 	chunk_size = simple_strtoul(argv[1], &end, 10);
 	if (*end) {
-		ti->error = "dm-stripe: Invalid chunk_size";
+		ti->error = "Invalid chunk_size";
 		return -EINVAL;
 	}
 
@@ -99,19 +101,19 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	 */
 	if (!chunk_size || (chunk_size & (chunk_size - 1)) ||
 	    (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
-		ti->error = "dm-stripe: Invalid chunk size";
+		ti->error = "Invalid chunk size";
 		return -EINVAL;
 	}
 
 	if (ti->len & (chunk_size - 1)) {
-		ti->error = "dm-stripe: Target length not divisible by "
+		ti->error = "Target length not divisible by "
 		    "chunk size";
 		return -EINVAL;
 	}
 
 	width = ti->len;
 	if (sector_div(width, stripes)) {
-		ti->error = "dm-stripe: Target length not divisible by "
+		ti->error = "Target length not divisible by "
 		    "number of stripes";
 		return -EINVAL;
 	}
@@ -120,14 +122,14 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	 * Do we have enough arguments for that many stripes ?
 	 */
 	if (argc != (2 + 2 * stripes)) {
-		ti->error = "dm-stripe: Not enough destinations "
+		ti->error = "Not enough destinations "
 			"specified";
 		return -EINVAL;
 	}
 
 	sc = alloc_context(stripes);
 	if (!sc) {
-		ti->error = "dm-stripe: Memory allocation for striped context "
+		ti->error = "Memory allocation for striped context "
 		    "failed";
 		return -ENOMEM;
 	}
@@ -149,8 +151,7 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 		r = get_stripe(ti, sc, i, argv);
 		if (r < 0) {
-			ti->error = "dm-stripe: Couldn't parse stripe "
-				"destination";
+			ti->error = "Couldn't parse stripe destination";
 			while (i--)
 				dm_put_device(ti, sc->stripe[i].dev);
 			kfree(sc);
@@ -227,7 +228,7 @@ int __init dm_stripe_init(void)
 
 	r = dm_register_target(&stripe_target);
 	if (r < 0)
-		DMWARN("striped target registration failed");
+		DMWARN("target registration failed");
 
 	return r;
 }
@@ -235,7 +236,7 @@ int __init dm_stripe_init(void)
 void dm_stripe_exit(void)
 {
 	if (dm_unregister_target(&stripe_target))
-		DMWARN("striped target unregistration failed");
+		DMWARN("target unregistration failed");
 
 	return;
 }
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 8f56a54cf0c..75fe9493e6a 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -17,6 +17,8 @@
 #include <linux/mutex.h>
 #include <asm/atomic.h>
 
+#define DM_MSG_PREFIX "table"
+
 #define MAX_DEPTH 16
 #define NODE_SIZE L1_CACHE_BYTES
 #define KEYS_PER_NODE (NODE_SIZE / sizeof(sector_t))
@@ -237,6 +239,44 @@ int dm_table_create(struct dm_table **result, int mode,
 	return 0;
 }
 
+int dm_create_error_table(struct dm_table **result, struct mapped_device *md)
+{
+	struct dm_table *t;
+	sector_t dev_size = 1;
+	int r;
+
+	/*
+	 * Find current size of device.
+	 * Default to 1 sector if inactive.
+	 */
+	t = dm_get_table(md);
+	if (t) {
+		dev_size = dm_table_get_size(t);
+		dm_table_put(t);
+	}
+
+	r = dm_table_create(&t, FMODE_READ, 1, md);
+	if (r)
+		return r;
+
+	r = dm_table_add_target(t, "error", 0, dev_size, NULL);
+	if (r)
+		goto out;
+
+	r = dm_table_complete(t);
+	if (r)
+		goto out;
+
+	*result = t;
+
+out:
+	if (r)
+		dm_table_put(t);
+
+	return r;
+}
+EXPORT_SYMBOL_GPL(dm_create_error_table);
+
 static void free_devices(struct list_head *devices)
 {
 	struct list_head *tmp, *next;
@@ -590,6 +630,12 @@ int dm_split_args(int *argc, char ***argvp, char *input)
 	unsigned array_size = 0;
 
 	*argc = 0;
+
+	if (!input) {
+		*argvp = NULL;
+		return 0;
+	}
+
 	argv = realloc_argv(&array_size, argv);
 	if (!argv)
 		return -ENOMEM;
@@ -671,15 +717,14 @@ int dm_table_add_target(struct dm_table *t, const char *type,
 	memset(tgt, 0, sizeof(*tgt));
 
 	if (!len) {
-		tgt->error = "zero-length target";
-		DMERR("%s", tgt->error);
+		DMERR("%s: zero-length target", dm_device_name(t->md));
 		return -EINVAL;
 	}
 
 	tgt->type = dm_get_target_type(type);
 	if (!tgt->type) {
-		tgt->error = "unknown target type";
-		DMERR("%s", tgt->error);
+		DMERR("%s: %s: unknown target type", dm_device_name(t->md),
+		      type);
 		return -EINVAL;
 	}
 
@@ -716,7 +761,7 @@ int dm_table_add_target(struct dm_table *t, const char *type,
 	return 0;
 
  bad:
-	DMERR("%s", tgt->error);
+	DMERR("%s: %s: %s", dm_device_name(t->md), type, tgt->error);
 	dm_put_target_type(tgt->type);
 	return r;
 }
@@ -802,7 +847,7 @@ sector_t dm_table_get_size(struct dm_table *t)
 
 struct dm_target *dm_table_get_target(struct dm_table *t, unsigned int index)
 {
-	if (index > t->num_targets)
+	if (index >= t->num_targets)
 		return NULL;
 
 	return t->targets + index;
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index 64fd8e79ea4..477a041a41c 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -12,6 +12,8 @@
 #include <linux/bio.h>
 #include <linux/slab.h>
 
+#define DM_MSG_PREFIX "target"
+
 struct tt_internal {
 	struct target_type tt;
 
diff --git a/drivers/md/dm-zero.c b/drivers/md/dm-zero.c
index 51c0639b248..ea569f7348d 100644
--- a/drivers/md/dm-zero.c
+++ b/drivers/md/dm-zero.c
@@ -10,13 +10,15 @@
 #include <linux/init.h>
 #include <linux/bio.h>
 
+#define DM_MSG_PREFIX "zero"
+
 /*
  * Construct a dummy mapping that only returns zeros
  */
 static int zero_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
 	if (argc != 0) {
-		ti->error = "dm-zero: No arguments required";
+		ti->error = "No arguments required";
 		return -EINVAL;
 	}
 
@@ -60,7 +62,7 @@ static int __init dm_zero_init(void)
 	int r = dm_register_target(&zero_target);
 
 	if (r < 0)
-		DMERR("zero: register failed %d", r);
+		DMERR("register failed %d", r);
 
 	return r;
 }
@@ -70,7 +72,7 @@ static void __exit dm_zero_exit(void)
 	int r = dm_unregister_target(&zero_target);
 
 	if (r < 0)
-		DMERR("zero: unregister failed %d", r);
+		DMERR("unregister failed %d", r);
 }
 
 module_init(dm_zero_init)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 4d710b7a133..c99bf9f0175 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
- * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
  *
  * This file is released under the GPL.
  */
@@ -21,11 +21,14 @@
 #include <linux/hdreg.h>
 #include <linux/blktrace_api.h>
 
+#define DM_MSG_PREFIX "core"
+
 static const char *_name = DM_NAME;
 
 static unsigned int major = 0;
 static unsigned int _major = 0;
 
+static DEFINE_SPINLOCK(_minor_lock);
 /*
  * One of these is allocated per bio.
  */
@@ -49,23 +52,28 @@ struct target_io {
 
 union map_info *dm_get_mapinfo(struct bio *bio)
 {
-        if (bio && bio->bi_private)
-                return &((struct target_io *)bio->bi_private)->info;
-        return NULL;
+	if (bio && bio->bi_private)
+		return &((struct target_io *)bio->bi_private)->info;
+	return NULL;
 }
 
+#define MINOR_ALLOCED ((void *)-1)
+
 /*
  * Bits for the md->flags field.
  */
 #define DMF_BLOCK_IO 0
 #define DMF_SUSPENDED 1
 #define DMF_FROZEN 2
+#define DMF_FREEING 3
+#define DMF_DELETING 4
 
 struct mapped_device {
 	struct rw_semaphore io_lock;
 	struct semaphore suspend_lock;
 	rwlock_t map_lock;
 	atomic_t holders;
+	atomic_t open_count;
 
 	unsigned long flags;
 
@@ -159,7 +167,7 @@ static void local_exit(void)
 	bioset_free(dm_set);
 
 	if (unregister_blkdev(_major, _name) < 0)
-		DMERR("devfs_unregister_blkdev failed");
+		DMERR("unregister_blkdev failed");
 
 	_major = 0;
 
@@ -218,9 +226,25 @@ static int dm_blk_open(struct inode *inode, struct file *file)
 {
 	struct mapped_device *md;
 
+	spin_lock(&_minor_lock);
+
 	md = inode->i_bdev->bd_disk->private_data;
+	if (!md)
+		goto out;
+
+	if (test_bit(DMF_FREEING, &md->flags) ||
+	    test_bit(DMF_DELETING, &md->flags)) {
+		md = NULL;
+		goto out;
+	}
+
 	dm_get(md);
-	return 0;
+	atomic_inc(&md->open_count);
+
+out:
+	spin_unlock(&_minor_lock);
+
+	return md ? 0 : -ENXIO;
 }
 
 static int dm_blk_close(struct inode *inode, struct file *file)
@@ -228,10 +252,35 @@ static int dm_blk_close(struct inode *inode, struct file *file)
 	struct mapped_device *md;
 
 	md = inode->i_bdev->bd_disk->private_data;
+	atomic_dec(&md->open_count);
 	dm_put(md);
 	return 0;
 }
 
+int dm_open_count(struct mapped_device *md)
+{
+	return atomic_read(&md->open_count);
+}
+
+/*
+ * Guarantees nothing is using the device before it's deleted.
+ */
+int dm_lock_for_deletion(struct mapped_device *md)
+{
+	int r = 0;
+
+	spin_lock(&_minor_lock);
+
+	if (dm_open_count(md))
+		r = -EBUSY;
+	else
+		set_bit(DMF_DELETING, &md->flags);
+
+	spin_unlock(&_minor_lock);
+
+	return r;
+}
+
 static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
 	struct mapped_device *md = bdev->bd_disk->private_data;
@@ -456,8 +505,8 @@ static void __map_bio(struct dm_target *ti, struct bio *clone,
 	if (r > 0) {
 		/* the bio has been remapped so dispatch it */
 
-		blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone, 
-				    tio->io->bio->bi_bdev->bd_dev, sector, 
+		blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone,
+				    tio->io->bio->bi_bdev->bd_dev, sector,
 				    clone->bi_sector);
 
 		generic_make_request(clone);
@@ -744,43 +793,39 @@ static int dm_any_congested(void *congested_data, int bdi_bits)
 /*-----------------------------------------------------------------
  * An IDR is used to keep track of allocated minor numbers.
  *---------------------------------------------------------------*/
-static DEFINE_MUTEX(_minor_lock);
 static DEFINE_IDR(_minor_idr);
 
-static void free_minor(unsigned int minor)
+static void free_minor(int minor)
 {
-	mutex_lock(&_minor_lock);
+	spin_lock(&_minor_lock);
 	idr_remove(&_minor_idr, minor);
-	mutex_unlock(&_minor_lock);
+	spin_unlock(&_minor_lock);
 }
 
 /*
  * See if the device with a specific minor # is free.
  */
-static int specific_minor(struct mapped_device *md, unsigned int minor)
+static int specific_minor(struct mapped_device *md, int minor)
 {
 	int r, m;
 
 	if (minor >= (1 << MINORBITS))
 		return -EINVAL;
 
-	mutex_lock(&_minor_lock);
+	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	spin_lock(&_minor_lock);
 
 	if (idr_find(&_minor_idr, minor)) {
 		r = -EBUSY;
 		goto out;
 	}
 
-	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
-	if (!r) {
-		r = -ENOMEM;
-		goto out;
-	}
-
-	r = idr_get_new_above(&_minor_idr, md, minor, &m);
-	if (r) {
+	r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
+	if (r)
 		goto out;
-	}
 
 	if (m != minor) {
 		idr_remove(&_minor_idr, m);
@@ -789,24 +834,21 @@ static int specific_minor(struct mapped_device *md, unsigned int minor)
 	}
 
 out:
-	mutex_unlock(&_minor_lock);
+	spin_unlock(&_minor_lock);
 	return r;
 }
 
-static int next_free_minor(struct mapped_device *md, unsigned int *minor)
+static int next_free_minor(struct mapped_device *md, int *minor)
 {
-	int r;
-	unsigned int m;
-
-	mutex_lock(&_minor_lock);
+	int r, m;
 
 	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
-	if (!r) {
-		r = -ENOMEM;
-		goto out;
-	}
+	if (!r)
+		return -ENOMEM;
+
+	spin_lock(&_minor_lock);
 
-	r = idr_get_new(&_minor_idr, md, &m);
+	r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
 	if (r) {
 		goto out;
 	}
@@ -820,7 +862,7 @@ static int next_free_minor(struct mapped_device *md, unsigned int *minor)
 	*minor = m;
 
 out:
-	mutex_unlock(&_minor_lock);
+	spin_unlock(&_minor_lock);
 	return r;
 }
 
@@ -829,18 +871,25 @@ static struct block_device_operations dm_blk_dops;
 /*
  * Allocate and initialise a blank device with a given minor.
  */
-static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
+static struct mapped_device *alloc_dev(int minor)
 {
 	int r;
 	struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
+	void *old_md;
 
 	if (!md) {
 		DMWARN("unable to allocate device, out of memory.");
 		return NULL;
 	}
 
+	if (!try_module_get(THIS_MODULE))
+		goto bad0;
+
 	/* get a minor number for the dev */
-	r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor);
+	if (minor == DM_ANY_MINOR)
+		r = next_free_minor(md, &minor);
+	else
+		r = specific_minor(md, minor);
 	if (r < 0)
 		goto bad1;
 
@@ -849,6 +898,7 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
 	init_MUTEX(&md->suspend_lock);
 	rwlock_init(&md->map_lock);
 	atomic_set(&md->holders, 1);
+	atomic_set(&md->open_count, 0);
 	atomic_set(&md->event_nr, 0);
 
 	md->queue = blk_alloc_queue(GFP_KERNEL);
@@ -875,6 +925,10 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
 	if (!md->disk)
 		goto bad4;
 
+	atomic_set(&md->pending, 0);
+	init_waitqueue_head(&md->wait);
+	init_waitqueue_head(&md->eventq);
+
 	md->disk->major = _major;
 	md->disk->first_minor = minor;
 	md->disk->fops = &dm_blk_dops;
@@ -884,9 +938,12 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
 	add_disk(md->disk);
 	format_dev_t(md->name, MKDEV(_major, minor));
 
-	atomic_set(&md->pending, 0);
-	init_waitqueue_head(&md->wait);
-	init_waitqueue_head(&md->eventq);
+	/* Populate the mapping, nobody knows we exist yet */
+	spin_lock(&_minor_lock);
+	old_md = idr_replace(&_minor_idr, md, minor);
+	spin_unlock(&_minor_lock);
+
+	BUG_ON(old_md != MINOR_ALLOCED);
 
 	return md;
 
@@ -898,13 +955,15 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
 	blk_cleanup_queue(md->queue);
 	free_minor(minor);
  bad1:
+	module_put(THIS_MODULE);
+ bad0:
 	kfree(md);
 	return NULL;
 }
 
 static void free_dev(struct mapped_device *md)
 {
-	unsigned int minor = md->disk->first_minor;
+	int minor = md->disk->first_minor;
 
 	if (md->suspended_bdev) {
 		thaw_bdev(md->suspended_bdev, NULL);
@@ -914,8 +973,14 @@ static void free_dev(struct mapped_device *md)
 	mempool_destroy(md->io_pool);
 	del_gendisk(md->disk);
 	free_minor(minor);
+
+	spin_lock(&_minor_lock);
+	md->disk->private_data = NULL;
+	spin_unlock(&_minor_lock);
+
 	put_disk(md->disk);
 	blk_cleanup_queue(md->queue);
+	module_put(THIS_MODULE);
 	kfree(md);
 }
 
@@ -984,12 +1049,11 @@ static void __unbind(struct mapped_device *md)
 /*
  * Constructor for a new device.
  */
-static int create_aux(unsigned int minor, int persistent,
-		      struct mapped_device **result)
+int dm_create(int minor, struct mapped_device **result)
 {
 	struct mapped_device *md;
 
-	md = alloc_dev(minor, persistent);
+	md = alloc_dev(minor);
 	if (!md)
 		return -ENXIO;
 
@@ -997,16 +1061,6 @@ static int create_aux(unsigned int minor, int persistent,
 	return 0;
 }
 
-int dm_create(struct mapped_device **result)
-{
-	return create_aux(0, 0, result);
-}
-
-int dm_create_with_minor(unsigned int minor, struct mapped_device **result)
-{
-	return create_aux(minor, 1, result);
-}
-
 static struct mapped_device *dm_find_md(dev_t dev)
 {
 	struct mapped_device *md;
@@ -1015,13 +1069,18 @@ static struct mapped_device *dm_find_md(dev_t dev)
 	if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
 		return NULL;
 
-	mutex_lock(&_minor_lock);
+	spin_lock(&_minor_lock);
 
 	md = idr_find(&_minor_idr, minor);
-	if (!md || (dm_disk(md)->first_minor != minor))
+	if (md && (md == MINOR_ALLOCED ||
+		   (dm_disk(md)->first_minor != minor) ||
+		   test_bit(DMF_FREEING, &md->flags))) {
 		md = NULL;
+		goto out;
+	}
 
-	mutex_unlock(&_minor_lock);
+out:
+	spin_unlock(&_minor_lock);
 
 	return md;
 }
@@ -1051,12 +1110,23 @@ void dm_get(struct mapped_device *md)
 	atomic_inc(&md->holders);
 }
 
+const char *dm_device_name(struct mapped_device *md)
+{
+	return md->name;
+}
+EXPORT_SYMBOL_GPL(dm_device_name);
+
 void dm_put(struct mapped_device *md)
 {
 	struct dm_table *map;
 
-	if (atomic_dec_and_test(&md->holders)) {
+	BUG_ON(test_bit(DMF_FREEING, &md->flags));
+
+	if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
 		map = dm_get_table(md);
+		idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
+		set_bit(DMF_FREEING, &md->flags);
+		spin_unlock(&_minor_lock);
 		if (!dm_suspended(md)) {
 			dm_table_presuspend_targets(map);
 			dm_table_postsuspend_targets(map);
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index fd90bc8f9e4..3c03c0ecab7 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -2,7 +2,7 @@
  * Internal header file for device mapper
  *
  * Copyright (C) 2001, 2002 Sistina Software
- * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
  *
  * This file is released under the LGPL.
  */
@@ -17,9 +17,10 @@
 #include <linux/hdreg.h>
 
 #define DM_NAME "device-mapper"
-#define DMWARN(f, x...) printk(KERN_WARNING DM_NAME ": " f "\n" , ## x)
-#define DMERR(f, x...) printk(KERN_ERR DM_NAME ": " f "\n" , ## x)
-#define DMINFO(f, x...) printk(KERN_INFO DM_NAME ": " f "\n" , ## x)
+
+#define DMERR(f, arg...) printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
+#define DMWARN(f, arg...) printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
+#define DMINFO(f, arg...) printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 
 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 			  0 : scnprintf(result + sz, maxlen - sz, x))
@@ -39,83 +40,16 @@ struct dm_dev {
 };
 
 struct dm_table;
-struct mapped_device;
-
-/*-----------------------------------------------------------------
- * Functions for manipulating a struct mapped_device.
- * Drop the reference with dm_put when you finish with the object.
- *---------------------------------------------------------------*/
-int dm_create(struct mapped_device **md);
-int dm_create_with_minor(unsigned int minor, struct mapped_device **md);
-void dm_set_mdptr(struct mapped_device *md, void *ptr);
-void *dm_get_mdptr(struct mapped_device *md);
-struct mapped_device *dm_get_md(dev_t dev);
-
-/*
- * Reference counting for md.
- */
-void dm_get(struct mapped_device *md);
-void dm_put(struct mapped_device *md);
-
-/*
- * A device can still be used while suspended, but I/O is deferred.
- */
-int dm_suspend(struct mapped_device *md, int with_lockfs);
-int dm_resume(struct mapped_device *md);
-
-/*
- * The device must be suspended before calling this method.
- */
-int dm_swap_table(struct mapped_device *md, struct dm_table *t);
-
-/*
- * Drop a reference on the table when you've finished with the
- * result.
- */
-struct dm_table *dm_get_table(struct mapped_device *md);
-
-/*
- * Event functions.
- */
-uint32_t dm_get_event_nr(struct mapped_device *md);
-int dm_wait_event(struct mapped_device *md, int event_nr);
-
-/*
- * Info functions.
- */
-struct gendisk *dm_disk(struct mapped_device *md);
-int dm_suspended(struct mapped_device *md);
-
-/*
- * Geometry functions.
- */
-int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
-int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 
 /*-----------------------------------------------------------------
- * Functions for manipulating a table.  Tables are also reference
- * counted.
+ * Internal table functions.
  *---------------------------------------------------------------*/
-int dm_table_create(struct dm_table **result, int mode,
-		    unsigned num_targets, struct mapped_device *md);
-
-void dm_table_get(struct dm_table *t);
-void dm_table_put(struct dm_table *t);
-
-int dm_table_add_target(struct dm_table *t, const char *type,
-			sector_t start,	sector_t len, char *params);
-int dm_table_complete(struct dm_table *t);
 void dm_table_event_callback(struct dm_table *t,
 			     void (*fn)(void *), void *context);
-void dm_table_event(struct dm_table *t);
-sector_t dm_table_get_size(struct dm_table *t);
 struct dm_target *dm_table_get_target(struct dm_table *t, unsigned int index);
 struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector);
 void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q);
-unsigned int dm_table_get_num_targets(struct dm_table *t);
 struct list_head *dm_table_get_devices(struct dm_table *t);
-int dm_table_get_mode(struct dm_table *t);
-struct mapped_device *dm_table_get_md(struct dm_table *t);
 void dm_table_presuspend_targets(struct dm_table *t);
 void dm_table_postsuspend_targets(struct dm_table *t);
 void dm_table_resume_targets(struct dm_table *t);
@@ -133,7 +67,6 @@ void dm_put_target_type(struct target_type *t);
 int dm_target_iterate(void (*iter_func)(struct target_type *tt,
 					void *param), void *param);
 
-
 /*-----------------------------------------------------------------
  * Useful inlines.
  *---------------------------------------------------------------*/
@@ -191,5 +124,7 @@ void dm_stripe_exit(void);
 
 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 union map_info *dm_get_mapinfo(struct bio *bio);
+int dm_open_count(struct mapped_device *md);
+int dm_lock_for_deletion(struct mapped_device *md);
 
 #endif
diff --git a/drivers/md/kcopyd.c b/drivers/md/kcopyd.c
index 72480a48d88..f1db6eff485 100644
--- a/drivers/md/kcopyd.c
+++ b/drivers/md/kcopyd.c
@@ -12,7 +12,6 @@
 #include <asm/atomic.h>
 
 #include <linux/blkdev.h>
-#include <linux/config.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/list.h>
@@ -314,7 +313,7 @@ static void complete_io(unsigned long error, void *context)
 
 	if (error) {
 		if (job->rw == WRITE)
-			job->write_err &= error;
+			job->write_err |= error;
 		else
 			job->read_err = 1;
 
@@ -460,7 +459,7 @@ static void segment_complete(int read_err,
 		job->read_err = 1;
 
 	if (write_err)
-		job->write_err &= write_err;
+		job->write_err |= write_err;
 
 	/*
 	 * Only dispatch more work if there hasn't been an error.
diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 777585458c8..ff83c9b5979 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -111,7 +111,7 @@ static int linear_issue_flush(request_queue_t *q, struct gendisk *disk,
 	return ret;
 }
 
-static int linear_run (mddev_t *mddev)
+static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
 {
 	linear_conf_t *conf;
 	dev_info_t **table;
@@ -121,20 +121,21 @@ static int linear_run (mddev_t *mddev)
 	sector_t curr_offset;
 	struct list_head *tmp;
 
-	conf = kzalloc (sizeof (*conf) + mddev->raid_disks*sizeof(dev_info_t),
+	conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
 			GFP_KERNEL);
 	if (!conf)
-		goto out;
+		return NULL;
+
 	mddev->private = conf;
 
 	cnt = 0;
-	mddev->array_size = 0;
+	conf->array_size = 0;
 
 	ITERATE_RDEV(mddev,rdev,tmp) {
 		int j = rdev->raid_disk;
 		dev_info_t *disk = conf->disks + j;
 
-		if (j < 0 || j > mddev->raid_disks || disk->rdev) {
+		if (j < 0 || j > raid_disks || disk->rdev) {
 			printk("linear: disk numbering problem. Aborting!\n");
 			goto out;
 		}
@@ -152,11 +153,11 @@ static int linear_run (mddev_t *mddev)
 			blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
 
 		disk->size = rdev->size;
-		mddev->array_size += rdev->size;
+		conf->array_size += rdev->size;
 
 		cnt++;
 	}
-	if (cnt != mddev->raid_disks) {
+	if (cnt != raid_disks) {
 		printk("linear: not enough drives present. Aborting!\n");
 		goto out;
 	}
@@ -200,7 +201,7 @@ static int linear_run (mddev_t *mddev)
 		unsigned round;
 		unsigned long base;
 
-		sz = mddev->array_size >> conf->preshift;
+		sz = conf->array_size >> conf->preshift;
 		sz += 1; /* force round-up */
 		base = conf->hash_spacing >> conf->preshift;
 		round = sector_div(sz, base);
@@ -247,14 +248,56 @@ static int linear_run (mddev_t *mddev)
 
 	BUG_ON(table - conf->hash_table > nb_zone);
 
+	return conf;
+
+out:
+	kfree(conf);
+	return NULL;
+}
+
+static int linear_run (mddev_t *mddev)
+{
+	linear_conf_t *conf;
+
+	conf = linear_conf(mddev, mddev->raid_disks);
+
+	if (!conf)
+		return 1;
+	mddev->private = conf;
+	mddev->array_size = conf->array_size;
+
 	blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
 	mddev->queue->unplug_fn = linear_unplug;
 	mddev->queue->issue_flush_fn = linear_issue_flush;
 	return 0;
+}
 
-out:
-	kfree(conf);
-	return 1;
+static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
+{
+	/* Adding a drive to a linear array allows the array to grow.
+	 * It is permitted if the new drive has a matching superblock
+	 * already on it, with raid_disk equal to raid_disks.
+	 * It is achieved by creating a new linear_private_data structure
+	 * and swapping it in in-place of the current one.
+	 * The current one is never freed until the array is stopped.
+	 * This avoids races.
+	 */
+	linear_conf_t *newconf;
+
+	if (rdev->raid_disk != mddev->raid_disks)
+		return -EINVAL;
+
+	newconf = linear_conf(mddev,mddev->raid_disks+1);
+
+	if (!newconf)
+		return -ENOMEM;
+
+	newconf->prev = mddev_to_conf(mddev);
+	mddev->private = newconf;
+	mddev->raid_disks++;
+	mddev->array_size = newconf->array_size;
+	set_capacity(mddev->gendisk, mddev->array_size << 1);
+	return 0;
 }
 
 static int linear_stop (mddev_t *mddev)
@@ -262,8 +305,12 @@ static int linear_stop (mddev_t *mddev)
 	linear_conf_t *conf = mddev_to_conf(mddev);
   
 	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
-	kfree(conf->hash_table);
-	kfree(conf);
+	do {
+		linear_conf_t *t = conf->prev;
+		kfree(conf->hash_table);
+		kfree(conf);
+		conf = t;
+	} while (conf);
 
 	return 0;
 }
@@ -360,6 +407,7 @@ static struct mdk_personality linear_personality =
 	.run		= linear_run,
 	.stop		= linear_stop,
 	.status		= linear_status,
+	.hot_add_disk	= linear_add,
 };
 
 static int __init linear_init (void)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index f19b874753a..2fe32c26192 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -33,17 +33,16 @@
 */
 
 #include <linux/module.h>
-#include <linux/config.h>
 #include <linux/kthread.h>
 #include <linux/linkage.h>
 #include <linux/raid/md.h>
 #include <linux/raid/bitmap.h>
 #include <linux/sysctl.h>
-#include <linux/devfs_fs_kernel.h>
 #include <linux/buffer_head.h> /* for invalidate_bdev */
 #include <linux/suspend.h>
 #include <linux/poll.h>
 #include <linux/mutex.h>
+#include <linux/ctype.h>
 
 #include <linux/init.h>
 
@@ -72,6 +71,10 @@ static void autostart_arrays (int part);
 static LIST_HEAD(pers_list);
 static DEFINE_SPINLOCK(pers_lock);
 
+static void md_print_devices(void);
+
+#define MD_BUG(x...) { printk("md: bug in file %s, line %d\n", __FILE__, __LINE__); md_print_devices(); }
+
 /*
  * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
  * is 1000 KB/sec, so the extra system load does not show up that much.
@@ -170,7 +173,7 @@ EXPORT_SYMBOL_GPL(md_new_event);
 /* Alternate version that can be called from interrupts
  * when calling sysfs_notify isn't needed.
  */
-void md_new_event_inintr(mddev_t *mddev)
+static void md_new_event_inintr(mddev_t *mddev)
 {
 	atomic_inc(&md_event_count);
 	wake_up(&md_event_waiters);
@@ -732,6 +735,7 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 {
 	mdp_disk_t *desc;
 	mdp_super_t *sb = (mdp_super_t *)page_address(rdev->sb_page);
+	__u64 ev1 = md_event(sb);
 
 	rdev->raid_disk = -1;
 	rdev->flags = 0;
@@ -748,7 +752,7 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 		mddev->layout = sb->layout;
 		mddev->raid_disks = sb->raid_disks;
 		mddev->size = sb->size;
-		mddev->events = md_event(sb);
+		mddev->events = ev1;
 		mddev->bitmap_offset = 0;
 		mddev->default_bitmap_offset = MD_SB_BYTES >> 9;
 
@@ -797,7 +801,6 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 
 	} else if (mddev->pers == NULL) {
 		/* Insist on good event counter while assembling */
-		__u64 ev1 = md_event(sb);
 		++ev1;
 		if (ev1 < mddev->events) 
 			return -EINVAL;
@@ -805,19 +808,21 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 		/* if adding to array with a bitmap, then we can accept an
 		 * older device ... but not too old.
 		 */
-		__u64 ev1 = md_event(sb);
 		if (ev1 < mddev->bitmap->events_cleared)
 			return 0;
-	} else /* just a hot-add of a new device, leave raid_disk at -1 */
-		return 0;
+	} else {
+		if (ev1 < mddev->events)
+			/* just a hot-add of a new device, leave raid_disk at -1 */
+			return 0;
+	}
 
 	if (mddev->level != LEVEL_MULTIPATH) {
 		desc = sb->disks + rdev->desc_nr;
 
 		if (desc->state & (1<<MD_DISK_FAULTY))
 			set_bit(Faulty, &rdev->flags);
-		else if (desc->state & (1<<MD_DISK_SYNC) &&
-			 desc->raid_disk < mddev->raid_disks) {
+		else if (desc->state & (1<<MD_DISK_SYNC) /* &&
+			    desc->raid_disk < mddev->raid_disks */) {
 			set_bit(In_sync, &rdev->flags);
 			rdev->raid_disk = desc->raid_disk;
 		}
@@ -1100,6 +1105,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
 static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 {
 	struct mdp_superblock_1 *sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
+	__u64 ev1 = le64_to_cpu(sb->events);
 
 	rdev->raid_disk = -1;
 	rdev->flags = 0;
@@ -1115,7 +1121,7 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 		mddev->layout = le32_to_cpu(sb->layout);
 		mddev->raid_disks = le32_to_cpu(sb->raid_disks);
 		mddev->size = le64_to_cpu(sb->size)/2;
-		mddev->events = le64_to_cpu(sb->events);
+		mddev->events = ev1;
 		mddev->bitmap_offset = 0;
 		mddev->default_bitmap_offset = 1024 >> 9;
 		
@@ -1149,7 +1155,6 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 
 	} else if (mddev->pers == NULL) {
 		/* Insist of good event counter while assembling */
-		__u64 ev1 = le64_to_cpu(sb->events);
 		++ev1;
 		if (ev1 < mddev->events)
 			return -EINVAL;
@@ -1157,12 +1162,13 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 		/* If adding to array with a bitmap, then we can accept an
 		 * older device, but not too old.
 		 */
-		__u64 ev1 = le64_to_cpu(sb->events);
 		if (ev1 < mddev->bitmap->events_cleared)
 			return 0;
-	} else /* just a hot-add of a new device, leave raid_disk at -1 */
-		return 0;
-
+	} else {
+		if (ev1 < mddev->events)
+			/* just a hot-add of a new device, leave raid_disk at -1 */
+			return 0;
+	}
 	if (mddev->level != LEVEL_MULTIPATH) {
 		int role;
 		rdev->desc_nr = le32_to_cpu(sb->dev_number);
@@ -1174,7 +1180,11 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 			set_bit(Faulty, &rdev->flags);
 			break;
 		default:
-			set_bit(In_sync, &rdev->flags);
+			if ((le32_to_cpu(sb->feature_map) &
+			     MD_FEATURE_RECOVERY_OFFSET))
+				rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
+			else
+				set_bit(In_sync, &rdev->flags);
 			rdev->raid_disk = role;
 			break;
 		}
@@ -1198,6 +1208,7 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
 
 	sb->feature_map = 0;
 	sb->pad0 = 0;
+	sb->recovery_offset = cpu_to_le64(0);
 	memset(sb->pad1, 0, sizeof(sb->pad1));
 	memset(sb->pad2, 0, sizeof(sb->pad2));
 	memset(sb->pad3, 0, sizeof(sb->pad3));
@@ -1218,6 +1229,14 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
 		sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_offset);
 		sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
 	}
+
+	if (rdev->raid_disk >= 0 &&
+	    !test_bit(In_sync, &rdev->flags) &&
+	    rdev->recovery_offset > 0) {
+		sb->feature_map |= cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
+		sb->recovery_offset = cpu_to_le64(rdev->recovery_offset);
+	}
+
 	if (mddev->reshape_position != MaxSector) {
 		sb->feature_map |= cpu_to_le32(MD_FEATURE_RESHAPE_ACTIVE);
 		sb->reshape_position = cpu_to_le64(mddev->reshape_position);
@@ -1242,11 +1261,12 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
 			sb->dev_roles[i] = cpu_to_le16(0xfffe);
 		else if (test_bit(In_sync, &rdev2->flags))
 			sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
+		else if (rdev2->raid_disk >= 0 && rdev2->recovery_offset > 0)
+			sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
 		else
 			sb->dev_roles[i] = cpu_to_le16(0xffff);
 	}
 
-	sb->recovery_offset = cpu_to_le64(0); /* not supported yet */
 	sb->sb_csum = calc_sb_1_csum(sb);
 }
 
@@ -1507,7 +1527,7 @@ static void print_rdev(mdk_rdev_t *rdev)
 		printk(KERN_INFO "md: no rdev superblock!\n");
 }
 
-void md_print_devices(void)
+static void md_print_devices(void)
 {
 	struct list_head *tmp, *tmp2;
 	mdk_rdev_t *rdev;
@@ -1536,15 +1556,30 @@ void md_print_devices(void)
 }
 
 
-static void sync_sbs(mddev_t * mddev)
+static void sync_sbs(mddev_t * mddev, int nospares)
 {
+	/* Update each superblock (in-memory image), but
+	 * if we are allowed to, skip spares which already
+	 * have the right event counter, or have one earlier
+	 * (which would mean they aren't being marked as dirty
+	 * with the rest of the array)
+	 */
 	mdk_rdev_t *rdev;
 	struct list_head *tmp;
 
 	ITERATE_RDEV(mddev,rdev,tmp) {
-		super_types[mddev->major_version].
-			sync_super(mddev, rdev);
-		rdev->sb_loaded = 1;
+		if (rdev->sb_events == mddev->events ||
+		    (nospares &&
+		     rdev->raid_disk < 0 &&
+		     (rdev->sb_events&1)==0 &&
+		     rdev->sb_events+1 == mddev->events)) {
+			/* Don't update this superblock */
+			rdev->sb_loaded = 2;
+		} else {
+			super_types[mddev->major_version].
+				sync_super(mddev, rdev);
+			rdev->sb_loaded = 1;
+		}
 	}
 }
 
@@ -1554,12 +1589,42 @@ void md_update_sb(mddev_t * mddev)
 	struct list_head *tmp;
 	mdk_rdev_t *rdev;
 	int sync_req;
+	int nospares = 0;
 
 repeat:
 	spin_lock_irq(&mddev->write_lock);
 	sync_req = mddev->in_sync;
 	mddev->utime = get_seconds();
-	mddev->events ++;
+	if (mddev->sb_dirty == 3)
+		/* just a clean<-> dirty transition, possibly leave spares alone,
+		 * though if events isn't the right even/odd, we will have to do
+		 * spares after all
+		 */
+		nospares = 1;
+
+	/* If this is just a dirty<->clean transition, and the array is clean
+	 * and 'events' is odd, we can roll back to the previous clean state */
+	if (mddev->sb_dirty == 3
+	    && (mddev->in_sync && mddev->recovery_cp == MaxSector)
+	    && (mddev->events & 1))
+		mddev->events--;
+	else {
+		/* otherwise we have to go forward and ... */
+		mddev->events ++;
+		if (!mddev->in_sync || mddev->recovery_cp != MaxSector) { /* not clean */
+			/* .. if the array isn't clean, insist on an odd 'events' */
+			if ((mddev->events&1)==0) {
+				mddev->events++;
+				nospares = 0;
+			}
+		} else {
+			/* otherwise insist on an even 'events' (for clean states) */
+			if ((mddev->events&1)) {
+				mddev->events++;
+				nospares = 0;
+			}
+		}
+	}
 
 	if (!mddev->events) {
 		/*
@@ -1571,7 +1636,7 @@ repeat:
 		mddev->events --;
 	}
 	mddev->sb_dirty = 2;
-	sync_sbs(mddev);
+	sync_sbs(mddev, nospares);
 
 	/*
 	 * do not write anything to disk if using
@@ -1593,6 +1658,8 @@ repeat:
 	ITERATE_RDEV(mddev,rdev,tmp) {
 		char b[BDEVNAME_SIZE];
 		dprintk(KERN_INFO "md: ");
+		if (rdev->sb_loaded != 1)
+			continue; /* no noise on spare devices */
 		if (test_bit(Faulty, &rdev->flags))
 			dprintk("(skipping faulty ");
 
@@ -1604,6 +1671,7 @@ repeat:
 			dprintk(KERN_INFO "(write) %s's sb offset: %llu\n",
 				bdevname(rdev->bdev,b),
 				(unsigned long long)rdev->sb_offset);
+			rdev->sb_events = mddev->events;
 
 		} else
 			dprintk(")\n");
@@ -1667,6 +1735,10 @@ state_show(mdk_rdev_t *rdev, char *page)
 		len += sprintf(page+len, "%sin_sync",sep);
 		sep = ",";
 	}
+	if (test_bit(WriteMostly, &rdev->flags)) {
+		len += sprintf(page+len, "%swrite_mostly",sep);
+		sep = ",";
+	}
 	if (!test_bit(Faulty, &rdev->flags) &&
 	    !test_bit(In_sync, &rdev->flags)) {
 		len += sprintf(page+len, "%sspare", sep);
@@ -1675,8 +1747,40 @@ state_show(mdk_rdev_t *rdev, char *page)
 	return len+sprintf(page+len, "\n");
 }
 
+static ssize_t
+state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
+{
+	/* can write
+	 *  faulty  - simulates and error
+	 *  remove  - disconnects the device
+	 *  writemostly - sets write_mostly
+	 *  -writemostly - clears write_mostly
+	 */
+	int err = -EINVAL;
+	if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
+		md_error(rdev->mddev, rdev);
+		err = 0;
+	} else if (cmd_match(buf, "remove")) {
+		if (rdev->raid_disk >= 0)
+			err = -EBUSY;
+		else {
+			mddev_t *mddev = rdev->mddev;
+			kick_rdev_from_array(rdev);
+			md_update_sb(mddev);
+			md_new_event(mddev);
+			err = 0;
+		}
+	} else if (cmd_match(buf, "writemostly")) {
+		set_bit(WriteMostly, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "-writemostly")) {
+		clear_bit(WriteMostly, &rdev->flags);
+		err = 0;
+	}
+	return err ? err : len;
+}
 static struct rdev_sysfs_entry
-rdev_state = __ATTR_RO(state);
+rdev_state = __ATTR(state, 0644, state_show, state_store);
 
 static ssize_t
 super_show(mdk_rdev_t *rdev, char *page)
@@ -1873,6 +1977,7 @@ static mdk_rdev_t *md_import_device(dev_t newdev, int super_format, int super_mi
 	rdev->desc_nr = -1;
 	rdev->flags = 0;
 	rdev->data_offset = 0;
+	rdev->sb_events = 0;
 	atomic_set(&rdev->nr_pending, 0);
 	atomic_set(&rdev->read_errors, 0);
 	atomic_set(&rdev->corrected_errors, 0);
@@ -1978,6 +2083,54 @@ static void analyze_sbs(mddev_t * mddev)
 }
 
 static ssize_t
+safe_delay_show(mddev_t *mddev, char *page)
+{
+	int msec = (mddev->safemode_delay*1000)/HZ;
+	return sprintf(page, "%d.%03d\n", msec/1000, msec%1000);
+}
+static ssize_t
+safe_delay_store(mddev_t *mddev, const char *cbuf, size_t len)
+{
+	int scale=1;
+	int dot=0;
+	int i;
+	unsigned long msec;
+	char buf[30];
+	char *e;
+	/* remove a period, and count digits after it */
+	if (len >= sizeof(buf))
+		return -EINVAL;
+	strlcpy(buf, cbuf, len);
+	buf[len] = 0;
+	for (i=0; i<len; i++) {
+		if (dot) {
+			if (isdigit(buf[i])) {
+				buf[i-1] = buf[i];
+				scale *= 10;
+			}
+			buf[i] = 0;
+		} else if (buf[i] == '.') {
+			dot=1;
+			buf[i] = 0;
+		}
+	}
+	msec = simple_strtoul(buf, &e, 10);
+	if (e == buf || (*e && *e != '\n'))
+		return -EINVAL;
+	msec = (msec * 1000) / scale;
+	if (msec == 0)
+		mddev->safemode_delay = 0;
+	else {
+		mddev->safemode_delay = (msec*HZ)/1000;
+		if (mddev->safemode_delay == 0)
+			mddev->safemode_delay = 1;
+	}
+	return len;
+}
+static struct md_sysfs_entry md_safe_delay =
+__ATTR(safe_mode_delay, 0644,safe_delay_show, safe_delay_store);
+
+static ssize_t
 level_show(mddev_t *mddev, char *page)
 {
 	struct mdk_personality *p = mddev->pers;
@@ -2012,6 +2165,32 @@ level_store(mddev_t *mddev, const char *buf, size_t len)
 static struct md_sysfs_entry md_level =
 __ATTR(level, 0644, level_show, level_store);
 
+
+static ssize_t
+layout_show(mddev_t *mddev, char *page)
+{
+	/* just a number, not meaningful for all levels */
+	return sprintf(page, "%d\n", mddev->layout);
+}
+
+static ssize_t
+layout_store(mddev_t *mddev, const char *buf, size_t len)
+{
+	char *e;
+	unsigned long n = simple_strtoul(buf, &e, 10);
+	if (mddev->pers)
+		return -EBUSY;
+
+	if (!*buf || (*e && *e != '\n'))
+		return -EINVAL;
+
+	mddev->layout = n;
+	return len;
+}
+static struct md_sysfs_entry md_layout =
+__ATTR(layout, 0655, layout_show, layout_store);
+
+
 static ssize_t
 raid_disks_show(mddev_t *mddev, char *page)
 {
@@ -2067,6 +2246,200 @@ static struct md_sysfs_entry md_chunk_size =
 __ATTR(chunk_size, 0644, chunk_size_show, chunk_size_store);
 
 static ssize_t
+resync_start_show(mddev_t *mddev, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)mddev->recovery_cp);
+}
+
+static ssize_t
+resync_start_store(mddev_t *mddev, const char *buf, size_t len)
+{
+	/* can only set chunk_size if array is not yet active */
+	char *e;
+	unsigned long long n = simple_strtoull(buf, &e, 10);
+
+	if (mddev->pers)
+		return -EBUSY;
+	if (!*buf || (*e && *e != '\n'))
+		return -EINVAL;
+
+	mddev->recovery_cp = n;
+	return len;
+}
+static struct md_sysfs_entry md_resync_start =
+__ATTR(resync_start, 0644, resync_start_show, resync_start_store);
+
+/*
+ * The array state can be:
+ *
+ * clear
+ *     No devices, no size, no level
+ *     Equivalent to STOP_ARRAY ioctl
+ * inactive
+ *     May have some settings, but array is not active
+ *        all IO results in error
+ *     When written, doesn't tear down array, but just stops it
+ * suspended (not supported yet)
+ *     All IO requests will block. The array can be reconfigured.
+ *     Writing this, if accepted, will block until array is quiessent
+ * readonly
+ *     no resync can happen.  no superblocks get written.
+ *     write requests fail
+ * read-auto
+ *     like readonly, but behaves like 'clean' on a write request.
+ *
+ * clean - no pending writes, but otherwise active.
+ *     When written to inactive array, starts without resync
+ *     If a write request arrives then
+ *       if metadata is known, mark 'dirty' and switch to 'active'.
+ *       if not known, block and switch to write-pending
+ *     If written to an active array that has pending writes, then fails.
+ * active
+ *     fully active: IO and resync can be happening.
+ *     When written to inactive array, starts with resync
+ *
+ * write-pending
+ *     clean, but writes are blocked waiting for 'active' to be written.
+ *
+ * active-idle
+ *     like active, but no writes have been seen for a while (100msec).
+ *
+ */
+enum array_state { clear, inactive, suspended, readonly, read_auto, clean, active,
+		   write_pending, active_idle, bad_word};
+static char *array_states[] = {
+	"clear", "inactive", "suspended", "readonly", "read-auto", "clean", "active",
+	"write-pending", "active-idle", NULL };
+
+static int match_word(const char *word, char **list)
+{
+	int n;
+	for (n=0; list[n]; n++)
+		if (cmd_match(word, list[n]))
+			break;
+	return n;
+}
+
+static ssize_t
+array_state_show(mddev_t *mddev, char *page)
+{
+	enum array_state st = inactive;
+
+	if (mddev->pers)
+		switch(mddev->ro) {
+		case 1:
+			st = readonly;
+			break;
+		case 2:
+			st = read_auto;
+			break;
+		case 0:
+			if (mddev->in_sync)
+				st = clean;
+			else if (mddev->safemode)
+				st = active_idle;
+			else
+				st = active;
+		}
+	else {
+		if (list_empty(&mddev->disks) &&
+		    mddev->raid_disks == 0 &&
+		    mddev->size == 0)
+			st = clear;
+		else
+			st = inactive;
+	}
+	return sprintf(page, "%s\n", array_states[st]);
+}
+
+static int do_md_stop(mddev_t * mddev, int ro);
+static int do_md_run(mddev_t * mddev);
+static int restart_array(mddev_t *mddev);
+
+static ssize_t
+array_state_store(mddev_t *mddev, const char *buf, size_t len)
+{
+	int err = -EINVAL;
+	enum array_state st = match_word(buf, array_states);
+	switch(st) {
+	case bad_word:
+		break;
+	case clear:
+		/* stopping an active array */
+		if (mddev->pers) {
+			if (atomic_read(&mddev->active) > 1)
+				return -EBUSY;
+			err = do_md_stop(mddev, 0);
+		}
+		break;
+	case inactive:
+		/* stopping an active array */
+		if (mddev->pers) {
+			if (atomic_read(&mddev->active) > 1)
+				return -EBUSY;
+			err = do_md_stop(mddev, 2);
+		}
+		break;
+	case suspended:
+		break; /* not supported yet */
+	case readonly:
+		if (mddev->pers)
+			err = do_md_stop(mddev, 1);
+		else {
+			mddev->ro = 1;
+			err = do_md_run(mddev);
+		}
+		break;
+	case read_auto:
+		/* stopping an active array */
+		if (mddev->pers) {
+			err = do_md_stop(mddev, 1);
+			if (err == 0)
+				mddev->ro = 2; /* FIXME mark devices writable */
+		} else {
+			mddev->ro = 2;
+			err = do_md_run(mddev);
+		}
+		break;
+	case clean:
+		if (mddev->pers) {
+			restart_array(mddev);
+			spin_lock_irq(&mddev->write_lock);
+			if (atomic_read(&mddev->writes_pending) == 0) {
+				mddev->in_sync = 1;
+				mddev->sb_dirty = 1;
+			}
+			spin_unlock_irq(&mddev->write_lock);
+		} else {
+			mddev->ro = 0;
+			mddev->recovery_cp = MaxSector;
+			err = do_md_run(mddev);
+		}
+		break;
+	case active:
+		if (mddev->pers) {
+			restart_array(mddev);
+			mddev->sb_dirty = 0;
+			wake_up(&mddev->sb_wait);
+			err = 0;
+		} else {
+			mddev->ro = 0;
+			err = do_md_run(mddev);
+		}
+		break;
+	case write_pending:
+	case active_idle:
+		/* these cannot be set */
+		break;
+	}
+	if (err)
+		return err;
+	else
+		return len;
+}
+static struct md_sysfs_entry md_array_state = __ATTR(array_state, 0644, array_state_show, array_state_store);
+
+static ssize_t
 null_show(mddev_t *mddev, char *page)
 {
 	return -EINVAL;
@@ -2428,11 +2801,15 @@ __ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);
 
 static struct attribute *md_default_attrs[] = {
 	&md_level.attr,
+	&md_layout.attr,
 	&md_raid_disks.attr,
 	&md_chunk_size.attr,
 	&md_size.attr,
+	&md_resync_start.attr,
 	&md_metadata.attr,
 	&md_new_device.attr,
+	&md_safe_delay.attr,
+	&md_array_state.attr,
 	NULL,
 };
 
@@ -2532,13 +2909,10 @@ static struct kobject *md_probe(dev_t dev, int *part, void *data)
 	}
 	disk->major = MAJOR(dev);
 	disk->first_minor = unit << shift;
-	if (partitioned) {
+	if (partitioned)
 		sprintf(disk->disk_name, "md_d%d", unit);
-		sprintf(disk->devfs_name, "md/d%d", unit);
-	} else {
+	else
 		sprintf(disk->disk_name, "md%d", unit);
-		sprintf(disk->devfs_name, "md/%d", unit);
-	}
 	disk->fops = &md_fops;
 	disk->private_data = mddev;
 	disk->queue = mddev->queue;
@@ -2553,8 +2927,6 @@ static struct kobject *md_probe(dev_t dev, int *part, void *data)
 	return NULL;
 }
 
-void md_wakeup_thread(mdk_thread_t *thread);
-
 static void md_safemode_timeout(unsigned long data)
 {
 	mddev_t *mddev = (mddev_t *) data;
@@ -2708,7 +3080,7 @@ static int do_md_run(mddev_t * mddev)
 	mddev->safemode = 0;
 	mddev->safemode_timer.function = md_safemode_timeout;
 	mddev->safemode_timer.data = (unsigned long) mddev;
-	mddev->safemode_delay = (20 * HZ)/1000 +1; /* 20 msec delay */
+	mddev->safemode_delay = (200 * HZ)/1000 +1; /* 200 msec delay */
 	mddev->in_sync = 1;
 
 	ITERATE_RDEV(mddev,rdev,tmp)
@@ -2736,6 +3108,36 @@ static int do_md_run(mddev_t * mddev)
 	mddev->queue->queuedata = mddev;
 	mddev->queue->make_request_fn = mddev->pers->make_request;
 
+	/* If there is a partially-recovered drive we need to
+	 * start recovery here.  If we leave it to md_check_recovery,
+	 * it will remove the drives and not do the right thing
+	 */
+	if (mddev->degraded) {
+		struct list_head *rtmp;
+		int spares = 0;
+		ITERATE_RDEV(mddev,rdev,rtmp)
+			if (rdev->raid_disk >= 0 &&
+			    !test_bit(In_sync, &rdev->flags) &&
+			    !test_bit(Faulty, &rdev->flags))
+				/* complete an interrupted recovery */
+				spares++;
+		if (spares && mddev->pers->sync_request) {
+			mddev->recovery = 0;
+			set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+			mddev->sync_thread = md_register_thread(md_do_sync,
+								mddev,
+								"%s_resync");
+			if (!mddev->sync_thread) {
+				printk(KERN_ERR "%s: could not start resync"
+				       " thread...\n",
+				       mdname(mddev));
+				/* leave the spares where they are, it shouldn't hurt */
+				mddev->recovery = 0;
+			} else
+				md_wakeup_thread(mddev->sync_thread);
+		}
+	}
+
 	mddev->changed = 1;
 	md_new_event(mddev);
 	return 0;
@@ -2769,18 +3171,47 @@ static int restart_array(mddev_t *mddev)
 		 */
 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 		md_wakeup_thread(mddev->thread);
+		md_wakeup_thread(mddev->sync_thread);
 		err = 0;
-	} else {
-		printk(KERN_ERR "md: %s has no personality assigned.\n",
-			mdname(mddev));
+	} else
 		err = -EINVAL;
-	}
 
 out:
 	return err;
 }
 
-static int do_md_stop(mddev_t * mddev, int ro)
+/* similar to deny_write_access, but accounts for our holding a reference
+ * to the file ourselves */
+static int deny_bitmap_write_access(struct file * file)
+{
+	struct inode *inode = file->f_mapping->host;
+
+	spin_lock(&inode->i_lock);
+	if (atomic_read(&inode->i_writecount) > 1) {
+		spin_unlock(&inode->i_lock);
+		return -ETXTBSY;
+	}
+	atomic_set(&inode->i_writecount, -1);
+	spin_unlock(&inode->i_lock);
+
+	return 0;
+}
+
+static void restore_bitmap_write_access(struct file *file)
+{
+	struct inode *inode = file->f_mapping->host;
+
+	spin_lock(&inode->i_lock);
+	atomic_set(&inode->i_writecount, 1);
+	spin_unlock(&inode->i_lock);
+}
+
+/* mode:
+ *   0 - completely stop and dis-assemble array
+ *   1 - switch to readonly
+ *   2 - stop but do not disassemble array
+ */
+static int do_md_stop(mddev_t * mddev, int mode)
 {
 	int err = 0;
 	struct gendisk *disk = mddev->gendisk;
@@ -2792,6 +3223,7 @@ static int do_md_stop(mddev_t * mddev, int ro)
 		}
 
 		if (mddev->sync_thread) {
+			set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
 			md_unregister_thread(mddev->sync_thread);
 			mddev->sync_thread = NULL;
@@ -2801,12 +3233,15 @@ static int do_md_stop(mddev_t * mddev, int ro)
 
 		invalidate_partition(disk, 0);
 
