Re: [PATCH] xfs: test for shut down fs in xfs_dir_fsync()

From: Mark Tinguely <tinguely@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Eric Sandeen <sandeen@redhat.com>,
	Boris Ranto <branto@redhat.com>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH] xfs: test for shut down fs in xfs_dir_fsync()
Date: Mon, 28 Apr 2014 16:39:50 -0500	[thread overview]
Message-ID: <535ECAA6.3050200@sgi.com> (raw)
In-Reply-To: <20140428205420.GB18672@dastard>

On 04/28/14 15:54, Dave Chinner wrote:
> On Mon, Apr 28, 2014 at 11:35:16AM -0500, Eric Sandeen wrote:
>> Similar to xfs_file_fsync(), I think xfs_dir_fsync() needs
>> to test for a shut down fs, lest we go down paths we'll
>> never be able to complete; Boris reported that during some
>> stress tests he had threads stuck in xlog_cil_force_lsn
>> via xfs_dir_fsync().
>>
>> [ 3663.361709] sfsuspend-par   D ffff88042f0b4540     0  3981   3947 0x00000080
>>
>> [ 3663.394472] Call Trace:
>> [ 3663.397199]  [<ffffffff815f1889>] schedule+0x29/0x70
>> [ 3663.402743]  [<ffffffffa01feda5>] xlog_cil_force_lsn+0x185/0x1a0 [xfs]
>> [ 3663.416249]  [<ffffffffa01fd3af>] _xfs_log_force_lsn+0x6f/0x2f0 [xfs]
>> [ 3663.429271]  [<ffffffffa01a339d>] xfs_dir_fsync+0x7d/0xe0 [xfs]
>> [ 3663.435873]  [<ffffffff811df8c5>] do_fsync+0x65/0xa0
>> [ 3663.441408]  [<ffffffff811dfbc0>] SyS_fsync+0x10/0x20
>> [ 3663.447043]  [<ffffffff815fc7d9>] system_call_fastpath+0x16/0x1b
>
> Wow, I believe it's taken this long for us to notice that we can't
> break out of xlog_cil_force_lsn() if we fail on xlog_write()
> from a CIL push.
>
> I'd say that xlog_cil_force_lsn() needs log shutdown checks before
> it goes to sleep in xlog_wait()....
>
>> Reported-by: Boris Ranto<branto@redhat.com>
>> Signed-off-by: Eric Sandeen<sandeen@redhat.com>
>> ---
>>
>> NB: While I've not asked Boris to test this yet, it seems
>> clear (?) that dir_fsync should behave the same as
>> file_fsync() in the face of a shut-down fs.
>>
>> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
>> index 4c749ab..2b94362 100644
>> --- a/fs/xfs/xfs_file.c
>> +++ b/fs/xfs/xfs_file.c
>> @@ -146,6 +146,9 @@ xfs_dir_fsync(
>>
>>   	trace_xfs_dir_fsync(ip);
>>
>> +	if (XFS_FORCED_SHUTDOWN(mp))
>> +		return -XFS_ERROR(EIO);
>> +
>
> That won't hurt, but it won't fix the problem.
>
> Cheers,
>
> Dave.

Similar to what Jeff Liu mention in Dec:

   http://oss.sgi.com/archives/xfs/2013-12/msg00870.html

--Mark.

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