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From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Jeff Layton <jlayton@kernel.org>
Cc: "Theodore Y. Ts'o" <tytso@mit.edu>,
	Matthew Wilcox <willy@infradead.org>,
	linux-fsdevel@vger.kernel.org, fstests@vger.kernel.org
Subject: Re: commit b4678df184b causing xfstests regressions
Date: Sat, 19 May 2018 08:25:03 -0700	[thread overview]
Message-ID: <20180519152503.GA4507@magnolia> (raw)
In-Reply-To: <630faadb74f608aa5a42649b81657e8b62d46bc3.camel@kernel.org>

On Sat, May 19, 2018 at 09:09:46AM -0400, Jeff Layton wrote:
> On Fri, 2018-05-18 at 18:50 -0400, Theodore Y. Ts'o wrote:
> > Hi Matthew,
> > 
> > Commit b4678df184b: "errseq: Always report a writeback error once"
> > appears to be causing xfstests regressions.  For ext4, running
> > "gce-xfstests -c 4k -g auto" will result in reliable shared/298
> > failures which go away if I revert b4678df184b.
> > 
> > Darrick has also reported occasional generic/047 failures, which I
> > have seen at least once as well.  I believe two are linked, because
> > after instrumenting mke2fs in shared/298, the failure is happening
> > after creating a new 300 MB file:
> > 
> > dd if=/dev/zero of=$img_file bs=1M count=300 &> /dev/null
> > 
> > creating a new loop device
> > 
> > loop_dev=$(_create_loop_device $img_file)
> > 
> > ... and then run mke2fs on that loop device.
> > 
> > The instrumentation of mke2fs shows that the first fsync() on
> > /dev/loop0 (in lib/ext2fs/closefs.c) which is failing with EIO.
> > 
> > I haven't had a chance to really drill down on it, but I think what is
> > going on is there is some former test which exercises an error path
> > (using dm_error, or some such), and somehow the errseq_t for the loop
> > device isn't getting reset, or the inode for the underlying backing
> > file, had an unitialized errseq_t.
> > 
> > Can you take a closer look at this?
> > 
> > Thanks,
> > 
> > 					- Ted
> > 
> 
> Thanks Ted. I'm not that familiar with the loopdev code, but after
> giving it a quick look, I suspect that you're correct. We probably need
> to do something like reset the loop device's bd_inode->i_mapping->wb_err 
> back to zero when we detach the file that backs it.
> 
> I wonder if we could roll a test that would do:
> 
> create a scratch fs on a dm-error dev with a file on it
> set up a loop device on that file
> have the backing device of the scratch file throw errors
> write to the device
> detach loop device
> clear dm-error condition
> delete file and recreate it
> attach same loop device to new file
> fsync loop device
> 
> My suspicion is that that last fsync would throw an error now and it
> wouldn't have before.

I /think/ it's because inode_init_always doesn't clear mapping->wb_err
(even though it clears mapping->flags) when recycling struct inodes.
Will send patch shortly.

--D

> -- 
> Jeff Layton <jlayton@kernel.org>

  reply	other threads:[~2018-05-19 15:25 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-18 22:50 Theodore Y. Ts'o
2018-05-19  2:17 ` Matthew Wilcox
2018-05-19 13:09 ` Jeff Layton
2018-05-19 15:25   ` Darrick J. Wong [this message]
2018-05-19 15:27   ` [PATCH] fs: clear writeback errors in inode_init_always Darrick J. Wong
2018-05-19 15:36     ` Matthew Wilcox
2018-05-21 17:54       ` Darrick J. Wong
2018-05-22 10:30         ` Jeff Layton
2018-05-22 22:09           ` Dave Chinner
2018-05-23 10:56             ` Jeff Layton
2018-05-24  3:59               ` Dave Chinner
2018-05-19 23:19     ` Theodore Y. Ts'o
2018-05-20 11:45       ` Jeff Layton
2018-05-20 12:58         ` Matthew Wilcox
2018-05-20 13:18           ` Jeff Layton
2018-05-20 16:29           ` Theodore Y. Ts'o
2018-05-20 19:20             ` Matthew Wilcox
2018-05-20 19:41               ` Theodore Y. Ts'o
2018-05-21 11:20                 ` Jeff Layton
2018-05-21 14:43                   ` Theodore Y. Ts'o
2018-05-20 17:57         ` Theodore Y. Ts'o
2018-05-22  4:06     ` [PATCH v2] " Darrick J. Wong
2018-05-22 10:14       ` Jeff Layton
2018-05-22 12:14       ` Brian Foster
2018-05-22 14:37         ` Darrick J. Wong
2018-05-22 16:43     ` [PATCH v3] " Darrick J. Wong
2018-05-22 18:40       ` Brian Foster
2018-05-22 18:47         ` Darrick J. Wong
2018-05-22 22:05       ` Dave Chinner
2018-05-23  3:00         ` Darrick J. Wong

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