-		if (ro) {
+		switch(mode) {
+		case 1: /* readonly */
 			err  = -ENXIO;
 			if (mddev->ro==1)
 				goto out;
 			mddev->ro = 1;
-		} else {
+			break;
+		case 0: /* disassemble */
+		case 2: /* stop */
 			bitmap_flush(mddev);
 			md_super_wait(mddev);
 			if (mddev->ro)
@@ -2821,19 +3256,20 @@ static int do_md_stop(mddev_t * mddev, int ro)
 			if (mddev->ro)
 				mddev->ro = 0;
 		}
-		if (!mddev->in_sync) {
+		if (!mddev->in_sync || mddev->sb_dirty) {
 			/* mark array as shutdown cleanly */
 			mddev->in_sync = 1;
 			md_update_sb(mddev);
 		}
-		if (ro)
+		if (mode == 1)
 			set_disk_ro(disk, 1);
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 	}
 
 	/*
 	 * Free resources if final stop
 	 */
-	if (!ro) {
+	if (mode == 0) {
 		mdk_rdev_t *rdev;
 		struct list_head *tmp;
 		struct gendisk *disk;
@@ -2841,7 +3277,7 @@ static int do_md_stop(mddev_t * mddev, int ro)
 
 		bitmap_destroy(mddev);
 		if (mddev->bitmap_file) {
-			atomic_set(&mddev->bitmap_file->f_dentry->d_inode->i_writecount, 1);
+			restore_bitmap_write_access(mddev->bitmap_file);
 			fput(mddev->bitmap_file);
 			mddev->bitmap_file = NULL;
 		}
@@ -2857,11 +3293,15 @@ static int do_md_stop(mddev_t * mddev, int ro)
 		export_array(mddev);
 
 		mddev->array_size = 0;
+		mddev->size = 0;
+		mddev->raid_disks = 0;
+		mddev->recovery_cp = 0;
+
 		disk = mddev->gendisk;
 		if (disk)
 			set_capacity(disk, 0);
 		mddev->changed = 1;
-	} else
+	} else if (mddev->pers)
 		printk(KERN_INFO "md: %s switched to read-only mode.\n",
 			mdname(mddev));
 	err = 0;
@@ -3264,6 +3704,17 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
 
 		rdev->raid_disk = -1;
 		err = bind_rdev_to_array(rdev, mddev);
+		if (!err && !mddev->pers->hot_remove_disk) {
+			/* If there is hot_add_disk but no hot_remove_disk
+			 * then added disks for geometry changes,
+			 * and should be added immediately.
+			 */
+			super_types[mddev->major_version].
+				validate_super(mddev, rdev);
+			err = mddev->pers->hot_add_disk(mddev, rdev);
+			if (err)
+				unbind_rdev_from_array(rdev);
+		}
 		if (err)
 			export_rdev(rdev);
 
@@ -3434,23 +3885,6 @@ abort_export:
 	return err;
 }
 
-/* similar to deny_write_access, but accounts for our holding a reference
- * to the file ourselves */
-static int deny_bitmap_write_access(struct file * file)
-{
-	struct inode *inode = file->f_mapping->host;
-
-	spin_lock(&inode->i_lock);
-	if (atomic_read(&inode->i_writecount) > 1) {
-		spin_unlock(&inode->i_lock);
-		return -ETXTBSY;
-	}
-	atomic_set(&inode->i_writecount, -1);
-	spin_unlock(&inode->i_lock);
-
-	return 0;
-}
-
 static int set_bitmap_file(mddev_t *mddev, int fd)
 {
 	int err;
@@ -3491,12 +3925,17 @@ static int set_bitmap_file(mddev_t *mddev, int fd)
 		mddev->pers->quiesce(mddev, 1);
 		if (fd >= 0)
 			err = bitmap_create(mddev);
-		if (fd < 0 || err)
+		if (fd < 0 || err) {
 			bitmap_destroy(mddev);
+			fd = -1; /* make sure to put the file */
+		}
 		mddev->pers->quiesce(mddev, 0);
-	} else if (fd < 0) {
-		if (mddev->bitmap_file)
+	}
+	if (fd < 0) {
+		if (mddev->bitmap_file) {
+			restore_bitmap_write_access(mddev->bitmap_file);
 			fput(mddev->bitmap_file);
+		}
 		mddev->bitmap_file = NULL;
 	}
 
@@ -3977,11 +4416,6 @@ static int md_ioctl(struct inode *inode, struct file *file,
 			goto done_unlock;
 
 		default:
-			if (_IOC_TYPE(cmd) == MD_MAJOR)
-				printk(KERN_WARNING "md: %s(pid %d) used"
-					" obsolete MD ioctl, upgrade your"
-					" software to use new ictls.\n",
-					current->comm, current->pid);
 			err = -EINVAL;
 			goto abort_unlock;
 	}
@@ -4586,7 +5020,7 @@ void md_write_start(mddev_t *mddev, struct bio *bi)
 		spin_lock_irq(&mddev->write_lock);
 		if (mddev->in_sync) {
 			mddev->in_sync = 0;
-			mddev->sb_dirty = 1;
+			mddev->sb_dirty = 3;
 			md_wakeup_thread(mddev->thread);
 		}
 		spin_unlock_irq(&mddev->write_lock);
@@ -4599,7 +5033,7 @@ void md_write_end(mddev_t *mddev)
 	if (atomic_dec_and_test(&mddev->writes_pending)) {
 		if (mddev->safemode == 2)
 			md_wakeup_thread(mddev->thread);
-		else
+		else if (mddev->safemode_delay)
 			mod_timer(&mddev->safemode_timer, jiffies + mddev->safemode_delay);
 	}
 }
@@ -4620,10 +5054,14 @@ void md_do_sync(mddev_t *mddev)
 	struct list_head *tmp;
 	sector_t last_check;
 	int skipped = 0;
+	struct list_head *rtmp;
+	mdk_rdev_t *rdev;
 
 	/* just incase thread restarts... */
 	if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
 		return;
+	if (mddev->ro) /* never try to sync a read-only array */
+		return;
 
 	/* we overload curr_resync somewhat here.
 	 * 0 == not engaged in resync at all
@@ -4682,17 +5120,30 @@ void md_do_sync(mddev_t *mddev)
 		}
 	} while (mddev->curr_resync < 2);
 
+	j = 0;
 	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
 		/* resync follows the size requested by the personality,
 		 * which defaults to physical size, but can be virtual size
 		 */
 		max_sectors = mddev->resync_max_sectors;
 		mddev->resync_mismatches = 0;
+		/* we don't use the checkpoint if there's a bitmap */
+		if (!mddev->bitmap &&
+		    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+			j = mddev->recovery_cp;
 	} else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
 		max_sectors = mddev->size << 1;
-	else
+	else {
 		/* recovery follows the physical size of devices */
 		max_sectors = mddev->size << 1;
+		j = MaxSector;
+		ITERATE_RDEV(mddev,rdev,rtmp)
+			if (rdev->raid_disk >= 0 &&
+			    !test_bit(Faulty, &rdev->flags) &&
+			    !test_bit(In_sync, &rdev->flags) &&
+			    rdev->recovery_offset < j)
+				j = rdev->recovery_offset;
+	}
 
 	printk(KERN_INFO "md: syncing RAID array %s\n", mdname(mddev));
 	printk(KERN_INFO "md: minimum _guaranteed_ reconstruction speed:"
@@ -4702,12 +5153,7 @@ void md_do_sync(mddev_t *mddev)
 	       speed_max(mddev));
 
 	is_mddev_idle(mddev); /* this also initializes IO event counters */
-	/* we don't use the checkpoint if there's a bitmap */
-	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && !mddev->bitmap
-	    && ! test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
-		j = mddev->recovery_cp;
-	else
-		j = 0;
+
 	io_sectors = 0;
 	for (m = 0; m < SYNC_MARKS; m++) {
 		mark[m] = jiffies;
@@ -4828,15 +5274,28 @@ void md_do_sync(mddev_t *mddev)
 	if (!test_bit(MD_RECOVERY_ERR, &mddev->recovery) &&
 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery) &&
 	    !test_bit(MD_RECOVERY_CHECK, &mddev->recovery) &&
-	    mddev->curr_resync > 2 &&
-	    mddev->curr_resync >= mddev->recovery_cp) {
-		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
-			printk(KERN_INFO 
-				"md: checkpointing recovery of %s.\n",
-				mdname(mddev));
-			mddev->recovery_cp = mddev->curr_resync;
-		} else
-			mddev->recovery_cp = MaxSector;
+	    mddev->curr_resync > 2) {
+		if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
+			if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
+				if (mddev->curr_resync >= mddev->recovery_cp) {
+					printk(KERN_INFO
+					       "md: checkpointing recovery of %s.\n",
+					       mdname(mddev));
+					mddev->recovery_cp = mddev->curr_resync;
+				}
+			} else
+				mddev->recovery_cp = MaxSector;
+		} else {
+			if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+				mddev->curr_resync = MaxSector;
+			ITERATE_RDEV(mddev,rdev,rtmp)
+				if (rdev->raid_disk >= 0 &&
+				    !test_bit(Faulty, &rdev->flags) &&
+				    !test_bit(In_sync, &rdev->flags) &&
+				    rdev->recovery_offset < mddev->curr_resync)
+					rdev->recovery_offset = mddev->curr_resync;
+			mddev->sb_dirty = 1;
+		}
 	}
 
  skip:
@@ -4908,7 +5367,7 @@ void md_check_recovery(mddev_t *mddev)
 		if (mddev->safemode && !atomic_read(&mddev->writes_pending) &&
 		    !mddev->in_sync && mddev->recovery_cp == MaxSector) {
 			mddev->in_sync = 1;
-			mddev->sb_dirty = 1;
+			mddev->sb_dirty = 3;
 		}
 		if (mddev->safemode == 1)
 			mddev->safemode = 0;
@@ -4957,6 +5416,8 @@ void md_check_recovery(mddev_t *mddev)
 		clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
 		clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
 
+		if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+			goto unlock;
 		/* no recovery is running.
 		 * remove any failed drives, then
 		 * add spares if possible.
@@ -4979,6 +5440,7 @@ void md_check_recovery(mddev_t *mddev)
 			ITERATE_RDEV(mddev,rdev,rtmp)
 				if (rdev->raid_disk < 0
 				    && !test_bit(Faulty, &rdev->flags)) {
+					rdev->recovery_offset = 0;
 					if (mddev->pers->hot_add_disk(mddev,rdev)) {
 						char nm[20];
 						sprintf(nm, "rd%d", rdev->raid_disk);
@@ -5071,8 +5533,6 @@ static void md_geninit(void)
 
 static int __init md_init(void)
 {
-	int minor;
-
 	printk(KERN_INFO "md: md driver %d.%d.%d MAX_MD_DEVS=%d,"
 			" MD_SB_DISKS=%d\n",
 			MD_MAJOR_VERSION, MD_MINOR_VERSION,
@@ -5086,23 +5546,11 @@ static int __init md_init(void)
 		unregister_blkdev(MAJOR_NR, "md");
 		return -1;
 	}
-	devfs_mk_dir("md");
 	blk_register_region(MKDEV(MAJOR_NR, 0), MAX_MD_DEVS, THIS_MODULE,
 				md_probe, NULL, NULL);
 	blk_register_region(MKDEV(mdp_major, 0), MAX_MD_DEVS<<MdpMinorShift, THIS_MODULE,
 			    md_probe, NULL, NULL);
 
-	for (minor=0; minor < MAX_MD_DEVS; ++minor)
-		devfs_mk_bdev(MKDEV(MAJOR_NR, minor),
-				S_IFBLK|S_IRUSR|S_IWUSR,
-				"md/%d", minor);
-
-	for (minor=0; minor < MAX_MD_DEVS; ++minor)
-		devfs_mk_bdev(MKDEV(mdp_major, minor<<MdpMinorShift),
-			      S_IFBLK|S_IRUSR|S_IWUSR,
-			      "md/mdp%d", minor);
-
-
 	register_reboot_notifier(&md_notifier);
 	raid_table_header = register_sysctl_table(raid_root_table, 1);
 
@@ -5158,15 +5606,9 @@ static __exit void md_exit(void)
 {
 	mddev_t *mddev;
 	struct list_head *tmp;
-	int i;
+
 	blk_unregister_region(MKDEV(MAJOR_NR,0), MAX_MD_DEVS);
 	blk_unregister_region(MKDEV(mdp_major,0), MAX_MD_DEVS << MdpMinorShift);
-	for (i=0; i < MAX_MD_DEVS; i++)
-		devfs_remove("md/%d", i);
-	for (i=0; i < MAX_MD_DEVS; i++)
-		devfs_remove("md/d%d", i);
-
-	devfs_remove("md");
 
 	unregister_blkdev(MAJOR_NR,"md");
 	unregister_blkdev(mdp_major, "mdp");
@@ -5216,7 +5658,6 @@ EXPORT_SYMBOL(md_write_end);
 EXPORT_SYMBOL(md_register_thread);
 EXPORT_SYMBOL(md_unregister_thread);
 EXPORT_SYMBOL(md_wakeup_thread);
-EXPORT_SYMBOL(md_print_devices);
 EXPORT_SYMBOL(md_check_recovery);
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("md");
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 4070eff6f0f..cead918578a 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -374,26 +374,26 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
 	 * already.
 	 */
 	if (atomic_dec_and_test(&r1_bio->remaining)) {
-		if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
+		if (test_bit(R1BIO_BarrierRetry, &r1_bio->state))
 			reschedule_retry(r1_bio);
-			goto out;
-		}
-		/* it really is the end of this request */
-		if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
-			/* free extra copy of the data pages */
-			int i = bio->bi_vcnt;
-			while (i--)
-				safe_put_page(bio->bi_io_vec[i].bv_page);
+		else {
+			/* it really is the end of this request */
+			if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
+				/* free extra copy of the data pages */
+				int i = bio->bi_vcnt;
+				while (i--)
+					safe_put_page(bio->bi_io_vec[i].bv_page);
+			}
+			/* clear the bitmap if all writes complete successfully */
+			bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
+					r1_bio->sectors,
+					!test_bit(R1BIO_Degraded, &r1_bio->state),
+					behind);
+			md_write_end(r1_bio->mddev);
+			raid_end_bio_io(r1_bio);
 		}
-		/* clear the bitmap if all writes complete successfully */
-		bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
-				r1_bio->sectors,
-				!test_bit(R1BIO_Degraded, &r1_bio->state),
-				behind);
-		md_write_end(r1_bio->mddev);
-		raid_end_bio_io(r1_bio);
 	}
- out:
+
 	if (to_put)
 		bio_put(to_put);
 
@@ -1625,6 +1625,12 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
 	/* before building a request, check if we can skip these blocks..
 	 * This call the bitmap_start_sync doesn't actually record anything
 	 */
+	if (mddev->bitmap == NULL &&
+	    mddev->recovery_cp == MaxSector &&
+	    conf->fullsync == 0) {
+		*skipped = 1;
+		return max_sector - sector_nr;
+	}
 	if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
 	    !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
 		/* We can skip this block, and probably several more */
@@ -1888,7 +1894,8 @@ static int run(mddev_t *mddev)
 
 		disk = conf->mirrors + i;
 
-		if (!disk->rdev) {
+		if (!disk->rdev ||
+		    !test_bit(In_sync, &disk->rdev->flags)) {
 			disk->head_position = 0;
 			mddev->degraded++;
 		}
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 1440935414e..7f636283a1b 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -29,6 +29,7 @@
  *    raid_disks
  *    near_copies (stored in low byte of layout)
  *    far_copies (stored in second byte of layout)
+ *    far_offset (stored in bit 16 of layout )
  *
  * The data to be stored is divided into chunks using chunksize.
  * Each device is divided into far_copies sections.
@@ -36,10 +37,14 @@
  * near_copies copies of each chunk is stored (each on a different drive).
  * The starting device for each section is offset near_copies from the starting
  * device of the previous section.
- * Thus there are (near_copies*far_copies) of each chunk, and each is on a different
+ * Thus they are (near_copies*far_copies) of each chunk, and each is on a different
  * drive.
  * near_copies and far_copies must be at least one, and their product is at most
  * raid_disks.
+ *
+ * If far_offset is true, then the far_copies are handled a bit differently.
+ * The copies are still in different stripes, but instead of be very far apart
+ * on disk, there are adjacent stripes.
  */
 
 /*
@@ -357,8 +362,7 @@ static int raid10_end_write_request(struct bio *bio, unsigned int bytes_done, in
  * With this layout, and block is never stored twice on the one device.
  *
  * raid10_find_phys finds the sector offset of a given virtual sector
- * on each device that it is on. If a block isn't on a device,
- * that entry in the array is set to MaxSector.
+ * on each device that it is on.
  *
  * raid10_find_virt does the reverse mapping, from a device and a
  * sector offset to a virtual address
@@ -381,6 +385,8 @@ static void raid10_find_phys(conf_t *conf, r10bio_t *r10bio)
 	chunk *= conf->near_copies;
 	stripe = chunk;
 	dev = sector_div(stripe, conf->raid_disks);
+	if (conf->far_offset)
+		stripe *= conf->far_copies;
 
 	sector += stripe << conf->chunk_shift;
 
@@ -414,16 +420,24 @@ static sector_t raid10_find_virt(conf_t *conf, sector_t sector, int dev)
 {
 	sector_t offset, chunk, vchunk;
 
-	while (sector > conf->stride) {
-		sector -= conf->stride;
-		if (dev < conf->near_copies)
-			dev += conf->raid_disks - conf->near_copies;
-		else
-			dev -= conf->near_copies;
-	}
-
 	offset = sector & conf->chunk_mask;
-	chunk = sector >> conf->chunk_shift;
+	if (conf->far_offset) {
+		int fc;
+		chunk = sector >> conf->chunk_shift;
+		fc = sector_div(chunk, conf->far_copies);
+		dev -= fc * conf->near_copies;
+		if (dev < 0)
+			dev += conf->raid_disks;
+	} else {
+		while (sector > conf->stride) {
+			sector -= conf->stride;
+			if (dev < conf->near_copies)
+				dev += conf->raid_disks - conf->near_copies;
+			else
+				dev -= conf->near_copies;
+		}
+		chunk = sector >> conf->chunk_shift;
+	}
 	vchunk = chunk * conf->raid_disks + dev;
 	sector_div(vchunk, conf->near_copies);
 	return (vchunk << conf->chunk_shift) + offset;
@@ -900,9 +914,12 @@ static void status(struct seq_file *seq, mddev_t *mddev)
 		seq_printf(seq, " %dK chunks", mddev->chunk_size/1024);
 	if (conf->near_copies > 1)
 		seq_printf(seq, " %d near-copies", conf->near_copies);
-	if (conf->far_copies > 1)
-		seq_printf(seq, " %d far-copies", conf->far_copies);
-
+	if (conf->far_copies > 1) {
+		if (conf->far_offset)
+			seq_printf(seq, " %d offset-copies", conf->far_copies);
+		else
+			seq_printf(seq, " %d far-copies", conf->far_copies);
+	}
 	seq_printf(seq, " [%d/%d] [", conf->raid_disks,
 						conf->working_disks);
 	for (i = 0; i < conf->raid_disks; i++)
@@ -1915,7 +1932,7 @@ static int run(mddev_t *mddev)
 	mirror_info_t *disk;
 	mdk_rdev_t *rdev;
 	struct list_head *tmp;
-	int nc, fc;
+	int nc, fc, fo;
 	sector_t stride, size;
 
 	if (mddev->chunk_size == 0) {
@@ -1925,8 +1942,9 @@ static int run(mddev_t *mddev)
 
 	nc = mddev->layout & 255;
 	fc = (mddev->layout >> 8) & 255;
+	fo = mddev->layout & (1<<16);
 	if ((nc*fc) <2 || (nc*fc) > mddev->raid_disks ||
-	    (mddev->layout >> 16)) {
+	    (mddev->layout >> 17)) {
 		printk(KERN_ERR "raid10: %s: unsupported raid10 layout: 0x%8x\n",
 		       mdname(mddev), mddev->layout);
 		goto out;
@@ -1958,12 +1976,16 @@ static int run(mddev_t *mddev)
 	conf->near_copies = nc;
 	conf->far_copies = fc;
 	conf->copies = nc*fc;
+	conf->far_offset = fo;
 	conf->chunk_mask = (sector_t)(mddev->chunk_size>>9)-1;
 	conf->chunk_shift = ffz(~mddev->chunk_size) - 9;
-	stride = mddev->size >> (conf->chunk_shift-1);
-	sector_div(stride, fc);
-	conf->stride = stride << conf->chunk_shift;
-
+	if (fo)
+		conf->stride = 1 << conf->chunk_shift;
+	else {
+		stride = mddev->size >> (conf->chunk_shift-1);
+		sector_div(stride, fc);
+		conf->stride = stride << conf->chunk_shift;
+	}
 	conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
 						r10bio_pool_free, conf);
 	if (!conf->r10bio_pool) {
@@ -2015,7 +2037,8 @@ static int run(mddev_t *mddev)
 
 		disk = conf->mirrors + i;
 
-		if (!disk->rdev) {
+		if (!disk->rdev ||
+		    !test_bit(In_sync, &rdev->flags)) {
 			disk->head_position = 0;
 			mddev->degraded++;
 		}
@@ -2037,7 +2060,13 @@ static int run(mddev_t *mddev)
 	/*
 	 * Ok, everything is just fine now
 	 */
-	size = conf->stride * conf->raid_disks;
+	if (conf->far_offset) {
+		size = mddev->size >> (conf->chunk_shift-1);
+		size *= conf->raid_disks;
+		size <<= conf->chunk_shift;
+		sector_div(size, conf->far_copies);
+	} else
+		size = conf->stride * conf->raid_disks;
 	sector_div(size, conf->near_copies);
 	mddev->array_size = size/2;
 	mddev->resync_max_sectors = size;
@@ -2050,7 +2079,7 @@ static int run(mddev_t *mddev)
 	 * maybe...
 	 */
 	{
-		int stripe = conf->raid_disks * mddev->chunk_size / PAGE_SIZE;
+		int stripe = conf->raid_disks * (mddev->chunk_size / PAGE_SIZE);
 		stripe /= conf->near_copies;
 		if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
 			mddev->queue->backing_dev_info.ra_pages = 2* stripe;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 31843604049..7433871f4b3 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2,8 +2,11 @@
  * raid5.c : Multiple Devices driver for Linux
  *	   Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
  *	   Copyright (C) 1999, 2000 Ingo Molnar
+ *	   Copyright (C) 2002, 2003 H. Peter Anvin
  *
- * RAID-5 management functions.
+ * RAID-4/5/6 management functions.
+ * Thanks to Penguin Computing for making the RAID-6 development possible
+ * by donating a test server!
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,14 +19,13 @@
  */
 
 
-#include <linux/config.h>
 #include <linux/module.h>
 #include <linux/slab.h>
-#include <linux/raid/raid5.h>
 #include <linux/highmem.h>
 #include <linux/bitops.h>
 #include <linux/kthread.h>
 #include <asm/atomic.h>
+#include "raid6.h"
 
 #include <linux/raid/bitmap.h>
 
@@ -68,6 +70,16 @@
 #define __inline__
 #endif
 
+#if !RAID6_USE_EMPTY_ZERO_PAGE
+/* In .bss so it's zeroed */
+const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
+#endif
+
+static inline int raid6_next_disk(int disk, int raid_disks)
+{
+	disk++;
+	return (disk < raid_disks) ? disk : 0;
+}
 static void print_raid5_conf (raid5_conf_t *conf);
 
 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
@@ -104,7 +116,7 @@ static void release_stripe(struct stripe_head *sh)
 {
 	raid5_conf_t *conf = sh->raid_conf;
 	unsigned long flags;
-	
+
 	spin_lock_irqsave(&conf->device_lock, flags);
 	__release_stripe(conf, sh);
 	spin_unlock_irqrestore(&conf->device_lock, flags);
@@ -117,7 +129,7 @@ static inline void remove_hash(struct stripe_head *sh)
 	hlist_del_init(&sh->hash);
 }
 
-static void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
+static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
 {
 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
 
@@ -190,7 +202,7 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int
 		(unsigned long long)sh->sector);
 
 	remove_hash(sh);
-	
+
 	sh->sector = sector;
 	sh->pd_idx = pd_idx;
 	sh->state = 0;
@@ -269,8 +281,9 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
 			} else {
 				if (!test_bit(STRIPE_HANDLE, &sh->state))
 					atomic_inc(&conf->active_stripes);
-				if (!list_empty(&sh->lru))
-					list_del_init(&sh->lru);
+				if (list_empty(&sh->lru))
+					BUG();
+				list_del_init(&sh->lru);
 			}
 		}
 	} while (sh == NULL);
@@ -321,10 +334,9 @@ static int grow_stripes(raid5_conf_t *conf, int num)
 		return 1;
 	conf->slab_cache = sc;
 	conf->pool_size = devs;
-	while (num--) {
+	while (num--)
 		if (!grow_one_stripe(conf))
 			return 1;
-	}
 	return 0;
 }
 
@@ -631,8 +643,7 @@ static void raid5_build_block (struct stripe_head *sh, int i)
 	dev->req.bi_private = sh;
 
 	dev->flags = 0;
-	if (i != sh->pd_idx)
-		dev->sector = compute_blocknr(sh, i);
+	dev->sector = compute_blocknr(sh, i);
 }
 
 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
@@ -659,7 +670,7 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 			" Operation continuing on %d devices\n",
 			bdevname(rdev->bdev,b), conf->working_disks);
 	}
-}	
+}
 
 /*
  * Input: a 'big' sector number,
@@ -697,9 +708,12 @@ static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
 	/*
 	 * Select the parity disk based on the user selected algorithm.
 	 */
-	if (conf->level == 4)
+	switch(conf->level) {
+	case 4:
 		*pd_idx = data_disks;
-	else switch (conf->algorithm) {
+		break;
+	case 5:
+		switch (conf->algorithm) {
 		case ALGORITHM_LEFT_ASYMMETRIC:
 			*pd_idx = data_disks - stripe % raid_disks;
 			if (*dd_idx >= *pd_idx)
@@ -721,6 +735,39 @@ static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
 		default:
 			printk(KERN_ERR "raid5: unsupported algorithm %d\n",
 				conf->algorithm);
+		}
+		break;
+	case 6:
+
+		/**** FIX THIS ****/
+		switch (conf->algorithm) {
+		case ALGORITHM_LEFT_ASYMMETRIC:
+			*pd_idx = raid_disks - 1 - (stripe % raid_disks);
+			if (*pd_idx == raid_disks-1)
+				(*dd_idx)++; 	/* Q D D D P */
+			else if (*dd_idx >= *pd_idx)
+				(*dd_idx) += 2; /* D D P Q D */
+			break;
+		case ALGORITHM_RIGHT_ASYMMETRIC:
+			*pd_idx = stripe % raid_disks;
+			if (*pd_idx == raid_disks-1)
+				(*dd_idx)++; 	/* Q D D D P */
+			else if (*dd_idx >= *pd_idx)
+				(*dd_idx) += 2; /* D D P Q D */
+			break;
+		case ALGORITHM_LEFT_SYMMETRIC:
+			*pd_idx = raid_disks - 1 - (stripe % raid_disks);
+			*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
+			break;
+		case ALGORITHM_RIGHT_SYMMETRIC:
+			*pd_idx = stripe % raid_disks;
+			*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
+			break;
+		default:
+			printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
+				conf->algorithm);
+		}
+		break;
 	}
 
 	/*
@@ -742,12 +789,17 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
 	int chunk_number, dummy1, dummy2, dd_idx = i;
 	sector_t r_sector;
 
+
 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
 	stripe = new_sector;
 	BUG_ON(new_sector != stripe);
 
