xfs: remove subdirectories

Use the move from Linux 2.6 to Linux 3.x as an excuse to kill the
annoying subdirectories in the XFS source code.  Besides the large
amount of file rename the only changes are to the Makefile, a few
files including headers with the subdirectory prefix, and the binary
sysctl compat code that includes a header under fs/xfs/ from
kernel/.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 1499 insertions, 0 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
new file mode 100644
index 00000000000..63e971e2b83
--- /dev/null
+++ b/fs/xfs/xfs_aops.c
@@ -0,0 +1,1499 @@
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "xfs.h"
+#include "xfs_bit.h"
+#include "xfs_log.h"
+#include "xfs_inum.h"
+#include "xfs_sb.h"
+#include "xfs_ag.h"
+#include "xfs_trans.h"
+#include "xfs_mount.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_dinode.h"
+#include "xfs_inode.h"
+#include "xfs_alloc.h"
+#include "xfs_error.h"
+#include "xfs_rw.h"
+#include "xfs_iomap.h"
+#include "xfs_vnodeops.h"
+#include "xfs_trace.h"
+#include "xfs_bmap.h"
+#include <linux/gfp.h>
+#include <linux/mpage.h>
+#include <linux/pagevec.h>
+#include <linux/writeback.h>
+
+
+/*
+ * Prime number of hash buckets since address is used as the key.
+ */
+#define NVSYNC		37
+#define to_ioend_wq(v)	(&xfs_ioend_wq[((unsigned long)v) % NVSYNC])
+static wait_queue_head_t xfs_ioend_wq[NVSYNC];
+
+void __init
+xfs_ioend_init(void)
+{
+	int i;
+
+	for (i = 0; i < NVSYNC; i++)
+		init_waitqueue_head(&xfs_ioend_wq[i]);
+}
+
+void
+xfs_ioend_wait(
+	xfs_inode_t	*ip)
+{
+	wait_queue_head_t *wq = to_ioend_wq(ip);
+
+	wait_event(*wq, (atomic_read(&ip->i_iocount) == 0));
+}
+
+STATIC void
+xfs_ioend_wake(
+	xfs_inode_t	*ip)
+{
+	if (atomic_dec_and_test(&ip->i_iocount))
+		wake_up(to_ioend_wq(ip));
+}
+
+void
+xfs_count_page_state(
+	struct page		*page,
+	int			*delalloc,
+	int			*unwritten)
+{
+	struct buffer_head	*bh, *head;
+
+	*delalloc = *unwritten = 0;
+
+	bh = head = page_buffers(page);
+	do {
+		if (buffer_unwritten(bh))
+			(*unwritten) = 1;
+		else if (buffer_delay(bh))
+			(*delalloc) = 1;
+	} while ((bh = bh->b_this_page) != head);
+}
+
+STATIC struct block_device *
+xfs_find_bdev_for_inode(
+	struct inode		*inode)
+{
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+
+	if (XFS_IS_REALTIME_INODE(ip))
+		return mp->m_rtdev_targp->bt_bdev;
+	else
+		return mp->m_ddev_targp->bt_bdev;
+}
+
+/*
+ * We're now finished for good with this ioend structure.
+ * Update the page state via the associated buffer_heads,
+ * release holds on the inode and bio, and finally free
+ * up memory.  Do not use the ioend after this.
+ */
+STATIC void
+xfs_destroy_ioend(
+	xfs_ioend_t		*ioend)
+{
+	struct buffer_head	*bh, *next;
+	struct xfs_inode	*ip = XFS_I(ioend->io_inode);
+
+	for (bh = ioend->io_buffer_head; bh; bh = next) {
+		next = bh->b_private;
+		bh->b_end_io(bh, !ioend->io_error);
+	}
+
+	/*
+	 * Volume managers supporting multiple paths can send back ENODEV
+	 * when the final path disappears.  In this case continuing to fill
+	 * the page cache with dirty data which cannot be written out is
+	 * evil, so prevent that.
+	 */
+	if (unlikely(ioend->io_error == -ENODEV)) {
+		xfs_do_force_shutdown(ip->i_mount, SHUTDOWN_DEVICE_REQ,
+				      __FILE__, __LINE__);
+	}
+
+	xfs_ioend_wake(ip);
+	mempool_free(ioend, xfs_ioend_pool);
+}
+
+/*
+ * If the end of the current ioend is beyond the current EOF,
+ * return the new EOF value, otherwise zero.
+ */
+STATIC xfs_fsize_t
+xfs_ioend_new_eof(
+	xfs_ioend_t		*ioend)
+{
+	xfs_inode_t		*ip = XFS_I(ioend->io_inode);
+	xfs_fsize_t		isize;
+	xfs_fsize_t		bsize;
+
+	bsize = ioend->io_offset + ioend->io_size;
+	isize = MAX(ip->i_size, ip->i_new_size);
+	isize = MIN(isize, bsize);
+	return isize > ip->i_d.di_size ? isize : 0;
+}
+
+/*
+ * Update on-disk file size now that data has been written to disk.  The
+ * current in-memory file size is i_size.  If a write is beyond eof i_new_size
+ * will be the intended file size until i_size is updated.  If this write does
+ * not extend all the way to the valid file size then restrict this update to
+ * the end of the write.
