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Commit 69e07c4a authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

blk-mq: update comments on blk_mq_quiesce_queue() 



Actually what we want to get from blk_mq_quiesce_queue()
isn't only to wait for completion of all ongoing .queue_rq().

In the typical context of canceling requests, we need to
make sure that the following is done in the dispatch path
before starting to cancel requests:

	- failed dispatched request is finished
	- busy dispatched request is requeued, and the STARTED
	flag is cleared

So update comment to keep code, doc and our expection consistent.

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent f4560ffe

block/blk-mq.c

+4 −3
Original line number Diff line number Diff line
@@ -155,12 +155,13 @@ void blk_mq_unfreeze_queue(struct request_queue *q) 
EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);



/**

 * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished

 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished

 * @q: request queue.

 *

 * Note: this function does not prevent that the struct request end_io()

 * callback function is invoked. Additionally, it is not prevented that

 * new queue_rq() calls occur unless the queue has been stopped first.

 * callback function is invoked. Once this function is returned, we make

 * sure no dispatch can happen until the queue is unquiesced via

 * blk_mq_unquiesce_queue().

 */

void blk_mq_quiesce_queue(struct request_queue *q)

{