From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 560C07F37 for ; Tue, 23 Apr 2013 08:47:58 -0500 (CDT) Message-ID: <51769111.3050103@sgi.com> Date: Tue, 23 Apr 2013 08:48:01 -0500 From: Mark Tinguely MIME-Version: 1.0 Subject: Re: [PATCH] xfs: shutdown filesystem if xfs_perag_get fails References: <20130419204102.736961610@sgi.com> <20130421174107.007313126@sgi.com> <5174603A.8030208@sandeen.net> <51753EDE.6000301@sgi.com> <51754A13.5000808@sandeen.net> <5175532B.3050509@sgi.com> <20130422233033.GK30622@dastard> In-Reply-To: <20130422233033.GK30622@dastard> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Dave Chinner Cc: Eric Sandeen , xfs@oss.sgi.com On 04/22/13 18:30, Dave Chinner wrote: > On Mon, Apr 22, 2013 at 10:11:39AM -0500, Mark Tinguely wrote: >> #6 [ffff880135603980] _xfs_buf_find at ffffffffa01a7fef [xfs] >> #7 [ffff8801356039f0] xfs_buf_get at ffffffffa01a824a [xfs] >> #8 [ffff880135603a30] xfs_buf_read at ffffffffa01a83a4 [xfs] >> #9 [ffff880135603a60] xlog_recover_inode_pass2 at ffffffffa0193629 [xfs] > > So it's the same problem as this bug fix addresses: > > commit 10616b806d1d7835b1d23b8d75ef638f92cb98b6 > Author: Dave Chinner > Date: Mon Jan 21 23:53:52 2013 +1100 > > xfs: fix _xfs_buf_find oops on blocks beyond the filesystem end > > When _xfs_buf_find is passed an out of range address, it will fail > to find a relevant struct xfs_perag and oops with a null > dereference. This can happen when trying to walk a filesystem with a > metadata inode that has a partially corrupted extent map (i.e. the > block number returned is corrupt, but is otherwise intact) and we > try to read from the corrupted block address. > > In this case, just fail the lookup. If it is readahead being issued, > it will simply not be done, but if it is real read that fails we > will get an error being reported. Ideally this case should result > in an EFSCORRUPTED error being reported, but we cannot return an > error through xfs_buf_read() or xfs_buf_get() so this lookup failure > may result in ENOMEM or EIO errors being reported instead. > > Signed-off-by: Dave Chinner > Reviewed-by: Brian Foster > Reviewed-by: Ben Myers > Signed-off-by: Ben Myers > >> The recovery value is bad and is a problem on its own, but XFS does >> not verify the validity of ag number when doing a xfs_perag_get(). > > Right, that's what the above fix does, but it can't be done on older > kernels because grwofs relies on being able to get buffers beyond > the existing filesystem limits... > > Cheers, > > Dave. Thank-you, that make sense. I still do not like assuming xfs_perag_get() will always return a valid perag pointer. --Mark. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs