From: Christoph Hellwig <hch@infradead.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Guoqing Jiang <guoqing.jiang@linux.dev>,
song@kernel.org, linux-raid@vger.kernel.org,
jens@chianterastutte.eu, linux-block@vger.kernel.org
Subject: Re: [PATCH] raid1: ensure bio doesn't have more than BIO_MAX_VECS sectors
Date: Tue, 17 Aug 2021 06:06:12 +0100 [thread overview]
Message-ID: <YRtDxEw7Zp2H7mxp@infradead.org> (raw)
In-Reply-To: <YRpOwFewTw4imskn@T590>
On Mon, Aug 16, 2021 at 07:40:48PM +0800, Ming Lei wrote:
> > >
> > > 0 ~ 254: each bvec's length is 512
> > > 255: bvec's length is 8192
> > >
> > > the total length is just 512*255 + 8192 = 138752 bytes = 271 sectors, but it
> > > still may need 257 bvecs, which can't be allocated via bio_alloc_bioset().
> >
> > Yes, we still need the rounding magic that alloc_behind_master_bio uses
> > here.
>
> But it is wrong to use max sectors to limit number of bvecs(segments), isn't it?
The raid1 write behind code cares about the size ofa bio it can reach by
adding order 0 pages to it. The bvecs are part of that and I think the
calculation in the patch documents that a well.
next prev parent reply other threads:[~2021-08-17 5:07 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-13 6:05 [PATCH] raid1: ensure bio doesn't have more than BIO_MAX_VECS sectors Guoqing Jiang
2021-08-13 7:49 ` Christoph Hellwig
2021-08-13 8:38 ` Guoqing Jiang
2021-08-14 7:55 ` Christoph Hellwig
2021-08-14 8:57 ` Ming Lei
2021-08-16 6:27 ` Guoqing Jiang
2021-08-16 7:13 ` Ming Lei
2021-08-16 9:37 ` Christoph Hellwig
2021-08-16 11:40 ` Ming Lei
2021-08-17 5:06 ` Christoph Hellwig [this message]
2021-08-17 12:32 ` Ming Lei
2021-09-24 15:34 ` Jens Stutte (Archiv)
2021-09-25 23:02 ` Guoqing Jiang
2021-08-13 9:27 ` kernel test robot
2021-08-13 10:12 ` kernel test robot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YRtDxEw7Zp2H7mxp@infradead.org \
--to=hch@infradead.org \
--cc=guoqing.jiang@linux.dev \
--cc=jens@chianterastutte.eu \
--cc=linux-block@vger.kernel.org \
--cc=linux-raid@vger.kernel.org \
--cc=ming.lei@redhat.com \
--cc=song@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox