diff --git a/fs/buffer.c b/fs/buffer.c
index 763c5b59492..7ff6e9346fa 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -78,6 +78,7 @@ EXPORT_SYMBOL(__lock_buffer);
 
 void fastcall unlock_buffer(struct buffer_head *bh)
 {
+	smp_mb__before_clear_bit();
 	clear_buffer_locked(bh);
 	smp_mb__after_clear_bit();
 	wake_up_bit(&bh->b_state, BH_Lock);