1 files changed, 19 insertions, 1 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 72680a6715fc..61693d3404d0 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1225,10 +1225,11 @@ static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
         cfq_put_cfqg(cfqg);
 }
 
-static void cfq_release_cfq_groups(struct cfq_data *cfqd)
+static bool cfq_release_cfq_groups(struct cfq_data *cfqd)
 {
         struct hlist_node *pos, *n;
         struct cfq_group *cfqg;
+        bool empty = true;
 
         hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
                 /*
@@ -1238,7 +1239,10 @@ static void cfq_release_cfq_groups(struct cfq_data *cfqd)
                  */
                 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
                         cfq_destroy_cfqg(cfqd, cfqg);
+                else
+                        empty = false;
         }
+        return empty;
 }
 
 /*
@@ -1265,6 +1269,19 @@ static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
         spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
 }
 
+static struct elevator_type iosched_cfq;
+
+static bool cfq_clear_queue(struct request_queue *q)
+{
+        lockdep_assert_held(q->queue_lock);
+
+        /* shoot down blkgs iff the current elevator is cfq */
+        if (!q->elevator || q->elevator->type != &iosched_cfq)
+                return true;
+
+        return cfq_release_cfq_groups(q->elevator->elevator_data);
+}
+
 #else /* GROUP_IOSCHED */
 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
 {
@@ -3875,6 +3892,7 @@ static struct elevator_type iosched_cfq = {
 static struct blkio_policy_type blkio_policy_cfq = {
         .ops = {
                 .blkio_unlink_group_fn =        cfq_unlink_blkio_group,
+                .blkio_clear_queue_fn = cfq_clear_queue,
                 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
         },
         .plid = BLKIO_POLICY_PROP,