Merge branch 'master'

1 files changed, 2224 insertions, 32 deletions

diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index be9fd1dd423..72753389181 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -19,11 +19,24 @@
  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#include <linux/pagemap.h>
 #include <linux/buffer_head.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/sched.h>
+#include <linux/swap.h>
+#include <linux/uio.h>
+#include <linux/writeback.h>
 
+#include <asm/page.h>
+#include <asm/uaccess.h>
+
+#include "attrib.h"
+#include "bitmap.h"
 #include "inode.h"
 #include "debug.h"
+#include "lcnalloc.h"
+#include "malloc.h"
+#include "mft.h"
 #include "ntfs.h"
 
 /**
@@ -56,6 +69,2185 @@ static int ntfs_file_open(struct inode *vi, struct file *filp)
 #ifdef NTFS_RW
 
 /**
+ * ntfs_attr_extend_initialized - extend the initialized size of an attribute
+ * @ni:			ntfs inode of the attribute to extend
+ * @new_init_size:	requested new initialized size in bytes
+ * @cached_page:	store any allocated but unused page here
+ * @lru_pvec:		lru-buffering pagevec of the caller
+ *
+ * Extend the initialized size of an attribute described by the ntfs inode @ni
+ * to @new_init_size bytes.  This involves zeroing any non-sparse space between
+ * the old initialized size and @new_init_size both in the page cache and on
+ * disk (if relevant complete pages are already uptodate in the page cache then
+ * these are simply marked dirty).
+ *
+ * As a side-effect, the file size (vfs inode->i_size) may be incremented as,
+ * in the resident attribute case, it is tied to the initialized size and, in
+ * the non-resident attribute case, it may not fall below the initialized size.
+ *
+ * Note that if the attribute is resident, we do not need to touch the page
+ * cache at all.  This is because if the page cache page is not uptodate we
+ * bring it uptodate later, when doing the write to the mft record since we
+ * then already have the page mapped.  And if the page is uptodate, the
+ * non-initialized region will already have been zeroed when the page was
+ * brought uptodate and the region may in fact already have been overwritten
+ * with new data via mmap() based writes, so we cannot just zero it.  And since
+ * POSIX specifies that the behaviour of resizing a file whilst it is mmap()ped
+ * is unspecified, we choose not to do zeroing and thus we do not need to touch
+ * the page at all.  For a more detailed explanation see ntfs_truncate() in
+ * fs/ntfs/inode.c.
+ *
+ * @cached_page and @lru_pvec are just optimizations for dealing with multiple
+ * pages.
+ *
+ * Return 0 on success and -errno on error.  In the case that an error is
+ * encountered it is possible that the initialized size will already have been
+ * incremented some way towards @new_init_size but it is guaranteed that if
+ * this is the case, the necessary zeroing will also have happened and that all
+ * metadata is self-consistent.
+ *
+ * Locking: i_sem on the vfs inode corrseponsind to the ntfs inode @ni must be
+ *	    held by the caller.
+ */
+static int ntfs_attr_extend_initialized(ntfs_inode *ni, const s64 new_init_size,
+		struct page **cached_page, struct pagevec *lru_pvec)
+{
+	s64 old_init_size;
+	loff_t old_i_size;
+	pgoff_t index, end_index;
+	unsigned long flags;
+	struct inode *vi = VFS_I(ni);
+	ntfs_inode *base_ni;
+	MFT_RECORD *m = NULL;
+	ATTR_RECORD *a;
+	ntfs_attr_search_ctx *ctx = NULL;
+	struct address_space *mapping;
+	struct page *page = NULL;
+	u8 *kattr;
+	int err;
+	u32 attr_len;
+
+	read_lock_irqsave(&ni->size_lock, flags);
+	old_init_size = ni->initialized_size;
+	old_i_size = i_size_read(vi);
+	BUG_ON(new_init_size > ni->allocated_size);
+	read_unlock_irqrestore(&ni->size_lock, flags);
+	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
+			"old_initialized_size 0x%llx, "
+			"new_initialized_size 0x%llx, i_size 0x%llx.",
+			vi->i_ino, (unsigned)le32_to_cpu(ni->type),
+			(unsigned long long)old_init_size,
+			(unsigned long long)new_init_size, old_i_size);
+	if (!NInoAttr(ni))
+		base_ni = ni;
+	else
+		base_ni = ni->ext.base_ntfs_ino;
+	/* Use goto to reduce indentation and we need the label below anyway. */
+	if (NInoNonResident(ni))
+		goto do_non_resident_extend;
+	BUG_ON(old_init_size != old_i_size);
+	m = map_mft_record(base_ni);
+	if (IS_ERR(m)) {
+		err = PTR_ERR(m);
+		m = NULL;
+		goto err_out;
+	}
+	ctx = ntfs_attr_get_search_ctx(base_ni, m);
+	if (unlikely(!ctx)) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+			CASE_SENSITIVE, 0, NULL, 0, ctx);
+	if (unlikely(err)) {
+		if (err == -ENOENT)
+			err = -EIO;
+		goto err_out;
+	}
+	m = ctx->mrec;
+	a = ctx->attr;
+	BUG_ON(a->non_resident);
+	/* The total length of the attribute value. */
+	attr_len = le32_to_cpu(a->data.resident.value_length);
+	BUG_ON(old_i_size != (loff_t)attr_len);
+	/*
+	 * Do the zeroing in the mft record and update the attribute size in
+	 * the mft record.
+	 */
+	kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
+	memset(kattr + attr_len, 0, new_init_size - attr_len);
+	a->data.resident.value_length = cpu_to_le32((u32)new_init_size);
+	/* Finally, update the sizes in the vfs and ntfs inodes. */
+	write_lock_irqsave(&ni->size_lock, flags);
+	i_size_write(vi, new_init_size);
+	ni->initialized_size = new_init_size;
+	write_unlock_irqrestore(&ni->size_lock, flags);
+	goto done;
+do_non_resident_extend:
+	/*
+	 * If the new initialized size @new_init_size exceeds the current file
+	 * size (vfs inode->i_size), we need to extend the file size to the
+	 * new initialized size.
+	 */
+	if (new_init_size > old_i_size) {
+		m = map_mft_record(base_ni);
+		if (IS_ERR(m)) {
+			err = PTR_ERR(m);
+			m = NULL;
+			goto err_out;
+		}
+		ctx = ntfs_attr_get_search_ctx(base_ni, m);
+		if (unlikely(!ctx)) {
+			err = -ENOMEM;
+			goto err_out;
+		}
+		err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+				CASE_SENSITIVE, 0, NULL, 0, ctx);
+		if (unlikely(err)) {
+			if (err == -ENOENT)
+				err = -EIO;
+			goto err_out;
+		}
+		m = ctx->mrec;
+		a = ctx->attr;
+		BUG_ON(!a->non_resident);
+		BUG_ON(old_i_size != (loff_t)
+				sle64_to_cpu(a->data.non_resident.data_size));
+		a->data.non_resident.data_size = cpu_to_sle64(new_init_size);
+		flush_dcache_mft_record_page(ctx->ntfs_ino);
+		mark_mft_record_dirty(ctx->ntfs_ino);
+		/* Update the file size in the vfs inode. */
+		i_size_write(vi, new_init_size);
+		ntfs_attr_put_search_ctx(ctx);
+		ctx = NULL;
+		unmap_mft_record(base_ni);
+		m = NULL;
+	}
+	mapping = vi->i_mapping;
+	index = old_init_size >> PAGE_CACHE_SHIFT;
+	end_index = (new_init_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+	do {
+		/*
+		 * Read the page.  If the page is not present, this will zero
+		 * the uninitialized regions for us.
+		 */
+		page = read_cache_page(mapping, index,
+				(filler_t*)mapping->a_ops->readpage, NULL);
+		if (IS_ERR(page)) {
+			err = PTR_ERR(page);
+			goto init_err_out;
+		}
+		wait_on_page_locked(page);
+		if (unlikely(!PageUptodate(page) || PageError(page))) {
+			page_cache_release(page);
+			err = -EIO;
+			goto init_err_out;
+		}
+		/*
+		 * Update the initialized size in the ntfs inode.  This is
+		 * enough to make ntfs_writepage() work.
+		 */
+		write_lock_irqsave(&ni->size_lock, flags);
+		ni->initialized_size = (index + 1) << PAGE_CACHE_SHIFT;
+		if (ni->initialized_size > new_init_size)
+			ni->initialized_size = new_init_size;
+		write_unlock_irqrestore(&ni->size_lock, flags);
+		/* Set the page dirty so it gets written out. */
+		set_page_dirty(page);
+		page_cache_release(page);
+		/*
+		 * Play nice with the vm and the rest of the system.  This is
+		 * very much needed as we can potentially be modifying the
+		 * initialised size from a very small value to a really huge
+		 * value, e.g.
+		 *	f = open(somefile, O_TRUNC);
+		 *	truncate(f, 10GiB);
+		 *	seek(f, 10GiB);
+		 *	write(f, 1);
+		 * And this would mean we would be marking dirty hundreds of
+		 * thousands of pages or as in the above example more than
+		 * two and a half million pages!
+		 *
+		 * TODO: For sparse pages could optimize this workload by using
+		 * the FsMisc / MiscFs page bit as a "PageIsSparse" bit.  This
+		 * would be set in readpage for sparse pages and here we would
+		 * not need to mark dirty any pages which have this bit set.
+		 * The only caveat is that we have to clear the bit everywhere
+		 * where we allocate any clusters that lie in the page or that
+		 * contain the page.
+		 *
+		 * TODO: An even greater optimization would be for us to only
+		 * call readpage() on pages which are not in sparse regions as
+		 * determined from the runlist.  This would greatly reduce the
+		 * number of pages we read and make dirty in the case of sparse
+		 * files.
