From: NeilBrown <neilb@suse.com>
To: Christoph Hellwig <hch@infradead.org>, Shaohua Li <shli@kernel.org>
Cc: linux-raid@vger.kernel.org, linux-block@vger.kernel.org
Subject: Re: "creative" bio usage in the RAID code
Date: Mon, 14 Nov 2016 10:03:20 +1100 [thread overview]
Message-ID: <87shqvj83r.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <20161110194636.GA32241@infradead.org>
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On Fri, Nov 11 2016, Christoph Hellwig wrote:
>
> Another not quite as urgent issue is how the RAID5 code abuses
> ->bi_phys_segments as and outstanding I/O counter, and I have no
> really good answer to that either.
I would suggest adding a "bi_dev_private" field to the bio which is for
use by the lowest-level driver (much as bi_private is for use by the
top-level initiator).
That could be in a union with any or all of:
unsigned int bi_phys_segments;
unsigned int bi_seg_front_size;
unsigned int bi_seg_back_size;
(any driver that needs those, would see a 'request' rather than a 'bio'
and so could use rq->special)
raid5.c could then use bi_dev_private (or bi_special, or whatever it is call).
NeilBrown
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next prev parent reply other threads:[~2016-11-13 23:03 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-10 19:46 "creative" bio usage in the RAID code Christoph Hellwig
2016-11-11 19:02 ` Shaohua Li
2016-11-12 17:42 ` Christoph Hellwig
2016-11-13 22:53 ` NeilBrown
2016-11-14 8:57 ` Christoph Hellwig
2016-11-14 9:51 ` NeilBrown
2016-11-15 0:13 ` Shaohua Li
2016-11-15 1:30 ` Ming Lei
2016-11-13 23:03 ` NeilBrown [this message]
2016-11-14 8:51 ` Christoph Hellwig
2016-11-14 9:43 ` NeilBrown
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