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xfs: reduce the number of atomic when locking a buffer after lookup 

Avoid an extra atomic operation in the non-trylock case by only
doing a trylock if the XBF_TRYLOCK flag is set. This follows the
pattern in the IO path with NOWAIT semantics where the
"trylock-fail-lock" path showed 5-10% reduced throughput compared to
just using single lock call when not under NOWAIT conditions. So
make that same change here, too.

See commit 942491c9e6 ("xfs: fix AIM7 regression") for details.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Dave Chinner 2022-07-14 12:04:38 +10:00 committed by Dave Chinner
parent 348000804a
commit d8d9bbb0ee
1 changed files with 3 additions and 2 deletions
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5
fs/xfs/xfs_buf.c
View File

@ -534,11 +534,12 @@ xfs_buf_find_lock(
struct xfs_buf *bp,
xfs_buf_flags_t flags)
{
if (!xfs_buf_trylock(bp)) {
if (flags & XBF_TRYLOCK) {
if (flags & XBF_TRYLOCK) {
if (!xfs_buf_trylock(bp)) {
XFS_STATS_INC(bp->b_mount, xb_busy_locked);
return -EAGAIN;
}
} else {
xfs_buf_lock(bp);
XFS_STATS_INC(bp->b_mount, xb_get_locked_waited);
}