+		 */
+		balance_dirty_pages_ratelimited(mapping);
+		cond_resched();
+	} while (++index < end_index);
+	read_lock_irqsave(&ni->size_lock, flags);
+	BUG_ON(ni->initialized_size != new_init_size);
+	read_unlock_irqrestore(&ni->size_lock, flags);
+	/* Now bring in sync the initialized_size in the mft record. */
+	m = map_mft_record(base_ni);
+	if (IS_ERR(m)) {
+		err = PTR_ERR(m);
+		m = NULL;
+		goto init_err_out;
+	}
+	ctx = ntfs_attr_get_search_ctx(base_ni, m);
+	if (unlikely(!ctx)) {
+		err = -ENOMEM;
+		goto init_err_out;
+	}
+	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+			CASE_SENSITIVE, 0, NULL, 0, ctx);
+	if (unlikely(err)) {
+		if (err == -ENOENT)
+			err = -EIO;
+		goto init_err_out;
+	}
+	m = ctx->mrec;
+	a = ctx->attr;
+	BUG_ON(!a->non_resident);
+	a->data.non_resident.initialized_size = cpu_to_sle64(new_init_size);
+done:
+	flush_dcache_mft_record_page(ctx->ntfs_ino);
+	mark_mft_record_dirty(ctx->ntfs_ino);
+	if (ctx)
+		ntfs_attr_put_search_ctx(ctx);
+	if (m)
+		unmap_mft_record(base_ni);
+	ntfs_debug("Done, initialized_size 0x%llx, i_size 0x%llx.",
+			(unsigned long long)new_init_size, i_size_read(vi));
+	return 0;
+init_err_out:
+	write_lock_irqsave(&ni->size_lock, flags);
+	ni->initialized_size = old_init_size;
+	write_unlock_irqrestore(&ni->size_lock, flags);
+err_out:
+	if (ctx)
+		ntfs_attr_put_search_ctx(ctx);
+	if (m)
+		unmap_mft_record(base_ni);
+	ntfs_debug("Failed.  Returning error code %i.", err);
+	return err;
+}
+
+/**
+ * ntfs_fault_in_pages_readable -
+ *
+ * Fault a number of userspace pages into pagetables.
+ *
+ * Unlike include/linux/pagemap.h::fault_in_pages_readable(), this one copes
+ * with more than two userspace pages as well as handling the single page case
+ * elegantly.
+ *
+ * If you find this difficult to understand, then think of the while loop being
+ * the following code, except that we do without the integer variable ret:
+ *
+ *	do {
+ *		ret = __get_user(c, uaddr);
+ *		uaddr += PAGE_SIZE;
+ *	} while (!ret && uaddr < end);
+ *
+ * Note, the final __get_user() may well run out-of-bounds of the user buffer,
+ * but _not_ out-of-bounds of the page the user buffer belongs to, and since
+ * this is only a read and not a write, and since it is still in the same page,
+ * it should not matter and this makes the code much simpler.
+ */
+static inline void ntfs_fault_in_pages_readable(const char __user *uaddr,
+		int bytes)
+{
+	const char __user *end;
+	volatile char c;
+
+	/* Set @end to the first byte outside the last page we care about. */
+	end = (const char __user*)PAGE_ALIGN((ptrdiff_t __user)uaddr + bytes);
+
+	while (!__get_user(c, uaddr) && (uaddr += PAGE_SIZE, uaddr < end))
+		;
+}
+
+/**
+ * ntfs_fault_in_pages_readable_iovec -
+ *
+ * Same as ntfs_fault_in_pages_readable() but operates on an array of iovecs.
+ */
+static inline void ntfs_fault_in_pages_readable_iovec(const struct iovec *iov,
+		size_t iov_ofs, int bytes)
+{
+	do {
+		const char __user *buf;
+		unsigned len;
+
+		buf = iov->iov_base + iov_ofs;
+		len = iov->iov_len - iov_ofs;
+		if (len > bytes)
+			len = bytes;
+		ntfs_fault_in_pages_readable(buf, len);
+		bytes -= len;
+		iov++;
+		iov_ofs = 0;
+	} while (bytes);
+}
+
+/**
+ * __ntfs_grab_cache_pages - obtain a number of locked pages
+ * @mapping:	address space mapping from which to obtain page cache pages
+ * @index:	starting index in @mapping at which to begin obtaining pages
+ * @nr_pages:	number of page cache pages to obtain
+ * @pages:	array of pages in which to return the obtained page cache pages
+ * @cached_page: allocated but as yet unused page
+ * @lru_pvec:	lru-buffering pagevec of caller
+ *
+ * Obtain @nr_pages locked page cache pages from the mapping @maping and
+ * starting at index @index.
+ *
+ * If a page is newly created, increment its refcount and add it to the
+ * caller's lru-buffering pagevec @lru_pvec.
+ *
+ * This is the same as mm/filemap.c::__grab_cache_page(), except that @nr_pages
+ * are obtained at once instead of just one page and that 0 is returned on
+ * success and -errno on error.
+ *
+ * Note, the page locks are obtained in ascending page index order.
+ */
+static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
+		pgoff_t index, const unsigned nr_pages, struct page **pages,
+		struct page **cached_page, struct pagevec *lru_pvec)
+{
+	int err, nr;
+
+	BUG_ON(!nr_pages);
+	err = nr = 0;
+	do {
+		pages[nr] = find_lock_page(mapping, index);
+		if (!pages[nr]) {
+			if (!*cached_page) {
+				*cached_page = page_cache_alloc(mapping);
+				if (unlikely(!*cached_page)) {
+					err = -ENOMEM;
+					goto err_out;
+				}
+			}
+			err = add_to_page_cache(*cached_page, mapping, index,
+					GFP_KERNEL);
+			if (unlikely(err)) {
+				if (err == -EEXIST)
+					continue;
+				goto err_out;
+			}
+			pages[nr] = *cached_page;
+			page_cache_get(*cached_page);
+			if (unlikely(!pagevec_add(lru_pvec, *cached_page)))
+				__pagevec_lru_add(lru_pvec);
+			*cached_page = NULL;
+		}
+		index++;
+		nr++;
+	} while (nr < nr_pages);
+out:
+	return err;
+err_out:
+	while (nr > 0) {
+		unlock_page(pages[--nr]);
+		page_cache_release(pages[nr]);
+	}
+	goto out;
+}
+
+static inline int ntfs_submit_bh_for_read(struct buffer_head *bh)
+{
+	lock_buffer(bh);
+	get_bh(bh);
+	bh->b_end_io = end_buffer_read_sync;
+	return submit_bh(READ, bh);
+}
+
+/**
+ * ntfs_prepare_pages_for_non_resident_write - prepare pages for receiving data
+ * @pages:	array of destination pages
+ * @nr_pages:	number of pages in @pages
+ * @pos:	byte position in file at which the write begins
+ * @bytes:	number of bytes to be written
+ *
+ * This is called for non-resident attributes from ntfs_file_buffered_write()
+ * with i_sem held on the inode (@pages[0]->mapping->host).  There are
+ * @nr_pages pages in @pages which are locked but not kmap()ped.  The source
+ * data has not yet been copied into the @pages.
+ * 
+ * Need to fill any holes with actual clusters, allocate buffers if necessary,
+ * ensure all the buffers are mapped, and bring uptodate any buffers that are
+ * only partially being written to.
+ *
+ * If @nr_pages is greater than one, we are guaranteed that the cluster size is
+ * greater than PAGE_CACHE_SIZE, that all pages in @pages are entirely inside
+ * the same cluster and that they are the entirety of that cluster, and that
+ * the cluster is sparse, i.e. we need to allocate a cluster to fill the hole.
+ *
+ * i_size is not to be modified yet.
+ *
+ * Return 0 on success or -errno on error.
+ */
+static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
+		unsigned nr_pages, s64 pos, size_t bytes)
+{
+	VCN vcn, highest_vcn = 0, cpos, cend, bh_cpos, bh_cend;
+	LCN lcn;
+	s64 bh_pos, vcn_len, end, initialized_size;
+	sector_t lcn_block;
+	struct page *page;
+	struct inode *vi;
+	ntfs_inode *ni, *base_ni = NULL;
+	ntfs_volume *vol;
+	runlist_element *rl, *rl2;
+	struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
+	ntfs_attr_search_ctx *ctx = NULL;
+	MFT_RECORD *m = NULL;
+	ATTR_RECORD *a = NULL;
+	unsigned long flags;
+	u32 attr_rec_len = 0;
+	unsigned blocksize, u;
+	int err, mp_size;
+	BOOL rl_write_locked, was_hole, is_retry;
+	unsigned char blocksize_bits;
+	struct {
+		u8 runlist_merged:1;
+		u8 mft_attr_mapped:1;
+		u8 mp_rebuilt:1;
+		u8 attr_switched:1;
+	} status = { 0, 0, 0, 0 };
+
+	BUG_ON(!nr_pages);
+	BUG_ON(!pages);
+	BUG_ON(!*pages);
+	vi = pages[0]->mapping->host;
+	ni = NTFS_I(vi);
+	vol = ni->vol;
+	ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
+			"index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
+			vi->i_ino, ni->type, pages[0]->index, nr_pages,
+			(long long)pos, bytes);
+	blocksize_bits = vi->i_blkbits;
+	blocksize = 1 << blocksize_bits;
+	u = 0;
+	do {
+		struct page *page = pages[u];
+		/*
+		 * create_empty_buffers() will create uptodate/dirty buffers if
+		 * the page is uptodate/dirty.
+		 */
+		if (!page_has_buffers(page)) {
+			create_empty_buffers(page, blocksize, 0);
+			if (unlikely(!page_has_buffers(page)))
+				return -ENOMEM;
+		}
+	} while (++u < nr_pages);
+	rl_write_locked = FALSE;
+	rl = NULL;
+	err = 0;
+	vcn = lcn = -1;
+	vcn_len = 0;
+	lcn_block = -1;
+	was_hole = FALSE;
+	cpos = pos >> vol->cluster_size_bits;
+	end = pos + bytes;
+	cend = (end + vol->cluster_size - 1) >> vol->cluster_size_bits;
+	/*
+	 * Loop over each page and for each page over each buffer.  Use goto to
+	 * reduce indentation.
+	 */
+	u = 0;
+do_next_page:
+	page = pages[u];
+	bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
+	bh = head = page_buffers(page);
+	do {
+		VCN cdelta;
+		s64 bh_end;
+		unsigned bh_cofs;
+
+		/* Clear buffer_new on all buffers to reinitialise state. */
+		if (buffer_new(bh))
+			clear_buffer_new(bh);
+		bh_end = bh_pos + blocksize;
+		bh_cpos = bh_pos >> vol->cluster_size_bits;
+		bh_cofs = bh_pos & vol->cluster_size_mask;
+		if (buffer_mapped(bh)) {
+			/*
+			 * The buffer is already mapped.  If it is uptodate,
+			 * ignore it.
+			 */
+			if (buffer_uptodate(bh))
+				continue;
+			/*
+			 * The buffer is not uptodate.  If the page is uptodate
+			 * set the buffer uptodate and otherwise ignore it.
+			 */
+			if (PageUptodate(page)) {
+				set_buffer_uptodate(bh);
+				continue;
+			}
+			/*
+			 * Neither the page nor the buffer are uptodate.  If
+			 * the buffer is only partially being written to, we
+			 * need to read it in before the write, i.e. now.
+			 */
+			if ((bh_pos < pos && bh_end > pos) ||
+					(bh_pos < end && bh_end > end)) {
+				/*
+				 * If the buffer is fully or partially within
+				 * the initialized size, do an actual read.
