From: Keith Busch <kbusch@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Subject: Re: [PATCH] block: treat poll queue enter similarly to timeouts
Date: Fri, 20 Jan 2023 09:11:38 -0700 [thread overview]
Message-ID: <Y8q9OvUjPxSzif/j@kbusch-mbp> (raw)
In-Reply-To: <9590debc-ce87-f044-b687-59b551c24219@kernel.dk>
On Fri, Jan 20, 2023 at 07:59:34AM -0700, Jens Axboe wrote:
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -869,7 +869,16 @@ int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags)
> */
> blk_flush_plug(current->plug, false);
>
> - if (bio_queue_enter(bio))
> + /*
> + * We need to be able to enter a frozen queue, similar to how
> + * timeouts also need to do that. If that is blocked, then we can
> + * have pending IO when a queue freeze is started, and then the
> + * wait for the freeze to finish will wait for polled requests to
> + * timeout as the poller is preventer from entering the queue and
> + * completing them. As long as we prevent new IO from being queued,
> + * that should be all that matters.
> + */
> + if (!percpu_ref_tryget(&q->q_usage_counter))
> return 0;
> if (queue_is_mq(q)) {
> ret = blk_mq_poll(q, cookie, iob, flags);
Looks good!
Reviewed-by: Keith Busch <kbusch@kernel.org>
prev parent reply other threads:[~2023-01-20 16:11 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-20 14:59 [PATCH] block: treat poll queue enter similarly to timeouts Jens Axboe
2023-01-20 16:11 ` Keith Busch [this message]
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