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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Robbie Ko <robbieko@synology.com>,
        Filipe Manana <fdmanana@suse.com>,
        David Sterba <dsterba@suse.com>
Subject: [PATCH 4.19 093/146] btrfs: fix missing semaphore unlock in btrfs_sync_file
Date:   Thu, 16 Apr 2020 15:23:54 +0200
Message-Id: <20200416131255.505565278@linuxfoundation.org>
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From: Robbie Ko <robbieko@synology.com>

commit 6ff06729c22ec0b7498d900d79cc88cfb8aceaeb upstream.

Ordered ops are started twice in sync file, once outside of inode mutex
and once inside, taking the dio semaphore. There was one error path
missing the semaphore unlock.

Fixes: aab15e8ec2576 ("Btrfs: fix rare chances for data loss when doing a fast fsync")
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Robbie Ko <robbieko@synology.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
[ add changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/btrfs/file.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2137,6 +2137,7 @@ int btrfs_sync_file(struct file *file, l
 	 */
 	ret = start_ordered_ops(inode, start, end);
 	if (ret) {
+		up_write(&BTRFS_I(inode)->dio_sem);
 		inode_unlock(inode);
 		goto out;
 	}