+				 * Otherwise, simply zero the buffer.
+				 */
+				read_lock_irqsave(&ni->size_lock, flags);
+				initialized_size = ni->initialized_size;
+				read_unlock_irqrestore(&ni->size_lock, flags);
+				if (bh_pos < initialized_size) {
+					ntfs_submit_bh_for_read(bh);
+					*wait_bh++ = bh;
+				} else {
+					u8 *kaddr = kmap_atomic(page, KM_USER0);
+					memset(kaddr + bh_offset(bh), 0,
+							blocksize);
+					kunmap_atomic(kaddr, KM_USER0);
+					flush_dcache_page(page);
+					set_buffer_uptodate(bh);
+				}
+			}
+			continue;
+		}
+		/* Unmapped buffer.  Need to map it. */
+		bh->b_bdev = vol->sb->s_bdev;
+		/*
+		 * If the current buffer is in the same clusters as the map
+		 * cache, there is no need to check the runlist again.  The
+		 * map cache is made up of @vcn, which is the first cached file
+		 * cluster, @vcn_len which is the number of cached file
+		 * clusters, @lcn is the device cluster corresponding to @vcn,
+		 * and @lcn_block is the block number corresponding to @lcn.
+		 */
+		cdelta = bh_cpos - vcn;
+		if (likely(!cdelta || (cdelta > 0 && cdelta < vcn_len))) {
+map_buffer_cached:
+			BUG_ON(lcn < 0);
+			bh->b_blocknr = lcn_block +
+					(cdelta << (vol->cluster_size_bits -
+					blocksize_bits)) +
+					(bh_cofs >> blocksize_bits);
+			set_buffer_mapped(bh);
+			/*
+			 * If the page is uptodate so is the buffer.  If the
+			 * buffer is fully outside the write, we ignore it if
+			 * it was already allocated and we mark it dirty so it
+			 * gets written out if we allocated it.  On the other
+			 * hand, if we allocated the buffer but we are not
+			 * marking it dirty we set buffer_new so we can do
+			 * error recovery.
+			 */
+			if (PageUptodate(page)) {
+				if (!buffer_uptodate(bh))
+					set_buffer_uptodate(bh);
+				if (unlikely(was_hole)) {
+					/* We allocated the buffer. */
+					unmap_underlying_metadata(bh->b_bdev,
+							bh->b_blocknr);
+					if (bh_end <= pos || bh_pos >= end)
+						mark_buffer_dirty(bh);
+					else
+						set_buffer_new(bh);
+				}
+				continue;
+			}
+			/* Page is _not_ uptodate. */
+			if (likely(!was_hole)) {
+				/*
+				 * Buffer was already allocated.  If it is not
+				 * uptodate and is only partially being written
+				 * to, we need to read it in before the write,
+				 * i.e. now.
+				 */
+				if (!buffer_uptodate(bh) && bh_pos < end &&
+						bh_end > pos &&
+						(bh_pos < pos ||
+						bh_end > end)) {
+					/*
+					 * If the buffer is fully or partially
+					 * within the initialized size, do an
+					 * actual read.  Otherwise, simply zero
+					 * the buffer.
+					 */
+					read_lock_irqsave(&ni->size_lock,
+							flags);
+					initialized_size = ni->initialized_size;
+					read_unlock_irqrestore(&ni->size_lock,
+							flags);
+					if (bh_pos < initialized_size) {
+						ntfs_submit_bh_for_read(bh);
+						*wait_bh++ = bh;
+					} else {
+						u8 *kaddr = kmap_atomic(page,
+								KM_USER0);
+						memset(kaddr + bh_offset(bh),
+								0, blocksize);
+						kunmap_atomic(kaddr, KM_USER0);
+						flush_dcache_page(page);
+						set_buffer_uptodate(bh);
+					}
+				}
+				continue;
+			}
+			/* We allocated the buffer. */
+			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
+			/*
+			 * If the buffer is fully outside the write, zero it,
+			 * set it uptodate, and mark it dirty so it gets
+			 * written out.  If it is partially being written to,
+			 * zero region surrounding the write but leave it to
+			 * commit write to do anything else.  Finally, if the
+			 * buffer is fully being overwritten, do nothing.
+			 */
+			if (bh_end <= pos || bh_pos >= end) {
+				if (!buffer_uptodate(bh)) {
+					u8 *kaddr = kmap_atomic(page, KM_USER0);
+					memset(kaddr + bh_offset(bh), 0,
+							blocksize);
+					kunmap_atomic(kaddr, KM_USER0);
+					flush_dcache_page(page);
+					set_buffer_uptodate(bh);
+				}
+				mark_buffer_dirty(bh);
+				continue;
+			}
+			set_buffer_new(bh);
+			if (!buffer_uptodate(bh) &&
+					(bh_pos < pos || bh_end > end)) {
+				u8 *kaddr;
+				unsigned pofs;
+					
+				kaddr = kmap_atomic(page, KM_USER0);
+				if (bh_pos < pos) {
+					pofs = bh_pos & ~PAGE_CACHE_MASK;
+					memset(kaddr + pofs, 0, pos - bh_pos);
+				}
+				if (bh_end > end) {
+					pofs = end & ~PAGE_CACHE_MASK;
+					memset(kaddr + pofs, 0, bh_end - end);
+				}
+				kunmap_atomic(kaddr, KM_USER0);
+				flush_dcache_page(page);
+			}
+			continue;
+		}
+		/*
+		 * Slow path: this is the first buffer in the cluster.  If it
+		 * is outside allocated size and is not uptodate, zero it and
+		 * set it uptodate.
+		 */
+		read_lock_irqsave(&ni->size_lock, flags);
+		initialized_size = ni->allocated_size;
+		read_unlock_irqrestore(&ni->size_lock, flags);
+		if (bh_pos > initialized_size) {
+			if (PageUptodate(page)) {
+				if (!buffer_uptodate(bh))
+					set_buffer_uptodate(bh);
+			} else if (!buffer_uptodate(bh)) {
+				u8 *kaddr = kmap_atomic(page, KM_USER0);
+				memset(kaddr + bh_offset(bh), 0, blocksize);
+				kunmap_atomic(kaddr, KM_USER0);
+				flush_dcache_page(page);
+				set_buffer_uptodate(bh);
+			}
+			continue;
+		}
+		is_retry = FALSE;
+		if (!rl) {
+			down_read(&ni->runlist.lock);
+retry_remap:
+			rl = ni->runlist.rl;
+		}
+		if (likely(rl != NULL)) {
+			/* Seek to element containing target cluster. */
+			while (rl->length && rl[1].vcn <= bh_cpos)
+				rl++;
+			lcn = ntfs_rl_vcn_to_lcn(rl, bh_cpos);
+			if (likely(lcn >= 0)) {
+				/*
+				 * Successful remap, setup the map cache and
+				 * use that to deal with the buffer.
+				 */
+				was_hole = FALSE;
+				vcn = bh_cpos;
+				vcn_len = rl[1].vcn - vcn;
+				lcn_block = lcn << (vol->cluster_size_bits -
+						blocksize_bits);
+				cdelta = 0;
+				/*
+				 * If the number of remaining clusters touched
+				 * by the write is smaller or equal to the
+				 * number of cached clusters, unlock the
+				 * runlist as the map cache will be used from
+				 * now on.
+				 */
+				if (likely(vcn + vcn_len >= cend)) {
+					if (rl_write_locked) {
+						up_write(&ni->runlist.lock);
+						rl_write_locked = FALSE;
+					} else
+						up_read(&ni->runlist.lock);
+					rl = NULL;
+				}
+				goto map_buffer_cached;
+			}
+		} else
+			lcn = LCN_RL_NOT_MAPPED;
+		/*
+		 * If it is not a hole and not out of bounds, the runlist is
+		 * probably unmapped so try to map it now.
+		 */
+		if (unlikely(lcn != LCN_HOLE && lcn != LCN_ENOENT)) {
+			if (likely(!is_retry && lcn == LCN_RL_NOT_MAPPED)) {
+				/* Attempt to map runlist. */
+				if (!rl_write_locked) {
+					/*
+					 * We need the runlist locked for
+					 * writing, so if it is locked for
+					 * reading relock it now and retry in
+					 * case it changed whilst we dropped
+					 * the lock.
+					 */
+					up_read(&ni->runlist.lock);
+					down_write(&ni->runlist.lock);
+					rl_write_locked = TRUE;
+					goto retry_remap;
+				}
+				err = ntfs_map_runlist_nolock(ni, bh_cpos,
+						NULL);
+				if (likely(!err)) {
+					is_retry = TRUE;
+					goto retry_remap;
+				}
+				/*
+				 * If @vcn is out of bounds, pretend @lcn is
+				 * LCN_ENOENT.  As long as the buffer is out
+				 * of bounds this will work fine.
+				 */
+				if (err == -ENOENT) {
+					lcn = LCN_ENOENT;
+					err = 0;
+					goto rl_not_mapped_enoent;
+				}
+			} else
+				err = -EIO;
+			/* Failed to map the buffer, even after retrying. */
+			bh->b_blocknr = -1;
+			ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
+					"attribute type 0x%x, vcn 0x%llx, "
+					"vcn offset 0x%x, because its "
+					"location on disk could not be "
+					"determined%s (error code %i).",
+					ni->mft_no, ni->type,
+					(unsigned long long)bh_cpos,
+					(unsigned)bh_pos &
+					vol->cluster_size_mask,
+					is_retry ? " even after retrying" : "",
+					err);
+			break;
+		}
+rl_not_mapped_enoent:
+		/*
+		 * The buffer is in a hole or out of bounds.  We need to fill
+		 * the hole, unless the buffer is in a cluster which is not
+		 * touched by the write, in which case we just leave the buffer
+		 * unmapped.  This can only happen when the cluster size is
+		 * less than the page cache size.
+		 */
+		if (unlikely(vol->cluster_size < PAGE_CACHE_SIZE)) {
+			bh_cend = (bh_end + vol->cluster_size - 1) >>
+					vol->cluster_size_bits;
+			if ((bh_cend <= cpos || bh_cpos >= cend)) {
+				bh->b_blocknr = -1;
+				/*
+				 * If the buffer is uptodate we skip it.  If it
+				 * is not but the page is uptodate, we can set
+				 * the buffer uptodate.  If the page is not
+				 * uptodate, we can clear the buffer and set it
+				 * uptodate.  Whether this is worthwhile is
+				 * debatable and this could be removed.