+ *
+ * This function does not block as blocking on the inode lock in IO completion
+ * can lead to IO completion order dependency deadlocks.. If it can't get the
+ * inode ilock it will return EAGAIN. Callers must handle this.
+ */
+STATIC int
+xfs_setfilesize(
+	xfs_ioend_t		*ioend)
+{
+	xfs_inode_t		*ip = XFS_I(ioend->io_inode);
+	xfs_fsize_t		isize;
+
+	if (unlikely(ioend->io_error))
+		return 0;
+
+	if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
+		return EAGAIN;
+
+	isize = xfs_ioend_new_eof(ioend);
+	if (isize) {
+		trace_xfs_setfilesize(ip, ioend->io_offset, ioend->io_size);
+		ip->i_d.di_size = isize;
+		xfs_mark_inode_dirty(ip);
+	}
+
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return 0;
+}
+
+/*
+ * Schedule IO completion handling on the final put of an ioend.
+ */
+STATIC void
+xfs_finish_ioend(
+	struct xfs_ioend	*ioend)
+{
+	if (atomic_dec_and_test(&ioend->io_remaining)) {
+		if (ioend->io_type == IO_UNWRITTEN)
+			queue_work(xfsconvertd_workqueue, &ioend->io_work);
+		else
+			queue_work(xfsdatad_workqueue, &ioend->io_work);
+	}
+}
+
+/*
+ * IO write completion.
+ */
+STATIC void
+xfs_end_io(
+	struct work_struct *work)
+{
+	xfs_ioend_t	*ioend = container_of(work, xfs_ioend_t, io_work);
+	struct xfs_inode *ip = XFS_I(ioend->io_inode);
+	int		error = 0;
+
+	/*
+	 * For unwritten extents we need to issue transactions to convert a
+	 * range to normal written extens after the data I/O has finished.
+	 */
+	if (ioend->io_type == IO_UNWRITTEN &&
+	    likely(!ioend->io_error && !XFS_FORCED_SHUTDOWN(ip->i_mount))) {
+
+		error = xfs_iomap_write_unwritten(ip, ioend->io_offset,
+						 ioend->io_size);
+		if (error)
+			ioend->io_error = error;
+	}
+
+	/*
+	 * We might have to update the on-disk file size after extending
+	 * writes.
+	 */
+	error = xfs_setfilesize(ioend);
+	ASSERT(!error || error == EAGAIN);
+
+	/*
+	 * If we didn't complete processing of the ioend, requeue it to the
+	 * tail of the workqueue for another attempt later. Otherwise destroy
+	 * it.
+	 */
+	if (error == EAGAIN) {
+		atomic_inc(&ioend->io_remaining);
+		xfs_finish_ioend(ioend);
+		/* ensure we don't spin on blocked ioends */
+		delay(1);
+	} else {
+		if (ioend->io_iocb)
+			aio_complete(ioend->io_iocb, ioend->io_result, 0);
+		xfs_destroy_ioend(ioend);
+	}
+}
+
+/*
+ * Call IO completion handling in caller context on the final put of an ioend.
+ */
+STATIC void
+xfs_finish_ioend_sync(
+	struct xfs_ioend	*ioend)
+{
+	if (atomic_dec_and_test(&ioend->io_remaining))
+		xfs_end_io(&ioend->io_work);
+}
+
+/*
+ * Allocate and initialise an IO completion structure.
+ * We need to track unwritten extent write completion here initially.
+ * We'll need to extend this for updating the ondisk inode size later
+ * (vs. incore size).
+ */
+STATIC xfs_ioend_t *
+xfs_alloc_ioend(
+	struct inode		*inode,
+	unsigned int		type)
+{
+	xfs_ioend_t		*ioend;
+
+	ioend = mempool_alloc(xfs_ioend_pool, GFP_NOFS);
+
+	/*
+	 * Set the count to 1 initially, which will prevent an I/O
+	 * completion callback from happening before we have started
+	 * all the I/O from calling the completion routine too early.
