linux-kernel - Re: block: silently error unsupported empty barriers too

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

Message-ID: <20091028210325.GC1143@redhat.com>
Date:	Wed, 28 Oct 2009 17:03:25 -0400
From:	Mike Snitzer <snitzer@...hat.com>
To:	Andrew Patterson <andrew.patterson@...com>
Cc:	Mikulas Patocka <mpatocka@...hat.com>,
	device-mapper development <dm-devel@...hat.com>,
	Mark McLoughlin <markmc@...hat.com>, ". troy.heber"@hp.com,
	Rusty Russell <rusty@...tcorp.com.au>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	virtualization <virtualization@...ts.linux-foundation.org>,
	Jens Axboe <jens.axboe@...cle.com>,
	Alasdair G Kergon <agk@...hat.com>
Subject: Re: block: silently error unsupported empty barriers too

On Wed, Oct 28 2009 at  4:19pm -0400,
Andrew Patterson <andrew.patterson@...com> wrote:

> On Thu, 2009-08-06 at 21:50 -0400, Mikulas Patocka wrote:
> > On Thu, 6 Aug 2009, Alasdair G Kergon wrote:
> > 
> > > On Thu, Aug 06, 2009 at 12:14:17PM +0100, Mark McLoughlin wrote:
> > > > We should error all barriers, even empty barriers, on devices like
> > > > virtio_blk which don't support them.
> > >  
> > > Have you considered whether or not virtio_blk actually needs to
> > > support empty barriers?
> > > 
> > > Alasdair
> > 
> > This is only for request-based drivers, where it is the responsibility of 
> > blk-core to translate barriers. I think the empty barrier request anyway 
> > in blk_do_ordered, but with an error message. So the patch changes it to 
> > discard it early and queitly. It seems ok.
> > 
> > Mikulas
> > --
> 
> This patch seems to have been dropped.  I can reproduce the error using
> the following:
> 
>      1. Create an LVM logical volume on top of a cciss device (note that
>         the cciss driver does not support barriers)
>      2. Create an ext3 file system on top of the logical volume
>      3. Mount the file-system using -obarrier=1
>      4. Copy some files onto the file-system
>      5. Run sync (dm_flush is called)
> 
> If I apply the patch (with some munging), the 
> 
> "end_request: I/O error, dev cciss/cXdY, sector 0"
> 
> messages go away.
> 
> This is not strictly a regression, given that the problem was introduced
> in 2.6.31, but I think it should still be fixed for 2.6.32.

It was resubmitted last Friday:
http://lkml.org/lkml/2009/10/23/196

And is queued in Jens' 'for-linus' branch (meaning it should get
upstream in time for 2.6.32), see:
http://git.kernel.org/?p=linux/kernel/git/axboe/linux-2.6-block.git;a=commit;h=6cafb12dc85a5bdc722791cc5070968413264909

Mike
--
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/