+				 */
+				if (PageUptodate(page)) {
+					if (!buffer_uptodate(bh))
+						set_buffer_uptodate(bh);
+				} else if (!buffer_uptodate(bh)) {
+					u8 *kaddr = kmap_atomic(page, KM_USER0);
+					memset(kaddr + bh_offset(bh), 0,
+							blocksize);
+					kunmap_atomic(kaddr, KM_USER0);
+					flush_dcache_page(page);
+					set_buffer_uptodate(bh);
+				}
+				continue;
+			}
+		}
+		/*
+		 * Out of bounds buffer is invalid if it was not really out of
+		 * bounds.
+		 */
+		BUG_ON(lcn != LCN_HOLE);
+		/*
+		 * We need the runlist locked for writing, so if it is locked
+		 * for reading relock it now and retry in case it changed
+		 * whilst we dropped the lock.
+		 */
+		BUG_ON(!rl);
+		if (!rl_write_locked) {
+			up_read(&ni->runlist.lock);
+			down_write(&ni->runlist.lock);
+			rl_write_locked = TRUE;
+			goto retry_remap;
+		}
+		/* Find the previous last allocated cluster. */
+		BUG_ON(rl->lcn != LCN_HOLE);
+		lcn = -1;
+		rl2 = rl;
+		while (--rl2 >= ni->runlist.rl) {
+			if (rl2->lcn >= 0) {
+				lcn = rl2->lcn + rl2->length;
+				break;
+			}
+		}
+		rl2 = ntfs_cluster_alloc(vol, bh_cpos, 1, lcn, DATA_ZONE,
+				FALSE);
+		if (IS_ERR(rl2)) {
+			err = PTR_ERR(rl2);
+			ntfs_debug("Failed to allocate cluster, error code %i.",
+					err);
+			break;
+		}
+		lcn = rl2->lcn;
+		rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
+		if (IS_ERR(rl)) {
+			err = PTR_ERR(rl);
+			if (err != -ENOMEM)
+				err = -EIO;
+			if (ntfs_cluster_free_from_rl(vol, rl2)) {
+				ntfs_error(vol->sb, "Failed to release "
+						"allocated cluster in error "
+						"code path.  Run chkdsk to "
+						"recover the lost cluster.");
+				NVolSetErrors(vol);
+			}
+			ntfs_free(rl2);
+			break;
+		}
+		ni->runlist.rl = rl;
+		status.runlist_merged = 1;
+		ntfs_debug("Allocated cluster, lcn 0x%llx.", lcn);
+		/* Map and lock the mft record and get the attribute record. */
+		if (!NInoAttr(ni))
+			base_ni = ni;
+		else
+			base_ni = ni->ext.base_ntfs_ino;
+		m = map_mft_record(base_ni);
+		if (IS_ERR(m)) {
+			err = PTR_ERR(m);
+			break;
+		}
+		ctx = ntfs_attr_get_search_ctx(base_ni, m);
+		if (unlikely(!ctx)) {
+			err = -ENOMEM;
+			unmap_mft_record(base_ni);
+			break;
+		}
+		status.mft_attr_mapped = 1;
+		err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+				CASE_SENSITIVE, bh_cpos, NULL, 0, ctx);
+		if (unlikely(err)) {
+			if (err == -ENOENT)
+				err = -EIO;
+			break;
+		}
+		m = ctx->mrec;
+		a = ctx->attr;
+		/*
+		 * Find the runlist element with which the attribute extent
+		 * starts.  Note, we cannot use the _attr_ version because we
+		 * have mapped the mft record.  That is ok because we know the
+		 * runlist fragment must be mapped already to have ever gotten
+		 * here, so we can just use the _rl_ version.
+		 */
+		vcn = sle64_to_cpu(a->data.non_resident.lowest_vcn);
+		rl2 = ntfs_rl_find_vcn_nolock(rl, vcn);
+		BUG_ON(!rl2);
+		BUG_ON(!rl2->length);
+		BUG_ON(rl2->lcn < LCN_HOLE);
+		highest_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
+		/*
+		 * If @highest_vcn is zero, calculate the real highest_vcn
+		 * (which can really be zero).
+		 */
+		if (!highest_vcn)
+			highest_vcn = (sle64_to_cpu(
+					a->data.non_resident.allocated_size) >>
+					vol->cluster_size_bits) - 1;
+		/*
+		 * Determine the size of the mapping pairs array for the new
+		 * extent, i.e. the old extent with the hole filled.
+		 */
+		mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, vcn,
+				highest_vcn);
+		if (unlikely(mp_size <= 0)) {
+			if (!(err = mp_size))
+				err = -EIO;
+			ntfs_debug("Failed to get size for mapping pairs "
+					"array, error code %i.", err);
+			break;
+		}
+		/*
+		 * Resize the attribute record to fit the new mapping pairs
+		 * array.
+		 */
+		attr_rec_len = le32_to_cpu(a->length);
+		err = ntfs_attr_record_resize(m, a, mp_size + le16_to_cpu(
+				a->data.non_resident.mapping_pairs_offset));
+		if (unlikely(err)) {
+			BUG_ON(err != -ENOSPC);
+			// TODO: Deal with this by using the current attribute
+			// and fill it with as much of the mapping pairs
+			// array as possible.  Then loop over each attribute
+			// extent rewriting the mapping pairs arrays as we go
+			// along and if when we reach the end we have not
+			// enough space, try to resize the last attribute
+			// extent and if even that fails, add a new attribute
+			// extent.
+			// We could also try to resize at each step in the hope
+			// that we will not need to rewrite every single extent.
+			// Note, we may need to decompress some extents to fill
+			// the runlist as we are walking the extents...
+			ntfs_error(vol->sb, "Not enough space in the mft "
+					"record for the extended attribute "
+					"record.  This case is not "
+					"implemented yet.");
+			err = -EOPNOTSUPP;
+			break ;
+		}
+		status.mp_rebuilt = 1;
+		/*
+		 * Generate the mapping pairs array directly into the attribute
+		 * record.
+		 */
+		err = ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
+				a->data.non_resident.mapping_pairs_offset),
+				mp_size, rl2, vcn, highest_vcn, NULL);
+		if (unlikely(err)) {
+			ntfs_error(vol->sb, "Cannot fill hole in inode 0x%lx, "
+					"attribute type 0x%x, because building "
+					"the mapping pairs failed with error "
+					"code %i.", vi->i_ino,
+					(unsigned)le32_to_cpu(ni->type), err);
+			err = -EIO;
+			break;
+		}
+		/* Update the highest_vcn but only if it was not set. */
+		if (unlikely(!a->data.non_resident.highest_vcn))
+			a->data.non_resident.highest_vcn =
+					cpu_to_sle64(highest_vcn);
+		/*
+		 * If the attribute is sparse/compressed, update the compressed
+		 * size in the ntfs_inode structure and the attribute record.
+		 */
+		if (likely(NInoSparse(ni) || NInoCompressed(ni))) {
+			/*
+			 * If we are not in the first attribute extent, switch
+			 * to it, but first ensure the changes will make it to
+			 * disk later.
+			 */
+			if (a->data.non_resident.lowest_vcn) {
+				flush_dcache_mft_record_page(ctx->ntfs_ino);
+				mark_mft_record_dirty(ctx->ntfs_ino);
+				ntfs_attr_reinit_search_ctx(ctx);
+				err = ntfs_attr_lookup(ni->type, ni->name,
+						ni->name_len, CASE_SENSITIVE,
+						0, NULL, 0, ctx);
+				if (unlikely(err)) {
+					status.attr_switched = 1;
+					break;
+				}
+				/* @m is not used any more so do not set it. */
+				a = ctx->attr;
+			}
+			write_lock_irqsave(&ni->size_lock, flags);
+			ni->itype.compressed.size += vol->cluster_size;
+			a->data.non_resident.compressed_size =
+					cpu_to_sle64(ni->itype.compressed.size);
+			write_unlock_irqrestore(&ni->size_lock, flags);
+		}
+		/* Ensure the changes make it to disk. */
+		flush_dcache_mft_record_page(ctx->ntfs_ino);
+		mark_mft_record_dirty(ctx->ntfs_ino);
+		ntfs_attr_put_search_ctx(ctx);
+		unmap_mft_record(base_ni);
+		/* Successfully filled the hole. */
+		status.runlist_merged = 0;
+		status.mft_attr_mapped = 0;
+		status.mp_rebuilt = 0;
+		/* Setup the map cache and use that to deal with the buffer. */
+		was_hole = TRUE;
+		vcn = bh_cpos;
+		vcn_len = 1;
+		lcn_block = lcn << (vol->cluster_size_bits - blocksize_bits);
+		cdelta = 0;
+		/*
+		 * If the number of remaining clusters in the @pages is smaller
+		 * or equal to the number of cached clusters, unlock the
+		 * runlist as the map cache will be used from now on.
+		 */
+		if (likely(vcn + vcn_len >= cend)) {
+			up_write(&ni->runlist.lock);
+			rl_write_locked = FALSE;
+			rl = NULL;
+		}
+		goto map_buffer_cached;
+	} while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
+	/* If there are no errors, do the next page. */
+	if (likely(!err && ++u < nr_pages))
+		goto do_next_page;
+	/* If there are no errors, release the runlist lock if we took it. */
+	if (likely(!err)) {
+		if (unlikely(rl_write_locked)) {
+			up_write(&ni->runlist.lock);
+			rl_write_locked = FALSE;
+		} else if (unlikely(rl))
+			up_read(&ni->runlist.lock);
+		rl = NULL;
+	}
+	/* If we issued read requests, let them complete. */
+	read_lock_irqsave(&ni->size_lock, flags);
+	initialized_size = ni->initialized_size;
+	read_unlock_irqrestore(&ni->size_lock, flags);
+	while (wait_bh > wait) {
+		bh = *--wait_bh;
+		wait_on_buffer(bh);
+		if (likely(buffer_uptodate(bh))) {
+			page = bh->b_page;
+			bh_pos = ((s64)page->index << PAGE_CACHE_SHIFT) +
+					bh_offset(bh);
+			/*
+			 * If the buffer overflows the initialized size, need
+			 * to zero the overflowing region.
