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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>
This commit is contained in:
Tejun Heo 2012-03-06 21:24:55 +01:00 committed by Jens Axboe
parent ea5f4db8ec
commit b855b04a0b
1 changed files with 15 additions and 12 deletions
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27
block/blk-core.c
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@ -365,17 +365,24 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
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 @@ void blk_cleanup_queue(struct request_queue *q)
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 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
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]);