xfs: lockdep annotations for xfs_dqlock2

xfs_dqlock2 locks two xfs_dquots, which is fine as it always locks the
dquot with the lower id first.  Use mutex_lock_nested to tell lockdep
about this fact.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/fs/xfs/quota/xfs_dquot.h b/fs/xfs/quota/xfs_dquot.h
index 7e455337e2ba..d443e93b4331 100644
--- a/fs/xfs/quota/xfs_dquot.h
+++ b/fs/xfs/quota/xfs_dquot.h
@@ -97,6 +97,16 @@ typedef struct xfs_dquot {
 #define dq_hashlist     q_lists.dqm_hashlist
 #define dq_flags        q_lists.dqm_flags
 
+/*
+ * Lock hierachy for q_qlock:
+ *      XFS_QLOCK_NORMAL is the implicit default,
+ *      XFS_QLOCK_NESTED is the dquot with the higher id in xfs_dqlock2
+ */
+enum {
+        XFS_QLOCK_NORMAL = 0,
+        XFS_QLOCK_NESTED,
+};
+
 #define XFS_DQHOLD(dqp)         ((dqp)->q_nrefs++)
 
 #ifdef DEBUG