+			 */
+			if (unlikely(bh_pos + blocksize > initialized_size)) {
+				u8 *kaddr;
+				int ofs = 0;
+
+				if (likely(bh_pos < initialized_size))
+					ofs = initialized_size - bh_pos;
+				kaddr = kmap_atomic(page, KM_USER0);
+				memset(kaddr + bh_offset(bh) + ofs, 0,
+						blocksize - ofs);
+				kunmap_atomic(kaddr, KM_USER0);
+				flush_dcache_page(page);
+			}
+		} else /* if (unlikely(!buffer_uptodate(bh))) */
+			err = -EIO;
+	}
+	if (likely(!err)) {
+		/* Clear buffer_new on all buffers. */
+		u = 0;
+		do {
+			bh = head = page_buffers(pages[u]);
+			do {
+				if (buffer_new(bh))
+					clear_buffer_new(bh);
+			} while ((bh = bh->b_this_page) != head);
+		} while (++u < nr_pages);
+		ntfs_debug("Done.");
+		return err;
+	}
+	if (status.attr_switched) {
+		/* Get back to the attribute extent we modified. */
+		ntfs_attr_reinit_search_ctx(ctx);
+		if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+				CASE_SENSITIVE, bh_cpos, NULL, 0, ctx)) {
+			ntfs_error(vol->sb, "Failed to find required "
+					"attribute extent of attribute in "
+					"error code path.  Run chkdsk to "
+					"recover.");
+			write_lock_irqsave(&ni->size_lock, flags);
+			ni->itype.compressed.size += vol->cluster_size;
+			write_unlock_irqrestore(&ni->size_lock, flags);
+			flush_dcache_mft_record_page(ctx->ntfs_ino);
+			mark_mft_record_dirty(ctx->ntfs_ino);
+			/*
+			 * The only thing that is now wrong is the compressed
+			 * size of the base attribute extent which chkdsk
+			 * should be able to fix.
+			 */
+			NVolSetErrors(vol);
+		} else {
+			m = ctx->mrec;
+			a = ctx->attr;
+			status.attr_switched = 0;
+		}
+	}
+	/*
+	 * If the runlist has been modified, need to restore it by punching a
+	 * hole into it and we then need to deallocate the on-disk cluster as
+	 * well.  Note, we only modify the runlist if we are able to generate a
+	 * new mapping pairs array, i.e. only when the mapped attribute extent
+	 * is not switched.
+	 */
+	if (status.runlist_merged && !status.attr_switched) {
+		BUG_ON(!rl_write_locked);
+		/* Make the file cluster we allocated sparse in the runlist. */
+		if (ntfs_rl_punch_nolock(vol, &ni->runlist, bh_cpos, 1)) {
+			ntfs_error(vol->sb, "Failed to punch hole into "
+					"attribute runlist in error code "
+					"path.  Run chkdsk to recover the "
+					"lost cluster.");
+			make_bad_inode(vi);
+			make_bad_inode(VFS_I(base_ni));
+			NVolSetErrors(vol);
+		} else /* if (success) */ {
+			status.runlist_merged = 0;
+			/*
+			 * Deallocate the on-disk cluster we allocated but only
+			 * if we succeeded in punching its vcn out of the
+			 * runlist.
+			 */
+			down_write(&vol->lcnbmp_lock);
+			if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
+				ntfs_error(vol->sb, "Failed to release "
+						"allocated cluster in error "
+						"code path.  Run chkdsk to "
+						"recover the lost cluster.");
+				NVolSetErrors(vol);
+			}
+			up_write(&vol->lcnbmp_lock);
+		}
+	}
+	/*
+	 * Resize the attribute record to its old size and rebuild the mapping
+	 * pairs array.  Note, we only can do this if the runlist has been
+	 * restored to its old state which also implies that the mapped
+	 * attribute extent is not switched.
+	 */
+	if (status.mp_rebuilt && !status.runlist_merged) {
+		if (ntfs_attr_record_resize(m, a, attr_rec_len)) {
+			ntfs_error(vol->sb, "Failed to restore attribute "
+					"record in error code path.  Run "
+					"chkdsk to recover.");
+			make_bad_inode(vi);
+			make_bad_inode(VFS_I(base_ni));
+			NVolSetErrors(vol);
+		} else /* if (success) */ {
+			if (ntfs_mapping_pairs_build(vol, (u8*)a +
+					le16_to_cpu(a->data.non_resident.
+					mapping_pairs_offset), attr_rec_len -
+					le16_to_cpu(a->data.non_resident.
+					mapping_pairs_offset), ni->runlist.rl,
+					vcn, highest_vcn, NULL)) {
+				ntfs_error(vol->sb, "Failed to restore "
+						"mapping pairs array in error "
+						"code path.  Run chkdsk to "
+						"recover.");
+				make_bad_inode(vi);
+				make_bad_inode(VFS_I(base_ni));
+				NVolSetErrors(vol);
+			}
+			flush_dcache_mft_record_page(ctx->ntfs_ino);
+			mark_mft_record_dirty(ctx->ntfs_ino);
+		}
+	}
+	/* Release the mft record and the attribute. */
+	if (status.mft_attr_mapped) {
+		ntfs_attr_put_search_ctx(ctx);
+		unmap_mft_record(base_ni);
+	}
+	/* Release the runlist lock. */
+	if (rl_write_locked)
+		up_write(&ni->runlist.lock);
+	else if (rl)
+		up_read(&ni->runlist.lock);
+	/*
+	 * Zero out any newly allocated blocks to avoid exposing stale data.
+	 * If BH_New is set, we know that the block was newly allocated above
+	 * and that it has not been fully zeroed and marked dirty yet.
+	 */
+	nr_pages = u;
+	u = 0;
+	end = bh_cpos << vol->cluster_size_bits;
+	do {
+		page = pages[u];
+		bh = head = page_buffers(page);
+		do {
+			if (u == nr_pages &&
+					((s64)page->index << PAGE_CACHE_SHIFT) +
+					bh_offset(bh) >= end)
+				break;
+			if (!buffer_new(bh))
+				continue;
+			clear_buffer_new(bh);
+			if (!buffer_uptodate(bh)) {
+				if (PageUptodate(page))
+					set_buffer_uptodate(bh);
+				else {
+					u8 *kaddr = kmap_atomic(page, KM_USER0);
+					memset(kaddr + bh_offset(bh), 0,
+							blocksize);
+					kunmap_atomic(kaddr, KM_USER0);
+					flush_dcache_page(page);
+					set_buffer_uptodate(bh);
+				}
+			}
+			mark_buffer_dirty(bh);
+		} while ((bh = bh->b_this_page) != head);
+	} while (++u <= nr_pages);
+	ntfs_error(vol->sb, "Failed.  Returning error code %i.", err);
+	return err;
+}
+
+/*
+ * Copy as much as we can into the pages and return the number of bytes which
+ * were sucessfully copied.  If a fault is encountered then clear the pages
+ * out to (ofs + bytes) and return the number of bytes which were copied.
+ */
+static inline size_t ntfs_copy_from_user(struct page **pages,
+		unsigned nr_pages, unsigned ofs, const char __user *buf,
+		size_t bytes)
+{
+	struct page **last_page = pages + nr_pages;
+	char *kaddr;
+	size_t total = 0;
+	unsigned len;
+	int left;
+
+	do {
+		len = PAGE_CACHE_SIZE - ofs;
+		if (len > bytes)
+			len = bytes;
+		kaddr = kmap_atomic(*pages, KM_USER0);
+		left = __copy_from_user_inatomic(kaddr + ofs, buf, len);
+		kunmap_atomic(kaddr, KM_USER0);
+		if (unlikely(left)) {
+			/* Do it the slow way. */
+			kaddr = kmap(*pages);
+			left = __copy_from_user(kaddr + ofs, buf, len);
+			kunmap(*pages);
+			if (unlikely(left))
+				goto err_out;
+		}
+		total += len;
+		bytes -= len;
+		if (!bytes)
+			break;
+		buf += len;
+		ofs = 0;
+	} while (++pages < last_page);
+out:
+	return total;
+err_out:
+	total += len - left;
+	/* Zero the rest of the target like __copy_from_user(). */
+	while (++pages < last_page) {
+		bytes -= len;
+		if (!bytes)
+			break;
+		len = PAGE_CACHE_SIZE;
+		if (len > bytes)
+			len = bytes;
+		kaddr = kmap_atomic(*pages, KM_USER0);
+		memset(kaddr, 0, len);
+		kunmap_atomic(kaddr, KM_USER0);
+	}
+	goto out;
+}
+
+static size_t __ntfs_copy_from_user_iovec(char *vaddr,
+		const struct iovec *iov, size_t iov_ofs, size_t bytes)
+{
+	size_t total = 0;
+
+	while (1) {
+		const char __user *buf = iov->iov_base + iov_ofs;
+		unsigned len;
+		size_t left;
+
+		len = iov->iov_len - iov_ofs;
+		if (len > bytes)
+			len = bytes;
+		left = __copy_from_user_inatomic(vaddr, buf, len);
+		total += len;
+		bytes -= len;
+		vaddr += len;
+		if (unlikely(left)) {
+			/*
+			 * Zero the rest of the target like __copy_from_user().
+			 */
+			memset(vaddr, 0, bytes);
+			total -= left;
+			break;
+		}
+		if (!bytes)
+			break;
+		iov++;
+		iov_ofs = 0;
+	}
+	return total;
+}
+
+static inline void ntfs_set_next_iovec(const struct iovec **iovp,
+		size_t *iov_ofsp, size_t bytes)
+{
+	const struct iovec *iov = *iovp;
+	size_t iov_ofs = *iov_ofsp;
+
+	while (bytes) {
+		unsigned len;
+
+		len = iov->iov_len - iov_ofs;
+		if (len > bytes)
+			len = bytes;
+		bytes -= len;
+		iov_ofs += len;
+		if (iov->iov_len == iov_ofs) {
+			iov++;
+			iov_ofs = 0;
+		}
+	}
+	*iovp = iov;
+	*iov_ofsp = iov_ofs;
+}
+
+/*
+ * This has the same side-effects and return value as ntfs_copy_from_user().
+ * The difference is that on a fault we need to memset the remainder of the
+ * pages (out to offset + bytes), to emulate ntfs_copy_from_user()'s
+ * single-segment behaviour.
+ *
+ * We call the same helper (__ntfs_copy_from_user_iovec()) both when atomic and
+ * when not atomic.  This is ok because __ntfs_copy_from_user_iovec() calls
+ * __copy_from_user_inatomic() and it is ok to call this when non-atomic.  In
+ * fact, the only difference between __copy_from_user_inatomic() and
+ * __copy_from_user() is that the latter calls might_sleep().  And on many
+ * architectures __copy_from_user_inatomic() is just defined to
+ * __copy_from_user() so it makes no difference at all on those architectures.