-	
-	switch (conf->algorithm) {
+	if (i == sh->pd_idx)
+		return 0;
+	switch(conf->level) {
+	case 4: break;
+	case 5:
+		switch (conf->algorithm) {
 		case ALGORITHM_LEFT_ASYMMETRIC:
 		case ALGORITHM_RIGHT_ASYMMETRIC:
 			if (i > sh->pd_idx)
@@ -761,7 +813,37 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
 			break;
 		default:
 			printk(KERN_ERR "raid5: unsupported algorithm %d\n",
+			       conf->algorithm);
+		}
+		break;
+	case 6:
+		data_disks = raid_disks - 2;
+		if (i == raid6_next_disk(sh->pd_idx, raid_disks))
+			return 0; /* It is the Q disk */
+		switch (conf->algorithm) {
+		case ALGORITHM_LEFT_ASYMMETRIC:
+		case ALGORITHM_RIGHT_ASYMMETRIC:
+		  	if (sh->pd_idx == raid_disks-1)
+				i--; 	/* Q D D D P */
+			else if (i > sh->pd_idx)
+				i -= 2; /* D D P Q D */
+			break;
+		case ALGORITHM_LEFT_SYMMETRIC:
+		case ALGORITHM_RIGHT_SYMMETRIC:
+			if (sh->pd_idx == raid_disks-1)
+				i--; /* Q D D D P */
+			else {
+				/* D D P Q D */
+				if (i < sh->pd_idx)
+					i += raid_disks;
+				i -= (sh->pd_idx + 2);
+			}
+			break;
+		default:
+			printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
 				conf->algorithm);
+		}
+		break;
 	}
 
 	chunk_number = stripe * data_disks + i;
@@ -778,10 +860,11 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
 
 
 /*
- * Copy data between a page in the stripe cache, and a bio.
- * There are no alignment or size guarantees between the page or the
- * bio except that there is some overlap.
- * All iovecs in the bio must be considered.
+ * Copy data between a page in the stripe cache, and one or more bion
+ * The page could align with the middle of the bio, or there could be
+ * several bion, each with several bio_vecs, which cover part of the page
+ * Multiple bion are linked together on bi_next.  There may be extras
+ * at the end of this list.  We ignore them.
  */
 static void copy_data(int frombio, struct bio *bio,
 		     struct page *page,
@@ -810,7 +893,7 @@ static void copy_data(int frombio, struct bio *bio,
 		if (len > 0 && page_offset + len > STRIPE_SIZE)
 			clen = STRIPE_SIZE - page_offset;
 		else clen = len;
-			
+
 		if (clen > 0) {
 			char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
 			if (frombio)
@@ -862,14 +945,14 @@ static void compute_block(struct stripe_head *sh, int dd_idx)
 	set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
 }
 
-static void compute_parity(struct stripe_head *sh, int method)
+static void compute_parity5(struct stripe_head *sh, int method)
 {
 	raid5_conf_t *conf = sh->raid_conf;
 	int i, pd_idx = sh->pd_idx, disks = sh->disks, count;
 	void *ptr[MAX_XOR_BLOCKS];
 	struct bio *chosen;
 
-	PRINTK("compute_parity, stripe %llu, method %d\n",
+	PRINTK("compute_parity5, stripe %llu, method %d\n",
 		(unsigned long long)sh->sector, method);
 
 	count = 1;
@@ -956,9 +1039,195 @@ static void compute_parity(struct stripe_head *sh, int method)
 		clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
 }
 
+static void compute_parity6(struct stripe_head *sh, int method)
+{
+	raid6_conf_t *conf = sh->raid_conf;
+	int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = conf->raid_disks, count;
+	struct bio *chosen;
+	/**** FIX THIS: This could be very bad if disks is close to 256 ****/
+	void *ptrs[disks];
+
+	qd_idx = raid6_next_disk(pd_idx, disks);
+	d0_idx = raid6_next_disk(qd_idx, disks);
+
+	PRINTK("compute_parity, stripe %llu, method %d\n",
+		(unsigned long long)sh->sector, method);
+
+	switch(method) {
+	case READ_MODIFY_WRITE:
+		BUG();		/* READ_MODIFY_WRITE N/A for RAID-6 */
+	case RECONSTRUCT_WRITE:
+		for (i= disks; i-- ;)
+			if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
+				chosen = sh->dev[i].towrite;
+				sh->dev[i].towrite = NULL;
+
+				if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+					wake_up(&conf->wait_for_overlap);
+
+				if (sh->dev[i].written) BUG();
+				sh->dev[i].written = chosen;
+			}
+		break;
+	case CHECK_PARITY:
+		BUG();		/* Not implemented yet */
+	}
+
+	for (i = disks; i--;)
+		if (sh->dev[i].written) {
+			sector_t sector = sh->dev[i].sector;
+			struct bio *wbi = sh->dev[i].written;
+			while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
+				copy_data(1, wbi, sh->dev[i].page, sector);
+				wbi = r5_next_bio(wbi, sector);
+			}
+
+			set_bit(R5_LOCKED, &sh->dev[i].flags);
+			set_bit(R5_UPTODATE, &sh->dev[i].flags);
+		}
+
+//	switch(method) {
+//	case RECONSTRUCT_WRITE:
+//	case CHECK_PARITY:
+//	case UPDATE_PARITY:
+		/* Note that unlike RAID-5, the ordering of the disks matters greatly. */
+		/* FIX: Is this ordering of drives even remotely optimal? */
+		count = 0;
+		i = d0_idx;
+		do {
+			ptrs[count++] = page_address(sh->dev[i].page);
+			if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
+				printk("block %d/%d not uptodate on parity calc\n", i,count);
+			i = raid6_next_disk(i, disks);
+		} while ( i != d0_idx );
+//		break;
+//	}
+
+	raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
+
+	switch(method) {
+	case RECONSTRUCT_WRITE:
+		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
+		set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
+		set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
+		set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
+		break;
+	case UPDATE_PARITY:
+		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
+		set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
+		break;
+	}
+}
+
+
+/* Compute one missing block */
+static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
+{
+	raid6_conf_t *conf = sh->raid_conf;
+	int i, count, disks = conf->raid_disks;
+	void *ptr[MAX_XOR_BLOCKS], *p;
+	int pd_idx = sh->pd_idx;
+	int qd_idx = raid6_next_disk(pd_idx, disks);
+
+	PRINTK("compute_block_1, stripe %llu, idx %d\n",
+		(unsigned long long)sh->sector, dd_idx);
+
+	if ( dd_idx == qd_idx ) {
+		/* We're actually computing the Q drive */
+		compute_parity6(sh, UPDATE_PARITY);
+	} else {
+		ptr[0] = page_address(sh->dev[dd_idx].page);
+		if (!nozero) memset(ptr[0], 0, STRIPE_SIZE);
+		count = 1;
+		for (i = disks ; i--; ) {
+			if (i == dd_idx || i == qd_idx)
+				continue;
+			p = page_address(sh->dev[i].page);
+			if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
+				ptr[count++] = p;
+			else
+				printk("compute_block() %d, stripe %llu, %d"
+				       " not present\n", dd_idx,
+				       (unsigned long long)sh->sector, i);
+
+			check_xor();
+		}
+		if (count != 1)
+			xor_block(count, STRIPE_SIZE, ptr);
+		if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
+		else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
+	}
+}
+
+/* Compute two missing blocks */
+static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
+{
+	raid6_conf_t *conf = sh->raid_conf;
+	int i, count, disks = conf->raid_disks;
+	int pd_idx = sh->pd_idx;
+	int qd_idx = raid6_next_disk(pd_idx, disks);
+	int d0_idx = raid6_next_disk(qd_idx, disks);
+	int faila, failb;
+
+	/* faila and failb are disk numbers relative to d0_idx */
+	/* pd_idx become disks-2 and qd_idx become disks-1 */
+	faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
+	failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
+
+	BUG_ON(faila == failb);
+	if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
+
+	PRINTK("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
+	       (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
+
+	if ( failb == disks-1 ) {
+		/* Q disk is one of the missing disks */
+		if ( faila == disks-2 ) {
+			/* Missing P+Q, just recompute */
+			compute_parity6(sh, UPDATE_PARITY);
+			return;
+		} else {
+			/* We're missing D+Q; recompute D from P */
+			compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
+			compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
+			return;
+		}
+	}
+
+	/* We're missing D+P or D+D; build pointer table */
+	{
+		/**** FIX THIS: This could be very bad if disks is close to 256 ****/
+		void *ptrs[disks];
+
+		count = 0;
+		i = d0_idx;
+		do {
+			ptrs[count++] = page_address(sh->dev[i].page);
+			i = raid6_next_disk(i, disks);
+			if (i != dd_idx1 && i != dd_idx2 &&
+			    !test_bit(R5_UPTODATE, &sh->dev[i].flags))
+				printk("compute_2 with missing block %d/%d\n", count, i);
+		} while ( i != d0_idx );
+
+		if ( failb == disks-2 ) {
+			/* We're missing D+P. */
+			raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
+		} else {
+			/* We're missing D+D. */
+			raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
+		}
+
+		/* Both the above update both missing blocks */
+		set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
+		set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
+	}
+}
+
+
+
 /*
  * Each stripe/dev can have one or more bion attached.
- * toread/towrite point to the first in a chain. 
+ * toread/towrite point to the first in a chain.
  * The bi_next chain must be in order.
  */
 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
@@ -1031,6 +1300,13 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
 
 static void end_reshape(raid5_conf_t *conf);
 
+static int page_is_zero(struct page *p)
+{
+	char *a = page_address(p);
+	return ((*(u32*)a) == 0 &&
+		memcmp(a, a+4, STRIPE_SIZE-4)==0);
+}
+
 static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
 {
 	int sectors_per_chunk = conf->chunk_size >> 9;
@@ -1062,7 +1338,7 @@ static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
  *
  */
  
-static void handle_stripe(struct stripe_head *sh)
+static void handle_stripe5(struct stripe_head *sh)
 {
 	raid5_conf_t *conf = sh->raid_conf;
 	int disks = sh->disks;
@@ -1394,7 +1670,7 @@ static void handle_stripe(struct stripe_head *sh)
 		if (locked == 0 && (rcw == 0 ||rmw == 0) &&
 		    !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
 			PRINTK("Computing parity...\n");
-			compute_parity(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE);
+			compute_parity5(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE);
 			/* now every locked buffer is ready to be written */
 			for (i=disks; i--;)
 				if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
@@ -1421,13 +1697,10 @@ static void handle_stripe(struct stripe_head *sh)
 	    !test_bit(STRIPE_INSYNC, &sh->state)) {
 		set_bit(STRIPE_HANDLE, &sh->state);
 		if (failed == 0) {
-			char *pagea;
 			BUG_ON(uptodate != disks);
-			compute_parity(sh, CHECK_PARITY);
+			compute_parity5(sh, CHECK_PARITY);
 			uptodate--;
-			pagea = page_address(sh->dev[sh->pd_idx].page);
-			if ((*(u32*)pagea) == 0 &&
-			    !memcmp(pagea, pagea+4, STRIPE_SIZE-4)) {
+			if (page_is_zero(sh->dev[sh->pd_idx].page)) {
 				/* parity is correct (on disc, not in buffer any more) */
 				set_bit(STRIPE_INSYNC, &sh->state);
 			} else {
@@ -1487,7 +1760,7 @@ static void handle_stripe(struct stripe_head *sh)
 		/* Need to write out all blocks after computing parity */
 		sh->disks = conf->raid_disks;
 		sh->pd_idx = stripe_to_pdidx(sh->sector, conf, conf->raid_disks);
-		compute_parity(sh, RECONSTRUCT_WRITE);
+		compute_parity5(sh, RECONSTRUCT_WRITE);
 		for (i= conf->raid_disks; i--;) {
 			set_bit(R5_LOCKED, &sh->dev[i].flags);
 			locked++;
@@ -1615,6 +1888,569 @@ static void handle_stripe(struct stripe_head *sh)
 	}
 }
 
+static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
+{
+	raid6_conf_t *conf = sh->raid_conf;
+	int disks = conf->raid_disks;
+	struct bio *return_bi= NULL;
+	struct bio *bi;
+	int i;
+	int syncing;
+	int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
+	int non_overwrite = 0;
+	int failed_num[2] = {0, 0};
+	struct r5dev *dev, *pdev, *qdev;
+	int pd_idx = sh->pd_idx;
+	int qd_idx = raid6_next_disk(pd_idx, disks);
+	int p_failed, q_failed;
+
+	PRINTK("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d, qd_idx=%d\n",
+	       (unsigned long long)sh->sector, sh->state, atomic_read(&sh->count),
+	       pd_idx, qd_idx);
+
+	spin_lock(&sh->lock);
+	clear_bit(STRIPE_HANDLE, &sh->state);
+	clear_bit(STRIPE_DELAYED, &sh->state);
+
+	syncing = test_bit(STRIPE_SYNCING, &sh->state);
+	/* Now to look around and see what can be done */
+
+	rcu_read_lock();
+	for (i=disks; i--; ) {
+		mdk_rdev_t *rdev;
+		dev = &sh->dev[i];
+		clear_bit(R5_Insync, &dev->flags);
+
+		PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
+			i, dev->flags, dev->toread, dev->towrite, dev->written);
+		/* maybe we can reply to a read */
+		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
+			struct bio *rbi, *rbi2;
+			PRINTK("Return read for disc %d\n", i);
+			spin_lock_irq(&conf->device_lock);
+			rbi = dev->toread;
+			dev->toread = NULL;
+			if (test_and_clear_bit(R5_Overlap, &dev->flags))
+				wake_up(&conf->wait_for_overlap);
+			spin_unlock_irq(&conf->device_lock);
+			while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
+				copy_data(0, rbi, dev->page, dev->sector);
+				rbi2 = r5_next_bio(rbi, dev->sector);
+				spin_lock_irq(&conf->device_lock);
+				if (--rbi->bi_phys_segments == 0) {
+					rbi->bi_next = return_bi;
+					return_bi = rbi;
+				}
+				spin_unlock_irq(&conf->device_lock);
+				rbi = rbi2;
+			}
+		}
+
+		/* now count some things */
+		if (test_bit(R5_LOCKED, &dev->flags)) locked++;
+		if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
+
+
+		if (dev->toread) to_read++;
+		if (dev->towrite) {
+			to_write++;
+			if (!test_bit(R5_OVERWRITE, &dev->flags))
+				non_overwrite++;
+		}
+		if (dev->written) written++;
+		rdev = rcu_dereference(conf->disks[i].rdev);
+		if (!rdev || !test_bit(In_sync, &rdev->flags)) {
+			/* The ReadError flag will just be confusing now */
+			clear_bit(R5_ReadError, &dev->flags);
+			clear_bit(R5_ReWrite, &dev->flags);
+		}
+		if (!rdev || !test_bit(In_sync, &rdev->flags)
+		    || test_bit(R5_ReadError, &dev->flags)) {
+			if ( failed < 2 )
+				failed_num[failed] = i;
+			failed++;
+		} else
+			set_bit(R5_Insync, &dev->flags);
+	}
+	rcu_read_unlock();
+	PRINTK("locked=%d uptodate=%d to_read=%d"
+	       " to_write=%d failed=%d failed_num=%d,%d\n",
+	       locked, uptodate, to_read, to_write, failed,
+	       failed_num[0], failed_num[1]);
+	/* check if the array has lost >2 devices and, if so, some requests might
+	 * need to be failed
+	 */
+	if (failed > 2 && to_read+to_write+written) {
+		for (i=disks; i--; ) {
+			int bitmap_end = 0;
+
+			if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
+				mdk_rdev_t *rdev;
+				rcu_read_lock();
+				rdev = rcu_dereference(conf->disks[i].rdev);
+				if (rdev && test_bit(In_sync, &rdev->flags))
+					/* multiple read failures in one stripe */
+					md_error(conf->mddev, rdev);
+				rcu_read_unlock();
+			}
+
+			spin_lock_irq(&conf->device_lock);
+			/* fail all writes first */
+			bi = sh->dev[i].towrite;
+			sh->dev[i].towrite = NULL;
+			if (bi) { to_write--; bitmap_end = 1; }
+
+			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+				wake_up(&conf->wait_for_overlap);
+
+			while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
+				struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
+				clear_bit(BIO_UPTODATE, &bi->bi_flags);
+				if (--bi->bi_phys_segments == 0) {
+					md_write_end(conf->mddev);
+					bi->bi_next = return_bi;
+					return_bi = bi;
+				}
+				bi = nextbi;
+			}
+			/* and fail all 'written' */
+			bi = sh->dev[i].written;
+			sh->dev[i].written = NULL;
+			if (bi) bitmap_end = 1;
+			while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
+				struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
+				clear_bit(BIO_UPTODATE, &bi->bi_flags);
+				if (--bi->bi_phys_segments == 0) {
+					md_write_end(conf->mddev);
+					bi->bi_next = return_bi;
+					return_bi = bi;
+				}
+				bi = bi2;
+			}
+
+			/* fail any reads if this device is non-operational */
+			if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
+			    test_bit(R5_ReadError, &sh->dev[i].flags)) {
+				bi = sh->dev[i].toread;
+				sh->dev[i].toread = NULL;
+				if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+					wake_up(&conf->wait_for_overlap);
+				if (bi) to_read--;
+				while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
+					struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
+					clear_bit(BIO_UPTODATE, &bi->bi_flags);
+					if (--bi->bi_phys_segments == 0) {
+						bi->bi_next = return_bi;
+						return_bi = bi;
+					}
+					bi = nextbi;
+				}
+			}
+			spin_unlock_irq(&conf->device_lock);
+			if (bitmap_end)
+				bitmap_endwrite(conf->mddev->bitmap, sh->sector,
+						STRIPE_SECTORS, 0, 0);
+		}
+	}
+	if (failed > 2 && syncing) {
+		md_done_sync(conf->mddev, STRIPE_SECTORS,0);
+		clear_bit(STRIPE_SYNCING, &sh->state);
+		syncing = 0;
+	}
+
+	/*
+	 * might be able to return some write requests if the parity blocks
+	 * are safe, or on a failed drive
+	 */
+	pdev = &sh->dev[pd_idx];
+	p_failed = (failed >= 1 && failed_num[0] == pd_idx)
+		|| (failed >= 2 && failed_num[1] == pd_idx);
+	qdev = &sh->dev[qd_idx];
+	q_failed = (failed >= 1 && failed_num[0] == qd_idx)
+		|| (failed >= 2 && failed_num[1] == qd_idx);
+
+	if ( written &&
+	     ( p_failed || ((test_bit(R5_Insync, &pdev->flags)
+			     && !test_bit(R5_LOCKED, &pdev->flags)
+			     && test_bit(R5_UPTODATE, &pdev->flags))) ) &&
+	     ( q_failed || ((test_bit(R5_Insync, &qdev->flags)
+			     && !test_bit(R5_LOCKED, &qdev->flags)
+			     && test_bit(R5_UPTODATE, &qdev->flags))) ) ) {
+		/* any written block on an uptodate or failed drive can be
+		 * returned.  Note that if we 'wrote' to a failed drive,
+		 * it will be UPTODATE, but never LOCKED, so we don't need
+		 * to test 'failed' directly.
+		 */
+		for (i=disks; i--; )
+			if (sh->dev[i].written) {
+				dev = &sh->dev[i];
+				if (!test_bit(R5_LOCKED, &dev->flags) &&
+				    test_bit(R5_UPTODATE, &dev->flags) ) {
+					/* We can return any write requests */
+					int bitmap_end = 0;
+					struct bio *wbi, *wbi2;
+					PRINTK("Return write for stripe %llu disc %d\n",
+					       (unsigned long long)sh->sector, i);
+					spin_lock_irq(&conf->device_lock);
+					wbi = dev->written;
+					dev->written = NULL;
+					while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
+						wbi2 = r5_next_bio(wbi, dev->sector);
+						if (--wbi->bi_phys_segments == 0) {
+							md_write_end(conf->mddev);
+							wbi->bi_next = return_bi;
+							return_bi = wbi;
+						}
+						wbi = wbi2;
+					}
+					if (dev->towrite == NULL)
+						bitmap_end = 1;
+					spin_unlock_irq(&conf->device_lock);
+					if (bitmap_end)
+						bitmap_endwrite(conf->mddev->bitmap, sh->sector,
+								STRIPE_SECTORS,
+								!test_bit(STRIPE_DEGRADED, &sh->state), 0);
+				}
+			}
+	}
+
+	/* Now we might consider reading some blocks, either to check/generate
+	 * parity, or to satisfy requests
+	 * or to load a block that is being partially written.
+	 */
+	if (to_read || non_overwrite || (to_write && failed) || (syncing && (uptodate < disks))) {
+		for (i=disks; i--;) {
+			dev = &sh->dev[i];
+			if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
+			    (dev->toread ||
+			     (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
+			     syncing ||
+			     (failed >= 1 && (sh->dev[failed_num[0]].toread || to_write)) ||
+			     (failed >= 2 && (sh->dev[failed_num[1]].toread || to_write))
+				    )
+				) {
+				/* we would like to get this block, possibly
+				 * by computing it, but we might not be able to
+				 */
+				if (uptodate == disks-1) {
+					PRINTK("Computing stripe %llu block %d\n",
+					       (unsigned long long)sh->sector, i);
+					compute_block_1(sh, i, 0);
+					uptodate++;
+				} else if ( uptodate == disks-2 && failed >= 2 ) {
+					/* Computing 2-failure is *very* expensive; only do it if failed >= 2 */
+					int other;
+					for (other=disks; other--;) {
+						if ( other == i )
+							continue;
+						if ( !test_bit(R5_UPTODATE, &sh->dev[other].flags) )
+							break;
+					}
+					BUG_ON(other < 0);
+					PRINTK("Computing stripe %llu blocks %d,%d\n",
+					       (unsigned long long)sh->sector, i, other);
+					compute_block_2(sh, i, other);
+					uptodate += 2;
+				} else if (test_bit(R5_Insync, &dev->flags)) {
+					set_bit(R5_LOCKED, &dev->flags);
+					set_bit(R5_Wantread, &dev->flags);
+#if 0
+					/* if I am just reading this block and we don't have
+					   a failed drive, or any pending writes then sidestep the cache */
+					if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext &&
+					    ! syncing && !failed && !to_write) {
+						sh->bh_cache[i]->b_page =  sh->bh_read[i]->b_page;
+						sh->bh_cache[i]->b_data =  sh->bh_read[i]->b_data;
+					}
+#endif
+					locked++;
+					PRINTK("Reading block %d (sync=%d)\n",
+						i, syncing);
+				}
+			}
+		}
+		set_bit(STRIPE_HANDLE, &sh->state);
+	}
+
+	/* now to consider writing and what else, if anything should be read */
+	if (to_write) {
+		int rcw=0, must_compute=0;
+		for (i=disks ; i--;) {
+			dev = &sh->dev[i];
+			/* Would I have to read this buffer for reconstruct_write */
+			if (!test_bit(R5_OVERWRITE, &dev->flags)
+			    && i != pd_idx && i != qd_idx
+			    && (!test_bit(R5_LOCKED, &dev->flags)
+#if 0
+				|| sh->bh_page[i] != bh->b_page
+#endif
+				    ) &&
+			    !test_bit(R5_UPTODATE, &dev->flags)) {
+				if (test_bit(R5_Insync, &dev->flags)) rcw++;
+				else {
+					PRINTK("raid6: must_compute: disk %d flags=%#lx\n", i, dev->flags);
+					must_compute++;
+				}
+			}
+		}
+		PRINTK("for sector %llu, rcw=%d, must_compute=%d\n",
+		       (unsigned long long)sh->sector, rcw, must_compute);
+		set_bit(STRIPE_HANDLE, &sh->state);
+
+		if (rcw > 0)
+			/* want reconstruct write, but need to get some data */
+			for (i=disks; i--;) {
+				dev = &sh->dev[i];
+				if (!test_bit(R5_OVERWRITE, &dev->flags)
+				    && !(failed == 0 && (i == pd_idx || i == qd_idx))
+				    && !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
+				    test_bit(R5_Insync, &dev->flags)) {
+					if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
+					{
+						PRINTK("Read_old stripe %llu block %d for Reconstruct\n",
+						       (unsigned long long)sh->sector, i);
+						set_bit(R5_LOCKED, &dev->flags);
+						set_bit(R5_Wantread, &dev->flags);
+						locked++;
+					} else {
+						PRINTK("Request delayed stripe %llu block %d for Reconstruct\n",
+						       (unsigned long long)sh->sector, i);
+						set_bit(STRIPE_DELAYED, &sh->state);
+						set_bit(STRIPE_HANDLE, &sh->state);
+					}
+				}
+			}
+		/* now if nothing is locked, and if we have enough data, we can start a write request */
+		if (locked == 0 && rcw == 0 &&
+		    !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
+			if ( must_compute > 0 ) {
+				/* We have failed blocks and need to compute them */
+				switch ( failed ) {
+				case 0:	BUG();
+				case 1: compute_block_1(sh, failed_num[0], 0); break;
+				case 2: compute_block_2(sh, failed_num[0], failed_num[1]); break;
+				default: BUG();	/* This request should have been failed? */
+				}
+			}
+
+			PRINTK("Computing parity for stripe %llu\n", (unsigned long long)sh->sector);
+			compute_parity6(sh, RECONSTRUCT_WRITE);
+			/* now every locked buffer is ready to be written */
+			for (i=disks; i--;)
+				if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
+					PRINTK("Writing stripe %llu block %d\n",
+					       (unsigned long long)sh->sector, i);
+					locked++;
+					set_bit(R5_Wantwrite, &sh->dev[i].flags);
+				}
+			/* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
+			set_bit(STRIPE_INSYNC, &sh->state);
+
+			if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
+				atomic_dec(&conf->preread_active_stripes);
+				if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
+					md_wakeup_thread(conf->mddev->thread);
+			}
+		}
+	}
+
+	/* maybe we need to check and possibly fix the parity for this stripe
+	 * Any reads will already have been scheduled, so we just see if enough data
+	 * is available
+	 */
+	if (syncing && locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state)) {
+		int update_p = 0, update_q = 0;
+		struct r5dev *dev;
+
+		set_bit(STRIPE_HANDLE, &sh->state);
+
+		BUG_ON(failed>2);
+		BUG_ON(uptodate < disks);
+		/* Want to check and possibly repair P and Q.
+		 * However there could be one 'failed' device, in which
+		 * case we can only check one of them, possibly using the
+		 * other to generate missing data
+		 */
+
+		/* If !tmp_page, we cannot do the calculations,
+		 * but as we have set STRIPE_HANDLE, we will soon be called
+		 * by stripe_handle with a tmp_page - just wait until then.
+		 */
+		if (tmp_page) {
+			if (failed == q_failed) {
+				/* The only possible failed device holds 'Q', so it makes
+				 * sense to check P (If anything else were failed, we would
+				 * have used P to recreate it).
+				 */
+				compute_block_1(sh, pd_idx, 1);
+				if (!page_is_zero(sh->dev[pd_idx].page)) {
+					compute_block_1(sh,pd_idx,0);
+					update_p = 1;
+				}
+			}
+			if (!q_failed && failed < 2) {
+				/* q is not failed, and we didn't use it to generate
+				 * anything, so it makes sense to check it
+				 */
+				memcpy(page_address(tmp_page),
+				       page_address(sh->dev[qd_idx].page),
+				       STRIPE_SIZE);
+				compute_parity6(sh, UPDATE_PARITY);
+				if (memcmp(page_address(tmp_page),
+					   page_address(sh->dev[qd_idx].page),
+					   STRIPE_SIZE)!= 0) {
+					clear_bit(STRIPE_INSYNC, &sh->state);
+					update_q = 1;
+				}
+			}
+			if (update_p || update_q) {
+				conf->mddev->resync_mismatches += STRIPE_SECTORS;
+				if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
+					/* don't try to repair!! */
+					update_p = update_q = 0;
+			}
+
+			/* now write out any block on a failed drive,
+			 * or P or Q if they need it
+			 */
+
+			if (failed == 2) {
+				dev = &sh->dev[failed_num[1]];
+				locked++;
+				set_bit(R5_LOCKED, &dev->flags);
+				set_bit(R5_Wantwrite, &dev->flags);
+			}
+			if (failed >= 1) {
+				dev = &sh->dev[failed_num[0]];
+				locked++;
+				set_bit(R5_LOCKED, &dev->flags);
+				set_bit(R5_Wantwrite, &dev->flags);
+			}
+
+			if (update_p) {
+				dev = &sh->dev[pd_idx];
+				locked ++;
+				set_bit(R5_LOCKED, &dev->flags);
+				set_bit(R5_Wantwrite, &dev->flags);
+			}
+			if (update_q) {
+				dev = &sh->dev[qd_idx];
+				locked++;
+				set_bit(R5_LOCKED, &dev->flags);
+				set_bit(R5_Wantwrite, &dev->flags);
+			}
+			clear_bit(STRIPE_DEGRADED, &sh->state);
+
+			set_bit(STRIPE_INSYNC, &sh->state);
+		}
+	}
+
+	if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
+		md_done_sync(conf->mddev, STRIPE_SECTORS,1);
+		clear_bit(STRIPE_SYNCING, &sh->state);
+	}
+
+	/* If the failed drives are just a ReadError, then we might need
+	 * to progress the repair/check process
+	 */
+	if (failed <= 2 && ! conf->mddev->ro)
+		for (i=0; i<failed;i++) {
+			dev = &sh->dev[failed_num[i]];
+			if (test_bit(R5_ReadError, &dev->flags)
+			    && !test_bit(R5_LOCKED, &dev->flags)
+			    && test_bit(R5_UPTODATE, &dev->flags)
+				) {
+				if (!test_bit(R5_ReWrite, &dev->flags)) {
+					set_bit(R5_Wantwrite, &dev->flags);
+					set_bit(R5_ReWrite, &dev->flags);
+					set_bit(R5_LOCKED, &dev->flags);
+				} else {
+					/* let's read it back */
+					set_bit(R5_Wantread, &dev->flags);
+					set_bit(R5_LOCKED, &dev->flags);
+				}
+			}
+		}
+	spin_unlock(&sh->lock);
+
+	while ((bi=return_bi)) {
+		int bytes = bi->bi_size;
+
+		return_bi = bi->bi_next;
+		bi->bi_next = NULL;
+		bi->bi_size = 0;
+		bi->bi_end_io(bi, bytes, 0);
+	}
+	for (i=disks; i-- ;) {
+		int rw;
+		struct bio *bi;
+		mdk_rdev_t *rdev;
+		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
+			rw = 1;
+		else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
+			rw = 0;
+		else
+			continue;
+
+		bi = &sh->dev[i].req;
+
+		bi->bi_rw = rw;
+		if (rw)
+			bi->bi_end_io = raid5_end_write_request;
+		else
+			bi->bi_end_io = raid5_end_read_request;
+
+		rcu_read_lock();
+		rdev = rcu_dereference(conf->disks[i].rdev);
+		if (rdev && test_bit(Faulty, &rdev->flags))
+			rdev = NULL;
+		if (rdev)
+			atomic_inc(&rdev->nr_pending);
+		rcu_read_unlock();
+
+		if (rdev) {
+			if (syncing)
+				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
+
+			bi->bi_bdev = rdev->bdev;
+			PRINTK("for %llu schedule op %ld on disc %d\n",
+				(unsigned long long)sh->sector, bi->bi_rw, i);
+			atomic_inc(&sh->count);
+			bi->bi_sector = sh->sector + rdev->data_offset;
+			bi->bi_flags = 1 << BIO_UPTODATE;
+			bi->bi_vcnt = 1;
+			bi->bi_max_vecs = 1;
+			bi->bi_idx = 0;
+			bi->bi_io_vec = &sh->dev[i].vec;
+			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
+			bi->bi_io_vec[0].bv_offset = 0;
+			bi->bi_size = STRIPE_SIZE;
+			bi->bi_next = NULL;
+			if (rw == WRITE &&
+			    test_bit(R5_ReWrite, &sh->dev[i].flags))
+				atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
+			generic_make_request(bi);
+		} else {
+			if (rw == 1)
+				set_bit(STRIPE_DEGRADED, &sh->state);
+			PRINTK("skip op %ld on disc %d for sector %llu\n",
+				bi->bi_rw, i, (unsigned long long)sh->sector);
+			clear_bit(R5_LOCKED, &sh->dev[i].flags);
+			set_bit(STRIPE_HANDLE, &sh->state);
+		}
+	}
+}
+
+static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
+{
+	if (sh->raid_conf->level == 6)
+		handle_stripe6(sh, tmp_page);
+	else
+		handle_stripe5(sh);
+}
+
+
+
 static void raid5_activate_delayed(raid5_conf_t *conf)
 {
 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
@@ -1753,7 +2589,7 @@ static int make_request(request_queue_t *q, struct bio * bi)
 
