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 1560C7FB7 for ; Thu, 20 Feb 2014 13:09:23 -0600 (CST) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay1.corp.sgi.com (Postfix) with ESMTP id C58738F8035 for ; Thu, 20 Feb 2014 11:09:19 -0800 (PST) Received: from sandeen.net (sandeen.net [63.231.237.45]) by cuda.sgi.com with ESMTP id jJyE5y2Ih0VWFzNG for ; Thu, 20 Feb 2014 11:09:15 -0800 (PST) Message-ID: <530652DA.7010706@sandeen.net> Date: Thu, 20 Feb 2014 13:09:14 -0600 From: Eric Sandeen MIME-Version: 1.0 Subject: Re: [PATCH 2/2] libxfs: clear stale buffer errors on write References: <1392875722-4390-1-git-send-email-david@fromorbit.com> <1392875722-4390-3-git-send-email-david@fromorbit.com> In-Reply-To: <1392875722-4390-3-git-send-email-david@fromorbit.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Dave Chinner , xfs@oss.sgi.com On 2/19/14, 11:55 PM, Dave Chinner wrote: > From: Dave Chinner > > If we've read a buffer and it's had an error (e.g a bad CRC) and the > caller corrects the problem with the buffer and writes it via > libxfs_writebuf() without clearing the error on the buffer, > subsequent reads of the buffer while it is still in cache can see > that error and fail inappropriately. > > xfs/033 demonstrates this error, where phase 3 detects the corrupted > root inode and clears, but doesn't clear the b_error field. Later in > phase 6, the code that rebuilds the root directory tries to read the > root inode and sees a buffer with an error on it, thereby triggering > a fatal repair failure: > > Phase 3 - for each AG... > - scan and clear agi unlinked lists... > - process known inodes and perform inode discovery... > - agno = 0 > xfs_inode_buf_verify: XFS_CORRUPTION_ERROR > bad magic number 0x0 on inode 64 > .... > cleared root inode 64 > .... > Phase 6 - check inode connectivity... > reinitializing root directory > xfs_imap_to_bp: xfs_trans_read_buf() returned error 117. > > fatal error -- could not iget root inode -- error - 117 > # > > Fix this by assuming buffers that are written are clean and correct > and hence we can zero the b_error field before retiring the buffer > to the cache. Thanks; Reviewed-by: Eric Sandeen > Reported-by: Eric Sandeen > Signed-off-by: Dave Chinner > --- > libxfs/rdwr.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c > index 78a9b37..d0ff15b 100644 > --- a/libxfs/rdwr.c > +++ b/libxfs/rdwr.c > @@ -890,6 +890,11 @@ libxfs_writebufr(xfs_buf_t *bp) > int > libxfs_writebuf_int(xfs_buf_t *bp, int flags) > { > + /* > + * Clear any error hanging over from reading the buffer. This prevents > + * subsequent reads after this write from seeing stale errors. > + */ > + bp->b_error = 0; > bp->b_flags |= (LIBXFS_B_DIRTY | flags); > return 0; > } > @@ -903,6 +908,11 @@ libxfs_writebuf(xfs_buf_t *bp, int flags) > (long long)LIBXFS_BBTOOFF64(bp->b_bn), > (long long)bp->b_bn); > #endif > + /* > + * Clear any error hanging over from reading the buffer. This prevents > + * subsequent reads after this write from seeing stale errors. > + */ > + bp->b_error = 0; > bp->b_flags |= (LIBXFS_B_DIRTY | flags); > libxfs_putbuf(bp); > return 0; > _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs