Merge branch 'for-linus' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "Four smaller fixes for the current series.  This contains:

   - A fix for clones of discard bio's, that can cause data corruption.
     From Martin.

   - A fix for null_blk, where in certain queue modes it could access a
     request after it had been freed.  From Mike Krinkin.

   - An error handling leak fix for blkcg, from Tejun.

   - Also from Tejun, export of the functions that a file system needs
     to implement cgroup writeback support"

* 'for-linus' of git://git.kernel.dk/linux-block:
  block: Do a full clone when splitting discard bios
  block: export bio_associate_*() and wbc_account_io()
  blkcg: fix gendisk reference leak in blkg_conf_prep()
  null_blk: fix use-after-free problem

1 files changed, 9 insertions, 9 deletions

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 69de41a87b74..3177b245d2bd 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -240,19 +240,19 @@ static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
 	while ((entry = llist_del_all(&cq->list)) != NULL) {
 		entry = llist_reverse_order(entry);
 		do {
+			struct request_queue *q = NULL;
+
 			cmd = container_of(entry, struct nullb_cmd, ll_list);
 			entry = entry->next;
+			if (cmd->rq)
+				q = cmd->rq->q;
 			end_cmd(cmd);
 
-			if (cmd->rq) {
-				struct request_queue *q = cmd->rq->q;
-
-				if (!q->mq_ops && blk_queue_stopped(q)) {
-					spin_lock(q->queue_lock);
-					if (blk_queue_stopped(q))
-						blk_start_queue(q);
-					spin_unlock(q->queue_lock);
-				}
+			if (q && !q->mq_ops && blk_queue_stopped(q)) {
+				spin_lock(q->queue_lock);
+				if (blk_queue_stopped(q))
+					blk_start_queue(q);
+				spin_unlock(q->queue_lock);
 			}
 		} while (entry);
 	}