+ */
+static inline size_t ntfs_copy_from_user_iovec(struct page **pages,
+		unsigned nr_pages, unsigned ofs, const struct iovec **iov,
+		size_t *iov_ofs, size_t bytes)
+{
+	struct page **last_page = pages + nr_pages;
+	char *kaddr;
+	size_t copied, len, total = 0;
+
+	do {
+		len = PAGE_CACHE_SIZE - ofs;
+		if (len > bytes)
+			len = bytes;
+		kaddr = kmap_atomic(*pages, KM_USER0);
+		copied = __ntfs_copy_from_user_iovec(kaddr + ofs,
+				*iov, *iov_ofs, len);
+		kunmap_atomic(kaddr, KM_USER0);
+		if (unlikely(copied != len)) {
+			/* Do it the slow way. */
+			kaddr = kmap(*pages);
+			copied = __ntfs_copy_from_user_iovec(kaddr + ofs,
+					*iov, *iov_ofs, len);
+			kunmap(*pages);
+			if (unlikely(copied != len))
+				goto err_out;
+		}
+		total += len;
+		bytes -= len;
+		if (!bytes)
+			break;
+		ntfs_set_next_iovec(iov, iov_ofs, len);
+		ofs = 0;
+	} while (++pages < last_page);
+out:
+	return total;
+err_out:
+	total += copied;
+	/* Zero the rest of the target like __copy_from_user(). */
+	while (++pages < last_page) {
+		bytes -= len;
+		if (!bytes)
+			break;
+		len = PAGE_CACHE_SIZE;
+		if (len > bytes)
+			len = bytes;
+		kaddr = kmap_atomic(*pages, KM_USER0);
+		memset(kaddr, 0, len);
+		kunmap_atomic(kaddr, KM_USER0);
+	}
+	goto out;
+}
+
+static inline void ntfs_flush_dcache_pages(struct page **pages,
+		unsigned nr_pages)
+{
+	BUG_ON(!nr_pages);
+	do {
+		/*
+		 * Warning: Do not do the decrement at the same time as the
+		 * call because flush_dcache_page() is a NULL macro on i386
+		 * and hence the decrement never happens.
+		 */
+		flush_dcache_page(pages[nr_pages]);
+	} while (--nr_pages > 0);
+}
+
+/**
+ * ntfs_commit_pages_after_non_resident_write - commit the received data
+ * @pages:	array of destination pages
+ * @nr_pages:	number of pages in @pages
+ * @pos:	byte position in file at which the write begins
+ * @bytes:	number of bytes to be written
+ *
+ * See description of ntfs_commit_pages_after_write(), below.
+ */
+static inline int ntfs_commit_pages_after_non_resident_write(
+		struct page **pages, const unsigned nr_pages,
+		s64 pos, size_t bytes)
+{
+	s64 end, initialized_size;
+	struct inode *vi;
+	ntfs_inode *ni, *base_ni;
+	struct buffer_head *bh, *head;
+	ntfs_attr_search_ctx *ctx;
+	MFT_RECORD *m;
+	ATTR_RECORD *a;
+	unsigned long flags;
+	unsigned blocksize, u;
+	int err;
+
+	vi = pages[0]->mapping->host;
+	ni = NTFS_I(vi);
+	blocksize = 1 << vi->i_blkbits;
+	end = pos + bytes;
+	u = 0;
+	do {
+		s64 bh_pos;
+		struct page *page;
+		BOOL partial;
+
+		page = pages[u];
+		bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
+		bh = head = page_buffers(page);
+		partial = FALSE;
+		do {
+			s64 bh_end;
+
+			bh_end = bh_pos + blocksize;
+			if (bh_end <= pos || bh_pos >= end) {
+				if (!buffer_uptodate(bh))
+					partial = TRUE;
+			} else {
+				set_buffer_uptodate(bh);
+				mark_buffer_dirty(bh);
+			}
+		} while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
+		/*
+		 * If all buffers are now uptodate but the page is not, set the
+		 * page uptodate.
+		 */
+		if (!partial && !PageUptodate(page))
+			SetPageUptodate(page);
+	} while (++u < nr_pages);
+	/*
+	 * Finally, if we do not need to update initialized_size or i_size we
+	 * are finished.
+	 */
+	read_lock_irqsave(&ni->size_lock, flags);
+	initialized_size = ni->initialized_size;
+	read_unlock_irqrestore(&ni->size_lock, flags);
+	if (end <= initialized_size) {
+		ntfs_debug("Done.");
+		return 0;
+	}
+	/*
+	 * Update initialized_size/i_size as appropriate, both in the inode and
+	 * the mft record.
+	 */
+	if (!NInoAttr(ni))
+		base_ni = ni;
+	else
+		base_ni = ni->ext.base_ntfs_ino;
+	/* Map, pin, and lock the mft record. */
+	m = map_mft_record(base_ni);
+	if (IS_ERR(m)) {
+		err = PTR_ERR(m);
+		m = NULL;
+		ctx = NULL;
+		goto err_out;
+	}
+	BUG_ON(!NInoNonResident(ni));
+	ctx = ntfs_attr_get_search_ctx(base_ni, m);
+	if (unlikely(!ctx)) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+			CASE_SENSITIVE, 0, NULL, 0, ctx);
+	if (unlikely(err)) {
+		if (err == -ENOENT)
+			err = -EIO;
+		goto err_out;
+	}
+	a = ctx->attr;
+	BUG_ON(!a->non_resident);
+	write_lock_irqsave(&ni->size_lock, flags);
+	BUG_ON(end > ni->allocated_size);
+	ni->initialized_size = end;
+	a->data.non_resident.initialized_size = cpu_to_sle64(end);
+	if (end > i_size_read(vi)) {
+		i_size_write(vi, end);
+		a->data.non_resident.data_size =
+				a->data.non_resident.initialized_size;
+	}
+	write_unlock_irqrestore(&ni->size_lock, flags);
+	/* Mark the mft record dirty, so it gets written back. */
+	flush_dcache_mft_record_page(ctx->ntfs_ino);
+	mark_mft_record_dirty(ctx->ntfs_ino);
+	ntfs_attr_put_search_ctx(ctx);
+	unmap_mft_record(base_ni);
+	ntfs_debug("Done.");
+	return 0;
+err_out:
+	if (ctx)
+		ntfs_attr_put_search_ctx(ctx);
+	if (m)
+		unmap_mft_record(base_ni);
+	ntfs_error(vi->i_sb, "Failed to update initialized_size/i_size (error "
+			"code %i).", err);
+	if (err != -ENOMEM) {
+		NVolSetErrors(ni->vol);
+		make_bad_inode(VFS_I(base_ni));
+		make_bad_inode(vi);
+	}
+	return err;
+}
+
+/**
+ * ntfs_commit_pages_after_write - commit the received data
+ * @pages:	array of destination pages
+ * @nr_pages:	number of pages in @pages
+ * @pos:	byte position in file at which the write begins
+ * @bytes:	number of bytes to be written
+ *
+ * This is called from ntfs_file_buffered_write() with i_sem held on the inode
+ * (@pages[0]->mapping->host).  There are @nr_pages pages in @pages which are
+ * locked but not kmap()ped.  The source data has already been copied into the
+ * @page.  ntfs_prepare_pages_for_non_resident_write() has been called before
+ * the data was copied (for non-resident attributes only) and it returned
+ * success.
+ *
+ * Need to set uptodate and mark dirty all buffers within the boundary of the
+ * write.  If all buffers in a page are uptodate we set the page uptodate, too.
+ *
+ * Setting the buffers dirty ensures that they get written out later when
+ * ntfs_writepage() is invoked by the VM.
+ *
+ * Finally, we need to update i_size and initialized_size as appropriate both
+ * in the inode and the mft record.
+ *
+ * This is modelled after fs/buffer.c::generic_commit_write(), which marks
+ * buffers uptodate and dirty, sets the page uptodate if all buffers in the
+ * page are uptodate, and updates i_size if the end of io is beyond i_size.  In
+ * that case, it also marks the inode dirty.
+ *
+ * If things have gone as outlined in
+ * ntfs_prepare_pages_for_non_resident_write(), we do not need to do any page
+ * content modifications here for non-resident attributes.  For resident
+ * attributes we need to do the uptodate bringing here which we combine with
+ * the copying into the mft record which means we save one atomic kmap.
+ *
+ * Return 0 on success or -errno on error.
+ */
+static int ntfs_commit_pages_after_write(struct page **pages,
+		const unsigned nr_pages, s64 pos, size_t bytes)
+{
+	s64 end, initialized_size;
+	loff_t i_size;
+	struct inode *vi;
+	ntfs_inode *ni, *base_ni;
+	struct page *page;
+	ntfs_attr_search_ctx *ctx;
+	MFT_RECORD *m;
+	ATTR_RECORD *a;
+	char *kattr, *kaddr;
+	unsigned long flags;
+	u32 attr_len;
+	int err;
+
+	BUG_ON(!nr_pages);
+	BUG_ON(!pages);
+	page = pages[0];
+	BUG_ON(!page);
+	vi = page->mapping->host;
+	ni = NTFS_I(vi);
+	ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
+			"index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
+			vi->i_ino, ni->type, page->index, nr_pages,
+			(long long)pos, bytes);
+	if (NInoNonResident(ni))
+		return ntfs_commit_pages_after_non_resident_write(pages,
+				nr_pages, pos, bytes);
+	BUG_ON(nr_pages > 1);
+	/*
+	 * Attribute is resident, implying it is not compressed, encrypted, or
+	 * sparse.
+	 */
+	if (!NInoAttr(ni))
+		base_ni = ni;
+	else
+		base_ni = ni->ext.base_ntfs_ino;
+	BUG_ON(NInoNonResident(ni));
+	/* Map, pin, and lock the mft record. */
+	m = map_mft_record(base_ni);
+	if (IS_ERR(m)) {
+		err = PTR_ERR(m);
+		m = NULL;
+		ctx = NULL;
+		goto err_out;
+	}
+	ctx = ntfs_attr_get_search_ctx(base_ni, m);
+	if (unlikely(!ctx)) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+			CASE_SENSITIVE, 0, NULL, 0, ctx);
+	if (unlikely(err)) {
+		if (err == -ENOENT)
+			err = -EIO;
+		goto err_out;
+	}
+	a = ctx->attr;
+	BUG_ON(a->non_resident);
+	/* The total length of the attribute value. */
+	attr_len = le32_to_cpu(a->data.resident.value_length);
+	i_size = i_size_read(vi);
+	BUG_ON(attr_len != i_size);
+	BUG_ON(pos > attr_len);
+	end = pos + bytes;
+	BUG_ON(end > le32_to_cpu(a->length) -
+			le16_to_cpu(a->data.resident.value_offset));
+	kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
+	kaddr = kmap_atomic(page, KM_USER0);
+	/* Copy the received data from the page to the mft record. */
+	memcpy(kattr + pos, kaddr + pos, bytes);
+	/* Update the attribute length if necessary. */
+	if (end > attr_len) {
+		attr_len = end;
+		a->data.resident.value_length = cpu_to_le32(attr_len);
+	}
+	/*
+	 * If the page is not uptodate, bring the out of bounds area(s)
+	 * uptodate by copying data from the mft record to the page.