 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
 		DEFINE_WAIT(w);
-		int disks;
+		int disks, data_disks;
 
 	retry:
 		prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
@@ -1781,7 +2617,9 @@ static int make_request(request_queue_t *q, struct bio * bi)
 			}
 			spin_unlock_irq(&conf->device_lock);
 		}
- 		new_sector = raid5_compute_sector(logical_sector, disks, disks - 1,
+		data_disks = disks - conf->max_degraded;
+
+ 		new_sector = raid5_compute_sector(logical_sector, disks, data_disks,
 						  &dd_idx, &pd_idx, conf);
 		PRINTK("raid5: make_request, sector %llu logical %llu\n",
 			(unsigned long long)new_sector, 
@@ -1833,7 +2671,7 @@ static int make_request(request_queue_t *q, struct bio * bi)
 			}
 			finish_wait(&conf->wait_for_overlap, &w);
 			raid5_plug_device(conf);
-			handle_stripe(sh);
+			handle_stripe(sh, NULL);
 			release_stripe(sh);
 		} else {
 			/* cannot get stripe for read-ahead, just give-up */
@@ -1849,7 +2687,7 @@ static int make_request(request_queue_t *q, struct bio * bi)
 	if (remaining == 0) {
 		int bytes = bi->bi_size;
 
-		if ( bio_data_dir(bi) == WRITE )
+		if ( rw == WRITE )
 			md_write_end(mddev);
 		bi->bi_size = 0;
 		bi->bi_end_io(bi, bytes, 0);
@@ -1857,17 +2695,141 @@ static int make_request(request_queue_t *q, struct bio * bi)
 	return 0;
 }
 
-/* FIXME go_faster isn't used */
-static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
+static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
 {
+	/* reshaping is quite different to recovery/resync so it is
+	 * handled quite separately ... here.
+	 *
+	 * On each call to sync_request, we gather one chunk worth of
+	 * destination stripes and flag them as expanding.
+	 * Then we find all the source stripes and request reads.
+	 * As the reads complete, handle_stripe will copy the data
+	 * into the destination stripe and release that stripe.
+	 */
 	raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
 	struct stripe_head *sh;
 	int pd_idx;
 	sector_t first_sector, last_sector;
+	int raid_disks;
+	int data_disks;
+	int i;
+	int dd_idx;
+	sector_t writepos, safepos, gap;
+
+	if (sector_nr == 0 &&
+	    conf->expand_progress != 0) {
+		/* restarting in the middle, skip the initial sectors */
+		sector_nr = conf->expand_progress;
+		sector_div(sector_nr, conf->raid_disks-1);
+		*skipped = 1;
+		return sector_nr;
+	}
+
+	/* we update the metadata when there is more than 3Meg
+	 * in the block range (that is rather arbitrary, should
+	 * probably be time based) or when the data about to be
+	 * copied would over-write the source of the data at
+	 * the front of the range.
+	 * i.e. one new_stripe forward from expand_progress new_maps
+	 * to after where expand_lo old_maps to
+	 */
+	writepos = conf->expand_progress +
+		conf->chunk_size/512*(conf->raid_disks-1);
+	sector_div(writepos, conf->raid_disks-1);
+	safepos = conf->expand_lo;
+	sector_div(safepos, conf->previous_raid_disks-1);
+	gap = conf->expand_progress - conf->expand_lo;
+
+	if (writepos >= safepos ||
+	    gap > (conf->raid_disks-1)*3000*2 /*3Meg*/) {
+		/* Cannot proceed until we've updated the superblock... */
+		wait_event(conf->wait_for_overlap,
+			   atomic_read(&conf->reshape_stripes)==0);
+		mddev->reshape_position = conf->expand_progress;
+		mddev->sb_dirty = 1;
+		md_wakeup_thread(mddev->thread);
+		wait_event(mddev->sb_wait, mddev->sb_dirty == 0 ||
+			   kthread_should_stop());
+		spin_lock_irq(&conf->device_lock);
+		conf->expand_lo = mddev->reshape_position;
+		spin_unlock_irq(&conf->device_lock);
+		wake_up(&conf->wait_for_overlap);
+	}
+
+	for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
+		int j;
+		int skipped = 0;
+		pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
+		sh = get_active_stripe(conf, sector_nr+i,
+				       conf->raid_disks, pd_idx, 0);
+		set_bit(STRIPE_EXPANDING, &sh->state);
+		atomic_inc(&conf->reshape_stripes);
+		/* If any of this stripe is beyond the end of the old
+		 * array, then we need to zero those blocks
+		 */
+		for (j=sh->disks; j--;) {
+			sector_t s;
+			if (j == sh->pd_idx)
+				continue;
+			s = compute_blocknr(sh, j);
+			if (s < (mddev->array_size<<1)) {
+				skipped = 1;
+				continue;
+			}
+			memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
+			set_bit(R5_Expanded, &sh->dev[j].flags);
+			set_bit(R5_UPTODATE, &sh->dev[j].flags);
+		}
+		if (!skipped) {
+			set_bit(STRIPE_EXPAND_READY, &sh->state);
+			set_bit(STRIPE_HANDLE, &sh->state);
+		}
+		release_stripe(sh);
+	}
+	spin_lock_irq(&conf->device_lock);
+	conf->expand_progress = (sector_nr + i)*(conf->raid_disks-1);
+	spin_unlock_irq(&conf->device_lock);
+	/* Ok, those stripe are ready. We can start scheduling
+	 * reads on the source stripes.
+	 * The source stripes are determined by mapping the first and last
+	 * block on the destination stripes.
+	 */
+	raid_disks = conf->previous_raid_disks;
+	data_disks = raid_disks - 1;
+	first_sector =
+		raid5_compute_sector(sector_nr*(conf->raid_disks-1),
+				     raid_disks, data_disks,
+				     &dd_idx, &pd_idx, conf);
+	last_sector =
+		raid5_compute_sector((sector_nr+conf->chunk_size/512)
+				     *(conf->raid_disks-1) -1,
+				     raid_disks, data_disks,
+				     &dd_idx, &pd_idx, conf);
+	if (last_sector >= (mddev->size<<1))
+		last_sector = (mddev->size<<1)-1;
+	while (first_sector <= last_sector) {
+		pd_idx = stripe_to_pdidx(first_sector, conf, conf->previous_raid_disks);
+		sh = get_active_stripe(conf, first_sector,
+				       conf->previous_raid_disks, pd_idx, 0);
+		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
+		set_bit(STRIPE_HANDLE, &sh->state);
+		release_stripe(sh);
+		first_sector += STRIPE_SECTORS;
+	}
+	return conf->chunk_size>>9;
+}
+
+/* FIXME go_faster isn't used */
+static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
+{
+	raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
+	struct stripe_head *sh;
+	int pd_idx;
 	int raid_disks = conf->raid_disks;
-	int data_disks = raid_disks-1;
 	sector_t max_sector = mddev->size << 1;
 	int sync_blocks;
+	int still_degraded = 0;
+	int i;
 
 	if (sector_nr >= max_sector) {
 		/* just being told to finish up .. nothing much to do */
@@ -1880,134 +2842,22 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
 		if (mddev->curr_resync < max_sector) /* aborted */
 			bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
 					&sync_blocks, 1);
-		else /* compelted sync */
+		else /* completed sync */
 			conf->fullsync = 0;
 		bitmap_close_sync(mddev->bitmap);
 
 		return 0;
 	}
 
-	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
-		/* reshaping is quite different to recovery/resync so it is
-		 * handled quite separately ... here.
-		 *
-		 * On each call to sync_request, we gather one chunk worth of
-		 * destination stripes and flag them as expanding.
-		 * Then we find all the source stripes and request reads.
-		 * As the reads complete, handle_stripe will copy the data
-		 * into the destination stripe and release that stripe.
-		 */
-		int i;
-		int dd_idx;
-		sector_t writepos, safepos, gap;
-
-		if (sector_nr == 0 &&
-		    conf->expand_progress != 0) {
-			/* restarting in the middle, skip the initial sectors */
-			sector_nr = conf->expand_progress;
-			sector_div(sector_nr, conf->raid_disks-1);
-			*skipped = 1;
-			return sector_nr;
-		}
-
-		/* we update the metadata when there is more than 3Meg
-		 * in the block range (that is rather arbitrary, should
-		 * probably be time based) or when the data about to be
-		 * copied would over-write the source of the data at
-		 * the front of the range.
-		 * i.e. one new_stripe forward from expand_progress new_maps
-		 * to after where expand_lo old_maps to
-		 */
-		writepos = conf->expand_progress +
-			conf->chunk_size/512*(conf->raid_disks-1);
-		sector_div(writepos, conf->raid_disks-1);
-		safepos = conf->expand_lo;
-		sector_div(safepos, conf->previous_raid_disks-1);
-		gap = conf->expand_progress - conf->expand_lo;
-
-		if (writepos >= safepos ||
-		    gap > (conf->raid_disks-1)*3000*2 /*3Meg*/) {
-			/* Cannot proceed until we've updated the superblock... */
-			wait_event(conf->wait_for_overlap,
-				   atomic_read(&conf->reshape_stripes)==0);
-			mddev->reshape_position = conf->expand_progress;
-			mddev->sb_dirty = 1;
-			md_wakeup_thread(mddev->thread);
-			wait_event(mddev->sb_wait, mddev->sb_dirty == 0 ||
-				   kthread_should_stop());
-			spin_lock_irq(&conf->device_lock);
-			conf->expand_lo = mddev->reshape_position;
-			spin_unlock_irq(&conf->device_lock);
-			wake_up(&conf->wait_for_overlap);
-		}
-
-		for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
-			int j;
-			int skipped = 0;
-			pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
-			sh = get_active_stripe(conf, sector_nr+i,
-					       conf->raid_disks, pd_idx, 0);
-			set_bit(STRIPE_EXPANDING, &sh->state);
-			atomic_inc(&conf->reshape_stripes);
-			/* If any of this stripe is beyond the end of the old
-			 * array, then we need to zero those blocks
-			 */
-			for (j=sh->disks; j--;) {
-				sector_t s;
-				if (j == sh->pd_idx)
-					continue;
-				s = compute_blocknr(sh, j);
-				if (s < (mddev->array_size<<1)) {
-					skipped = 1;
-					continue;
-				}
-				memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
-				set_bit(R5_Expanded, &sh->dev[j].flags);
-				set_bit(R5_UPTODATE, &sh->dev[j].flags);
-			}
-			if (!skipped) {
-				set_bit(STRIPE_EXPAND_READY, &sh->state);
-				set_bit(STRIPE_HANDLE, &sh->state);
-			}
-			release_stripe(sh);
-		}
-		spin_lock_irq(&conf->device_lock);
-		conf->expand_progress = (sector_nr + i)*(conf->raid_disks-1);
-		spin_unlock_irq(&conf->device_lock);
-		/* Ok, those stripe are ready. We can start scheduling
-		 * reads on the source stripes.
-		 * The source stripes are determined by mapping the first and last
-		 * block on the destination stripes.
-		 */
-		raid_disks = conf->previous_raid_disks;
-		data_disks = raid_disks - 1;
-		first_sector =
-			raid5_compute_sector(sector_nr*(conf->raid_disks-1),
-					     raid_disks, data_disks,
-					     &dd_idx, &pd_idx, conf);
-		last_sector =
-			raid5_compute_sector((sector_nr+conf->chunk_size/512)
-					       *(conf->raid_disks-1) -1,
-					     raid_disks, data_disks,
-					     &dd_idx, &pd_idx, conf);
-		if (last_sector >= (mddev->size<<1))
-			last_sector = (mddev->size<<1)-1;
-		while (first_sector <= last_sector) {
-			pd_idx = stripe_to_pdidx(first_sector, conf, conf->previous_raid_disks);
-			sh = get_active_stripe(conf, first_sector,
-					       conf->previous_raid_disks, pd_idx, 0);
-			set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
-			set_bit(STRIPE_HANDLE, &sh->state);
-			release_stripe(sh);
-			first_sector += STRIPE_SECTORS;
-		}
-		return conf->chunk_size>>9;
-	}
-	/* if there is 1 or more failed drives and we are trying
+	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+		return reshape_request(mddev, sector_nr, skipped);
+
+	/* if there is too many failed drives and we are trying
 	 * to resync, then assert that we are finished, because there is
 	 * nothing we can do.
 	 */
-	if (mddev->degraded >= 1 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
+	if (mddev->degraded >= conf->max_degraded &&
+	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
 		sector_t rv = (mddev->size << 1) - sector_nr;
 		*skipped = 1;
 		return rv;
@@ -2026,17 +2876,26 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
 	if (sh == NULL) {
 		sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
 		/* make sure we don't swamp the stripe cache if someone else
-		 * is trying to get access 
+		 * is trying to get access
 		 */
 		schedule_timeout_uninterruptible(1);
 	}
-	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 0);
-	spin_lock(&sh->lock);	
+	/* Need to check if array will still be degraded after recovery/resync
+	 * We don't need to check the 'failed' flag as when that gets set,
+	 * recovery aborts.
+	 */
+	for (i=0; i<mddev->raid_disks; i++)
+		if (conf->disks[i].rdev == NULL)
+			still_degraded = 1;
+
+	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
+
+	spin_lock(&sh->lock);
 	set_bit(STRIPE_SYNCING, &sh->state);
 	clear_bit(STRIPE_INSYNC, &sh->state);
 	spin_unlock(&sh->lock);
 
-	handle_stripe(sh);
+	handle_stripe(sh, NULL);
 	release_stripe(sh);
 
 	return STRIPE_SECTORS;
@@ -2091,7 +2950,7 @@ static void raid5d (mddev_t *mddev)
 		spin_unlock_irq(&conf->device_lock);
 		
 		handled++;
-		handle_stripe(sh);
+		handle_stripe(sh, conf->spare_page);
 		release_stripe(sh);
 
 		spin_lock_irq(&conf->device_lock);
@@ -2181,8 +3040,8 @@ static int run(mddev_t *mddev)
 	struct disk_info *disk;
 	struct list_head *tmp;
 
-	if (mddev->level != 5 && mddev->level != 4) {
-		printk(KERN_ERR "raid5: %s: raid level not set to 4/5 (%d)\n",
+	if (mddev->level != 5 && mddev->level != 4 && mddev->level != 6) {
+		printk(KERN_ERR "raid5: %s: raid level not set to 4/5/6 (%d)\n",
 		       mdname(mddev), mddev->level);
 		return -EIO;
 	}
@@ -2251,6 +3110,11 @@ static int run(mddev_t *mddev)
 	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
 		goto abort;
 
+	if (mddev->level == 6) {
+		conf->spare_page = alloc_page(GFP_KERNEL);
+		if (!conf->spare_page)
+			goto abort;
+	}
 	spin_lock_init(&conf->device_lock);
 	init_waitqueue_head(&conf->wait_for_stripe);
 	init_waitqueue_head(&conf->wait_for_overlap);
@@ -2282,12 +3146,16 @@ static int run(mddev_t *mddev)
 	}
 
 	/*
-	 * 0 for a fully functional array, 1 for a degraded array.
+	 * 0 for a fully functional array, 1 or 2 for a degraded array.
 	 */
 	mddev->degraded = conf->failed_disks = conf->raid_disks - conf->working_disks;
 	conf->mddev = mddev;
 	conf->chunk_size = mddev->chunk_size;
 	conf->level = mddev->level;
+	if (conf->level == 6)
+		conf->max_degraded = 2;
+	else
+		conf->max_degraded = 1;
 	conf->algorithm = mddev->layout;
 	conf->max_nr_stripes = NR_STRIPES;
 	conf->expand_progress = mddev->reshape_position;
@@ -2296,6 +3164,11 @@ static int run(mddev_t *mddev)
 	mddev->size &= ~(mddev->chunk_size/1024 -1);
 	mddev->resync_max_sectors = mddev->size << 1;
 
+	if (conf->level == 6 && conf->raid_disks < 4) {
+		printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
+		       mdname(mddev), conf->raid_disks);
+		goto abort;
+	}
 	if (!conf->chunk_size || conf->chunk_size % 4) {
 		printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
 			conf->chunk_size, mdname(mddev));
@@ -2307,14 +3180,14 @@ static int run(mddev_t *mddev)
 			conf->algorithm, mdname(mddev));
 		goto abort;
 	}
-	if (mddev->degraded > 1) {
+	if (mddev->degraded > conf->max_degraded) {
 		printk(KERN_ERR "raid5: not enough operational devices for %s"
 			" (%d/%d failed)\n",
 			mdname(mddev), conf->failed_disks, conf->raid_disks);
 		goto abort;
 	}
 
-	if (mddev->degraded == 1 &&
+	if (mddev->degraded > 0 &&
 	    mddev->recovery_cp != MaxSector) {
 		if (mddev->ok_start_degraded)
 			printk(KERN_WARNING
@@ -2379,11 +3252,12 @@ static int run(mddev_t *mddev)
 	}
 
 	/* read-ahead size must cover two whole stripes, which is
-	 * 2 * (n-1) * chunksize where 'n' is the number of raid devices
+	 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
 	 */
 	{
-		int stripe = (mddev->raid_disks-1) * mddev->chunk_size
-			/ PAGE_SIZE;
+		int data_disks = conf->previous_raid_disks - conf->max_degraded;
+		int stripe = data_disks *
+			(mddev->chunk_size / PAGE_SIZE);
 		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
 			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
 	}
@@ -2393,12 +3267,14 @@ static int run(mddev_t *mddev)
 
 	mddev->queue->unplug_fn = raid5_unplug_device;
 	mddev->queue->issue_flush_fn = raid5_issue_flush;
-	mddev->array_size =  mddev->size * (conf->previous_raid_disks - 1);
+	mddev->array_size =  mddev->size * (conf->previous_raid_disks -
+					    conf->max_degraded);
 
 	return 0;
 abort:
 	if (conf) {
 		print_raid5_conf(conf);
+		safe_put_page(conf->spare_page);
 		kfree(conf->disks);
 		kfree(conf->stripe_hashtbl);
 		kfree(conf);
@@ -2427,23 +3303,23 @@ static int stop(mddev_t *mddev)
 }
 
 #if RAID5_DEBUG
-static void print_sh (struct stripe_head *sh)
+static void print_sh (struct seq_file *seq, struct stripe_head *sh)
 {
 	int i;
 
-	printk("sh %llu, pd_idx %d, state %ld.\n",
-		(unsigned long long)sh->sector, sh->pd_idx, sh->state);
-	printk("sh %llu,  count %d.\n",
-		(unsigned long long)sh->sector, atomic_read(&sh->count));
-	printk("sh %llu, ", (unsigned long long)sh->sector);
+	seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
+		   (unsigned long long)sh->sector, sh->pd_idx, sh->state);
+	seq_printf(seq, "sh %llu,  count %d.\n",
+		   (unsigned long long)sh->sector, atomic_read(&sh->count));
+	seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
 	for (i = 0; i < sh->disks; i++) {
-		printk("(cache%d: %p %ld) ", 
-			i, sh->dev[i].page, sh->dev[i].flags);
+		seq_printf(seq, "(cache%d: %p %ld) ",
+			   i, sh->dev[i].page, sh->dev[i].flags);
 	}
-	printk("\n");
+	seq_printf(seq, "\n");
 }
 
-static void printall (raid5_conf_t *conf)
+static void printall (struct seq_file *seq, raid5_conf_t *conf)
 {
 	struct stripe_head *sh;
 	struct hlist_node *hn;
@@ -2454,7 +3330,7 @@ static void printall (raid5_conf_t *conf)
 		hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
 			if (sh->raid_conf != conf)
 				continue;
-			print_sh(sh);
+			print_sh(seq, sh);
 		}
 	}
 	spin_unlock_irq(&conf->device_lock);
@@ -2474,9 +3350,8 @@ static void status (struct seq_file *seq, mddev_t *mddev)
 			       test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
 	seq_printf (seq, "]");
 #if RAID5_DEBUG
-#define D(x) \
-	seq_printf (seq, "<"#x":%d>", atomic_read(&conf->x))
-	printall(conf);
+	seq_printf (seq, "\n");
+	printall(seq, conf);
 #endif
 }
 
@@ -2560,14 +3435,20 @@ static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 	int disk;
 	struct disk_info *p;
 
-	if (mddev->degraded > 1)
+	if (mddev->degraded > conf->max_degraded)
 		/* no point adding a device */
 		return 0;
 
 	/*
-	 * find the disk ...
+	 * find the disk ... but prefer rdev->saved_raid_disk
+	 * if possible.
 	 */
-	for (disk=0; disk < conf->raid_disks; disk++)
+	if (rdev->saved_raid_disk >= 0 &&
+	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
+		disk = rdev->saved_raid_disk;
+	else
+		disk = 0;
+	for ( ; disk < conf->raid_disks; disk++)
 		if ((p=conf->disks + disk)->rdev == NULL) {
 			clear_bit(In_sync, &rdev->flags);
 			rdev->raid_disk = disk;
@@ -2590,8 +3471,10 @@ static int raid5_resize(mddev_t *mddev, sector_t sectors)
 	 * any io in the removed space completes, but it hardly seems
 	 * worth it.
 	 */
+	raid5_conf_t *conf = mddev_to_conf(mddev);
+
 	sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
-	mddev->array_size = (sectors * (mddev->raid_disks-1))>>1;
+	mddev->array_size = (sectors * (mddev->raid_disks-conf->max_degraded))>>1;
 	set_capacity(mddev->gendisk, mddev->array_size << 1);
 	mddev->changed = 1;
 	if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
@@ -2680,6 +3563,7 @@ static int raid5_start_reshape(mddev_t *mddev)
 				set_bit(In_sync, &rdev->flags);
 				conf->working_disks++;
 				added_devices++;
+				rdev->recovery_offset = 0;
 				sprintf(nm, "rd%d", rdev->raid_disk);
 				sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
 			} else
@@ -2731,6 +3615,17 @@ static void end_reshape(raid5_conf_t *conf)
 		conf->expand_progress = MaxSector;
 		spin_unlock_irq(&conf->device_lock);
 		conf->mddev->reshape_position = MaxSector;
+
+		/* read-ahead size must cover two whole stripes, which is
+		 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
+		 */
+		{
+			int data_disks = conf->previous_raid_disks - conf->max_degraded;
+			int stripe = data_disks *
+				(conf->mddev->chunk_size / PAGE_SIZE);
+			if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
+				conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
+		}
 	}
 }
 
@@ -2762,6 +3657,23 @@ static void raid5_quiesce(mddev_t *mddev, int state)
 	}
 }
 
