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btrfs: simplify inode locking for RWF_NOWAIT 

This is similar to 942491c9e6 ("xfs: fix AIM7 regression"). Apparently
our current rwsem code doesn't like doing the trylock, then lock for
real scheme. This causes extra contention on the lock and can be
measured eg. by AIM7 benchmark.  So change our read/write methods to
just do the trylock for the RWF_NOWAIT case.

Fixes: edf064e7c6 ("btrfs: nowait aio support")
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Goldwyn Rodrigues 2019-09-11 11:45:15 -05:00 committed by David Sterba
parent af42d3466b
commit 9cf35f6735
1 changed files with 3 additions and 2 deletions
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5
fs/btrfs/file.c
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@ -1903,9 +1903,10 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
(iocb->ki_flags & IOCB_NOWAIT))
return -EOPNOTSUPP;
if (!inode_trylock(inode)) {
if (iocb->ki_flags & IOCB_NOWAIT)
if (iocb->ki_flags & IOCB_NOWAIT) {
if (!inode_trylock(inode))
return -EAGAIN;
} else {
inode_lock(inode);
}