+	 */
+	if (!PageUptodate(page)) {
+		if (pos > 0)
+			memcpy(kaddr, kattr, pos);
+		if (end < attr_len)
+			memcpy(kaddr + end, kattr + end, attr_len - end);
+		/* Zero the region outside the end of the attribute value. */
+		memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
+		flush_dcache_page(page);
+		SetPageUptodate(page);
+	}
+	kunmap_atomic(kaddr, KM_USER0);
+	/* Update initialized_size/i_size if necessary. */
+	read_lock_irqsave(&ni->size_lock, flags);
+	initialized_size = ni->initialized_size;
+	BUG_ON(end > ni->allocated_size);
+	read_unlock_irqrestore(&ni->size_lock, flags);
+	BUG_ON(initialized_size != i_size);
+	if (end > initialized_size) {
+		unsigned long flags;
+
+		write_lock_irqsave(&ni->size_lock, flags);
+		ni->initialized_size = end;
+		i_size_write(vi, end);
+		write_unlock_irqrestore(&ni->size_lock, flags);
+	}
+	/* Mark the mft record dirty, so it gets written back. */
+	flush_dcache_mft_record_page(ctx->ntfs_ino);
+	mark_mft_record_dirty(ctx->ntfs_ino);
+	ntfs_attr_put_search_ctx(ctx);
+	unmap_mft_record(base_ni);
+	ntfs_debug("Done.");
+	return 0;
+err_out:
+	if (err == -ENOMEM) {
+		ntfs_warning(vi->i_sb, "Error allocating memory required to "
+				"commit the write.");
+		if (PageUptodate(page)) {
+			ntfs_warning(vi->i_sb, "Page is uptodate, setting "
+					"dirty so the write will be retried "
+					"later on by the VM.");
+			/*
+			 * Put the page on mapping->dirty_pages, but leave its
+			 * buffers' dirty state as-is.
+			 */
+			__set_page_dirty_nobuffers(page);
+			err = 0;
+		} else
+			ntfs_error(vi->i_sb, "Page is not uptodate.  Written "
+					"data has been lost.");
+	} else {
+		ntfs_error(vi->i_sb, "Resident attribute commit write failed "
+				"with error %i.", err);
+		NVolSetErrors(ni->vol);
+		make_bad_inode(VFS_I(base_ni));
+		make_bad_inode(vi);
+	}
+	if (ctx)
+		ntfs_attr_put_search_ctx(ctx);
+	if (m)
+		unmap_mft_record(base_ni);
+	return err;
+}
+
+/**
+ * ntfs_file_buffered_write -
+ *
+ * Locking: The vfs is holding ->i_sem on the inode.
+ */
+static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
+		const struct iovec *iov, unsigned long nr_segs,
+		loff_t pos, loff_t *ppos, size_t count)
+{
+	struct file *file = iocb->ki_filp;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *vi = mapping->host;
+	ntfs_inode *ni = NTFS_I(vi);
+	ntfs_volume *vol = ni->vol;
+	struct page *pages[NTFS_MAX_PAGES_PER_CLUSTER];
+	struct page *cached_page = NULL;
+	char __user *buf = NULL;
+	s64 end, ll;
+	VCN last_vcn;
+	LCN lcn;
+	unsigned long flags;
+	size_t bytes, iov_ofs = 0;	/* Offset in the current iovec. */
+	ssize_t status, written;
+	unsigned nr_pages;
+	int err;
+	struct pagevec lru_pvec;
+
+	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
+			"pos 0x%llx, count 0x%lx.",
+			vi->i_ino, (unsigned)le32_to_cpu(ni->type),
+			(unsigned long long)pos, (unsigned long)count);
+	if (unlikely(!count))
+		return 0;
+	BUG_ON(NInoMstProtected(ni));
+	/*
+	 * If the attribute is not an index root and it is encrypted or
+	 * compressed, we cannot write to it yet.  Note we need to check for
+	 * AT_INDEX_ALLOCATION since this is the type of both directory and
+	 * index inodes.
+	 */
+	if (ni->type != AT_INDEX_ALLOCATION) {
+		/* If file is encrypted, deny access, just like NT4. */
+		if (NInoEncrypted(ni)) {
+			/*
+			 * Reminder for later: Encrypted files are _always_
+			 * non-resident so that the content can always be
+			 * encrypted.
+			 */
+			ntfs_debug("Denying write access to encrypted file.");
+			return -EACCES;
+		}
+		if (NInoCompressed(ni)) {
+			/* Only unnamed $DATA attribute can be compressed. */
+			BUG_ON(ni->type != AT_DATA);
+			BUG_ON(ni->name_len);
+			/*
+			 * Reminder for later: If resident, the data is not
+			 * actually compressed.  Only on the switch to non-
+			 * resident does compression kick in.  This is in
+			 * contrast to encrypted files (see above).
+			 */
+			ntfs_error(vi->i_sb, "Writing to compressed files is "
+					"not implemented yet.  Sorry.");
+			return -EOPNOTSUPP;
+		}
+	}
+	/*
+	 * If a previous ntfs_truncate() failed, repeat it and abort if it
+	 * fails again.
+	 */
+	if (unlikely(NInoTruncateFailed(ni))) {
+		down_write(&vi->i_alloc_sem);
+		err = ntfs_truncate(vi);
+		up_write(&vi->i_alloc_sem);
+		if (err || NInoTruncateFailed(ni)) {
+			if (!err)
+				err = -EIO;
+			ntfs_error(vol->sb, "Cannot perform write to inode "
+					"0x%lx, attribute type 0x%x, because "
+					"ntfs_truncate() failed (error code "
+					"%i).", vi->i_ino,
+					(unsigned)le32_to_cpu(ni->type), err);
+			return err;
+		}
+	}
+	/* The first byte after the write. */
+	end = pos + count;
+	/*
+	 * If the write goes beyond the allocated size, extend the allocation
+	 * to cover the whole of the write, rounded up to the nearest cluster.
+	 */
+	read_lock_irqsave(&ni->size_lock, flags);
+	ll = ni->allocated_size;
+	read_unlock_irqrestore(&ni->size_lock, flags);
+	if (end > ll) {
+		/* Extend the allocation without changing the data size. */
+		ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
+		if (likely(ll >= 0)) {
+			BUG_ON(pos >= ll);
+			/* If the extension was partial truncate the write. */
+			if (end > ll) {
+				ntfs_debug("Truncating write to inode 0x%lx, "
+						"attribute type 0x%x, because "
+						"the allocation was only "
+						"partially extended.",
+						vi->i_ino, (unsigned)
+						le32_to_cpu(ni->type));
+				end = ll;
+				count = ll - pos;
+			}
+		} else {
+			err = ll;
+			read_lock_irqsave(&ni->size_lock, flags);
+			ll = ni->allocated_size;
+			read_unlock_irqrestore(&ni->size_lock, flags);
+			/* Perform a partial write if possible or fail. */
+			if (pos < ll) {
+				ntfs_debug("Truncating write to inode 0x%lx, "
+						"attribute type 0x%x, because "
+						"extending the allocation "
+						"failed (error code %i).",
+						vi->i_ino, (unsigned)
+						le32_to_cpu(ni->type), err);
+				end = ll;
+				count = ll - pos;
+			} else {
+				ntfs_error(vol->sb, "Cannot perform write to "
+						"inode 0x%lx, attribute type "
+						"0x%x, because extending the "
+						"allocation failed (error "
+						"code %i).", vi->i_ino,
+						(unsigned)
+						le32_to_cpu(ni->type), err);
+				return err;
+			}
+		}
+	}
+	pagevec_init(&lru_pvec, 0);
+	written = 0;
+	/*
+	 * If the write starts beyond the initialized size, extend it up to the
+	 * beginning of the write and initialize all non-sparse space between
+	 * the old initialized size and the new one.  This automatically also
+	 * increments the vfs inode->i_size to keep it above or equal to the
+	 * initialized_size.
+	 */
+	read_lock_irqsave(&ni->size_lock, flags);
+	ll = ni->initialized_size;
+	read_unlock_irqrestore(&ni->size_lock, flags);
+	if (pos > ll) {
+		err = ntfs_attr_extend_initialized(ni, pos, &cached_page,
+				&lru_pvec);
+		if (err < 0) {
+			ntfs_error(vol->sb, "Cannot perform write to inode "
+					"0x%lx, attribute type 0x%x, because "
+					"extending the initialized size "
+					"failed (error code %i).", vi->i_ino,
+					(unsigned)le32_to_cpu(ni->type), err);
+			status = err;
+			goto err_out;
+		}
+	}
+	/*
+	 * Determine the number of pages per cluster for non-resident
+	 * attributes.
+	 */
+	nr_pages = 1;
+	if (vol->cluster_size > PAGE_CACHE_SIZE && NInoNonResident(ni))
+		nr_pages = vol->cluster_size >> PAGE_CACHE_SHIFT;
+	/* Finally, perform the actual write. */
+	last_vcn = -1;
+	if (likely(nr_segs == 1))
+		buf = iov->iov_base;
+	do {
+		VCN vcn;
+		pgoff_t idx, start_idx;
+		unsigned ofs, do_pages, u;
+		size_t copied;
+
+		start_idx = idx = pos >> PAGE_CACHE_SHIFT;
+		ofs = pos & ~PAGE_CACHE_MASK;
+		bytes = PAGE_CACHE_SIZE - ofs;
+		do_pages = 1;
+		if (nr_pages > 1) {
+			vcn = pos >> vol->cluster_size_bits;
+			if (vcn != last_vcn) {
+				last_vcn = vcn;
+				/*
+				 * Get the lcn of the vcn the write is in.  If
+				 * it is a hole, need to lock down all pages in
+				 * the cluster.
+				 */
+				down_read(&ni->runlist.lock);
+				lcn = ntfs_attr_vcn_to_lcn_nolock(ni, pos >>
+						vol->cluster_size_bits, FALSE);
+				up_read(&ni->runlist.lock);
+				if (unlikely(lcn < LCN_HOLE)) {
+					status = -EIO;
+					if (lcn == LCN_ENOMEM)
+						status = -ENOMEM;
+					else
+						ntfs_error(vol->sb, "Cannot "
+							"perform write to "
+							"inode 0x%lx, "
+							"attribute type 0x%x, "
+							"because the attribute "
+							"is corrupt.",
+							vi->i_ino, (unsigned)
+							le32_to_cpu(ni->type));
+					break;
+				}
+				if (lcn == LCN_HOLE) {
+					start_idx = (pos & ~(s64)
+							vol->cluster_size_mask)
+							>> PAGE_CACHE_SHIFT;
+					bytes = vol->cluster_size - (pos &
+							vol->cluster_size_mask);
+					do_pages = nr_pages;
+				}
+			}
+		}
+		if (bytes > count)
+			bytes = count;
+		/*
+		 * Bring in the user page(s) that we will copy from _first_.