+static struct mdk_personality raid6_personality =
+{
+	.name		= "raid6",
+	.level		= 6,
+	.owner		= THIS_MODULE,
+	.make_request	= make_request,
+	.run		= run,
+	.stop		= stop,
+	.status		= status,
+	.error_handler	= error,
+	.hot_add_disk	= raid5_add_disk,
+	.hot_remove_disk= raid5_remove_disk,
+	.spare_active	= raid5_spare_active,
+	.sync_request	= sync_request,
+	.resize		= raid5_resize,
+	.quiesce	= raid5_quiesce,
+};
 static struct mdk_personality raid5_personality =
 {
 	.name		= "raid5",
@@ -2804,6 +3716,12 @@ static struct mdk_personality raid4_personality =
 
 static int __init raid5_init(void)
 {
+	int e;
+
+	e = raid6_select_algo();
+	if ( e )
+		return e;
+	register_md_personality(&raid6_personality);
 	register_md_personality(&raid5_personality);
 	register_md_personality(&raid4_personality);
 	return 0;
@@ -2811,6 +3729,7 @@ static int __init raid5_init(void)
 
 static void raid5_exit(void)
 {
+	unregister_md_personality(&raid6_personality);
 	unregister_md_personality(&raid5_personality);
 	unregister_md_personality(&raid4_personality);
 }
@@ -2823,3 +3742,10 @@ MODULE_ALIAS("md-raid5");
 MODULE_ALIAS("md-raid4");
 MODULE_ALIAS("md-level-5");
 MODULE_ALIAS("md-level-4");
+MODULE_ALIAS("md-personality-8"); /* RAID6 */
+MODULE_ALIAS("md-raid6");
+MODULE_ALIAS("md-level-6");
+
+/* This used to be two separate modules, they were: */
+MODULE_ALIAS("raid5");
+MODULE_ALIAS("raid6");
diff --git a/drivers/md/raid6algos.c b/drivers/md/raid6algos.c
index 51c63c0cf1c..92657615657 100644
--- a/drivers/md/raid6algos.c
+++ b/drivers/md/raid6algos.c
@@ -139,15 +139,14 @@ int __init raid6_select_algo(void)
 		}
 	}
 
-	if ( best )
+	if (best) {
 		printk("raid6: using algorithm %s (%ld MB/s)\n",
 		       best->name,
 		       (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
-	else
+		raid6_call = *best;
+	} else
 		printk("raid6: Yikes!  No algorithm found!\n");
 
-	raid6_call = *best;
-
 	free_pages((unsigned long)syndromes, 1);
 
