From: Christoph Hellwig <hch@lst.de>
To: Mike Snitzer <snitzer@redhat.com>
Cc: axboe@kernel.dk, ming.lei@redhat.com, hch@lst.de,
dm-devel@redhat.com, linux-block@vger.kernel.org
Subject: Re: [PATCH v5 2/2] dm: support bio polling
Date: Sun, 6 Mar 2022 10:29:37 +0100 [thread overview]
Message-ID: <20220306092937.GC22883@lst.de> (raw)
In-Reply-To: <20220305020804.54010-3-snitzer@redhat.com>
> +/*
> + * Reuse ->bi_end_io as hlist head for storing all dm_io instances
> + * associated with this bio, and this bio's bi_end_io has to be
> + * stored in one of 'dm_io' instance first.
> + */
> +static inline struct hlist_head *dm_get_bio_hlist_head(struct bio *bio)
> +{
> + WARN_ON_ONCE(!(bio->bi_opf & REQ_DM_POLL_LIST));
> +
> + return (struct hlist_head *)&bio->bi_end_io;
> +}
So this reuse is what I really hated. I still think we should be able
to find space in the bio by creatively shifting fields around to just
add the hlist there directly, which would remove the need for this
override and more importantly the quite cumbersome saving and restoring
of the end_io handler.
next prev parent reply other threads:[~2022-03-06 9:29 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-05 2:08 [PATCH v5 0/2] block/dm: support bio polling Mike Snitzer
2022-03-05 2:08 ` [PATCH v5 1/2] block: add ->poll_bio to block_device_operations Mike Snitzer
2022-03-06 9:27 ` Christoph Hellwig
2022-03-05 2:08 ` [PATCH v5 2/2] dm: support bio polling Mike Snitzer
2022-03-06 9:29 ` Christoph Hellwig [this message]
2022-03-07 1:48 ` Jens Axboe
2022-03-07 2:20 ` Ming Lei
2022-03-07 2:25 ` Jens Axboe
2022-03-07 2:41 ` Ming Lei
2022-03-07 3:39 ` Ming Lei
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