From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>, xfs@oss.sgi.com
Subject: Re: [PATCH 4/4] xfs: implement freezing by emptying the AIL
Date: Sat, 24 Mar 2012 13:08:48 -0400 [thread overview]
Message-ID: <20120324170848.GA32591@infradead.org> (raw)
In-Reply-To: <20120324170618.GD21708@infradead.org>
On Sat, Mar 24, 2012 at 01:06:18PM -0400, Christoph Hellwig wrote:
> On Thu, Mar 22, 2012 at 10:57:38AM +1100, Dave Chinner wrote:
> > > + * threshold.
> > > + */
> > > + if (atomic_read(&ailp->xa_wait_empty))
> > > + target = xfs_ail_max(ailp)->li_lsn;
> >
> > I don't think this is safe - we may have finished pushing the AIL to
> > empty, but the waiter that decrements xa_wait_empty may not have run
> > yet and we can race with that. In that case, xfs_ail_max() will
> > return NULL as the AIL is empty.
>
> True - I'll add a check for that.
Actually - we do the xfs_trans_ail_cursor_first check just above - if
the AIL is empty we'll already exit after that and never reach this
code, so we should be fine.
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prev parent reply other threads:[~2012-03-24 17:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-16 17:55 [PATCH 0/4] implement filesystem freezing by emptying the AIL Christoph Hellwig
2012-03-16 17:55 ` [PATCH 1/4] xfs: remove log item from AIL in xfs_qm_dqflush after a shutdown Christoph Hellwig
2012-03-21 23:16 ` Dave Chinner
2012-03-16 17:55 ` [PATCH 2/4] xfs: remove log item from AIL in xfs_iflush " Christoph Hellwig
2012-03-21 23:20 ` Dave Chinner
2012-03-24 13:47 ` Christoph Hellwig
2012-03-16 17:55 ` [PATCH 3/4] xfs: allow assigning the tail lsn with the AIL lock held Christoph Hellwig
2012-03-21 17:22 ` Mark Tinguely
2012-03-21 23:29 ` Dave Chinner
2012-03-24 13:48 ` Christoph Hellwig
2012-03-16 17:55 ` [PATCH 4/4] xfs: implement freezing by emptying the AIL Christoph Hellwig
2012-03-21 23:57 ` Dave Chinner
2012-03-24 17:06 ` Christoph Hellwig
2012-03-24 17:08 ` Christoph Hellwig [this message]
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