Re: [PATCH] blk-mq-sched: add might_sleep() check for flush/fua insert

[Bart Van Assche <Bart.VanAssche@sandisk.com>]

On Thu, 2017-04-20 at 17:09 -0600, Jens Axboe wrote:
> From: Jens Axboe <axboe@fb.com>
> Subject: [PATCH] blk-mq: add might_sleep check to blk_mq_get_driver_tag()
>=20
> If the caller passes in wait=3Dtrue, it has to be able to block
> for a driver tag. We just had a bug where flush insertion
> would block on tag allocation, while we had preempt disabled.
> Ensure that we catch cases like that earlier next time.
>=20
> Signed-off-by: Jens Axboe <axboe@fb.com>
>=20
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 992f09772f8a..dd6e5dd62804 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -866,6 +866,8 @@ bool blk_mq_get_driver_tag(struct request *rq, struct=
 blk_mq_hw_ctx **hctx,
>  		.flags =3D wait ? 0 : BLK_MQ_REQ_NOWAIT,
>  	};
> =20
> +	might_sleep_if(wait);
> +
>  	if (rq->tag !=3D -1)
>  		goto done;
> =20
>=20

Thanks!

Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>=