+	 */
+	atomic_set(&ioend->io_remaining, 1);
+	ioend->io_error = 0;
+	ioend->io_list = NULL;
+	ioend->io_type = type;
+	ioend->io_inode = inode;
+	ioend->io_buffer_head = NULL;
+	ioend->io_buffer_tail = NULL;
+	atomic_inc(&XFS_I(ioend->io_inode)->i_iocount);
+	ioend->io_offset = 0;
+	ioend->io_size = 0;
+	ioend->io_iocb = NULL;
+	ioend->io_result = 0;
+
+	INIT_WORK(&ioend->io_work, xfs_end_io);
+	return ioend;
+}
+
+STATIC int
+xfs_map_blocks(
+	struct inode		*inode,
+	loff_t			offset,
+	struct xfs_bmbt_irec	*imap,
+	int			type,
+	int			nonblocking)
+{
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	ssize_t			count = 1 << inode->i_blkbits;
+	xfs_fileoff_t		offset_fsb, end_fsb;
+	int			error = 0;
+	int			bmapi_flags = XFS_BMAPI_ENTIRE;
+	int			nimaps = 1;
+
+	if (XFS_FORCED_SHUTDOWN(mp))
+		return -XFS_ERROR(EIO);
+
+	if (type == IO_UNWRITTEN)
+		bmapi_flags |= XFS_BMAPI_IGSTATE;
+
+	if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) {
+		if (nonblocking)
+			return -XFS_ERROR(EAGAIN);
+		xfs_ilock(ip, XFS_ILOCK_SHARED);
+	}
+
+	ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
+	       (ip->i_df.if_flags & XFS_IFEXTENTS));
+	ASSERT(offset <= mp->m_maxioffset);
+
+	if (offset + count > mp->m_maxioffset)
+		count = mp->m_maxioffset - offset;
+	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
+	offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	error = xfs_bmapi(NULL, ip, offset_fsb, end_fsb - offset_fsb,
+			  bmapi_flags,  NULL, 0, imap, &nimaps, NULL);
+	xfs_iunlock(ip, XFS_ILOCK_SHARED);
+
+	if (error)
+		return -XFS_ERROR(error);
+
+	if (type == IO_DELALLOC &&
+	    (!nimaps || isnullstartblock(imap->br_startblock))) {
+		error = xfs_iomap_write_allocate(ip, offset, count, imap);
+		if (!error)
+			trace_xfs_map_blocks_alloc(ip, offset, count, type, imap);
+		return -XFS_ERROR(error);
+	}
+
+#ifdef DEBUG
+	if (type == IO_UNWRITTEN) {
+		ASSERT(nimaps);
+		ASSERT(imap->br_startblock != HOLESTARTBLOCK);
+		ASSERT(imap->br_startblock != DELAYSTARTBLOCK);
+	}
+#endif
+	if (nimaps)
+		trace_xfs_map_blocks_found(ip, offset, count, type, imap);
+	return 0;
+}
+
+STATIC int
+xfs_imap_valid(
+	struct inode		*inode,
+	struct xfs_bmbt_irec	*imap,
+	xfs_off_t		offset)
+{
+	offset >>= inode->i_blkbits;
+
+	return offset >= imap->br_startoff &&
+		offset < imap->br_startoff + imap->br_blockcount;
+}
+
+/*
+ * BIO completion handler for buffered IO.
+ */
+STATIC void
+xfs_end_bio(
+	struct bio		*bio,
+	int			error)
+{
+	xfs_ioend_t		*ioend = bio->bi_private;
+
+	ASSERT(atomic_read(&bio->bi_cnt) >= 1);
+	ioend->io_error = test_bit(BIO_UPTODATE, &bio->bi_flags) ? 0 : error;
+
+	/* Toss bio and pass work off to an xfsdatad thread */
+	bio->bi_private = NULL;
+	bio->bi_end_io = NULL;
+	bio_put(bio);
+
+	xfs_finish_ioend(ioend);
+}
+
+STATIC void
+xfs_submit_ioend_bio(
+	struct writeback_control *wbc,
+	xfs_ioend_t		*ioend,
+	struct bio		*bio)
+{
+	atomic_inc(&ioend->io_remaining);
+	bio->bi_private = ioend;
+	bio->bi_end_io = xfs_end_bio;
+
+	/*
+	 * If the I/O is beyond EOF we mark the inode dirty immediately
+	 * but don't update the inode size until I/O completion.
+	 */
+	if (xfs_ioend_new_eof(ioend))
+		xfs_mark_inode_dirty(XFS_I(ioend->io_inode));
+
+	submit_bio(wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE, bio);
+}
+
+STATIC struct bio *
+xfs_alloc_ioend_bio(
+	struct buffer_head	*bh)
+{
+	int			nvecs = bio_get_nr_vecs(bh->b_bdev);
+	struct bio		*bio = bio_alloc(GFP_NOIO, nvecs);
+
+	ASSERT(bio->bi_private == NULL);
+	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
+	bio->bi_bdev = bh->b_bdev;
+	return bio;
+}
+
+STATIC void
+xfs_start_buffer_writeback(
+	struct buffer_head	*bh)
+{
+	ASSERT(buffer_mapped(bh));
+	ASSERT(buffer_locked(bh));
+	ASSERT(!buffer_delay(bh));
+	ASSERT(!buffer_unwritten(bh));
+
+	mark_buffer_async_write(bh);
+	set_buffer_uptodate(bh);
+	clear_buffer_dirty(bh);
+}
+
+STATIC void
+xfs_start_page_writeback(
+	struct page		*page,
+	int			clear_dirty,
+	int			buffers)
+{
+	ASSERT(PageLocked(page));
+	ASSERT(!PageWriteback(page));
+	if (clear_dirty)
+		clear_page_dirty_for_io(page);
+	set_page_writeback(page);
+	unlock_page(page);
+	/* If no buffers on the page are to be written, finish it here */
+	if (!buffers)
+		end_page_writeback(page);
+}
+
+static inline int bio_add_buffer(struct bio *bio, struct buffer_head *bh)
+{
+	return bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
+}
+
+/*
+ * Submit all of the bios for all of the ioends we have saved up, covering the
+ * initial writepage page and also any probed pages.
