From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Brian Foster <bfoster@redhat.com>,
xfs@oss.sgi.com
Subject: Re: [PATCH v2 1/3] xfs: add scan owner field to xfs_eofblocks
Date: Tue, 27 May 2014 22:30:19 -0700 [thread overview]
Message-ID: <20140528053019.GB3816@infradead.org> (raw)
In-Reply-To: <20140527212653.GC6677@dastard>
On Wed, May 28, 2014 at 07:26:53AM +1000, Dave Chinner wrote:
> > Right... maybe I'm not parsing your point. The purpose here is to avoid
> > the trylock entirely. E.g., Indicate that we have already acquired the
> > lock and can proceed with xfs_free_eofblocks(), rather than fail a
> > trylock and skip (which appears to be a potential infinite loop scenario
> > here due to how the AG walking code handles EAGAIN).
>
> I think Christoph's concern here is that we are calling a function
> that can take the iolock while we already hold the iolock. i.e. the
> reason we have to add the anti-deadlock code in the first place.
Indeed.
> To
> address that, can we restructure xfs_file_buffered_aio_write() such
> that the ENOSPC/EDQUOT flush is done outside the iolock?
>
> >From a quick check, I don't think there is any problem with dropping
> the iolock, doing the flushes and then going all the way back to the
> start of the function again, but closer examination and testing is
> warranted...
I think we'd need some form of early space reservation, otherwise we'd
get non-atomic writes. Time to get those batches write patches out
again..
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next prev parent reply other threads:[~2014-05-28 5:30 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-23 11:52 [PATCH v2 0/3] xfs: run eofblocks scan on ENOSPC Brian Foster
2014-05-23 11:52 ` [PATCH v2 1/3] xfs: add scan owner field to xfs_eofblocks Brian Foster
2014-05-26 22:49 ` Dave Chinner
2014-05-27 10:44 ` Christoph Hellwig
2014-05-27 12:18 ` Brian Foster
2014-05-27 21:26 ` Dave Chinner
2014-05-28 5:30 ` Christoph Hellwig [this message]
2014-05-28 14:00 ` Brian Foster
2014-05-23 11:52 ` [PATCH v2 2/3] xfs: run an eofblocks scan on ENOSPC/EDQUOT Brian Foster
2014-05-26 22:57 ` Dave Chinner
2014-05-27 12:47 ` Brian Foster
2014-05-27 21:14 ` Dave Chinner
2014-05-28 12:42 ` Brian Foster
2014-05-23 11:52 ` [PATCH v2 3/3] xfs: squash prealloc while over quota free space as well Brian Foster
2014-05-26 23:00 ` Dave Chinner
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