+		 * Otherwise there is a nasty deadlock on copying from the same
+		 * page(s) as we are writing to, without it/them being marked
+		 * up-to-date.  Note, at present there is nothing to stop the
+		 * pages being swapped out between us bringing them into memory
+		 * and doing the actual copying.
+		 */
+		if (likely(nr_segs == 1))
+			ntfs_fault_in_pages_readable(buf, bytes);
+		else
+			ntfs_fault_in_pages_readable_iovec(iov, iov_ofs, bytes);
+		/* Get and lock @do_pages starting at index @start_idx. */
+		status = __ntfs_grab_cache_pages(mapping, start_idx, do_pages,
+				pages, &cached_page, &lru_pvec);
+		if (unlikely(status))
+			break;
+		/*
+		 * For non-resident attributes, we need to fill any holes with
+		 * actual clusters and ensure all bufferes are mapped.  We also
+		 * need to bring uptodate any buffers that are only partially
+		 * being written to.
+		 */
+		if (NInoNonResident(ni)) {
+			status = ntfs_prepare_pages_for_non_resident_write(
+					pages, do_pages, pos, bytes);
+			if (unlikely(status)) {
+				loff_t i_size;
+
+				do {
+					unlock_page(pages[--do_pages]);
+					page_cache_release(pages[do_pages]);
+				} while (do_pages);
+				/*
+				 * The write preparation may have instantiated
+				 * allocated space outside i_size.  Trim this
+				 * off again.  We can ignore any errors in this
+				 * case as we will just be waisting a bit of
+				 * allocated space, which is not a disaster.
+				 */
+				i_size = i_size_read(vi);
+				if (pos + bytes > i_size)
+					vmtruncate(vi, i_size);
+				break;
+			}
+		}
+		u = (pos >> PAGE_CACHE_SHIFT) - pages[0]->index;
+		if (likely(nr_segs == 1)) {
+			copied = ntfs_copy_from_user(pages + u, do_pages - u,
+					ofs, buf, bytes);
+			buf += copied;
+		} else
+			copied = ntfs_copy_from_user_iovec(pages + u,
+					do_pages - u, ofs, &iov, &iov_ofs,
+					bytes);
+		ntfs_flush_dcache_pages(pages + u, do_pages - u);
+		status = ntfs_commit_pages_after_write(pages, do_pages, pos,
+				bytes);
+		if (likely(!status)) {
+			written += copied;
+			count -= copied;
+			pos += copied;
+			if (unlikely(copied != bytes))
+				status = -EFAULT;
+		}
+		do {
+			unlock_page(pages[--do_pages]);
+			mark_page_accessed(pages[do_pages]);
+			page_cache_release(pages[do_pages]);
+		} while (do_pages);
+		if (unlikely(status))
+			break;
+		balance_dirty_pages_ratelimited(mapping);
+		cond_resched();
+	} while (count);
+err_out:
+	*ppos = pos;
+	if (cached_page)
+		page_cache_release(cached_page);
+	/* For now, when the user asks for O_SYNC, we actually give O_DSYNC. */
+	if (likely(!status)) {
+		if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(vi))) {
+			if (!mapping->a_ops->writepage || !is_sync_kiocb(iocb))
+				status = generic_osync_inode(vi, mapping,
+						OSYNC_METADATA|OSYNC_DATA);
+		}
+  	}
+	pagevec_lru_add(&lru_pvec);
+	ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
+			written ? "written" : "status", (unsigned long)written,
+			(long)status);
+	return written ? written : status;
+}
+
+/**
+ * ntfs_file_aio_write_nolock -
+ */
+static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
+		const struct iovec *iov, unsigned long nr_segs, loff_t *ppos)
+{
+	struct file *file = iocb->ki_filp;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	loff_t pos;
+	unsigned long seg;
+	size_t count;		/* after file limit checks */
+	ssize_t written, err;
+
+	count = 0;
+	for (seg = 0; seg < nr_segs; seg++) {
+		const struct iovec *iv = &iov[seg];
+		/*
+		 * If any segment has a negative length, or the cumulative
+		 * length ever wraps negative then return -EINVAL.
+		 */
+		count += iv->iov_len;
+		if (unlikely((ssize_t)(count|iv->iov_len) < 0))
+			return -EINVAL;
+		if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
+			continue;
+		if (!seg)
+			return -EFAULT;
+		nr_segs = seg;
+		count -= iv->iov_len;	/* This segment is no good */
+		break;
+	}
+	pos = *ppos;
+	vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+	/* We can write back this queue in page reclaim. */
+	current->backing_dev_info = mapping->backing_dev_info;
+	written = 0;
+	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
+	if (err)
+		goto out;
+	if (!count)
+		goto out;
+	err = remove_suid(file->f_dentry);
+	if (err)
+		goto out;
+	inode_update_time(inode, 1);
+	written = ntfs_file_buffered_write(iocb, iov, nr_segs, pos, ppos,
+			count);
+out:
+	current->backing_dev_info = NULL;
+	return written ? written : err;
+}
+
+/**
+ * ntfs_file_aio_write -
+ */
+static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const char __user *buf,
+		size_t count, loff_t pos)
+{
+	struct file *file = iocb->ki_filp;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	ssize_t ret;
+	struct iovec local_iov = { .iov_base = (void __user *)buf,
+				   .iov_len = count };
+
+	BUG_ON(iocb->ki_pos != pos);
+
+	down(&inode->i_sem);
+	ret = ntfs_file_aio_write_nolock(iocb, &local_iov, 1, &iocb->ki_pos);
+	up(&inode->i_sem);
+	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
+		int err = sync_page_range(inode, mapping, pos, ret);
+		if (err < 0)
+			ret = err;
+	}
+	return ret;
+}
+
+/**
+ * ntfs_file_writev -
+ *
+ * Basically the same as generic_file_writev() except that it ends up calling
+ * ntfs_file_aio_write_nolock() instead of __generic_file_aio_write_nolock().
+ */
+static ssize_t ntfs_file_writev(struct file *file, const struct iovec *iov,
+		unsigned long nr_segs, loff_t *ppos)
+{
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	struct kiocb kiocb;
+	ssize_t ret;
+
+	down(&inode->i_sem);
+	init_sync_kiocb(&kiocb, file);
+	ret = ntfs_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
+	if (ret == -EIOCBQUEUED)
+		ret = wait_on_sync_kiocb(&kiocb);
+	up(&inode->i_sem);
+	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
+		int err = sync_page_range(inode, mapping, *ppos - ret, ret);
+		if (err < 0)
+			ret = err;
+	}
+	return ret;
+}
+
+/**
+ * ntfs_file_write - simple wrapper for ntfs_file_writev()
+ */
+static ssize_t ntfs_file_write(struct file *file, const char __user *buf,
+		size_t count, loff_t *ppos)
+{
+	struct iovec local_iov = { .iov_base = (void __user *)buf,
+				   .iov_len = count };
+
+	return ntfs_file_writev(file, &local_iov, 1, ppos);
+}
+
+/**
  * ntfs_file_fsync - sync a file to disk
  * @filp:	file to be synced
  * @dentry:	dentry describing the file to sync
@@ -113,39 +2305,39 @@ static int ntfs_file_fsync(struct file *filp, struct dentry *dentry,
 #endif /* NTFS_RW */
 
 struct file_operations ntfs_file_ops = {
-	.llseek		= generic_file_llseek,	  /* Seek inside file. */
-	.read		= generic_file_read,	  /* Read from file. */
-	.aio_read	= generic_file_aio_read,  /* Async read from file. */
-	.readv		= generic_file_readv,	  /* Read from file. */
+	.llseek		= generic_file_llseek,	 /* Seek inside file. */
+	.read		= generic_file_read,	 /* Read from file. */
+	.aio_read	= generic_file_aio_read, /* Async read from file. */
+	.readv		= generic_file_readv,	 /* Read from file. */
 #ifdef NTFS_RW
-	.write		= generic_file_write,	  /* Write to file. */
-	.aio_write	= generic_file_aio_write, /* Async write to file. */
-	.writev		= generic_file_writev,	  /* Write to file. */
-	/*.release	= ,*/			  /* Last file is closed.  See
-						     fs/ext2/file.c::
-						     ext2_release_file() for
-						     how to use this to discard
-						     preallocated space for
-						     write opened files. */
-	.fsync		= ntfs_file_fsync,	  /* Sync a file to disk. */
-	/*.aio_fsync	= ,*/			  /* Sync all outstanding async
-						     i/o operations on a
-						     kiocb. */
+	.write		= ntfs_file_write,	 /* Write to file. */
+	.aio_write	= ntfs_file_aio_write,	 /* Async write to file. */
+	.writev		= ntfs_file_writev,	 /* Write to file. */
+	/*.release	= ,*/			 /* Last file is closed.  See
+						    fs/ext2/file.c::
+						    ext2_release_file() for
+						    how to use this to discard
+						    preallocated space for
+						    write opened files. */
+	.fsync		= ntfs_file_fsync,	 /* Sync a file to disk. */
+	/*.aio_fsync	= ,*/			 /* Sync all outstanding async
+						    i/o operations on a
+						    kiocb. */
 #endif /* NTFS_RW */
-	/*.ioctl	= ,*/			  /* Perform function on the
-						     mounted filesystem. */
-	.mmap		= generic_file_mmap,	  /* Mmap file. */
-	.open		= ntfs_file_open,	  /* Open file. */
-	.sendfile	= generic_file_sendfile,  /* Zero-copy data send with
-						     the data source being on
-						     the ntfs partition.  We
-						     do not need to care about
-						     the data destination. */
-	/*.sendpage	= ,*/			  /* Zero-copy data send with
-						     the data destination being
-						     on the ntfs partition.  We
-						     do not need to care about
-						     the data source. */
+	/*.ioctl	= ,*/			 /* Perform function on the
+						    mounted filesystem. */
+	.mmap		= generic_file_mmap,	 /* Mmap file. */
+	.open		= ntfs_file_open,	 /* Open file. */
+	.sendfile	= generic_file_sendfile, /* Zero-copy data send with
+						    the data source being on
+						    the ntfs partition.  We do
+						    not need to care about the
+						    data destination. */
+	/*.sendpage	= ,*/			 /* Zero-copy data send with
+						    the data destination being
+						    on the ntfs partition.  We
+						    do not need to care about
+						    the data source. */
 };
 
 struct inode_operations ntfs_file_inode_ops = {