+ *
+ * Because we may have multiple ioends spanning a page, we need to start
+ * writeback on all the buffers before we submit them for I/O. If we mark the
+ * buffers as we got, then we can end up with a page that only has buffers
+ * marked async write and I/O complete on can occur before we mark the other
+ * buffers async write.
+ *
+ * The end result of this is that we trip a bug in end_page_writeback() because
+ * we call it twice for the one page as the code in end_buffer_async_write()
+ * assumes that all buffers on the page are started at the same time.
+ *
+ * The fix is two passes across the ioend list - one to start writeback on the
+ * buffer_heads, and then submit them for I/O on the second pass.
+ */
+STATIC void
+xfs_submit_ioend(
+	struct writeback_control *wbc,
+	xfs_ioend_t		*ioend)
+{
+	xfs_ioend_t		*head = ioend;
+	xfs_ioend_t		*next;
+	struct buffer_head	*bh;
+	struct bio		*bio;
+	sector_t		lastblock = 0;
+
+	/* Pass 1 - start writeback */
+	do {
+		next = ioend->io_list;
+		for (bh = ioend->io_buffer_head; bh; bh = bh->b_private)
+			xfs_start_buffer_writeback(bh);
+	} while ((ioend = next) != NULL);
+
+	/* Pass 2 - submit I/O */
+	ioend = head;
+	do {
+		next = ioend->io_list;
+		bio = NULL;
+
+		for (bh = ioend->io_buffer_head; bh; bh = bh->b_private) {
+
+			if (!bio) {
+ retry:
+				bio = xfs_alloc_ioend_bio(bh);
+			} else if (bh->b_blocknr != lastblock + 1) {
+				xfs_submit_ioend_bio(wbc, ioend, bio);
+				goto retry;
+			}
+
+			if (bio_add_buffer(bio, bh) != bh->b_size) {
+				xfs_submit_ioend_bio(wbc, ioend, bio);
+				goto retry;
+			}
+
+			lastblock = bh->b_blocknr;
+		}
+		if (bio)
+			xfs_submit_ioend_bio(wbc, ioend, bio);
+		xfs_finish_ioend(ioend);
+	} while ((ioend = next) != NULL);
+}
+
+/*
+ * Cancel submission of all buffer_heads so far in this endio.
+ * Toss the endio too.  Only ever called for the initial page
+ * in a writepage request, so only ever one page.
+ */
+STATIC void
+xfs_cancel_ioend(
+	xfs_ioend_t		*ioend)
+{
+	xfs_ioend_t		*next;
+	struct buffer_head	*bh, *next_bh;
+
+	do {
+		next = ioend->io_list;
+		bh = ioend->io_buffer_head;
+		do {
+			next_bh = bh->b_private;
+			clear_buffer_async_write(bh);
+			unlock_buffer(bh);
+		} while ((bh = next_bh) != NULL);
+
+		xfs_ioend_wake(XFS_I(ioend->io_inode));
+		mempool_free(ioend, xfs_ioend_pool);
+	} while ((ioend = next) != NULL);
+}
+
+/*
+ * Test to see if we've been building up a completion structure for
+ * earlier buffers -- if so, we try to append to this ioend if we
+ * can, otherwise we finish off any current ioend and start another.
+ * Return true if we've finished the given ioend.
