linux-ext4 - [PATCH 1/3] btrfs: fix inode rwsem regression

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Date:   Wed, 11 Sep 2019 11:45:15 -0500
From:   Goldwyn Rodrigues <rgoldwyn@...e.de>
To:     linux-fsdevel@...r.kernel.org
Cc:     linux-ext4@...r.kernel.org, linux-btrfs@...r.kernel.org,
        hch@...radead.org, andres@...razel.de, david@...morbit.com,
        riteshh@...ux.ibm.com, linux-f2fs-devel@...ts.sourceforge.net,
        Goldwyn Rodrigues <rgoldwyn@...e.com>
Subject: [PATCH 1/3] btrfs: fix inode rwsem regression

From: Goldwyn Rodrigues <rgoldwyn@...e.com>

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.  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@...e.com>
---
 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 58a18ed11546..651b2b1f4219 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1893,9 +1893,10 @@ 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);
 	}
 
-- 
2.16.4