4 files changed, 20 insertions, 13 deletions

diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c
index 3c6902f0ae9d..c7485e902718 100644
--- a/drivers/md/bcache/alloc.c
+++ b/drivers/md/bcache/alloc.c
@@ -74,19 +74,27 @@ static void alloc_failed(struct cache *ca)
 	struct cache_set *c = ca->set;
 	unsigned i, gc_count;
 
+	gc_count = bch_gc_count(c);
+
+	/* Check if there are caches in higher tiers; we could potentially
+	 * make room on our cache by tiering */
 	for (i = CACHE_TIER(&ca->sb) + 1;
 	     i < ARRAY_SIZE(c->cache_by_alloc);
 	     i++)
 		if (c->cache_by_alloc[i].nr_devices) {
 			c->tiering_pd.rate.rate = UINT_MAX;
 			bch_ratelimit_reset(&c->tiering_pd.rate);
+			wake_up_process(c->tiering_thread);
+			trace_bcache_alloc_wake_tiering(ca);
+			goto wait;
 		}
 
-	trace_bcache_alloc_wait(ca);
+	/* If this is the highest tier cache, just do a btree GC */
+	wake_up_process(ca->moving_gc_thread);
+	trace_bcache_alloc_wake_moving(ca);
 
+wait:
 	mutex_unlock(&c->bucket_lock);
-	gc_count = bch_gc_count(c);
-	wake_up_gc(c);
 	bch_wait_for_next_gc(c, gc_count);
 	mutex_lock(&c->bucket_lock);
 }
diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
index dcd5718c0f93..fa83cd68f840 100644
--- a/drivers/md/bcache/movinggc.c
+++ b/drivers/md/bcache/movinggc.c
@@ -233,20 +233,13 @@ static int bch_moving_gc_thread(void *arg)
 	struct cache *ca = arg;
 	struct cache_set *c = ca->set;
 	unsigned long last = jiffies;
-	unsigned gc_count;
 
 	do {
-		gc_count = bch_gc_count(c);
-		bch_wait_for_next_gc(c, gc_count);
-
 		if (kthread_wait_freezable(c->copy_gc_enabled))
 			break;
 
-		if (bch_moving_gc(ca)) {
-			gc_count = bch_gc_count(c);
-			wake_up_gc(c);
-			bch_wait_for_next_gc(c, gc_count);
-		}
+		bch_moving_gc(ca);
+		wake_up_gc(c);
 	} while (!bch_kthread_loop_ratelimit(&last,
 					     c->btree_scan_ratelimit * HZ));
 
diff --git a/drivers/md/bcache/tier.c b/drivers/md/bcache/tier.c
index 180cf1463046..034974b61996 100644
--- a/drivers/md/bcache/tier.c
+++ b/drivers/md/bcache/tier.c
@@ -147,6 +147,7 @@ static int bch_tiering_thread(void *arg)
 			break;
 
 		read_tiering(c);
+		wake_up_gc(c);
 	} while (!bch_kthread_loop_ratelimit(&last,
 					     c->btree_scan_ratelimit * HZ));
 
diff --git a/include/trace/events/bcache.h b/include/trace/events/bcache.h
index 3f66e2512ba6..defd85ca1d4c 100644
--- a/include/trace/events/bcache.h
+++ b/include/trace/events/bcache.h
@@ -380,7 +380,12 @@ DECLARE_EVENT_CLASS(cache,
 	TP_printk("%pU", __entry->uuid)
 );
 
-DEFINE_EVENT(cache, bcache_alloc_wait,
+DEFINE_EVENT(cache, bcache_alloc_wake_tiering,
+	TP_PROTO(struct cache *ca),
+	TP_ARGS(ca)
+);
+
+DEFINE_EVENT(cache, bcache_alloc_wake_moving,
 	TP_PROTO(struct cache *ca),
 	TP_ARGS(ca)
 );