block: blk-throttle should be drained regardless of q->elevator
Currently, blk_cleanup_queue() doesn't call elv_drain_elevator() if
q->elevator doesn't exist; however, bio based drivers don't have
elevator initialized but can still use blk-throttle. This patch moves
q->elevator test inside blk_drain_queue() such that only
elv_drain_elevator() is skipped if !q->elevator.
-v2: loop can have registered queue which has NULL request_fn. Make
sure we don't call into __blk_run_queue() in such cases.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Vivek Goyal <vgoyal@redhat.com>
Fold in bug fix from Vivek.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-core.c b/block/blk-core.c
index 3a78b00..fccb250 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -365,17 +365,24 @@
spin_lock_irq(q->queue_lock);
- elv_drain_elevator(q);
+ /*
+ * The caller might be trying to drain @q before its
+ * elevator is initialized.
+ */
+ if (q->elevator)
+ elv_drain_elevator(q);
+
if (drain_all)
blk_throtl_drain(q);
/*
* This function might be called on a queue which failed
- * driver init after queue creation. Some drivers
- * (e.g. fd) get unhappy in such cases. Kick queue iff
- * dispatch queue has something on it.
+ * driver init after queue creation or is not yet fully
+ * active yet. Some drivers (e.g. fd and loop) get unhappy
+ * in such cases. Kick queue iff dispatch queue has
+ * something on it and @q has request_fn set.
*/
- if (!list_empty(&q->queue_head))
+ if (!list_empty(&q->queue_head) && q->request_fn)
__blk_run_queue(q);
drain |= q->rq.elvpriv;
@@ -428,13 +435,8 @@
spin_unlock_irq(lock);
mutex_unlock(&q->sysfs_lock);
- /*
- * Drain all requests queued before DEAD marking. The caller might
- * be trying to tear down @q before its elevator is initialized, in
- * which case we don't want to call into draining.
- */
- if (q->elevator)
- blk_drain_queue(q, true);
+ /* drain all requests queued before DEAD marking */
+ blk_drain_queue(q, true);
/* @q won't process any more request, flush async actions */
del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
@@ -504,6 +506,7 @@
setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
laptop_mode_timer_fn, (unsigned long) q);
setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
+ INIT_LIST_HEAD(&q->queue_head);
INIT_LIST_HEAD(&q->timeout_list);
INIT_LIST_HEAD(&q->icq_list);
INIT_LIST_HEAD(&q->flush_queue[0]);