bcache: fix for gc crashing when no sectors are used

Signed-off-by: Nicholas Swenson <nks@daterainc.com>
Signed-off-by: Kent Overstreet <kmo@daterainc.com>

diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
index 7c1275e66025b691ec8ee4896448d46e28a2c5d9..46c952379fabf09fc09b093f4211c2f3f394189e 100644 (file)
--- a/drivers/md/bcache/movinggc.c
+++ b/drivers/md/bcache/movinggc.c
@@ -184,7 +184,8 @@ static bool bucket_cmp(struct bucket *l, struct bucket *r)
 
 static unsigned bucket_heap_top(struct cache *ca)
 {
-       return GC_SECTORS_USED(heap_peek(&ca->heap));
+       struct bucket *b;
+       return (b = heap_peek(&ca->heap)) ? GC_SECTORS_USED(b) : 0;
 }
 
 void bch_moving_gc(struct cache_set *c)