From: Mark Tinguely <tinguely@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [RFC] xfs: wait for the write of the superblock on unmount
Date: Fri, 20 Jul 2012 08:21:59 -0500 [thread overview]
Message-ID: <50095B77.7090203@sgi.com> (raw)
In-Reply-To: <20120719015809.GC23387@dastard>
On 07/18/12 20:58, Dave Chinner wrote:
> On Wed, Jul 18, 2012 at 12:33:58PM -0500, tinguely@sgi.com wrote:
>> Sorry, I have been distracted away from this regression. This was previously
>> titled "xfs: synchronously write the superblock on unmount".
>>
>> xfs_wait_buftarg() does not wait for the completion of the write of the
>> uncached superblock. This write can race with the shutdown of the log and
>> causes a panic if the write does not win the race.
>>
>> The log write of the superblock is important for possible recovery, but a
>> second syncronous write of the same superblock seems redundant. Would just
>> waiting for the iodone() of the log write before tearing down the log be
>> enough?
>
> Yes. i.e. something like:
>
> /*
> * The superblock buffer is uncached, so xfs_wait_buftarg()
> * will not wait for it. Hence we need to explicitly wait
> * for IO completion on the superblock to occur here.
> */
> error = xfs_buf_iowait(mp->m_sb_bp);
> if (error)
> AAAAIEEEE!
>
> This fix is also needed in xfs_quiesce_attr() for the freeze and
> ro,remount cases as well.
>
> Cheers,
>
> Dave.
>
Thanks for the feedback.
I chose the ugly lock to block on the superblock buffer because it has
XBF_ASYNC set at that point and won't go through the complete() patch. I
will look at turning the XBF_ASYNC flag off and wait on a xfs_buf_iowait().
--Mark.
_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs
next prev parent reply other threads:[~2012-07-20 13:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20120717215957.855744999@tinguelysgi.com>
2012-07-18 17:33 ` [RFC] xfs: wait for the write of the superblock on unmount tinguely
2012-07-19 1:58 ` Dave Chinner
2012-07-20 13:21 ` Mark Tinguely [this message]
2012-07-20 21:24 ` Mark Tinguely
2012-07-24 13:57 ` Christoph Hellwig
2012-07-24 14:03 ` Mark Tinguely
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=50095B77.7090203@sgi.com \
--to=tinguely@sgi.com \
--cc=david@fromorbit.com \
--cc=xfs@oss.sgi.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox