4 files changed, 25 insertions, 4 deletions

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index dc9d78fb7bac..b6a9f6dde55a 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -193,6 +193,9 @@ xfs_free_perag(
 		spin_unlock(&mp->m_perag_lock);
 		ASSERT(pag);
 		ASSERT(atomic_read(&pag->pag_ref) == 0);
+#ifdef CONFIG_XFS_ONLINE_SCRUB
+		ASSERT(atomic_read(&pag->pag_intents) == 0);
+#endif
 
 		cancel_delayed_work_sync(&pag->pag_blockgc_work);
 		xfs_iunlink_destroy(pag);
@@ -254,6 +257,9 @@ xfs_initialize_perag(
 		spin_lock_init(&pag->pag_state_lock);
 		INIT_DELAYED_WORK(&pag->pag_blockgc_work, xfs_blockgc_worker);
 		INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
+#ifdef CONFIG_XFS_ONLINE_SCRUB
+		init_waitqueue_head(&pag->pag_intents_wq);
+#endif
 		init_waitqueue_head(&pag->pagb_wait);
 		pag->pagb_count = 0;
 		pag->pagb_tree = RB_ROOT;
diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
index c9e198e62b74..cfc51a5af74a 100644
--- a/fs/xfs/libxfs/xfs_ag.h
+++ b/fs/xfs/libxfs/xfs_ag.h
@@ -103,6 +103,17 @@ struct xfs_perag {
 	 * or have some other means to control concurrency.
 	 */
 	struct rhashtable	pagi_unlinked_hash;
+
+#ifdef CONFIG_XFS_ONLINE_SCRUB
+	/*
+	 * Counter of live intents.  We track the number of log intent items
+	 * that have been queued (but not yet processed) so that scrub can
+	 * detect the presence of other threads that are in the middle of
+	 * processing a chain of deferred items.
+	 */
+	atomic_t		pag_intents;
+	wait_queue_head_t	pag_intents_wq;
+#endif
 };
 
 int xfs_initialize_perag(struct xfs_mount *mp, xfs_agnumber_t agcount,
diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index 3045ad184972..108d950b6f41 100644
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -363,7 +363,8 @@ xfs_defer_cancel_list(
 		list_for_each_safe(pwi, n, &dfp->dfp_work) {
 			list_del(pwi);
 			dfp->dfp_count--;
-			ops->cancel_item(pwi);
+			trace_xfs_defer_cancel_item(mp, dfp, pwi);
+			ops->cancel_item(mp, pwi);
 		}
 		ASSERT(dfp->dfp_count == 0);
 		kmem_free(dfp);
@@ -442,6 +443,7 @@ xfs_defer_finish_one(
 	list_for_each_safe(li, n, &dfp->dfp_work) {
 		list_del(li);
 		dfp->dfp_count--;
+		trace_xfs_defer_finish_item(tp->t_mountp, dfp, li);
 		error = ops->finish_item(tp, dfp->dfp_done, li, &state);
 		if (error == -EAGAIN) {
 			/*
@@ -585,7 +587,7 @@ xfs_defer_add(
 	struct list_head		*li)
 {
 	struct xfs_defer_pending	*dfp = NULL;
-	const struct xfs_defer_op_type	*ops;
+	const struct xfs_defer_op_type	*ops = defer_op_types[type];
 
 	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
 	BUILD_BUG_ON(ARRAY_SIZE(defer_op_types) != XFS_DEFER_OPS_TYPE_MAX);
@@ -598,7 +600,6 @@ xfs_defer_add(
 	if (!list_empty(&tp->t_dfops)) {
 		dfp = list_last_entry(&tp->t_dfops,
 				struct xfs_defer_pending, dfp_list);
-		ops = defer_op_types[dfp->dfp_type];
 		if (dfp->dfp_type != type ||
 		    (ops->max_items && dfp->dfp_count >= ops->max_items))
 			dfp = NULL;
@@ -616,6 +617,8 @@ xfs_defer_add(
 	}
 
 	list_add_tail(li, &dfp->dfp_work);
+	trace_xfs_defer_add_item(tp->t_mountp, dfp, li);
+	ops->add_item(tp->t_mountp, li);
 	dfp->dfp_count++;
 }
 
diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
index b4d23235931d..51e7c992d95e 100644
--- a/fs/xfs/libxfs/xfs_defer.h
+++ b/fs/xfs/libxfs/xfs_defer.h
@@ -55,7 +55,8 @@ struct xfs_defer_op_type {
 			struct list_head *item, struct xfs_btree_cur **state);
 	void (*finish_cleanup)(struct xfs_trans *tp,
 			struct xfs_btree_cur *state, int error);
-	void (*cancel_item)(struct list_head *item);
+	void (*cancel_item)(struct xfs_mount *mp, struct list_head *item);
+	void (*add_item)(struct xfs_mount *mp, const struct list_head *item);
 	unsigned int		max_items;
 };