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 503FE7CBE for ; Fri, 26 Apr 2013 10:32:37 -0500 (CDT) Message-ID: <517A9E12.1030907@sgi.com> Date: Fri, 26 Apr 2013 10:32:34 -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> <51769111.3050103@sgi.com> <1366732475.3762.32402.camel@chandra-dt.ibm.com> <20130423204956.GM10481@dastard> <1366929706.4098.6.camel@chandra-dt.ibm.com> In-Reply-To: <1366929706.4098.6.camel@chandra-dt.ibm.com> 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: sekharan@us.ibm.com Cc: Eric Sandeen , xfs@oss.sgi.com On 04/25/13 17:41, Chandra Seetharaman wrote: > In which case something along the lines of > > --- > diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c > index 3806088..3fb2fa6 100644 > --- a/fs/xfs/xfs_mount.c > +++ b/fs/xfs/xfs_mount.c > @@ -203,7 +203,13 @@ xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t > agno) > if (pag) { > ASSERT(atomic_read(&pag->pag_ref)>= 0); > ref = atomic_inc_return(&pag->pag_ref); > - } > + } else > + /* > + * xfs_perag_get() is called with invalid agno, > + * which cannot happen. This indicates a problem > + * in the calling code. > + */ > + BUG(); > rcu_read_unlock(); > trace_xfs_perag_get(mp, agno, ref, _RET_IP_); > return pag; > -------- > > would be useful ?. Since we have a NULL pag, we will trip somewhere > else. At least with this, there is a pointer to the debugger/sysadmin > about where/what to look for (may be with more valuable/correct comment > than above). > We will have to make sure the callers of xfs_perag_get() handle the NULL before dereferencing it. Sometimes the NULL is normal and just means the perag structure has not been initialize yet. Properly handling the NULL from xfs_perag_get() in the caller will also mean that the callers of the callers of xfs_perag_get() have to handle the NULL returned to them. I will come back to this once the CRC stuff has been put to rest. --Mark. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs