From: Mike Snitzer <snitzer@redhat.com>
To: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
Christoph Hellwig <hch@lst.de>, Hannes Reinecke <hare@suse.com>,
Johannes Thumshirn <jthumshirn@suse.de>
Subject: Re: block: Make __bio_clone_fast() copy bi_vcnt
Date: Thu, 28 Jun 2018 11:32:12 -0400 [thread overview]
Message-ID: <20180628153211.GA17723@redhat.com> (raw)
In-Reply-To: <5e78949d-6169-5a5a-869b-731a3468e2de@wdc.com>
On Thu, Jun 28 2018 at 11:21am -0400,
Bart Van Assche <bart.vanassche@wdc.com> wrote:
> On 06/27/18 17:30, Ming Lei wrote:
> >One core idea of immutable bvec is to use bio->bi_iter and the original
> >bvec table to iterate over anywhere in the bio. That is why .bi_io_vec
> >needs to copy, but not see any reason why .bi_vcnt needs to do.
> >
> >Do you have use cases on .bi_vcnt for cloned bio?
>
> So far this is only a theoretical concern. There are many functions
> in the block layer that use .bi_vcnt, and it is a lot of work to
> figure out all the callers of all these functions.
No point wasting time with that. I don't understand why Ming cares.
Your change is obviously correct. The state should get transfered over
to reflect reality.
This patch doesn't harm anything, it just prevents some clone-specific
failure in the future.
Acked-by: Mike Snitzer <snitzer@redhat.com>
next prev parent reply other threads:[~2018-06-28 15:32 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-27 20:12 [PATCH] block: Make __bio_clone_fast() copy bi_vcnt Bart Van Assche
2018-06-27 23:50 ` Ming Lei
2018-06-27 23:59 ` Bart Van Assche
2018-06-28 0:30 ` Ming Lei
2018-06-28 15:21 ` Bart Van Assche
2018-06-28 15:32 ` Mike Snitzer [this message]
2018-06-28 23:10 ` Ming Lei
2018-06-28 23:16 ` Kent Overstreet
2018-06-28 23:54 ` Bart Van Assche
2018-06-29 0:04 ` Kent Overstreet
2018-06-29 20:00 ` Bart Van Assche
2018-06-30 23:38 ` Kent Overstreet
2018-06-29 2:18 ` Jens Axboe
2018-06-28 15:53 ` Jens Axboe
2018-06-28 22:53 ` Ming Lei
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