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>
diff --git a/fs/xfs/quota/xfs_dquot.c b/fs/xfs/quota/xfs_dquot.c
index d68b4e1..ebdf3c8 100644
--- a/fs/xfs/quota/xfs_dquot.c
+++ b/fs/xfs/quota/xfs_dquot.c
@@ -1383,6 +1383,12 @@
mutex_unlock(&(dqp->q_qlock));
}
+/*
+ * Lock two xfs_dquot structures.
+ *
+ * To avoid deadlocks we always lock the quota structure with
+ * the lowerd id first.
+ */
void
xfs_dqlock2(
xfs_dquot_t *d1,
@@ -1392,18 +1398,16 @@
ASSERT(d1 != d2);
if (be32_to_cpu(d1->q_core.d_id) >
be32_to_cpu(d2->q_core.d_id)) {
- xfs_dqlock(d2);
- xfs_dqlock(d1);
+ mutex_lock(&d2->q_qlock);
+ mutex_lock_nested(&d1->q_qlock, XFS_QLOCK_NESTED);
} else {
- xfs_dqlock(d1);
- xfs_dqlock(d2);
+ mutex_lock(&d1->q_qlock);
+ mutex_lock_nested(&d2->q_qlock, XFS_QLOCK_NESTED);
}
- } else {
- if (d1) {
- xfs_dqlock(d1);
- } else if (d2) {
- xfs_dqlock(d2);
- }
+ } else if (d1) {
+ mutex_lock(&d1->q_qlock);
+ } else if (d2) {
+ mutex_lock(&d2->q_qlock);
}
}