From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 6DBB47F3F for ; Tue, 22 Apr 2014 18:46:37 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay2.corp.sgi.com (Postfix) with ESMTP id 4170F304032 for ; Tue, 22 Apr 2014 16:46:34 -0700 (PDT) Received: from ipmail05.adl6.internode.on.net (ipmail05.adl6.internode.on.net [150.101.137.143]) by cuda.sgi.com with ESMTP id Omu147G3ENjE88p5 for ; Tue, 22 Apr 2014 16:46:32 -0700 (PDT) Date: Wed, 23 Apr 2014 09:46:28 +1000 From: Dave Chinner Subject: Re: [PATCH] xfs: remote attribute overwrite causes transaction overrun Message-ID: <20140422234628.GN18672@dastard> References: <1398149949-11324-1-git-send-email-david@fromorbit.com> <535659F7.4060702@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <535659F7.4060702@oracle.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Jeff Liu Cc: xfs@oss.sgi.com On Tue, Apr 22, 2014 at 08:00:55PM +0800, Jeff Liu wrote: > = > On 04/22 2014 14:59 PM, Dave Chinner wrote: > > From: Dave Chinner > > = > > Commit e461fcb ("xfs: remote attribute lookups require the value > > length") passes the remote attribute length in the xfs_da_args > > structure on lookup so that CRC calculations and validity checking > > can be performed correctly by related code. This, unfortunately has > > the side effect of changing the args->valuelen parameter in cases > > where it shouldn't. > > = > > That is, when we replace a remote attribute, the incoming > > replacement stores the value and length in args->value and > > args->valuelen, but then the lookup which finds the existing remote > > attribute overwrites args->valuelen with the length of the remote > > attribute being replaced. Hence when we go to create the new > > attribute, we create it of the size of the existing remote > > attribute, not the size it is supposed to be. When the new attribute > > is much smaller than the old attribute, this results in a > > transaction overrun and an ASSERT() failure on a debug kernel: > > = > > XFS: Assertion failed: tp->t_blk_res_used <=3D tp->t_blk_res, file: fs/= xfs/xfs_trans.c, line: 331 > > = > > Fix this by keeping the remote attribute value length separate to > > the attribute value length in the xfs_da_args structure. The enables > > us to pass the length of the remote attribute to be removed without > > overwriting the new attribute's length. > > = > > Signed-off-by: Dave Chinner .... > > @@ -348,6 +348,11 @@ xfs_attr_rmtval_get( > > = > > ASSERT(!(args->flags & ATTR_KERNOVAL)); > > = > > + /* remote value might be different size to the buffer supplied. */ > > + if (args->rmtvaluelen =3D args->valuelen) > ^^^ > Here is a typo... Oh, well spotted. But, hold on a minute, shouldn't gcc be catching those sorts of typos? /me groans $ gcc t.c $ gcc -Wall t.c t.c: In function =BFmain=BF: t.c:10:2: warning: suggest parentheses around assignment used as truth valu= e [-Wparentheses] if (foo =3D bar) ^ $ Only if -Wparentheses is specified. Why the hell are we suppressing useful warnings on the kernel build? Cheers, Dave. -- = Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs