From: Christoph Hellwig <hch@lst.de>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>,
"Darrick J . Wong" <darrick.wong@oracle.com>,
Dave Chinner <david@fromorbit.com>,
linux-xfs <linux-xfs@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Josef Bacik <jbacik@fb.com>,
"stable [v4.9]" <stable@vger.kernel.org>
Subject: Re: [PATCH] xfs: fix incorrect log_flushed on fsync
Date: Fri, 1 Sep 2017 11:47:09 +0200 [thread overview]
Message-ID: <20170901094708.GB24482@lst.de> (raw)
In-Reply-To: <CAOQ4uxgrdijqVpFm+rZ4JE_ZY0A_CZdSPHQEb8S1_R_dyJYzSg@mail.gmail.com>
On Thu, Aug 31, 2017 at 05:37:06PM +0300, Amir Goldstein wrote:
> > index bcb2f860e508..3c0cbb98581e 100644
> > --- a/fs/xfs/xfs_log.c
> > +++ b/fs/xfs/xfs_log.c
> > @@ -2922,6 +2922,8 @@ xlog_state_done_syncing(
> > iclog->ic_state = XLOG_STATE_DONE_SYNC;
> > }
> >
> > + log->l_mp->m_flushseq++;
>
> I recon this should use WRITE_ONCE or smp_wmb()
> and then also increment m_flush_submitted_seq *before*
> issueing flush
It's under l_icloglock, so we shouldn't need a WRITE_ONCE.
If we did we'd need an atomic_t.
> If state machine does not allow more than a single flush
> to be in flight (?) then the 2 seq counters could be reduced
> to single seq counter with (m_flushseq % 2) == 1 for submitted
> and (m_flushseq % 2) == 0 for completed and the test in fsync
> would be (flushseq % 2) == (READ_ONCE(mp->m_flushseq) % 2)
The state machine allows multiple flushes to in flight.
next prev parent reply other threads:[~2017-09-01 9:47 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-30 13:38 [PATCH] xfs: fix incorrect log_flushed on fsync Amir Goldstein
2017-08-30 13:46 ` Christoph Hellwig
2017-08-30 14:12 ` Amir Goldstein
2017-08-30 14:21 ` Christoph Hellwig
2017-08-30 17:01 ` Darrick J. Wong
2017-08-31 13:47 ` Christoph Hellwig
2017-08-31 14:37 ` Amir Goldstein
2017-08-31 16:39 ` Brian Foster
2017-08-31 19:20 ` Amir Goldstein
2017-08-31 20:10 ` Brian Foster
2017-09-01 7:58 ` Amir Goldstein
2017-09-01 10:46 ` Brian Foster
2017-09-01 9:52 ` Christoph Hellwig
2017-09-01 10:37 ` Amir Goldstein
2017-09-01 10:43 ` Christoph Hellwig
2017-09-01 9:47 ` Christoph Hellwig [this message]
2017-09-15 12:40 ` Amir Goldstein
2017-09-18 17:11 ` Darrick J. Wong
2017-09-18 18:00 ` Amir Goldstein
2017-09-18 18:35 ` Greg KH
2017-09-18 19:29 ` Amir Goldstein
2017-09-19 6:32 ` Greg KH
2018-06-09 4:44 ` Amir Goldstein
2018-06-09 7:13 ` Greg KH
2017-09-18 21:24 ` Dave Chinner
2017-09-19 5:31 ` Amir Goldstein
2017-09-19 5:45 ` Darrick J. Wong
2017-09-20 0:40 ` Dave Chinner
2017-09-20 1:08 ` Vijay Chidambaram
2017-09-20 8:59 ` Eryu Guan
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