[PATCH 3.10 091/180] xfs: fix inode validity check in xfs_iflush_cluster

[Willy Tarreau]

From: Dave Chinner <dchinner@xxxxxxxxxx>

commit 51b07f30a71c27405259a0248206ed4e22adbee2 upstream.

Some careless idiot(*) wrote crap code in commit 1a3e8f3 ("xfs:
convert inode cache lookups to use RCU locking") back in late 2010,
and so xfs_iflush_cluster checks the wrong inode for whether it is
still valid under RCU protection. Fix it to lock and check the
correct inode.

(*) Careless-idiot: Dave Chinner <dchinner@xxxxxxxxxx>

cc: <stable@xxxxxxxxxxxxxxx> # 3.10.x-
Discovered-by: Brain Foster <bfoster@xxxxxxxxxx>
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Dave Chinner <david@xxxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
 fs/xfs/xfs_inode.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 1f9c806..52faf49 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2604,13 +2604,13 @@ xfs_iflush_cluster(
 		 * We need to check under the i_flags_lock for a valid inode
 		 * here. Skip it if it is not valid or the wrong inode.
 		 */
-		spin_lock(&ip->i_flags_lock);
-		if (!ip->i_ino ||
+		spin_lock(&iq->i_flags_lock);
+		if (!iq->i_ino ||
 		    (XFS_INO_TO_AGINO(mp, iq->i_ino) & mask) != first_index) {
-			spin_unlock(&ip->i_flags_lock);
+			spin_unlock(&iq->i_flags_lock);
 			continue;
 		}
-		spin_unlock(&ip->i_flags_lock);
+		spin_unlock(&iq->i_flags_lock);
 
 		/*
 		 * Do an un-protected check to see if the inode is dirty and
-- 
2.8.0.rc2.1.gbe9624a