+ */
+STATIC void
+xfs_add_to_ioend(
+	struct inode		*inode,
+	struct buffer_head	*bh,
+	xfs_off_t		offset,
+	unsigned int		type,
+	xfs_ioend_t		**result,
+	int			need_ioend)
+{
+	xfs_ioend_t		*ioend = *result;
+
+	if (!ioend || need_ioend || type != ioend->io_type) {
+		xfs_ioend_t	*previous = *result;
+
+		ioend = xfs_alloc_ioend(inode, type);
+		ioend->io_offset = offset;
+		ioend->io_buffer_head = bh;
+		ioend->io_buffer_tail = bh;
+		if (previous)
+			previous->io_list = ioend;
+		*result = ioend;
+	} else {
+		ioend->io_buffer_tail->b_private = bh;
+		ioend->io_buffer_tail = bh;
+	}
+
+	bh->b_private = NULL;
+	ioend->io_size += bh->b_size;
+}
+
+STATIC void
+xfs_map_buffer(
+	struct inode		*inode,
+	struct buffer_head	*bh,
+	struct xfs_bmbt_irec	*imap,
+	xfs_off_t		offset)
+{
+	sector_t		bn;
+	struct xfs_mount	*m = XFS_I(inode)->i_mount;
+	xfs_off_t		iomap_offset = XFS_FSB_TO_B(m, imap->br_startoff);
+	xfs_daddr_t		iomap_bn = xfs_fsb_to_db(XFS_I(inode), imap->br_startblock);
+
+	ASSERT(imap->br_startblock != HOLESTARTBLOCK);
+	ASSERT(imap->br_startblock != DELAYSTARTBLOCK);
+
+	bn = (iomap_bn >> (inode->i_blkbits - BBSHIFT)) +
+	      ((offset - iomap_offset) >> inode->i_blkbits);
+
+	ASSERT(bn || XFS_IS_REALTIME_INODE(XFS_I(inode)));
+
+	bh->b_blocknr = bn;
+	set_buffer_mapped(bh);
+}
+
+STATIC void
+xfs_map_at_offset(
+	struct inode		*inode,
+	struct buffer_head	*bh,
+	struct xfs_bmbt_irec	*imap,
+	xfs_off_t		offset)
+{
+	ASSERT(imap->br_startblock != HOLESTARTBLOCK);
+	ASSERT(imap->br_startblock != DELAYSTARTBLOCK);
+
+	xfs_map_buffer(inode, bh, imap, offset);
+	set_buffer_mapped(bh);
+	clear_buffer_delay(bh);
+	clear_buffer_unwritten(bh);
+}
+
+/*
+ * Test if a given page is suitable for writing as part of an unwritten
+ * or delayed allocate extent.
+ */
+STATIC int
+xfs_is_delayed_page(
+	struct page		*page,
+	unsigned int		type)
+{
+	if (PageWriteback(page))
+		return 0;
+
+	if (page->mapping && page_has_buffers(page)) {
+		struct buffer_head	*bh, *head;
+		int			acceptable = 0;
+
+		bh = head = page_buffers(page);
+		do {
+			if (buffer_unwritten(bh))
+				acceptable = (type == IO_UNWRITTEN);
+			else if (buffer_delay(bh))
+				acceptable = (type == IO_DELALLOC);
+			else if (buffer_dirty(bh) && buffer_mapped(bh))
+				acceptable = (type == IO_OVERWRITE);
+			else
+				break;
+		} while ((bh = bh->b_this_page) != head);
+
+		if (acceptable)
+			return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * Allocate & map buffers for page given the extent map. Write it out.
+ * except for the original page of a writepage, this is called on
+ * delalloc/unwritten pages only, for the original page it is possible
+ * that the page has no mapping at all.
+ */
+STATIC int
+xfs_convert_page(
+	struct inode		*inode,
+	struct page		*page,
+	loff_t			tindex,
+	struct xfs_bmbt_irec	*imap,
+	xfs_ioend_t		**ioendp,
+	struct writeback_control *wbc)
+{
+	struct buffer_head	*bh, *head;
+	xfs_off_t		end_offset;
+	unsigned long		p_offset;
+	unsigned int		type;
+	int			len, page_dirty;
+	int			count = 0, done = 0, uptodate = 1;
+ 	xfs_off_t		offset = page_offset(page);
+
+	if (page->index != tindex)
+		goto fail;
+	if (!trylock_page(page))
+		goto fail;
+	if (PageWriteback(page))
+		goto fail_unlock_page;
+	if (page->mapping != inode->i_mapping)
+		goto fail_unlock_page;
+	if (!xfs_is_delayed_page(page, (*ioendp)->io_type))
+		goto fail_unlock_page;
+
+	/*
+	 * page_dirty is initially a count of buffers on the page before
+	 * EOF and is decremented as we move each into a cleanable state.
+	 *
+	 * Derivation:
+	 *
+	 * End offset is the highest offset that this page should represent.
+	 * If we are on the last page, (end_offset & (PAGE_CACHE_SIZE - 1))
+	 * will evaluate non-zero and be less than PAGE_CACHE_SIZE and
+	 * hence give us the correct page_dirty count. On any other page,
+	 * it will be zero and in that case we need page_dirty to be the
+	 * count of buffers on the page.
