From 3eb81bbf4e0b8eaf33c8315562f693128f683f02 Mon Sep 17 00:00:00 2001 From: Goldwyn Rodrigues Date: Wed, 11 Sep 2019 11:45:15 -0500 Subject: [PATCH] btrfs: simplify inode locking for RWF_NOWAIT commit 9cf35f673583ccc9f3e2507498b3079d56614ad3 upstream. This is similar to 942491c9e6d6 ("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: edf064e7c6fe ("btrfs: nowait aio support") Signed-off-by: Goldwyn Rodrigues Reviewed-by: David Sterba [ update changelog ] Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/file.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index eaafd00f93d4..5739b8fc7fff 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -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); }