blob: f7a983b570f5e72e5e0de7be2f2167c8e666a856 [file] [log] [blame]
From 17741892eb9076cd581130b2b5592d554a629bfe Mon Sep 17 00:00:00 2001
From: Goldwyn Rodrigues <rgoldwyn@suse.com>
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 <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index f77c4f0aaf3e..95c3b7b22e06 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1912,9 +1912,10 @@ 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);
}
--
2.7.4