4 files changed, 29 insertions, 16 deletions

diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c
index ce13c272c387..48ce750bf70a 100644
--- a/drivers/md/bcache/alloc.c
+++ b/drivers/md/bcache/alloc.c
@@ -129,12 +129,9 @@ static inline bool can_inc_bucket_gen(struct bucket *b)
 
 bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b)
 {
-	BUG_ON(!ca->set->gc_mark_valid);
-
-	return (!GC_MARK(b) ||
-		GC_MARK(b) == GC_MARK_RECLAIMABLE) &&
-		!atomic_read(&b->pin) &&
-		can_inc_bucket_gen(b);
+	return (ca->set->gc_mark_valid || b->reclaimable_in_gc) &&
+	       ((!GC_MARK(b) || GC_MARK(b) == GC_MARK_RECLAIMABLE) &&
+	       !atomic_read(&b->pin) && can_inc_bucket_gen(b));
 }
 
 void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b)
@@ -148,6 +145,7 @@ void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b)
 	bch_inc_gen(ca, b);
 	b->prio = INITIAL_PRIO;
 	atomic_inc(&b->pin);
+	b->reclaimable_in_gc = 0;
 }
 
 static void bch_invalidate_one_bucket(struct cache *ca, struct bucket *b)
@@ -352,8 +350,7 @@ static int bch_allocator_thread(void *arg)
 		 */
 
 retry_invalidate:
-		allocator_wait(ca, ca->set->gc_mark_valid &&
-			       !ca->invalidate_needs_gc);
+		allocator_wait(ca, !ca->invalidate_needs_gc);
 		invalidate_buckets(ca);
 
 		/*
@@ -501,8 +498,8 @@ int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
 
 	ca = c->cache;
 	b = bch_bucket_alloc(ca, reserve, wait);
-	if (b == -1)
-		goto err;
+	if (b < 0)
+		return -1;
 
 	k->ptr[0] = MAKE_PTR(ca->buckets[b].gen,
 			     bucket_to_sector(c, b),
@@ -511,10 +508,6 @@ int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
 	SET_KEY_PTRS(k, 1);
 
 	return 0;
-err:
-	bch_bucket_free(c, k);
-	bkey_put(c, k);
-	return -1;
 }
 
 int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 4e6afa89921f..1d33e40d26ea 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -200,6 +200,7 @@ struct bucket {
 	uint8_t		gen;
 	uint8_t		last_gc; /* Most out of date gen in the btree */
 	uint16_t	gc_mark; /* Bitfield used by GC. See below for field */
+	uint16_t	reclaimable_in_gc:1;
 };
 
 /*
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index d011a7154d33..4e6ccf2c8a0b 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -1741,18 +1741,20 @@ static void btree_gc_start(struct cache_set *c)
 
 	mutex_lock(&c->bucket_lock);
 
-	c->gc_mark_valid = 0;
 	c->gc_done = ZERO_KEY;
 
 	ca = c->cache;
 	for_each_bucket(b, ca) {
 		b->last_gc = b->gen;
+		if (bch_can_invalidate_bucket(ca, b))
+			b->reclaimable_in_gc = 1;
 		if (!atomic_read(&b->pin)) {
 			SET_GC_MARK(b, 0);
 			SET_GC_SECTORS_USED(b, 0);
 		}
 	}
 
+	c->gc_mark_valid = 0;
 	mutex_unlock(&c->bucket_lock);
 }
 
@@ -1809,6 +1811,9 @@ static void bch_btree_gc_finish(struct cache_set *c)
 	for_each_bucket(b, ca) {
 		c->need_gc	= max(c->need_gc, bucket_gc_gen(b));
 
+		if (b->reclaimable_in_gc)
+			b->reclaimable_in_gc = 0;
+
 		if (atomic_read(&b->pin))
 			continue;
 
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 83d112bd2b1c..af345dc6fde1 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -369,10 +369,24 @@ static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
 	struct io *i;
 
 	if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
-	    c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
 	    (bio_op(bio) == REQ_OP_DISCARD))
 		goto skip;
 
+	if (c->gc_stats.in_use > CUTOFF_CACHE_ADD) {
+		/*
+		 * If cached buckets are all clean now, 'true' will be
+		 * returned and all requests will bypass the cache device.
+		 * Then c->sectors_to_gc has no chance to be negative, and
+		 * gc thread won't wake up and caching won't work forever.
+		 * Here call force_wake_up_gc() to avoid such aftermath.
+		 */
+		if (BDEV_STATE(&dc->sb) == BDEV_STATE_CLEAN &&
+		    c->gc_mark_valid)
+			force_wake_up_gc(c);
+
+		goto skip;
+	}
+
 	if (mode == CACHE_MODE_NONE ||
 	    (mode == CACHE_MODE_WRITEAROUND &&
 	     op_is_write(bio_op(bio))))