linux-kernel - Re: Device loses barrier support (was: Fixed patch for simple barriers.)

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]

Message-ID: <20081207041711.GA22525@disturbed>
Date:	Sun, 7 Dec 2008 15:17:11 +1100
From:	Dave Chinner <david@...morbit.com>
To:	Mikulas Patocka <mpatocka@...hat.com>
Cc:	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	xfs@....sgi.com, Alasdair G Kergon <agk@...hat.com>,
	Andi Kleen <andi-suse@...stfloor.org>,
	Milan Broz <mbroz@...hat.com>
Subject: Re: Device loses barrier support (was: Fixed patch for simple
	barriers.)

On Thu, Dec 04, 2008 at 11:45:44AM -0500, Mikulas Patocka wrote:
> > The write block with barrier bit varies, jbd/gfs2 do it synchronously
> > too and xfs does it asynchronously (with io done callbacks), but
> 
> And how does xfs preserve write ordering, if the barrier asynchronously 
> fails with -EOPNOTSUPP and there are other writes submitted after the 
> barrier?

Doesn't matter. XFS executes journal state changes during the I/O
completion callbacks a layer above this resubmit code. Hence,
if the I/O is resubmitted before the completion callbacks are
run, it just appears that the I/O has taken longer than expected
and the state change is delayed....

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
--
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/