+	 */
+	end_offset = min_t(unsigned long long,
+			(xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
+			i_size_read(inode));
+
+	len = 1 << inode->i_blkbits;
+	p_offset = min_t(unsigned long, end_offset & (PAGE_CACHE_SIZE - 1),
+					PAGE_CACHE_SIZE);
+	p_offset = p_offset ? roundup(p_offset, len) : PAGE_CACHE_SIZE;
+	page_dirty = p_offset / len;
+
+	bh = head = page_buffers(page);
+	do {
+		if (offset >= end_offset)
+			break;
+		if (!buffer_uptodate(bh))
+			uptodate = 0;
+		if (!(PageUptodate(page) || buffer_uptodate(bh))) {
+			done = 1;
+			continue;
+		}
+
+		if (buffer_unwritten(bh) || buffer_delay(bh) ||
+		    buffer_mapped(bh)) {
+			if (buffer_unwritten(bh))
+				type = IO_UNWRITTEN;
+			else if (buffer_delay(bh))
+				type = IO_DELALLOC;
+			else
+				type = IO_OVERWRITE;
+
+			if (!xfs_imap_valid(inode, imap, offset)) {
+				done = 1;
+				continue;
+			}
+
+			lock_buffer(bh);
+			if (type != IO_OVERWRITE)
+				xfs_map_at_offset(inode, bh, imap, offset);
+			xfs_add_to_ioend(inode, bh, offset, type,
+					 ioendp, done);
+
+			page_dirty--;
+			count++;
+		} else {
+			done = 1;
+		}
+	} while (offset += len, (bh = bh->b_this_page) != head);
+
+	if (uptodate && bh == head)
+		SetPageUptodate(page);
+
+	if (count) {
+		if (--wbc->nr_to_write <= 0 &&
+		    wbc->sync_mode == WB_SYNC_NONE)
+			done = 1;
+	}
+	xfs_start_page_writeback(page, !page_dirty, count);
+
+	return done;
+ fail_unlock_page:
+	unlock_page(page);
+ fail:
+	return 1;
+}
+
+/*
+ * Convert & write out a cluster of pages in the same extent as defined
+ * by mp and following the start page.
+ */
+STATIC void
+xfs_cluster_write(
+	struct inode		*inode,
+	pgoff_t			tindex,
+	struct xfs_bmbt_irec	*imap,
+	xfs_ioend_t		**ioendp,
+	struct writeback_control *wbc,
+	pgoff_t			tlast)
+{
+	struct pagevec		pvec;
+	int			done = 0, i;
+
+	pagevec_init(&pvec, 0);
+	while (!done && tindex <= tlast) {
+		unsigned len = min_t(pgoff_t, PAGEVEC_SIZE, tlast - tindex + 1);
+
+		if (!pagevec_lookup(&pvec, inode->i_mapping, tindex, len))
+			break;
+
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			done = xfs_convert_page(inode, pvec.pages[i], tindex++,
+					imap, ioendp, wbc);
+			if (done)
+				break;
+		}
+
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+}
+
+STATIC void
+xfs_vm_invalidatepage(
+	struct page		*page,
+	unsigned long		offset)
+{
+	trace_xfs_invalidatepage(page->mapping->host, page, offset);
+	block_invalidatepage(page, offset);
+}
+
+/*
+ * If the page has delalloc buffers on it, we need to punch them out before we
+ * invalidate the page. If we don't, we leave a stale delalloc mapping on the
+ * inode that can trip a BUG() in xfs_get_blocks() later on if a direct IO read
+ * is done on that same region - the delalloc extent is returned when none is
+ * supposed to be there.
+ *
+ * We prevent this by truncating away the delalloc regions on the page before
+ * invalidating it. Because they are delalloc, we can do this without needing a
+ * transaction. Indeed - if we get ENOSPC errors, we have to be able to do this
+ * truncation without a transaction as there is no space left for block
+ * reservation (typically why we see a ENOSPC in writeback).
+ *
+ * This is not a performance critical path, so for now just do the punching a
+ * buffer head at a time.
+ */
+STATIC void
+xfs_aops_discard_page(
+	struct page		*page)
+{
+	struct inode		*inode = page->mapping->host;
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct buffer_head	*bh, *head;
+	loff_t			offset = page_offset(page);
+
+	if (!xfs_is_delayed_page(page, IO_DELALLOC))
+		goto out_invalidate;
+
+	if (XFS_FORCED_SHUTDOWN(ip->i_mount))
+		goto out_invalidate;
+
+	xfs_alert(ip->i_mount,
+		"page discard on page %p, inode 0x%llx, offset %llu.",
+			page, ip->i_ino, offset);
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	bh = head = page_buffers(page);
+	do {
+		int		error;
+		xfs_fileoff_t	start_fsb;
+
+		if (!buffer_delay(bh))
+			goto next_buffer;
+
+		start_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
+		error = xfs_bmap_punch_delalloc_range(ip, start_fsb, 1);
+		if (error) {
+			/* something screwed, just bail */
+			if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+				xfs_alert(ip->i_mount,
+			"page discard unable to remove delalloc mapping.");
+			}
+			break;
+		}
+next_buffer:
+		offset += 1 << inode->i_blkbits;
+
+	} while ((bh = bh->b_this_page) != head);
+
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+out_invalidate:
+	xfs_vm_invalidatepage(page, 0);
+	return;
+}
+
+/*
+ * Write out a dirty page.
+ *
+ * For delalloc space on the page we need to allocate space and flush it.
+ * For unwritten space on the page we need to start the conversion to
+ * regular allocated space.
+ * For any other dirty buffer heads on the page we should flush them.
+ */
+STATIC int
+xfs_vm_writepage(
+	struct page		*page,
+	struct writeback_control *wbc)
+{
+	struct inode		*inode = page->mapping->host;
+	struct buffer_head	*bh, *head;
+	struct xfs_bmbt_irec	imap;
+	xfs_ioend_t		*ioend = NULL, *iohead = NULL;
+	loff_t			offset;
+	unsigned int		type;
+	__uint64_t              end_offset;
+	pgoff_t                 end_index, last_index;
+	ssize_t			len;
+	int			err, imap_valid = 0, uptodate = 1;
+	int			count = 0;
+	int			nonblocking = 0;
+
+	trace_xfs_writepage(inode, page, 0);
+
+	ASSERT(page_has_buffers(page));
+
+	/*
+	 * Refuse to write the page out if we are called from reclaim context.
+	 *
+	 * This avoids stack overflows when called from deeply used stacks in
+	 * random callers for direct reclaim or memcg reclaim.  We explicitly
+	 * allow reclaim from kswapd as the stack usage there is relatively low.
+	 *
+	 * This should really be done by the core VM, but until that happens
+	 * filesystems like XFS, btrfs and ext4 have to take care of this
+	 * by themselves.
+	 */
+	if ((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == PF_MEMALLOC)
+		goto redirty;
+
+	/*
+	 * Given that we do not allow direct reclaim to call us, we should
+	 * never be called while in a filesystem transaction.
+	 */
+	if (WARN_ON(current->flags & PF_FSTRANS))
+		goto redirty;
+
+	/* Is this page beyond the end of the file? */
+	offset = i_size_read(inode);
+	end_index = offset >> PAGE_CACHE_SHIFT;
+	last_index = (offset - 1) >> PAGE_CACHE_SHIFT;
+	if (page->index >= end_index) {
+		if ((page->index >= end_index + 1) ||
+		    !(i_size_read(inode) & (PAGE_CACHE_SIZE - 1))) {
+			unlock_page(page);
+			return 0;
+		}
+	}
+
+	end_offset = min_t(unsigned long long,
+			(xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
+			offset);
+	len = 1 << inode->i_blkbits;
+
+	bh = head = page_buffers(page);
+	offset = page_offset(page);
+	type = IO_OVERWRITE;
+
+	if (wbc->sync_mode == WB_SYNC_NONE)
+		nonblocking = 1;
+
+	do {
+		int new_ioend = 0;
+
+		if (offset >= end_offset)
+			break;
+		if (!buffer_uptodate(bh))
+			uptodate = 0;
+
+		/*
+		 * set_page_dirty dirties all buffers in a page, independent
+		 * of their state.  The dirty state however is entirely
+		 * meaningless for holes (!mapped && uptodate), so skip
+		 * buffers covering holes here.
+		 */
+		if (!buffer_mapped(bh) && buffer_uptodate(bh)) {
+			imap_valid = 0;
+			continue;
+		}
+
+		if (buffer_unwritten(bh)) {
+			if (type != IO_UNWRITTEN) {
+				type = IO_UNWRITTEN;
+				imap_valid = 0;
+			}
+		} else if (buffer_delay(bh)) {
+			if (type != IO_DELALLOC) {
+				type = IO_DELALLOC;
+				imap_valid = 0;
+			}
+		} else if (buffer_uptodate(bh)) {
+			if (type != IO_OVERWRITE) {
+				type = IO_OVERWRITE;
+				imap_valid = 0;
+			}
+		} else {
+			if (PageUptodate(page)) {
+				ASSERT(buffer_mapped(bh));
+				imap_valid = 0;
+			}
+			continue;
+		}
+
+		if (imap_valid)
+			imap_valid = xfs_imap_valid(inode, &imap, offset);
+		if (!imap_valid) {
+			/*
+			 * If we didn't have a valid mapping then we need to
+			 * put the new mapping into a separate ioend structure.
+			 * This ensures non-contiguous extents always have
+			 * separate ioends, which is particularly important
+			 * for unwritten extent conversion at I/O completion
+			 * time.