 	return best ? 0 : -EINVAL;
diff --git a/drivers/md/raid6main.c b/drivers/md/raid6main.c
deleted file mode 100644
index bc69355e010..00000000000
--- a/drivers/md/raid6main.c
+++ /dev/null
@@ -1,2427 +0,0 @@
-/*
- * raid6main.c : Multiple Devices driver for Linux
- *	   Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
- *	   Copyright (C) 1999, 2000 Ingo Molnar
- *	   Copyright (C) 2002, 2003 H. Peter Anvin
- *
- * RAID-6 management functions.  This code is derived from raid5.c.
- * Last merge from raid5.c bkcvs version 1.79 (kernel 2.6.1).
- *
- * Thanks to Penguin Computing for making the RAID-6 development possible
- * by donating a test server!
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * You should have received a copy of the GNU General Public License
- * (for example /usr/src/linux/COPYING); if not, write to the Free
- * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-
-
-#include <linux/config.h>
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/highmem.h>
-#include <linux/bitops.h>
-#include <asm/atomic.h>
-#include "raid6.h"
-
-#include <linux/raid/bitmap.h>
-
-/*
- * Stripe cache
- */
-
-#define NR_STRIPES		256
-#define STRIPE_SIZE		PAGE_SIZE
-#define STRIPE_SHIFT		(PAGE_SHIFT - 9)
-#define STRIPE_SECTORS		(STRIPE_SIZE>>9)
-#define	IO_THRESHOLD		1
-#define NR_HASH			(PAGE_SIZE / sizeof(struct hlist_head))
-#define HASH_MASK		(NR_HASH - 1)
-
-#define stripe_hash(conf, sect)	(&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
-
-/* bio's attached to a stripe+device for I/O are linked together in bi_sector
- * order without overlap.  There may be several bio's per stripe+device, and
- * a bio could span several devices.
- * When walking this list for a particular stripe+device, we must never proceed
- * beyond a bio that extends past this device, as the next bio might no longer
- * be valid.
- * This macro is used to determine the 'next' bio in the list, given the sector
- * of the current stripe+device
- */
-#define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
-/*
- * The following can be used to debug the driver
- */
-#define RAID6_DEBUG	0	/* Extremely verbose printk */
-#define RAID6_PARANOIA	1	/* Check spinlocks */
-#define RAID6_DUMPSTATE 0	/* Include stripe cache state in /proc/mdstat */
-#if RAID6_PARANOIA && defined(CONFIG_SMP)
-# define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
-#else
-# define CHECK_DEVLOCK()
-#endif
-
-#define PRINTK(x...) ((void)(RAID6_DEBUG && printk(KERN_DEBUG x)))
-#if RAID6_DEBUG
-#undef inline
-#undef __inline__
-#define inline
-#define __inline__
-#endif
-
-#if !RAID6_USE_EMPTY_ZERO_PAGE
-/* In .bss so it's zeroed */
-const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
-#endif
-
-static inline int raid6_next_disk(int disk, int raid_disks)
-{
-	disk++;
-	return (disk < raid_disks) ? disk : 0;
-}
-
-static void print_raid6_conf (raid6_conf_t *conf);
-
-static void __release_stripe(raid6_conf_t *conf, struct stripe_head *sh)
-{
-	if (atomic_dec_and_test(&sh->count)) {
-		BUG_ON(!list_empty(&sh->lru));
-		BUG_ON(atomic_read(&conf->active_stripes)==0);
-		if (test_bit(STRIPE_HANDLE, &sh->state)) {
-			if (test_bit(STRIPE_DELAYED, &sh->state))
-				list_add_tail(&sh->lru, &conf->delayed_list);
-			else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
-				 conf->seq_write == sh->bm_seq)
-				list_add_tail(&sh->lru, &conf->bitmap_list);
-			else {
-				clear_bit(STRIPE_BIT_DELAY, &sh->state);
-				list_add_tail(&sh->lru, &conf->handle_list);
-			}
-			md_wakeup_thread(conf->mddev->thread);
-		} else {
-			if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
-				atomic_dec(&conf->preread_active_stripes);
-				if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
-					md_wakeup_thread(conf->mddev->thread);
-			}
-			list_add_tail(&sh->lru, &conf->inactive_list);
-			atomic_dec(&conf->active_stripes);
-			if (!conf->inactive_blocked ||
-			    atomic_read(&conf->active_stripes) < (conf->max_nr_stripes*3/4))
-				wake_up(&conf->wait_for_stripe);
-		}
-	}
-}
-static void release_stripe(struct stripe_head *sh)
-{
-	raid6_conf_t *conf = sh->raid_conf;
-	unsigned long flags;
-
-	spin_lock_irqsave(&conf->device_lock, flags);
-	__release_stripe(conf, sh);
-	spin_unlock_irqrestore(&conf->device_lock, flags);
-}
-
-static inline void remove_hash(struct stripe_head *sh)
-{
-	PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
-
-	hlist_del_init(&sh->hash);
-}
-
-static inline void insert_hash(raid6_conf_t *conf, struct stripe_head *sh)
-{
-	struct hlist_head *hp = stripe_hash(conf, sh->sector);
-
-	PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
-
-	CHECK_DEVLOCK();
-	hlist_add_head(&sh->hash, hp);
-}
-
-
-/* find an idle stripe, make sure it is unhashed, and return it. */
-static struct stripe_head *get_free_stripe(raid6_conf_t *conf)
-{
-	struct stripe_head *sh = NULL;
-	struct list_head *first;
-
-	CHECK_DEVLOCK();
-	if (list_empty(&conf->inactive_list))
-		goto out;
-	first = conf->inactive_list.next;
-	sh = list_entry(first, struct stripe_head, lru);
-	list_del_init(first);
-	remove_hash(sh);
-	atomic_inc(&conf->active_stripes);
-out:
-	return sh;
-}
-
-static void shrink_buffers(struct stripe_head *sh, int num)
-{
-	struct page *p;
-	int i;
-
-	for (i=0; i<num ; i++) {
-		p = sh->dev[i].page;
-		if (!p)
-			continue;
-		sh->dev[i].page = NULL;
-		put_page(p);
-	}
-}
-
-static int grow_buffers(struct stripe_head *sh, int num)
-{
-	int i;
-
-	for (i=0; i<num; i++) {
-		struct page *page;
-
-		if (!(page = alloc_page(GFP_KERNEL))) {
-			return 1;
-		}
-		sh->dev[i].page = page;
-	}
-	return 0;
-}
-
-static void raid6_build_block (struct stripe_head *sh, int i);
-
-static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx)
-{
-	raid6_conf_t *conf = sh->raid_conf;
-	int disks = conf->raid_disks, i;
-
-	BUG_ON(atomic_read(&sh->count) != 0);
-	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
-
-	CHECK_DEVLOCK();
-	PRINTK("init_stripe called, stripe %llu\n",
-		(unsigned long long)sh->sector);
-
-	remove_hash(sh);
-
-	sh->sector = sector;
-	sh->pd_idx = pd_idx;
-	sh->state = 0;
-
-	for (i=disks; i--; ) {
-		struct r5dev *dev = &sh->dev[i];
-
-		if (dev->toread || dev->towrite || dev->written ||
-		    test_bit(R5_LOCKED, &dev->flags)) {
-			PRINTK("sector=%llx i=%d %p %p %p %d\n",
-			       (unsigned long long)sh->sector, i, dev->toread,
-			       dev->towrite, dev->written,
-			       test_bit(R5_LOCKED, &dev->flags));
-			BUG();
-		}
-		dev->flags = 0;
-		raid6_build_block(sh, i);
-	}
-	insert_hash(conf, sh);
-}
-
-static struct stripe_head *__find_stripe(raid6_conf_t *conf, sector_t sector)
-{
-	struct stripe_head *sh;
-	struct hlist_node *hn;
-
-	CHECK_DEVLOCK();
-	PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
-	hlist_for_each_entry (sh, hn,  stripe_hash(conf, sector), hash)
-		if (sh->sector == sector)
-			return sh;
-	PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
-	return NULL;
-}
-
-static void unplug_slaves(mddev_t *mddev);
-
-static struct stripe_head *get_active_stripe(raid6_conf_t *conf, sector_t sector,
-					     int pd_idx, int noblock)
-{
-	struct stripe_head *sh;
-
-	PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector);
-
-	spin_lock_irq(&conf->device_lock);
-
-	do {
-		wait_event_lock_irq(conf->wait_for_stripe,
-				    conf->quiesce == 0,
-				    conf->device_lock, /* nothing */);
-		sh = __find_stripe(conf, sector);
-		if (!sh) {
-			if (!conf->inactive_blocked)
-				sh = get_free_stripe(conf);
-			if (noblock && sh == NULL)
-				break;
-			if (!sh) {
-				conf->inactive_blocked = 1;
-				wait_event_lock_irq(conf->wait_for_stripe,
-						    !list_empty(&conf->inactive_list) &&
-						    (atomic_read(&conf->active_stripes)
-						     < (conf->max_nr_stripes *3/4)
-						     || !conf->inactive_blocked),
-						    conf->device_lock,
-						    unplug_slaves(conf->mddev);
-					);
-				conf->inactive_blocked = 0;
-			} else
-				init_stripe(sh, sector, pd_idx);
-		} else {
-			if (atomic_read(&sh->count)) {
-				BUG_ON(!list_empty(&sh->lru));
-			} else {
-				if (!test_bit(STRIPE_HANDLE, &sh->state))
-					atomic_inc(&conf->active_stripes);
-				BUG_ON(list_empty(&sh->lru));
-				list_del_init(&sh->lru);
-			}
-		}
-	} while (sh == NULL);
-
-	if (sh)
-		atomic_inc(&sh->count);
-
-	spin_unlock_irq(&conf->device_lock);
-	return sh;
-}
-
-static int grow_one_stripe(raid6_conf_t *conf)
-{
-	struct stripe_head *sh;
-	sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
-	if (!sh)
-		return 0;
-	memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
-	sh->raid_conf = conf;
-	spin_lock_init(&sh->lock);
-
-	if (grow_buffers(sh, conf->raid_disks)) {
-		shrink_buffers(sh, conf->raid_disks);
-		kmem_cache_free(conf->slab_cache, sh);
-		return 0;
-	}
-	/* we just created an active stripe so... */
-	atomic_set(&sh->count, 1);
-	atomic_inc(&conf->active_stripes);
-	INIT_LIST_HEAD(&sh->lru);
-	release_stripe(sh);
-	return 1;
-}
-
-static int grow_stripes(raid6_conf_t *conf, int num)
-{
-	kmem_cache_t *sc;
-	int devs = conf->raid_disks;
-
-	sprintf(conf->cache_name[0], "raid6/%s", mdname(conf->mddev));
-
-	sc = kmem_cache_create(conf->cache_name[0],
-			       sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
-			       0, 0, NULL, NULL);
-	if (!sc)
-		return 1;
-	conf->slab_cache = sc;
-	while (num--)
-		if (!grow_one_stripe(conf))
-			return 1;
-	return 0;
-}
-
-static int drop_one_stripe(raid6_conf_t *conf)
-{
-	struct stripe_head *sh;
-	spin_lock_irq(&conf->device_lock);
-	sh = get_free_stripe(conf);
-	spin_unlock_irq(&conf->device_lock);
-	if (!sh)
-		return 0;
-	BUG_ON(atomic_read(&sh->count));
-	shrink_buffers(sh, conf->raid_disks);
-	kmem_cache_free(conf->slab_cache, sh);
-	atomic_dec(&conf->active_stripes);
-	return 1;
-}
-
-static void shrink_stripes(raid6_conf_t *conf)
-{
-	while (drop_one_stripe(conf))
-		;
-
-	if (conf->slab_cache)
-		kmem_cache_destroy(conf->slab_cache);
-	conf->slab_cache = NULL;
-}
-
-static int raid6_end_read_request(struct bio * bi, unsigned int bytes_done,
-				  int error)
-{
- 	struct stripe_head *sh = bi->bi_private;
-	raid6_conf_t *conf = sh->raid_conf;
-	int disks = conf->raid_disks, i;
-	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
-
-	if (bi->bi_size)
-		return 1;
-
-	for (i=0 ; i<disks; i++)
-		if (bi == &sh->dev[i].req)
-			break;
-
-	PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n",
-		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
-		uptodate);
-	if (i == disks) {
-		BUG();
-		return 0;
-	}
-
-	if (uptodate) {
-#if 0
-		struct bio *bio;
-		unsigned long flags;
-		spin_lock_irqsave(&conf->device_lock, flags);
-		/* we can return a buffer if we bypassed the cache or
-		 * if the top buffer is not in highmem.  If there are
-		 * multiple buffers, leave the extra work to
-		 * handle_stripe
-		 */
-		buffer = sh->bh_read[i];
-		if (buffer &&
-		    (!PageHighMem(buffer->b_page)
-		     || buffer->b_page == bh->b_page )
-			) {
-			sh->bh_read[i] = buffer->b_reqnext;
-			buffer->b_reqnext = NULL;
-		} else
-			buffer = NULL;
-		spin_unlock_irqrestore(&conf->device_lock, flags);
-		if (sh->bh_page[i]==bh->b_page)
-			set_buffer_uptodate(bh);
-		if (buffer) {
-			if (buffer->b_page != bh->b_page)
-				memcpy(buffer->b_data, bh->b_data, bh->b_size);
-			buffer->b_end_io(buffer, 1);
-		}
-#else
-		set_bit(R5_UPTODATE, &sh->dev[i].flags);
-#endif
-		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
-			printk(KERN_INFO "raid6: read error corrected!!\n");
-			clear_bit(R5_ReadError, &sh->dev[i].flags);
-			clear_bit(R5_ReWrite, &sh->dev[i].flags);
-		}
-		if (atomic_read(&conf->disks[i].rdev->read_errors))
-			atomic_set(&conf->disks[i].rdev->read_errors, 0);
-	} else {
-		int retry = 0;
-		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
-		atomic_inc(&conf->disks[i].rdev->read_errors);
-		if (conf->mddev->degraded)
-			printk(KERN_WARNING "raid6: read error not correctable.\n");
-		else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
-			/* Oh, no!!! */
-			printk(KERN_WARNING "raid6: read error NOT corrected!!\n");
-		else if (atomic_read(&conf->disks[i].rdev->read_errors)
-			 > conf->max_nr_stripes)
-			printk(KERN_WARNING
-			       "raid6: Too many read errors, failing device.\n");
-		else
-			retry = 1;
-		if (retry)
-			set_bit(R5_ReadError, &sh->dev[i].flags);
-		else {
-			clear_bit(R5_ReadError, &sh->dev[i].flags);
-			clear_bit(R5_ReWrite, &sh->dev[i].flags);
-			md_error(conf->mddev, conf->disks[i].rdev);
-		}
-	}
-	rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
-#if 0
-	/* must restore b_page before unlocking buffer... */
-	if (sh->bh_page[i] != bh->b_page) {
-		bh->b_page = sh->bh_page[i];
-		bh->b_data = page_address(bh->b_page);
-		clear_buffer_uptodate(bh);
-	}
-#endif
-	clear_bit(R5_LOCKED, &sh->dev[i].flags);
-	set_bit(STRIPE_HANDLE, &sh->state);
-	release_stripe(sh);
-	return 0;
-}
-
-static int raid6_end_write_request (struct bio *bi, unsigned int bytes_done,
-				    int error)
-{
- 	struct stripe_head *sh = bi->bi_private;
-	raid6_conf_t *conf = sh->raid_conf;
-	int disks = conf->raid_disks, i;
-	unsigned long flags;
-	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
-
-	if (bi->bi_size)
-		return 1;
-
-	for (i=0 ; i<disks; i++)
-		if (bi == &sh->dev[i].req)
-			break;
-
-	PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n",
-		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
-		uptodate);
-	if (i == disks) {
-		BUG();
-		return 0;
-	}
-
-	spin_lock_irqsave(&conf->device_lock, flags);
-	if (!uptodate)
-		md_error(conf->mddev, conf->disks[i].rdev);
-
-	rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
-
-	clear_bit(R5_LOCKED, &sh->dev[i].flags);
-	set_bit(STRIPE_HANDLE, &sh->state);
-	__release_stripe(conf, sh);
-	spin_unlock_irqrestore(&conf->device_lock, flags);
-	return 0;
-}
-
-
-static sector_t compute_blocknr(struct stripe_head *sh, int i);
-
-static void raid6_build_block (struct stripe_head *sh, int i)
-{
-	struct r5dev *dev = &sh->dev[i];
-	int pd_idx = sh->pd_idx;
-	int qd_idx = raid6_next_disk(pd_idx, sh->raid_conf->raid_disks);
-
-	bio_init(&dev->req);
-	dev->req.bi_io_vec = &dev->vec;
-	dev->req.bi_vcnt++;
-	dev->req.bi_max_vecs++;
-	dev->vec.bv_page = dev->page;
-	dev->vec.bv_len = STRIPE_SIZE;
-	dev->vec.bv_offset = 0;
-
-	dev->req.bi_sector = sh->sector;
-	dev->req.bi_private = sh;
-
-	dev->flags = 0;
-	if (i != pd_idx && i != qd_idx)
-		dev->sector = compute_blocknr(sh, i);
-}
-
-static void error(mddev_t *mddev, mdk_rdev_t *rdev)
-{
-	char b[BDEVNAME_SIZE];
-	raid6_conf_t *conf = (raid6_conf_t *) mddev->private;
-	PRINTK("raid6: error called\n");
-
-	if (!test_bit(Faulty, &rdev->flags)) {
-		mddev->sb_dirty = 1;
-		if (test_bit(In_sync, &rdev->flags)) {
-			conf->working_disks--;
-			mddev->degraded++;
-			conf->failed_disks++;
-			clear_bit(In_sync, &rdev->flags);
-			/*
-			 * if recovery was running, make sure it aborts.
-			 */
-			set_bit(MD_RECOVERY_ERR, &mddev->recovery);
-		}
-		set_bit(Faulty, &rdev->flags);
-		printk (KERN_ALERT
-			"raid6: Disk failure on %s, disabling device."
-			" Operation continuing on %d devices\n",
-			bdevname(rdev->bdev,b), conf->working_disks);
-	}
-}
-
-/*
- * Input: a 'big' sector number,
- * Output: index of the data and parity disk, and the sector # in them.
- */
-static sector_t raid6_compute_sector(sector_t r_sector, unsigned int raid_disks,
-			unsigned int data_disks, unsigned int * dd_idx,
-			unsigned int * pd_idx, raid6_conf_t *conf)
-{
-	long stripe;
-	unsigned long chunk_number;
-	unsigned int chunk_offset;
-	sector_t new_sector;
-	int sectors_per_chunk = conf->chunk_size >> 9;
-
-	/* First compute the information on this sector */
-
-	/*
-	 * Compute the chunk number and the sector offset inside the chunk
-	 */
-	chunk_offset = sector_div(r_sector, sectors_per_chunk);
-	chunk_number = r_sector;
-	if ( r_sector != chunk_number ) {
-		printk(KERN_CRIT "raid6: ERROR: r_sector = %llu, chunk_number = %lu\n",
-		       (unsigned long long)r_sector, (unsigned long)chunk_number);
-		BUG();
-	}
-
-	/*
-	 * Compute the stripe number
-	 */
-	stripe = chunk_number / data_disks;
-
-	/*
-	 * Compute the data disk and parity disk indexes inside the stripe
-	 */
-	*dd_idx = chunk_number % data_disks;
-
-	/*
-	 * Select the parity disk based on the user selected algorithm.
-	 */
-
-	/**** FIX THIS ****/
-	switch (conf->algorithm) {
-	case ALGORITHM_LEFT_ASYMMETRIC:
-		*pd_idx = raid_disks - 1 - (stripe % raid_disks);
-		if (*pd_idx == raid_disks-1)
-		  	(*dd_idx)++; 	/* Q D D D P */
-		else if (*dd_idx >= *pd_idx)
-		  	(*dd_idx) += 2; /* D D P Q D */
-		break;
-	case ALGORITHM_RIGHT_ASYMMETRIC:
-		*pd_idx = stripe % raid_disks;
-		if (*pd_idx == raid_disks-1)
-		  	(*dd_idx)++; 	/* Q D D D P */
-		else if (*dd_idx >= *pd_idx)
-		  	(*dd_idx) += 2; /* D D P Q D */
-		break;
-	case ALGORITHM_LEFT_SYMMETRIC:
-		*pd_idx = raid_disks - 1 - (stripe % raid_disks);
-		*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
-		break;
-	case ALGORITHM_RIGHT_SYMMETRIC:
-		*pd_idx = stripe % raid_disks;
-		*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
-		break;
-	default:
-		printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
-			conf->algorithm);
-	}
-
-	PRINTK("raid6: chunk_number = %lu, pd_idx = %u, dd_idx = %u\n",
-	       chunk_number, *pd_idx, *dd_idx);
-
-	/*
-	 * Finally, compute the new sector number
-	 */
-	new_sector = (sector_t) stripe * sectors_per_chunk + chunk_offset;
-	return new_sector;
-}
-
-
-static sector_t compute_blocknr(struct stripe_head *sh, int i)
-{
-	raid6_conf_t *conf = sh->raid_conf;
-	int raid_disks = conf->raid_disks, data_disks = raid_disks - 2;
-	sector_t new_sector = sh->sector, check;
-	int sectors_per_chunk = conf->chunk_size >> 9;
-	sector_t stripe;
-	int chunk_offset;
-	int chunk_number, dummy1, dummy2, dd_idx = i;
-	sector_t r_sector;
-	int i0 = i;
-
-	chunk_offset = sector_div(new_sector, sectors_per_chunk);
-	stripe = new_sector;
-	if ( new_sector != stripe ) {
-		printk(KERN_CRIT "raid6: ERROR: new_sector = %llu, stripe = %lu\n",
-		       (unsigned long long)new_sector, (unsigned long)stripe);
-		BUG();
-	}
-
-	switch (conf->algorithm) {
-		case ALGORITHM_LEFT_ASYMMETRIC:
-		case ALGORITHM_RIGHT_ASYMMETRIC:
-		  	if (sh->pd_idx == raid_disks-1)
-				i--; 	/* Q D D D P */
-			else if (i > sh->pd_idx)
-				i -= 2; /* D D P Q D */
-			break;
-		case ALGORITHM_LEFT_SYMMETRIC:
-		case ALGORITHM_RIGHT_SYMMETRIC:
-			if (sh->pd_idx == raid_disks-1)
-				i--; /* Q D D D P */
-			else {
-				/* D D P Q D */
-				if (i < sh->pd_idx)
-					i += raid_disks;
-				i -= (sh->pd_idx + 2);
-			}
-			break;
-		default:
-			printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
-				conf->algorithm);
-	}
-
-	PRINTK("raid6: compute_blocknr: pd_idx = %u, i0 = %u, i = %u\n", sh->pd_idx, i0, i);
-
-	chunk_number = stripe * data_disks + i;
-	r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
-
-	check = raid6_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
-	if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
-		printk(KERN_CRIT "raid6: compute_blocknr: map not correct\n");
-		return 0;
-	}
-	return r_sector;
-}
-
-
-
-/*
- * Copy data between a page in the stripe cache, and one or more bion
- * The page could align with the middle of the bio, or there could be
- * several bion, each with several bio_vecs, which cover part of the page
- * Multiple bion are linked together on bi_next.  There may be extras
- * at the end of this list.  We ignore them.
- */
-static void copy_data(int frombio, struct bio *bio,
-		     struct page *page,
-		     sector_t sector)
-{
-	char *pa = page_address(page);
-	struct bio_vec *bvl;
-	int i;
-	int page_offset;
-
-	if (bio->bi_sector >= sector)
-		page_offset = (signed)(bio->bi_sector - sector) * 512;
-	else
-		page_offset = (signed)(sector - bio->bi_sector) * -512;
-	bio_for_each_segment(bvl, bio, i) {
-		int len = bio_iovec_idx(bio,i)->bv_len;
-		int clen;
-		int b_offset = 0;
-
-		if (page_offset < 0) {
-			b_offset = -page_offset;
-			page_offset += b_offset;
-			len -= b_offset;
-		}
-
-		if (len > 0 && page_offset + len > STRIPE_SIZE)
-			clen = STRIPE_SIZE - page_offset;
-		else clen = len;
-
-		if (clen > 0) {
-			char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
-			if (frombio)
-				memcpy(pa+page_offset, ba+b_offset, clen);
-			else
-				memcpy(ba+b_offset, pa+page_offset, clen);
-			__bio_kunmap_atomic(ba, KM_USER0);
-		}
-		if (clen < len) /* hit end of page */
-			break;
-		page_offset +=  len;
-	}
-}
-
-#define check_xor() 	do { 						\
-			   if (count == MAX_XOR_BLOCKS) {		\
-				xor_block(count, STRIPE_SIZE, ptr);	\
-				count = 1;				\
-			   }						\
-			} while(0)
-
-/* Compute P and Q syndromes */
-static void compute_parity(struct stripe_head *sh, int method)
-{
-	raid6_conf_t *conf = sh->raid_conf;
-	int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = conf->raid_disks, count;
-	struct bio *chosen;
-	/**** FIX THIS: This could be very bad if disks is close to 256 ****/
-	void *ptrs[disks];
-
-	qd_idx = raid6_next_disk(pd_idx, disks);
-	d0_idx = raid6_next_disk(qd_idx, disks);
-
-	PRINTK("compute_parity, stripe %llu, method %d\n",
-		(unsigned long long)sh->sector, method);
-
-	switch(method) {
-	case READ_MODIFY_WRITE:
-		BUG();		/* READ_MODIFY_WRITE N/A for RAID-6 */
-	case RECONSTRUCT_WRITE:
-		for (i= disks; i-- ;)
-			if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
-				chosen = sh->dev[i].towrite;
-				sh->dev[i].towrite = NULL;
-
-				if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
-					wake_up(&conf->wait_for_overlap);
-
-				BUG_ON(sh->dev[i].written);
-				sh->dev[i].written = chosen;
-			}
-		break;
-	case CHECK_PARITY:
-		BUG();		/* Not implemented yet */
-	}
-
-	for (i = disks; i--;)
-		if (sh->dev[i].written) {
-			sector_t sector = sh->dev[i].sector;
-			struct bio *wbi = sh->dev[i].written;
-			while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
-				copy_data(1, wbi, sh->dev[i].page, sector);
-				wbi = r5_next_bio(wbi, sector);
-			}
-
-			set_bit(R5_LOCKED, &sh->dev[i].flags);
-			set_bit(R5_UPTODATE, &sh->dev[i].flags);
-		}
-
-//	switch(method) {
-//	case RECONSTRUCT_WRITE:
-//	case CHECK_PARITY:
-//	case UPDATE_PARITY:
-		/* Note that unlike RAID-5, the ordering of the disks matters greatly. */
-		/* FIX: Is this ordering of drives even remotely optimal? */
-		count = 0;
-		i = d0_idx;
-		do {
-			ptrs[count++] = page_address(sh->dev[i].page);
-			if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
-				printk("block %d/%d not uptodate on parity calc\n", i,count);
-			i = raid6_next_disk(i, disks);
-		} while ( i != d0_idx );
-//		break;
-//	}
-
-	raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
-
-	switch(method) {
-	case RECONSTRUCT_WRITE:
-		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
-		set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
-		set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
-		set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
-		break;
-	case UPDATE_PARITY:
-		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
-		set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
-		break;
-	}
-}
-
-/* Compute one missing block */
-static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
-{
-	raid6_conf_t *conf = sh->raid_conf;
-	int i, count, disks = conf->raid_disks;
-	void *ptr[MAX_XOR_BLOCKS], *p;
-	int pd_idx = sh->pd_idx;
-	int qd_idx = raid6_next_disk(pd_idx, disks);
-
-	PRINTK("compute_block_1, stripe %llu, idx %d\n",
-		(unsigned long long)sh->sector, dd_idx);
-
-	if ( dd_idx == qd_idx ) {
-		/* We're actually computing the Q drive */
-		compute_parity(sh, UPDATE_PARITY);
-	} else {
-		ptr[0] = page_address(sh->dev[dd_idx].page);
-		if (!nozero) memset(ptr[0], 0, STRIPE_SIZE);
-		count = 1;
-		for (i = disks ; i--; ) {
-			if (i == dd_idx || i == qd_idx)
-				continue;
-			p = page_address(sh->dev[i].page);
-			if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
-				ptr[count++] = p;
-			else
-				printk("compute_block() %d, stripe %llu, %d"
-				       " not present\n", dd_idx,
-				       (unsigned long long)sh->sector, i);
-
-			check_xor();
-		}
-		if (count != 1)
-			xor_block(count, STRIPE_SIZE, ptr);
-		if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
-		else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
-	}
-}
-
-/* Compute two missing blocks */
-static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
-{
-	raid6_conf_t *conf = sh->raid_conf;
-	int i, count, disks = conf->raid_disks;
-	int pd_idx = sh->pd_idx;
-	int qd_idx = raid6_next_disk(pd_idx, disks);
-	int d0_idx = raid6_next_disk(qd_idx, disks);
-	int faila, failb;
-
-	/* faila and failb are disk numbers relative to d0_idx */
-	/* pd_idx become disks-2 and qd_idx become disks-1 */
-	faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
-	failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
-
-	BUG_ON(faila == failb);
-	if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
-
-	PRINTK("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
-	       (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
-
-	if ( failb == disks-1 ) {
-		/* Q disk is one of the missing disks */
-		if ( faila == disks-2 ) {
-			/* Missing P+Q, just recompute */
-			compute_parity(sh, UPDATE_PARITY);
-			return;
-		} else {
-			/* We're missing D+Q; recompute D from P */
-			compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
-			compute_parity(sh, UPDATE_PARITY); /* Is this necessary? */
-			return;
-		}
-	}
-
-	/* We're missing D+P or D+D; build pointer table */
-	{
-		/**** FIX THIS: This could be very bad if disks is close to 256 ****/
-		void *ptrs[disks];
-
-		count = 0;
-		i = d0_idx;
-		do {
-			ptrs[count++] = page_address(sh->dev[i].page);
-			i = raid6_next_disk(i, disks);
-			if (i != dd_idx1 && i != dd_idx2 &&
-			    !test_bit(R5_UPTODATE, &sh->dev[i].flags))
-				printk("compute_2 with missing block %d/%d\n", count, i);
-		} while ( i != d0_idx );
-
-		if ( failb == disks-2 ) {
-			/* We're missing D+P. */
-			raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
-		} else {
-			/* We're missing D+D. */
-			raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
-		}
-
-		/* Both the above update both missing blocks */
-		set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
-		set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
-	}
-}
-
-
-/*
- * Each stripe/dev can have one or more bion attached.
- * toread/towrite point to the first in a chain.
- * The bi_next chain must be in order.
- */
-static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
-{
-	struct bio **bip;
-	raid6_conf_t *conf = sh->raid_conf;
-	int firstwrite=0;
-
-	PRINTK("adding bh b#%llu to stripe s#%llu\n",
-		(unsigned long long)bi->bi_sector,
-		(unsigned long long)sh->sector);
-
-
-	spin_lock(&sh->lock);
-	spin_lock_irq(&conf->device_lock);
-	if (forwrite) {
-		bip = &sh->dev[dd_idx].towrite;
-		if (*bip == NULL && sh->dev[dd_idx].written == NULL)
-			firstwrite = 1;
-	} else
-		bip = &sh->dev[dd_idx].toread;
-	while (*bip && (*bip)->bi_sector < bi->bi_sector) {
-		if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
-			goto overlap;
-		bip = &(*bip)->bi_next;
-	}
-	if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
-		goto overlap;
-
-	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
-	if (*bip)
-		bi->bi_next = *bip;
-	*bip = bi;
-	bi->bi_phys_segments ++;
-	spin_unlock_irq(&conf->device_lock);
-	spin_unlock(&sh->lock);
-
-	PRINTK("added bi b#%llu to stripe s#%llu, disk %d.\n",
-		(unsigned long long)bi->bi_sector,
-		(unsigned long long)sh->sector, dd_idx);
-
-	if (conf->mddev->bitmap && firstwrite) {
-		sh->bm_seq = conf->seq_write;
-		bitmap_startwrite(conf->mddev->bitmap, sh->sector,
-				  STRIPE_SECTORS, 0);
-		set_bit(STRIPE_BIT_DELAY, &sh->state);
-	}
-
-	if (forwrite) {
-		/* check if page is covered */
-		sector_t sector = sh->dev[dd_idx].sector;
-		for (bi=sh->dev[dd_idx].towrite;
-		     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
-			     bi && bi->bi_sector <= sector;
-		     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
-			if (bi->bi_sector + (bi->bi_size>>9) >= sector)
-				sector = bi->bi_sector + (bi->bi_size>>9);
-		}
-		if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
-			set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
-	}
-	return 1;
-
- overlap:
-	set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
-	spin_unlock_irq(&conf->device_lock);
-	spin_unlock(&sh->lock);
-	return 0;
-}
-
-
-static int page_is_zero(struct page *p)
-{
-	char *a = page_address(p);
-	return ((*(u32*)a) == 0 &&
-		memcmp(a, a+4, STRIPE_SIZE-4)==0);
-}
-/*
- * handle_stripe - do things to a stripe.
- *
- * We lock the stripe and then examine the state of various bits
- * to see what needs to be done.
- * Possible results:
- *    return some read request which now have data
- *    return some write requests which are safely on disc
- *    schedule a read on some buffers
- *    schedule a write of some buffers
- *    return confirmation of parity correctness
- *
- * Parity calculations are done inside the stripe lock
- * buffers are taken off read_list or write_list, and bh_cache buffers
- * get BH_Lock set before the stripe lock is released.
- *
- */
-
-static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
-{
-	raid6_conf_t *conf = sh->raid_conf;
-	int disks = conf->raid_disks;
-	struct bio *return_bi= NULL;
-	struct bio *bi;
-	int i;
-	int syncing;
-	int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
-	int non_overwrite = 0;
-	int failed_num[2] = {0, 0};
-	struct r5dev *dev, *pdev, *qdev;
-	int pd_idx = sh->pd_idx;
-	int qd_idx = raid6_next_disk(pd_idx, disks);
-	int p_failed, q_failed;
-
-	PRINTK("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d, qd_idx=%d\n",
-	       (unsigned long long)sh->sector, sh->state, atomic_read(&sh->count),
-	       pd_idx, qd_idx);
-
-	spin_lock(&sh->lock);
-	clear_bit(STRIPE_HANDLE, &sh->state);
-	clear_bit(STRIPE_DELAYED, &sh->state);
-
-	syncing = test_bit(STRIPE_SYNCING, &sh->state);
-	/* Now to look around and see what can be done */
-
-	rcu_read_lock();
-	for (i=disks; i--; ) {
-		mdk_rdev_t *rdev;
-		dev = &sh->dev[i];
-		clear_bit(R5_Insync, &dev->flags);
-
-		PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
-			i, dev->flags, dev->toread, dev->towrite, dev->written);
-		/* maybe we can reply to a read */
-		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
-			struct bio *rbi, *rbi2;
-			PRINTK("Return read for disc %d\n", i);
-			spin_lock_irq(&conf->device_lock);
-			rbi = dev->toread;
-			dev->toread = NULL;
-			if (test_and_clear_bit(R5_Overlap, &dev->flags))
-				wake_up(&conf->wait_for_overlap);
-			spin_unlock_irq(&conf->device_lock);
-			while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
-				copy_data(0, rbi, dev->page, dev->sector);
-				rbi2 = r5_next_bio(rbi, dev->sector);
-				spin_lock_irq(&conf->device_lock);
-				if (--rbi->bi_phys_segments == 0) {
-					rbi->bi_next = return_bi;
-					return_bi = rbi;
-				}
-				spin_unlock_irq(&conf->device_lock);
-				rbi = rbi2;
-			}
-		}
-
-		/* now count some things */
-		if (test_bit(R5_LOCKED, &dev->flags)) locked++;
-		if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
-
-
-		if (dev->toread) to_read++;
-		if (dev->towrite) {
-			to_write++;
-			if (!test_bit(R5_OVERWRITE, &dev->flags))
-				non_overwrite++;
-		}
-		if (dev->written) written++;
-		rdev = rcu_dereference(conf->disks[i].rdev);
-		if (!rdev || !test_bit(In_sync, &rdev->flags)) {
-			/* The ReadError flag will just be confusing now */
-			clear_bit(R5_ReadError, &dev->flags);
-			clear_bit(R5_ReWrite, &dev->flags);
-		}
-		if (!rdev || !test_bit(In_sync, &rdev->flags)
-		    || test_bit(R5_ReadError, &dev->flags)) {
-			if ( failed < 2 )
-				failed_num[failed] = i;
-			failed++;
-		} else
-			set_bit(R5_Insync, &dev->flags);
-	}
-	rcu_read_unlock();
-	PRINTK("locked=%d uptodate=%d to_read=%d"
-	       " to_write=%d failed=%d failed_num=%d,%d\n",
-	       locked, uptodate, to_read, to_write, failed,
-	       failed_num[0], failed_num[1]);
-	/* check if the array has lost >2 devices and, if so, some requests might
-	 * need to be failed
-	 */
-	if (failed > 2 && to_read+to_write+written) {
-		for (i=disks; i--; ) {
-			int bitmap_end = 0;
-
-			if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
-				mdk_rdev_t *rdev;
-				rcu_read_lock();
-				rdev = rcu_dereference(conf->disks[i].rdev);
-				if (rdev && test_bit(In_sync, &rdev->flags))
-					/* multiple read failures in one stripe */
-					md_error(conf->mddev, rdev);
-				rcu_read_unlock();
-			}
-
-			spin_lock_irq(&conf->device_lock);
-			/* fail all writes first */
-			bi = sh->dev[i].towrite;
-			sh->dev[i].towrite = NULL;
-			if (bi) { to_write--; bitmap_end = 1; }
-
-			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
-				wake_up(&conf->wait_for_overlap);
-
-			while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
-				struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
-				clear_bit(BIO_UPTODATE, &bi->bi_flags);
-				if (--bi->bi_phys_segments == 0) {
-					md_write_end(conf->mddev);
-					bi->bi_next = return_bi;
-					return_bi = bi;
-				}
-				bi = nextbi;
-			}
-			/* and fail all 'written' */
-			bi = sh->dev[i].written;
-			sh->dev[i].written = NULL;
-			if (bi) bitmap_end = 1;
-			while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
-				struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
-				clear_bit(BIO_UPTODATE, &bi->bi_flags);
-				if (--bi->bi_phys_segments == 0) {
-					md_write_end(conf->mddev);
-					bi->bi_next = return_bi;
-					return_bi = bi;
-				}
-				bi = bi2;
-			}
-
-			/* fail any reads if this device is non-operational */
-			if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
-			    test_bit(R5_ReadError, &sh->dev[i].flags)) {
-				bi = sh->dev[i].toread;
-				sh->dev[i].toread = NULL;
-				if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
-					wake_up(&conf->wait_for_overlap);
-				if (bi) to_read--;
-				while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
-					struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
-					clear_bit(BIO_UPTODATE, &bi->bi_flags);
-					if (--bi->bi_phys_segments == 0) {
-						bi->bi_next = return_bi;
-						return_bi = bi;
-					}
-					bi = nextbi;
-				}
-			}
-			spin_unlock_irq(&conf->device_lock);
-			if (bitmap_end)
-				bitmap_endwrite(conf->mddev->bitmap, sh->sector,
-						STRIPE_SECTORS, 0, 0);
-		}
-	}
-	if (failed > 2 && syncing) {
-		md_done_sync(conf->mddev, STRIPE_SECTORS,0);
-		clear_bit(STRIPE_SYNCING, &sh->state);
-		syncing = 0;
-	}
-
-	/*
-	 * might be able to return some write requests if the parity blocks
-	 * are safe, or on a failed drive
-	 */
-	pdev = &sh->dev[pd_idx];
-	p_failed = (failed >= 1 && failed_num[0] == pd_idx)
