linux-kernel - Re: [PATCH V3] bio: modify __bio_add_page() to accept pages that don't start a new segment

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Tue, 27 May 2014 16:27:26 +0200
From:	Maurizio Lombardi <mlombard@...hat.com>
To:	Ming Lei <tom.leiming@...il.com>, axboe@...nel.dk
Cc:	Al Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux FS Devel <linux-fsdevel@...r.kernel.org>,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	Christoph Hellwig <hch@....de>, linux-scsi@...r.kernel.org,
	Kent Overstreet <kmo@...erainc.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Maurizio Lombardi <m.lombardi85@...il.com>
Subject: Re: [PATCH V3] bio: modify __bio_add_page() to accept pages that
 don't start a new segment

On Tue, May 27, 2014 at 10:04:58PM +0800, Ming Lei wrote:
> 
> Looks your approach is simpler.
> 
> But looks there is one problem if I understand correctly:
> __blk_recalc_rq_segments() may not cover the last vector
> because bio->bi_iter.bi_size isn't updated until the end of
> __bio_add_page().
> 
> But it shouldn't have been related with current virtio-blk problem.
>

This is a valid point, bi_iter.bi_size influences the behaviour of
blk_recount_segments(). Maybe Jens can confirm your observation.

Anyway it doesn't explain the reason behind the regression
introduced by commit 3979ef4dcf

Maurizio Lombardi
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/