From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>, Mike Snitzer <snitzer@redhat.com>,
linux-block@vger.kernel.org,
Jeffle Xu <jefflexu@linux.alibaba.com>,
dm-devel@redhat.com, Hannes Reinecke <hare@suse.de>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [RFC PATCH V2 2/3] block: add ->poll_bio to block_device_operations
Date: Mon, 21 Jun 2021 09:25:02 +0200 [thread overview]
Message-ID: <20210621072502.GC6651@lst.de> (raw)
In-Reply-To: <20210617103549.930311-3-ming.lei@redhat.com>
> + struct gendisk *disk = bio->bi_bdev->bd_disk;
> + struct request_queue *q = disk->queue;
> blk_qc_t cookie = READ_ONCE(bio->bi_cookie);
> int ret;
>
> - if (cookie == BLK_QC_T_NONE || !blk_queue_poll(q))
> + if ((queue_is_mq(q) && cookie == BLK_QC_T_NONE) ||
> + !blk_queue_poll(q))
> return 0;
How does polling for a bio without a cookie make sense even when
polling bio based?
But if we come up for a good rationale for this I'd really
split the conditions to make them more readable:
if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
return 0;
if (queue_is_mq(q) && cookie == BLK_QC_T_NONE)
return 0;
> + if (!queue_is_mq(q)) {
> + if (disk->fops->poll_bio) {
> + ret = disk->fops->poll_bio(bio, flags);
> + } else {
> + WARN_ON_ONCE(1);
> + ret = 0;
> + }
> + } else {
> ret = blk_mq_poll(q, cookie, flags);
I'd go for someting like:
if (queue_is_mq(q))
ret = blk_mq_poll(q, cookie, flags);
else if (disk->fops->poll_bio)
ret = disk->fops->poll_bio(bio, flags);
else
WARN_ON_ONCE(1);
with ret initialized to 0 at declaration time.
> struct block_device_operations {
> void (*submit_bio)(struct bio *bio);
> + /* ->poll_bio is for bio driver only */
I'd drop the comment, this is already nicely documented in add_disk
together with the actual check. We also don't note this for submit_bio
here.
next prev parent reply other threads:[~2021-06-21 7:25 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-17 10:35 [RFC PATCH V2 0/3] block/dm: support bio polling Ming Lei
2021-06-17 10:35 ` [RFC PATCH V2 1/3] block: add helper of blk_queue_poll Ming Lei
2021-06-21 7:20 ` Christoph Hellwig
2021-06-21 8:38 ` Ming Lei
2021-06-17 10:35 ` [RFC PATCH V2 2/3] block: add ->poll_bio to block_device_operations Ming Lei
2021-06-21 7:25 ` Christoph Hellwig [this message]
2021-06-21 8:41 ` Ming Lei
2021-06-17 10:35 ` [RFC PATCH V2 3/3] dm: support bio polling Ming Lei
2021-06-17 23:08 ` Ming Lei
2021-06-18 8:19 ` [dm-devel] " JeffleXu
2021-06-18 13:29 ` Ming Lei
2021-06-18 14:39 ` Ming Lei
2021-06-18 20:56 ` Mike Snitzer
2021-06-19 0:27 ` Ming Lei
2021-06-21 1:32 ` JeffleXu
2021-06-21 11:33 ` [dm-devel] " JeffleXu
2021-06-21 14:04 ` Ming Lei
2021-06-22 2:26 ` JeffleXu
2021-06-22 2:45 ` Ming Lei
2021-06-22 7:45 ` JeffleXu
2021-06-30 8:30 ` Ming Lei
2021-06-21 7:36 ` Christoph Hellwig
2021-06-21 9:09 ` Ming Lei
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