-		|| (failed >= 2 && failed_num[1] == pd_idx);
-	qdev = &sh->dev[qd_idx];
-	q_failed = (failed >= 1 && failed_num[0] == qd_idx)
-		|| (failed >= 2 && failed_num[1] == qd_idx);
-
-	if ( written &&
-	     ( p_failed || ((test_bit(R5_Insync, &pdev->flags)
-			     && !test_bit(R5_LOCKED, &pdev->flags)
-			     && test_bit(R5_UPTODATE, &pdev->flags))) ) &&
-	     ( q_failed || ((test_bit(R5_Insync, &qdev->flags)
-			     && !test_bit(R5_LOCKED, &qdev->flags)
-			     && test_bit(R5_UPTODATE, &qdev->flags))) ) ) {
-		/* any written block on an uptodate or failed drive can be
-		 * returned.  Note that if we 'wrote' to a failed drive,
-		 * it will be UPTODATE, but never LOCKED, so we don't need
-		 * to test 'failed' directly.
-		 */
-		for (i=disks; i--; )
-			if (sh->dev[i].written) {
-				dev = &sh->dev[i];
-				if (!test_bit(R5_LOCKED, &dev->flags) &&
-				    test_bit(R5_UPTODATE, &dev->flags) ) {
-					/* We can return any write requests */
-					int bitmap_end = 0;
-					struct bio *wbi, *wbi2;
-					PRINTK("Return write for stripe %llu disc %d\n",
-					       (unsigned long long)sh->sector, i);
-					spin_lock_irq(&conf->device_lock);
-					wbi = dev->written;
-					dev->written = NULL;
-					while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
-						wbi2 = r5_next_bio(wbi, dev->sector);
-						if (--wbi->bi_phys_segments == 0) {
-							md_write_end(conf->mddev);
-							wbi->bi_next = return_bi;
-							return_bi = wbi;
-						}
-						wbi = wbi2;
-					}
-					if (dev->towrite == NULL)
-						bitmap_end = 1;
-					spin_unlock_irq(&conf->device_lock);
-					if (bitmap_end)
-						bitmap_endwrite(conf->mddev->bitmap, sh->sector,
-								STRIPE_SECTORS,
-								!test_bit(STRIPE_DEGRADED, &sh->state), 0);
-				}
-			}
-	}
-
-	/* Now we might consider reading some blocks, either to check/generate
-	 * parity, or to satisfy requests
-	 * or to load a block that is being partially written.
-	 */
-	if (to_read || non_overwrite || (to_write && failed) || (syncing && (uptodate < disks))) {
-		for (i=disks; i--;) {
-			dev = &sh->dev[i];
-			if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
-			    (dev->toread ||
-			     (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
-			     syncing ||
-			     (failed >= 1 && (sh->dev[failed_num[0]].toread || to_write)) ||
-			     (failed >= 2 && (sh->dev[failed_num[1]].toread || to_write))
-				    )
-				) {
-				/* we would like to get this block, possibly
-				 * by computing it, but we might not be able to
-				 */
-				if (uptodate == disks-1) {
-					PRINTK("Computing stripe %llu block %d\n",
-					       (unsigned long long)sh->sector, i);
-					compute_block_1(sh, i, 0);
-					uptodate++;
-				} else if ( uptodate == disks-2 && failed >= 2 ) {
-					/* Computing 2-failure is *very* expensive; only do it if failed >= 2 */
-					int other;
-					for (other=disks; other--;) {
-						if ( other == i )
-							continue;
-						if ( !test_bit(R5_UPTODATE, &sh->dev[other].flags) )
-							break;
-					}
-					BUG_ON(other < 0);
-					PRINTK("Computing stripe %llu blocks %d,%d\n",
-					       (unsigned long long)sh->sector, i, other);
-					compute_block_2(sh, i, other);
-					uptodate += 2;
-				} else if (test_bit(R5_Insync, &dev->flags)) {
-					set_bit(R5_LOCKED, &dev->flags);
-					set_bit(R5_Wantread, &dev->flags);
-#if 0
-					/* if I am just reading this block and we don't have
-					   a failed drive, or any pending writes then sidestep the cache */
-					if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext &&
-					    ! syncing && !failed && !to_write) {
-						sh->bh_cache[i]->b_page =  sh->bh_read[i]->b_page;
-						sh->bh_cache[i]->b_data =  sh->bh_read[i]->b_data;
-					}
-#endif
-					locked++;
-					PRINTK("Reading block %d (sync=%d)\n",
-						i, syncing);
-				}
-			}
-		}
-		set_bit(STRIPE_HANDLE, &sh->state);
-	}
-
-	/* now to consider writing and what else, if anything should be read */
-	if (to_write) {
-		int rcw=0, must_compute=0;
-		for (i=disks ; i--;) {
-			dev = &sh->dev[i];
-			/* Would I have to read this buffer for reconstruct_write */
-			if (!test_bit(R5_OVERWRITE, &dev->flags)
-			    && i != pd_idx && i != qd_idx
-			    && (!test_bit(R5_LOCKED, &dev->flags)
-#if 0
-				|| sh->bh_page[i] != bh->b_page
-#endif
-				    ) &&
-			    !test_bit(R5_UPTODATE, &dev->flags)) {
-				if (test_bit(R5_Insync, &dev->flags)) rcw++;
-				else {
-					PRINTK("raid6: must_compute: disk %d flags=%#lx\n", i, dev->flags);
-					must_compute++;
-				}
-			}
-		}
-		PRINTK("for sector %llu, rcw=%d, must_compute=%d\n",
-		       (unsigned long long)sh->sector, rcw, must_compute);
-		set_bit(STRIPE_HANDLE, &sh->state);
-
-		if (rcw > 0)
-			/* want reconstruct write, but need to get some data */
-			for (i=disks; i--;) {
-				dev = &sh->dev[i];
-				if (!test_bit(R5_OVERWRITE, &dev->flags)
-				    && !(failed == 0 && (i == pd_idx || i == qd_idx))
-				    && !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
-				    test_bit(R5_Insync, &dev->flags)) {
-					if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
-					{
-						PRINTK("Read_old stripe %llu block %d for Reconstruct\n",
-						       (unsigned long long)sh->sector, i);
-						set_bit(R5_LOCKED, &dev->flags);
-						set_bit(R5_Wantread, &dev->flags);
-						locked++;
-					} else {
-						PRINTK("Request delayed stripe %llu block %d for Reconstruct\n",
-						       (unsigned long long)sh->sector, i);
-						set_bit(STRIPE_DELAYED, &sh->state);
-						set_bit(STRIPE_HANDLE, &sh->state);
-					}
-				}
-			}
-		/* now if nothing is locked, and if we have enough data, we can start a write request */
-		if (locked == 0 && rcw == 0 &&
-		    !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
-			if ( must_compute > 0 ) {
-				/* We have failed blocks and need to compute them */
-				switch ( failed ) {
-				case 0:	BUG();
-				case 1: compute_block_1(sh, failed_num[0], 0); break;
-				case 2: compute_block_2(sh, failed_num[0], failed_num[1]); break;
-				default: BUG();	/* This request should have been failed? */
-				}
-			}
-
-			PRINTK("Computing parity for stripe %llu\n", (unsigned long long)sh->sector);
-			compute_parity(sh, RECONSTRUCT_WRITE);
-			/* now every locked buffer is ready to be written */
-			for (i=disks; i--;)
-				if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
-					PRINTK("Writing stripe %llu block %d\n",
-					       (unsigned long long)sh->sector, i);
-					locked++;
-					set_bit(R5_Wantwrite, &sh->dev[i].flags);
-				}
-			/* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
-			set_bit(STRIPE_INSYNC, &sh->state);
-
-			if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
-				atomic_dec(&conf->preread_active_stripes);
-				if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
-					md_wakeup_thread(conf->mddev->thread);
-			}
-		}
-	}
-
-	/* maybe we need to check and possibly fix the parity for this stripe
-	 * Any reads will already have been scheduled, so we just see if enough data
-	 * is available
-	 */
-	if (syncing && locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state)) {
-		int update_p = 0, update_q = 0;
-		struct r5dev *dev;
-
-		set_bit(STRIPE_HANDLE, &sh->state);
-
-		BUG_ON(failed>2);
-		BUG_ON(uptodate < disks);
-		/* Want to check and possibly repair P and Q.
-		 * However there could be one 'failed' device, in which
-		 * case we can only check one of them, possibly using the
-		 * other to generate missing data
-		 */
-
-		/* If !tmp_page, we cannot do the calculations,
-		 * but as we have set STRIPE_HANDLE, we will soon be called
-		 * by stripe_handle with a tmp_page - just wait until then.
-		 */
-		if (tmp_page) {
-			if (failed == q_failed) {
-				/* The only possible failed device holds 'Q', so it makes
-				 * sense to check P (If anything else were failed, we would
-				 * have used P to recreate it).
-				 */
-				compute_block_1(sh, pd_idx, 1);
-				if (!page_is_zero(sh->dev[pd_idx].page)) {
-					compute_block_1(sh,pd_idx,0);
-					update_p = 1;
-				}
-			}
-			if (!q_failed && failed < 2) {
-				/* q is not failed, and we didn't use it to generate
-				 * anything, so it makes sense to check it
-				 */
-				memcpy(page_address(tmp_page),
-				       page_address(sh->dev[qd_idx].page),
-				       STRIPE_SIZE);
-				compute_parity(sh, UPDATE_PARITY);
-				if (memcmp(page_address(tmp_page),
-					   page_address(sh->dev[qd_idx].page),
-					   STRIPE_SIZE)!= 0) {
-					clear_bit(STRIPE_INSYNC, &sh->state);
-					update_q = 1;
-				}
-			}
-			if (update_p || update_q) {
-				conf->mddev->resync_mismatches += STRIPE_SECTORS;
-				if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
-					/* don't try to repair!! */
-					update_p = update_q = 0;
-			}
-
-			/* now write out any block on a failed drive,
-			 * or P or Q if they need it
-			 */
-
-			if (failed == 2) {
-				dev = &sh->dev[failed_num[1]];
-				locked++;
-				set_bit(R5_LOCKED, &dev->flags);
-				set_bit(R5_Wantwrite, &dev->flags);
-			}
-			if (failed >= 1) {
-				dev = &sh->dev[failed_num[0]];
-				locked++;
-				set_bit(R5_LOCKED, &dev->flags);
-				set_bit(R5_Wantwrite, &dev->flags);
-			}
-
-			if (update_p) {
-				dev = &sh->dev[pd_idx];
-				locked ++;
-				set_bit(R5_LOCKED, &dev->flags);
-				set_bit(R5_Wantwrite, &dev->flags);
-			}
-			if (update_q) {
-				dev = &sh->dev[qd_idx];
-				locked++;
-				set_bit(R5_LOCKED, &dev->flags);
-				set_bit(R5_Wantwrite, &dev->flags);
-			}
-			clear_bit(STRIPE_DEGRADED, &sh->state);
-
-			set_bit(STRIPE_INSYNC, &sh->state);
-		}
-	}
-
-	if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
-		md_done_sync(conf->mddev, STRIPE_SECTORS,1);
-		clear_bit(STRIPE_SYNCING, &sh->state);
-	}
-
-	/* If the failed drives are just a ReadError, then we might need
-	 * to progress the repair/check process
-	 */
-	if (failed <= 2 && ! conf->mddev->ro)
-		for (i=0; i<failed;i++) {
-			dev = &sh->dev[failed_num[i]];
-			if (test_bit(R5_ReadError, &dev->flags)
-			    && !test_bit(R5_LOCKED, &dev->flags)
-			    && test_bit(R5_UPTODATE, &dev->flags)
-				) {
-				if (!test_bit(R5_ReWrite, &dev->flags)) {
-					set_bit(R5_Wantwrite, &dev->flags);
-					set_bit(R5_ReWrite, &dev->flags);
-					set_bit(R5_LOCKED, &dev->flags);
-				} else {
-					/* let's read it back */
-					set_bit(R5_Wantread, &dev->flags);
-					set_bit(R5_LOCKED, &dev->flags);
-				}
-			}
-		}
-	spin_unlock(&sh->lock);
-
-	while ((bi=return_bi)) {
-		int bytes = bi->bi_size;
-
-		return_bi = bi->bi_next;
-		bi->bi_next = NULL;
-		bi->bi_size = 0;
-		bi->bi_end_io(bi, bytes, 0);
-	}
-	for (i=disks; i-- ;) {
-		int rw;
-		struct bio *bi;
-		mdk_rdev_t *rdev;
-		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
-			rw = 1;
-		else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
-			rw = 0;
-		else
-			continue;
-
-		bi = &sh->dev[i].req;
-
-		bi->bi_rw = rw;
-		if (rw)
-			bi->bi_end_io = raid6_end_write_request;
-		else
-			bi->bi_end_io = raid6_end_read_request;
-
-		rcu_read_lock();
-		rdev = rcu_dereference(conf->disks[i].rdev);
-		if (rdev && test_bit(Faulty, &rdev->flags))
-			rdev = NULL;
-		if (rdev)
-			atomic_inc(&rdev->nr_pending);
-		rcu_read_unlock();
-
-		if (rdev) {
-			if (syncing)
-				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
-
-			bi->bi_bdev = rdev->bdev;
-			PRINTK("for %llu schedule op %ld on disc %d\n",
-				(unsigned long long)sh->sector, bi->bi_rw, i);
-			atomic_inc(&sh->count);
-			bi->bi_sector = sh->sector + rdev->data_offset;
-			bi->bi_flags = 1 << BIO_UPTODATE;
-			bi->bi_vcnt = 1;
-			bi->bi_max_vecs = 1;
-			bi->bi_idx = 0;
-			bi->bi_io_vec = &sh->dev[i].vec;
-			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
-			bi->bi_io_vec[0].bv_offset = 0;
-			bi->bi_size = STRIPE_SIZE;
-			bi->bi_next = NULL;
-			if (rw == WRITE &&
-			    test_bit(R5_ReWrite, &sh->dev[i].flags))
-				atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
-			generic_make_request(bi);
-		} else {
-			if (rw == 1)
-				set_bit(STRIPE_DEGRADED, &sh->state);
-			PRINTK("skip op %ld on disc %d for sector %llu\n",
-				bi->bi_rw, i, (unsigned long long)sh->sector);
-			clear_bit(R5_LOCKED, &sh->dev[i].flags);
-			set_bit(STRIPE_HANDLE, &sh->state);
-		}
-	}
-}
-
-static void raid6_activate_delayed(raid6_conf_t *conf)
-{
-	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
-		while (!list_empty(&conf->delayed_list)) {
-			struct list_head *l = conf->delayed_list.next;
-			struct stripe_head *sh;
-			sh = list_entry(l, struct stripe_head, lru);
-			list_del_init(l);
-			clear_bit(STRIPE_DELAYED, &sh->state);
-			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
-				atomic_inc(&conf->preread_active_stripes);
-			list_add_tail(&sh->lru, &conf->handle_list);
-		}
-	}
-}
-
-static void activate_bit_delay(raid6_conf_t *conf)
-{
-	/* device_lock is held */
-	struct list_head head;
-	list_add(&head, &conf->bitmap_list);
-	list_del_init(&conf->bitmap_list);
-	while (!list_empty(&head)) {
-		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
-		list_del_init(&sh->lru);
-		atomic_inc(&sh->count);
-		__release_stripe(conf, sh);
-	}
-}
-
-static void unplug_slaves(mddev_t *mddev)
-{
-	raid6_conf_t *conf = mddev_to_conf(mddev);
-	int i;
-
-	rcu_read_lock();
-	for (i=0; i<mddev->raid_disks; i++) {
-		mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
-		if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
-			request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
-
-			atomic_inc(&rdev->nr_pending);
-			rcu_read_unlock();
-
-			if (r_queue->unplug_fn)
-				r_queue->unplug_fn(r_queue);
-
-			rdev_dec_pending(rdev, mddev);
-			rcu_read_lock();
-		}
-	}
-	rcu_read_unlock();
-}
-
-static void raid6_unplug_device(request_queue_t *q)
-{
-	mddev_t *mddev = q->queuedata;
-	raid6_conf_t *conf = mddev_to_conf(mddev);
-	unsigned long flags;
-
-	spin_lock_irqsave(&conf->device_lock, flags);
-
-	if (blk_remove_plug(q)) {
-		conf->seq_flush++;
-		raid6_activate_delayed(conf);
-	}
-	md_wakeup_thread(mddev->thread);
-
-	spin_unlock_irqrestore(&conf->device_lock, flags);
-
-	unplug_slaves(mddev);
-}
-
-static int raid6_issue_flush(request_queue_t *q, struct gendisk *disk,
-			     sector_t *error_sector)
-{
-	mddev_t *mddev = q->queuedata;
-	raid6_conf_t *conf = mddev_to_conf(mddev);
-	int i, ret = 0;
-
-	rcu_read_lock();
-	for (i=0; i<mddev->raid_disks && ret == 0; i++) {
-		mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
-		if (rdev && !test_bit(Faulty, &rdev->flags)) {
-			struct block_device *bdev = rdev->bdev;
-			request_queue_t *r_queue = bdev_get_queue(bdev);
-
-			if (!r_queue->issue_flush_fn)
-				ret = -EOPNOTSUPP;
-			else {
-				atomic_inc(&rdev->nr_pending);
-				rcu_read_unlock();
-				ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
-							      error_sector);
-				rdev_dec_pending(rdev, mddev);
-				rcu_read_lock();
-			}
-		}
-	}
-	rcu_read_unlock();
-	return ret;
-}
-
-static inline void raid6_plug_device(raid6_conf_t *conf)
-{
-	spin_lock_irq(&conf->device_lock);
-	blk_plug_device(conf->mddev->queue);
-	spin_unlock_irq(&conf->device_lock);
-}
-
-static int make_request (request_queue_t *q, struct bio * bi)
-{
-	mddev_t *mddev = q->queuedata;
-	raid6_conf_t *conf = mddev_to_conf(mddev);
-	const unsigned int raid_disks = conf->raid_disks;
-	const unsigned int data_disks = raid_disks - 2;
-	unsigned int dd_idx, pd_idx;
-	sector_t new_sector;
-	sector_t logical_sector, last_sector;
-	struct stripe_head *sh;
-	const int rw = bio_data_dir(bi);
-
-	if (unlikely(bio_barrier(bi))) {
-		bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
-		return 0;
-	}
-
-	md_write_start(mddev, bi);
-
-	disk_stat_inc(mddev->gendisk, ios[rw]);
-	disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
-
-	logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
-	last_sector = bi->bi_sector + (bi->bi_size>>9);
-
-	bi->bi_next = NULL;
-	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
-
-	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
-		DEFINE_WAIT(w);
-
-		new_sector = raid6_compute_sector(logical_sector,
-						  raid_disks, data_disks, &dd_idx, &pd_idx, conf);
-
-		PRINTK("raid6: make_request, sector %llu logical %llu\n",
-		       (unsigned long long)new_sector,
-		       (unsigned long long)logical_sector);
-
-	retry:
-		prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
-		sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
-		if (sh) {
-			if (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
-				/* Add failed due to overlap.  Flush everything
-				 * and wait a while
-				 */
-				raid6_unplug_device(mddev->queue);
-				release_stripe(sh);
-				schedule();
-				goto retry;
-			}
-			finish_wait(&conf->wait_for_overlap, &w);
-			raid6_plug_device(conf);
-			handle_stripe(sh, NULL);
-			release_stripe(sh);
-		} else {
-			/* cannot get stripe for read-ahead, just give-up */
-			clear_bit(BIO_UPTODATE, &bi->bi_flags);
-			finish_wait(&conf->wait_for_overlap, &w);
-			break;
-		}
-
-	}
-	spin_lock_irq(&conf->device_lock);
-	if (--bi->bi_phys_segments == 0) {
-		int bytes = bi->bi_size;
-
-		if (rw == WRITE )
-			md_write_end(mddev);
-		bi->bi_size = 0;
-		bi->bi_end_io(bi, bytes, 0);
-	}
-	spin_unlock_irq(&conf->device_lock);
-	return 0;
-}
-
-/* FIXME go_faster isn't used */
-static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
-{
-	raid6_conf_t *conf = (raid6_conf_t *) mddev->private;
-	struct stripe_head *sh;
-	int sectors_per_chunk = conf->chunk_size >> 9;
-	sector_t x;
-	unsigned long stripe;
-	int chunk_offset;
-	int dd_idx, pd_idx;
-	sector_t first_sector;
-	int raid_disks = conf->raid_disks;
-	int data_disks = raid_disks - 2;
-	sector_t max_sector = mddev->size << 1;
-	int sync_blocks;
-	int still_degraded = 0;
-	int i;
-
-	if (sector_nr >= max_sector) {
-		/* just being told to finish up .. nothing much to do */
-		unplug_slaves(mddev);
-
-		if (mddev->curr_resync < max_sector) /* aborted */
-			bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
-					&sync_blocks, 1);
-		else /* completed sync */
-			conf->fullsync = 0;
-		bitmap_close_sync(mddev->bitmap);
-
-		return 0;
-	}
-	/* if there are 2 or more failed drives and we are trying
-	 * to resync, then assert that we are finished, because there is
-	 * nothing we can do.
-	 */
-	if (mddev->degraded >= 2 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
-		sector_t rv = (mddev->size << 1) - sector_nr;
-		*skipped = 1;
-		return rv;
-	}
-	if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
-	    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
-	    !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
-		/* we can skip this block, and probably more */
-		sync_blocks /= STRIPE_SECTORS;
-		*skipped = 1;
-		return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
-	}
-
-	x = sector_nr;
-	chunk_offset = sector_div(x, sectors_per_chunk);
-	stripe = x;
-	BUG_ON(x != stripe);
-
-	first_sector = raid6_compute_sector((sector_t)stripe*data_disks*sectors_per_chunk
-		+ chunk_offset, raid_disks, data_disks, &dd_idx, &pd_idx, conf);
-	sh = get_active_stripe(conf, sector_nr, pd_idx, 1);
-	if (sh == NULL) {
-		sh = get_active_stripe(conf, sector_nr, pd_idx, 0);
-		/* make sure we don't swamp the stripe cache if someone else
-		 * is trying to get access
-		 */
-		schedule_timeout_uninterruptible(1);
-	}
-	/* Need to check if array will still be degraded after recovery/resync
-	 * We don't need to check the 'failed' flag as when that gets set,
-	 * recovery aborts.
-	 */
-	for (i=0; i<mddev->raid_disks; i++)
-		if (conf->disks[i].rdev == NULL)
-			still_degraded = 1;
-
-	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
-
-	spin_lock(&sh->lock);
-	set_bit(STRIPE_SYNCING, &sh->state);
-	clear_bit(STRIPE_INSYNC, &sh->state);
-	spin_unlock(&sh->lock);
-
-	handle_stripe(sh, NULL);
-	release_stripe(sh);
-
-	return STRIPE_SECTORS;
-}
-
-/*
- * This is our raid6 kernel thread.
- *
- * We scan the hash table for stripes which can be handled now.
- * During the scan, completed stripes are saved for us by the interrupt
- * handler, so that they will not have to wait for our next wakeup.
- */
-static void raid6d (mddev_t *mddev)
-{
-	struct stripe_head *sh;
-	raid6_conf_t *conf = mddev_to_conf(mddev);
-	int handled;
-
-	PRINTK("+++ raid6d active\n");
-
-	md_check_recovery(mddev);
-
-	handled = 0;
-	spin_lock_irq(&conf->device_lock);
-	while (1) {
-		struct list_head *first;
-
-		if (conf->seq_flush - conf->seq_write > 0) {
-			int seq = conf->seq_flush;
-			spin_unlock_irq(&conf->device_lock);
-			bitmap_unplug(mddev->bitmap);
-			spin_lock_irq(&conf->device_lock);
-			conf->seq_write = seq;
-			activate_bit_delay(conf);
-		}
-
-		if (list_empty(&conf->handle_list) &&
-		    atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
-		    !blk_queue_plugged(mddev->queue) &&
-		    !list_empty(&conf->delayed_list))
-			raid6_activate_delayed(conf);
-
-		if (list_empty(&conf->handle_list))
-			break;
-
-		first = conf->handle_list.next;
-		sh = list_entry(first, struct stripe_head, lru);
-
-		list_del_init(first);
-		atomic_inc(&sh->count);
-		BUG_ON(atomic_read(&sh->count)!= 1);
-		spin_unlock_irq(&conf->device_lock);
-
-		handled++;
-		handle_stripe(sh, conf->spare_page);
-		release_stripe(sh);
-
-		spin_lock_irq(&conf->device_lock);
-	}
-	PRINTK("%d stripes handled\n", handled);
-
-	spin_unlock_irq(&conf->device_lock);
-
-	unplug_slaves(mddev);
-
-	PRINTK("--- raid6d inactive\n");
-}
-
-static ssize_t
-raid6_show_stripe_cache_size(mddev_t *mddev, char *page)
-{
-	raid6_conf_t *conf = mddev_to_conf(mddev);
-	if (conf)
-		return sprintf(page, "%d\n", conf->max_nr_stripes);
-	else
-		return 0;
-}
-
-static ssize_t
-raid6_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
-{
-	raid6_conf_t *conf = mddev_to_conf(mddev);
-	char *end;
-	int new;
-	if (len >= PAGE_SIZE)
-		return -EINVAL;
-	if (!conf)
-		return -ENODEV;
-
-	new = simple_strtoul(page, &end, 10);
-	if (!*page || (*end && *end != '\n') )
-		return -EINVAL;
-	if (new <= 16 || new > 32768)
-		return -EINVAL;
-	while (new < conf->max_nr_stripes) {
-		if (drop_one_stripe(conf))
-			conf->max_nr_stripes--;
-		else
-			break;
-	}
-	while (new > conf->max_nr_stripes) {
-		if (grow_one_stripe(conf))
-			conf->max_nr_stripes++;
-		else break;
-	}
-	return len;
-}
-
-static struct md_sysfs_entry
-raid6_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
-				raid6_show_stripe_cache_size,
-				raid6_store_stripe_cache_size);
-
-static ssize_t
-stripe_cache_active_show(mddev_t *mddev, char *page)
-{
-	raid6_conf_t *conf = mddev_to_conf(mddev);
-	if (conf)
-		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
-	else
-		return 0;
-}
-
-static struct md_sysfs_entry
-raid6_stripecache_active = __ATTR_RO(stripe_cache_active);
-
-static struct attribute *raid6_attrs[] =  {
-	&raid6_stripecache_size.attr,
-	&raid6_stripecache_active.attr,
-	NULL,
-};
-static struct attribute_group raid6_attrs_group = {
-	.name = NULL,
-	.attrs = raid6_attrs,
-};
-
-static int run(mddev_t *mddev)
-{
-	raid6_conf_t *conf;
-	int raid_disk, memory;
-	mdk_rdev_t *rdev;
-	struct disk_info *disk;
-	struct list_head *tmp;
-
-	if (mddev->level != 6) {
-		PRINTK("raid6: %s: raid level not set to 6 (%d)\n", mdname(mddev), mddev->level);
-		return -EIO;
-	}
-
-	mddev->private = kzalloc(sizeof (raid6_conf_t), GFP_KERNEL);
-	if ((conf = mddev->private) == NULL)
-		goto abort;
-	conf->disks = kzalloc(mddev->raid_disks * sizeof(struct disk_info),
-				 GFP_KERNEL);
-	if (!conf->disks)
-		goto abort;
-
-	conf->mddev = mddev;
-
-	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
-		goto abort;
-
-	conf->spare_page = alloc_page(GFP_KERNEL);
-	if (!conf->spare_page)
-		goto abort;
-
-	spin_lock_init(&conf->device_lock);
-	init_waitqueue_head(&conf->wait_for_stripe);
-	init_waitqueue_head(&conf->wait_for_overlap);
-	INIT_LIST_HEAD(&conf->handle_list);
-	INIT_LIST_HEAD(&conf->delayed_list);
-	INIT_LIST_HEAD(&conf->bitmap_list);
-	INIT_LIST_HEAD(&conf->inactive_list);
-	atomic_set(&conf->active_stripes, 0);
-	atomic_set(&conf->preread_active_stripes, 0);
-
-	PRINTK("raid6: run(%s) called.\n", mdname(mddev));
-
-	ITERATE_RDEV(mddev,rdev,tmp) {
-		raid_disk = rdev->raid_disk;
-		if (raid_disk >= mddev->raid_disks
-		    || raid_disk < 0)
-			continue;
-		disk = conf->disks + raid_disk;
-
-		disk->rdev = rdev;
-
-		if (test_bit(In_sync, &rdev->flags)) {
-			char b[BDEVNAME_SIZE];
-			printk(KERN_INFO "raid6: device %s operational as raid"
-			       " disk %d\n", bdevname(rdev->bdev,b),
-			       raid_disk);
-			conf->working_disks++;
-		}
-	}
-
-	conf->raid_disks = mddev->raid_disks;
-
-	/*
-	 * 0 for a fully functional array, 1 or 2 for a degraded array.
-	 */
-	mddev->degraded = conf->failed_disks = conf->raid_disks - conf->working_disks;
-	conf->mddev = mddev;
-	conf->chunk_size = mddev->chunk_size;
-	conf->level = mddev->level;
-	conf->algorithm = mddev->layout;
-	conf->max_nr_stripes = NR_STRIPES;
-
-	/* device size must be a multiple of chunk size */
-	mddev->size &= ~(mddev->chunk_size/1024 -1);
-	mddev->resync_max_sectors = mddev->size << 1;
-
-	if (conf->raid_disks < 4) {
-		printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
-		       mdname(mddev), conf->raid_disks);
-		goto abort;
-	}
-	if (!conf->chunk_size || conf->chunk_size % 4) {
-		printk(KERN_ERR "raid6: invalid chunk size %d for %s\n",
-		       conf->chunk_size, mdname(mddev));
-		goto abort;
-	}
-	if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
-		printk(KERN_ERR
-		       "raid6: unsupported parity algorithm %d for %s\n",
-		       conf->algorithm, mdname(mddev));
-		goto abort;
-	}
-	if (mddev->degraded > 2) {
-		printk(KERN_ERR "raid6: not enough operational devices for %s"
-		       " (%d/%d failed)\n",
-		       mdname(mddev), conf->failed_disks, conf->raid_disks);
-		goto abort;
-	}
-
-	if (mddev->degraded > 0 &&
-	    mddev->recovery_cp != MaxSector) {
-		if (mddev->ok_start_degraded)
-			printk(KERN_WARNING "raid6: starting dirty degraded array:%s"
-			       "- data corruption possible.\n",
-			       mdname(mddev));
-		else {
-			printk(KERN_ERR "raid6: cannot start dirty degraded array"
-			       " for %s\n", mdname(mddev));
-			goto abort;
-		}
-	}
-
-	{
-		mddev->thread = md_register_thread(raid6d, mddev, "%s_raid6");
-		if (!mddev->thread) {
-			printk(KERN_ERR
-			       "raid6: couldn't allocate thread for %s\n",
-			       mdname(mddev));
-			goto abort;
-		}
-	}
-
-	memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
-		 conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
-	if (grow_stripes(conf, conf->max_nr_stripes)) {
-		printk(KERN_ERR
-		       "raid6: couldn't allocate %dkB for buffers\n", memory);
-		shrink_stripes(conf);
-		md_unregister_thread(mddev->thread);
-		goto abort;
-	} else
-		printk(KERN_INFO "raid6: allocated %dkB for %s\n",
-		       memory, mdname(mddev));
-
-	if (mddev->degraded == 0)
-		printk(KERN_INFO "raid6: raid level %d set %s active with %d out of %d"
-		       " devices, algorithm %d\n", conf->level, mdname(mddev),
-		       mddev->raid_disks-mddev->degraded, mddev->raid_disks,
-		       conf->algorithm);
-	else
-		printk(KERN_ALERT "raid6: raid level %d set %s active with %d"
-		       " out of %d devices, algorithm %d\n", conf->level,
-		       mdname(mddev), mddev->raid_disks - mddev->degraded,
-		       mddev->raid_disks, conf->algorithm);
-
-	print_raid6_conf(conf);
-
-	/* read-ahead size must cover two whole stripes, which is
-	 * 2 * (n-2) * chunksize where 'n' is the number of raid devices
-	 */
-	{
-		int stripe = (mddev->raid_disks-2) * mddev->chunk_size
-			/ PAGE_SIZE;
-		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
-			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
-	}
-
-	/* Ok, everything is just fine now */
-	sysfs_create_group(&mddev->kobj, &raid6_attrs_group);
-
-	mddev->array_size =  mddev->size * (mddev->raid_disks - 2);
-
-	mddev->queue->unplug_fn = raid6_unplug_device;
-	mddev->queue->issue_flush_fn = raid6_issue_flush;
-	return 0;
-abort:
-	if (conf) {
-		print_raid6_conf(conf);
-		safe_put_page(conf->spare_page);
-		kfree(conf->stripe_hashtbl);
-		kfree(conf->disks);
-		kfree(conf);
-	}
-	mddev->private = NULL;
-	printk(KERN_ALERT "raid6: failed to run raid set %s\n", mdname(mddev));
-	return -EIO;
-}
-
-
-
-static int stop (mddev_t *mddev)
-{
-	raid6_conf_t *conf = (raid6_conf_t *) mddev->private;
-
-	md_unregister_thread(mddev->thread);
-	mddev->thread = NULL;
-	shrink_stripes(conf);
-	kfree(conf->stripe_hashtbl);
-	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
-	sysfs_remove_group(&mddev->kobj, &raid6_attrs_group);
-	kfree(conf);
-	mddev->private = NULL;
-	return 0;
-}
-
-#if RAID6_DUMPSTATE
-static void print_sh (struct seq_file *seq, struct stripe_head *sh)
-{
-	int i;
-
-	seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
-		   (unsigned long long)sh->sector, sh->pd_idx, sh->state);
-	seq_printf(seq, "sh %llu,  count %d.\n",
-		   (unsigned long long)sh->sector, atomic_read(&sh->count));
-	seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
-	for (i = 0; i < sh->raid_conf->raid_disks; i++) {
-		seq_printf(seq, "(cache%d: %p %ld) ",
-			   i, sh->dev[i].page, sh->dev[i].flags);
-	}
-	seq_printf(seq, "\n");
-}
-
-static void printall (struct seq_file *seq, raid6_conf_t *conf)
-{
-	struct stripe_head *sh;
-	struct hlist_node *hn;
-	int i;
-
-	spin_lock_irq(&conf->device_lock);
-	for (i = 0; i < NR_HASH; i++) {
-		sh = conf->stripe_hashtbl[i];
-		hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
-			if (sh->raid_conf != conf)
-				continue;
-			print_sh(seq, sh);
-		}
-	}
-	spin_unlock_irq(&conf->device_lock);
-}
-#endif
-
-static void status (struct seq_file *seq, mddev_t *mddev)
-{
-	raid6_conf_t *conf = (raid6_conf_t *) mddev->private;
-	int i;
-
-	seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
-	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->working_disks);
-	for (i = 0; i < conf->raid_disks; i++)
- 		seq_printf (seq, "%s",
-			    conf->disks[i].rdev &&
-			    test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
-	seq_printf (seq, "]");
-#if RAID6_DUMPSTATE
-	seq_printf (seq, "\n");
-	printall(seq, conf);
-#endif
-}
-
-static void print_raid6_conf (raid6_conf_t *conf)
-{
-	int i;
-	struct disk_info *tmp;
-
-	printk("RAID6 conf printout:\n");
-	if (!conf) {
-		printk("(conf==NULL)\n");
-		return;
-	}
-	printk(" --- rd:%d wd:%d fd:%d\n", conf->raid_disks,
-		 conf->working_disks, conf->failed_disks);
-
-	for (i = 0; i < conf->raid_disks; i++) {
-		char b[BDEVNAME_SIZE];
-		tmp = conf->disks + i;
-		if (tmp->rdev)
-		printk(" disk %d, o:%d, dev:%s\n",
-			i, !test_bit(Faulty, &tmp->rdev->flags),
-			bdevname(tmp->rdev->bdev,b));
-	}
-}
-
-static int raid6_spare_active(mddev_t *mddev)
-{
-	int i;
-	raid6_conf_t *conf = mddev->private;
-	struct disk_info *tmp;
-
-	for (i = 0; i < conf->raid_disks; i++) {
-		tmp = conf->disks + i;
-		if (tmp->rdev
-		    && !test_bit(Faulty, &tmp->rdev->flags)
-		    && !test_bit(In_sync, &tmp->rdev->flags)) {
-			mddev->degraded--;
-			conf->failed_disks--;
-			conf->working_disks++;
-			set_bit(In_sync, &tmp->rdev->flags);
-		}
-	}
-	print_raid6_conf(conf);
-	return 0;
-}
-
-static int raid6_remove_disk(mddev_t *mddev, int number)
-{
-	raid6_conf_t *conf = mddev->private;
-	int err = 0;
-	mdk_rdev_t *rdev;
-	struct disk_info *p = conf->disks + number;
-
-	print_raid6_conf(conf);
-	rdev = p->rdev;
-	if (rdev) {
-		if (test_bit(In_sync, &rdev->flags) ||
-		    atomic_read(&rdev->nr_pending)) {
-			err = -EBUSY;
-			goto abort;
-		}
-		p->rdev = NULL;
-		synchronize_rcu();
-		if (atomic_read(&rdev->nr_pending)) {
-			/* lost the race, try later */
-			err = -EBUSY;
-			p->rdev = rdev;
-		}
-	}
-
-abort:
-
-	print_raid6_conf(conf);
-	return err;
-}
-
-static int raid6_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
-{
-	raid6_conf_t *conf = mddev->private;
-	int found = 0;
-	int disk;
-	struct disk_info *p;
-
-	if (mddev->degraded > 2)
-		/* no point adding a device */
-		return 0;
-	/*
-	 * find the disk ... but prefer rdev->saved_raid_disk
-	 * if possible.
-	 */
-	if (rdev->saved_raid_disk >= 0 &&
-	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
-		disk = rdev->saved_raid_disk;
-	else
-		disk = 0;
-	for ( ; disk < mddev->raid_disks; disk++)
-		if ((p=conf->disks + disk)->rdev == NULL) {
-			clear_bit(In_sync, &rdev->flags);
-			rdev->raid_disk = disk;
-			found = 1;
-			if (rdev->saved_raid_disk != disk)
-				conf->fullsync = 1;
-			rcu_assign_pointer(p->rdev, rdev);
-			break;
-		}
-	print_raid6_conf(conf);
-	return found;
-}
-
-static int raid6_resize(mddev_t *mddev, sector_t sectors)
-{
-	/* no resync is happening, and there is enough space
-	 * on all devices, so we can resize.
-	 * We need to make sure resync covers any new space.
-	 * If the array is shrinking we should possibly wait until
-	 * any io in the removed space completes, but it hardly seems
-	 * worth it.
-	 */
-	sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
-	mddev->array_size = (sectors * (mddev->raid_disks-2))>>1;
-	set_capacity(mddev->gendisk, mddev->array_size << 1);
-	mddev->changed = 1;
-	if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
-		mddev->recovery_cp = mddev->size << 1;
-		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-	}
-	mddev->size = sectors /2;
-	mddev->resync_max_sectors = sectors;
-	return 0;
-}
-
-static void raid6_quiesce(mddev_t *mddev, int state)
-{
-	raid6_conf_t *conf = mddev_to_conf(mddev);
-
-	switch(state) {
-	case 1: /* stop all writes */
-		spin_lock_irq(&conf->device_lock);
-		conf->quiesce = 1;
-		wait_event_lock_irq(conf->wait_for_stripe,
-				    atomic_read(&conf->active_stripes) == 0,
-				    conf->device_lock, /* nothing */);
-		spin_unlock_irq(&conf->device_lock);
-		break;
-
-	case 0: /* re-enable writes */
-		spin_lock_irq(&conf->device_lock);
-		conf->quiesce = 0;
-		wake_up(&conf->wait_for_stripe);
-		spin_unlock_irq(&conf->device_lock);
-		break;
-	}
-}
-
-static struct mdk_personality raid6_personality =
-{
-	.name		= "raid6",
-	.level		= 6,
-	.owner		= THIS_MODULE,
-	.make_request	= make_request,
-	.run		= run,
-	.stop		= stop,
-	.status		= status,
-	.error_handler	= error,
-	.hot_add_disk	= raid6_add_disk,
-	.hot_remove_disk= raid6_remove_disk,
-	.spare_active	= raid6_spare_active,
-	.sync_request	= sync_request,
-	.resize		= raid6_resize,
-	.quiesce	= raid6_quiesce,
-};
-
-static int __init raid6_init(void)
-{
-	int e;
-
-	e = raid6_select_algo();
-	if ( e )
-		return e;
-
-	return register_md_personality(&raid6_personality);
-}
-
-static void raid6_exit (void)
-{
-	unregister_md_personality(&raid6_personality);
-}
-
-module_init(raid6_init);
-module_exit(raid6_exit);
-MODULE_LICENSE("GPL");
-MODULE_ALIAS("md-personality-8"); /* RAID6 */
-MODULE_ALIAS("md-raid6");
-MODULE_ALIAS("md-level-6");