bcache: Fix moving_pred()

Avoid a potential null pointer deref (e.g. from check keys for cache misses)

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

1 files changed, 3 insertions, 5 deletions

diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
index 8c7205186d08..5e8e58701d37 100644
--- a/drivers/md/bcache/movinggc.c
+++ b/drivers/md/bcache/movinggc.c
@@ -24,12 +24,10 @@ static bool moving_pred(struct keybuf *buf, struct bkey *k)
                                            moving_gc_keys);
         unsigned i;
 
-        for (i = 0; i < KEY_PTRS(k); i++) {
-                struct bucket *g = PTR_BUCKET(c, k, i);
-
-                if (GC_MOVE(g))
+        for (i = 0; i < KEY_PTRS(k); i++)
+                if (ptr_available(c, k, i) &&
+                    GC_MOVE(PTR_BUCKET(c, k, i)))
                         return true;
-        }
 
         return false;
 }