xfs: add a lock class for group/project dquots

We can have both a user and a group/project dquot locked at the same time,
as long as the user dquot is locked first.  Tell lockdep about that fact
by making the group/project dquots a different lock class.

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

1 files changed, 11 insertions, 1 deletions

diff --git a/fs/xfs/quota/xfs_dquot.c b/fs/xfs/quota/xfs_dquot.c
index ebdf3c842dce..6543c0b29753 100644
--- a/fs/xfs/quota/xfs_dquot.c
+++ b/fs/xfs/quota/xfs_dquot.c
@@ -73,6 +73,8 @@ int xfs_dqreq_num;
 int xfs_dqerror_mod = 33;
 #endif
 
+static struct lock_class_key xfs_dquot_other_class;
+
 /*
  * Allocate and initialize a dquot. We don't always allocate fresh memory;
  * we try to reclaim a free dquot if the number of incore dquots are above
@@ -139,7 +141,15 @@ xfs_qm_dqinit(
                  ASSERT(dqp->q_trace);
                  xfs_dqtrace_entry(dqp, "DQRECLAIMED_INIT");
 #endif
-         }
+        }
+
+        /*
+         * In either case we need to make sure group quotas have a different
+         * lock class than user quotas, to make sure lockdep knows we can
+         * locks of one of each at the same time.
+         */
+        if (!(type & XFS_DQ_USER))
+                lockdep_set_class(&dqp->q_qlock, &xfs_dquot_other_class);
 
         /*
          * log item gets initialized later