[PATCH 3.16 103/305] xfs: fix inode validity check in xfs_iflush_cluster

Ben Hutchings
2016-08-14T11:37:52Z

From: Dave Chinner <dchinner@redhat.com>

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@redhat.com>

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/xfs/xfs_inode.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -3029,13 +3029,13 @@ 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