xfs: fix inode validity check in xfs_iflush_cluster

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@redhat.com>

cc: <stable@vger.kernel.org> # 3.10.x-
Discovered-by: Brain Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 696936c..a955b02 100644 (file)
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -3205,13 +3205,13 @@ 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