[PATCH 1/4] xfs: remove nonblocking mode from xfs_vm_writepage

Dave Chinner
2015-08-25T05:06:45Z

From: Dave Chinner <dchinner@redhat.com>

Remove the nonblocking optimisation done for mapping lookups during
writeback. It's not clear that leaving a hole in the writeback range
just because we couldn't get a lock is really a win, as it makes us
do another small random IO later on rather than a large sequential
IO now.

As this gets in the way of sane error handling later on, just remove
for the moment and we can re-introduce an equivalent optimisation in
future if we see problems due to extent map lock contention.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_aops.c | 20 +++-----------------
1 file changed, 3 insertions(+), 17 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 3859f5e..89fad6b 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -276,8 +276,7 @@ xfs_map_blocks(
struct inode *inode,
loff_t offset,
struct xfs_bmbt_irec *imap,
- int type,
- int nonblocking)
+ int type)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
@@ -293,12 +292,7 @@ xfs_map_blocks(
if (type == XFS_IO_UNWRITTEN)
bmapi_flags |= XFS_BMAPI_IGSTATE;

- if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) {
- if (nonblocking)
- return -EAGAIN;
- xfs_ilock(ip, XFS_ILOCK_SHARED);
- }
-
+ 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_super->s_maxbytes);
@@ -949,7 +943,6 @@ xfs_vm_writepage(
ssize_t len;
int err, imap_valid = 0, uptodate = 1;
int count = 0;
- int nonblocking = 0;

trace_xfs_writepage(inode, page, 0, 0);

@@ -1049,9 +1042,6 @@ xfs_vm_writepage(
offset = page_offset(page);
type = XFS_IO_OVERWRITE;

- if (wbc->sync_mode == WB_SYNC_NONE)
- nonblocking = 1;
-
do {
int new_ioend = 0;

@@ -1111,8 +1101,7 @@ xfs_vm_writepage(
* time.
*/
new_ioend = 1;
- err = xfs_map_blocks(inode, offset, &imap, type,
- nonblocking);
+ err = xfs_map_blocks(inode, offset, &imap, type);
if (err)
goto error;
imap_valid = xfs_imap_valid(inode, &imap, offset);
@@ -1182,9 +1171,6 @@ error:
if (iohead)
xfs_cancel_ioend(iohead);

- if (err == -EAGAIN)
- goto redirty;
-
xfs_aops_discard_page(page);
ClearPageUptodate(page);
unlock_page(page);
--
2.5.0