On Thu, 2017-04-20 at 16:45 -0600, Jens Axboe wrote:
> If we're doing a flush/fua insert, insertion might block on getting
> a driver tag, if can_block == true. Add a might_sleep check for that,
> since we just had a bug like that. This will help us catch a similar
> issue quicker in the future.
>
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index 9e3c0f92851b..57aec8462e93 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -372,6 +372,7 @@ void blk_mq_sched_insert_request(struct request *rq, bool at_head,
> struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
>
> if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) {
> + might_sleep_if(can_block);
> blk_mq_sched_insert_flush(hctx, rq, can_block);
> return;
> }
Hello Jens,
The above patch looks fine to me. But seeing that patch made me wonder
whether it would be useful to move that might_sleep_if() call into
blk_mq_get_driver_tag() such that if ever an additional call to
blk_mq_get_driver_tag() is added that might sleep would also be covered?
Bart.