+			 */
+			new_ioend = 1;
+			err = xfs_map_blocks(inode, offset, &imap, type,
+					     nonblocking);
+			if (err)
+				goto error;
+			imap_valid = xfs_imap_valid(inode, &imap, offset);
+		}
+		if (imap_valid) {
+			lock_buffer(bh);
+			if (type != IO_OVERWRITE)
+				xfs_map_at_offset(inode, bh, &imap, offset);
+			xfs_add_to_ioend(inode, bh, offset, type, &ioend,
+					 new_ioend);
+			count++;
+		}
+
+		if (!iohead)
+			iohead = ioend;
+
+	} while (offset += len, ((bh = bh->b_this_page) != head));
+
+	if (uptodate && bh == head)
+		SetPageUptodate(page);
+
+	xfs_start_page_writeback(page, 1, count);
+
+	if (ioend && imap_valid) {
+		xfs_off_t		end_index;
+
+		end_index = imap.br_startoff + imap.br_blockcount;
+
+		/* to bytes */
+		end_index <<= inode->i_blkbits;
+
+		/* to pages */
+		end_index = (end_index - 1) >> PAGE_CACHE_SHIFT;
+
+		/* check against file size */
+		if (end_index > last_index)
+			end_index = last_index;
+
+		xfs_cluster_write(inode, page->index + 1, &imap, &ioend,
+				  wbc, end_index);
+	}
+
+	if (iohead)
+		xfs_submit_ioend(wbc, iohead);
+
+	return 0;
+
+error:
+	if (iohead)
+		xfs_cancel_ioend(iohead);
+
+	if (err == -EAGAIN)
+		goto redirty;
+
+	xfs_aops_discard_page(page);
+	ClearPageUptodate(page);
+	unlock_page(page);
+	return err;
+
+redirty:
+	redirty_page_for_writepage(wbc, page);
+	unlock_page(page);
+	return 0;
+}
+
+STATIC int
+xfs_vm_writepages(
+	struct address_space	*mapping,
+	struct writeback_control *wbc)
+{
+	xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
+	return generic_writepages(mapping, wbc);
+}
+
+/*
+ * Called to move a page into cleanable state - and from there
+ * to be released. The page should already be clean. We always
+ * have buffer heads in this call.
+ *
+ * Returns 1 if the page is ok to release, 0 otherwise.
+ */
+STATIC int
+xfs_vm_releasepage(
+	struct page		*page,
+	gfp_t			gfp_mask)
+{
+	int			delalloc, unwritten;
+
+	trace_xfs_releasepage(page->mapping->host, page, 0);
+
+	xfs_count_page_state(page, &delalloc, &unwritten);
+
+	if (WARN_ON(delalloc))
+		return 0;
+	if (WARN_ON(unwritten))
+		return 0;
+
+	return try_to_free_buffers(page);
+}
+
+STATIC int
+__xfs_get_blocks(
+	struct inode		*inode,
+	sector_t		iblock,
+	struct buffer_head	*bh_result,
+	int			create,
+	int			direct)
+{
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_fileoff_t		offset_fsb, end_fsb;
+	int			error = 0;
+	int			lockmode = 0;
+	struct xfs_bmbt_irec	imap;
+	int			nimaps = 1;
+	xfs_off_t		offset;
+	ssize_t			size;
+	int			new = 0;
+
+	if (XFS_FORCED_SHUTDOWN(mp))
+		return -XFS_ERROR(EIO);
+
+	offset = (xfs_off_t)iblock << inode->i_blkbits;
+	ASSERT(bh_result->b_size >= (1 << inode->i_blkbits));
+	size = bh_result->b_size;
+
+	if (!create && direct && offset >= i_size_read(inode))
+		return 0;
+
+	if (create) {
+		lockmode = XFS_ILOCK_EXCL;
+		xfs_ilock(ip, lockmode);
+	} else {
+		lockmode = xfs_ilock_map_shared(ip);
+	}
+
+	ASSERT(offset <= mp->m_maxioffset);
+	if (offset + size > mp->m_maxioffset)
+		size = mp->m_maxioffset - offset;
+	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + size);
+	offset_fsb = XFS_B_TO_FSBT(mp, offset);
+
+	error = xfs_bmapi(NULL, ip, offset_fsb, end_fsb - offset_fsb,
+			  XFS_BMAPI_ENTIRE,  NULL, 0, &imap, &nimaps, NULL);
+	if (error)
+		goto out_unlock;
+
+	if (create &&
+	    (!nimaps ||
+	     (imap.br_startblock == HOLESTARTBLOCK ||
+	      imap.br_startblock == DELAYSTARTBLOCK))) {
+		if (direct) {
+			error = xfs_iomap_write_direct(ip, offset, size,
+						       &imap, nimaps);
+		} else {
+			error = xfs_iomap_write_delay(ip, offset, size, &imap);
+		}
+		if (error)
+			goto out_unlock;
+
+		trace_xfs_get_blocks_alloc(ip, offset, size, 0, &imap);
+	} else if (nimaps) {
+		trace_xfs_get_blocks_found(ip, offset, size, 0, &imap);
+	} else {
+		trace_xfs_get_blocks_notfound(ip, offset, size);
+		goto out_unlock;
+	}
+	xfs_iunlock(ip, lockmode);
+
+	if (imap.br_startblock != HOLESTARTBLOCK &&
+	    imap.br_startblock != DELAYSTARTBLOCK) {
+		/*
+		 * For unwritten extents do not report a disk address on
+		 * the read case (treat as if we're reading into a hole).
+		 */
+		if (create || !ISUNWRITTEN(&imap))
+			xfs_map_buffer(inode, bh_result, &imap, offset);
+		if (create && ISUNWRITTEN(&imap)) {
+			if (direct)