From: Brian Foster <bfoster@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH v2 1/3] xfs: add scan owner field to xfs_eofblocks
Date: Tue, 27 May 2014 08:18:11 -0400 [thread overview]
Message-ID: <20140527121810.GB63281@bfoster.bfoster> (raw)
In-Reply-To: <20140527104428.GC1440@infradead.org>
On Tue, May 27, 2014 at 03:44:28AM -0700, Christoph Hellwig wrote:
> On Fri, May 23, 2014 at 07:52:28AM -0400, Brian Foster wrote:
> > The scan owner field represents an optional inode number that is
> > responsible for the current scan. The purpose is to identify that an
> > inode is under iolock and as such, the iolock shouldn't be attempted
> > when trimming eofblocks. This is an internal only field.
>
> xfs_free_eofblocks already does a trylock, and without that calling it
> from one iolock holding process to another would be a deadlock waiting
> to happen.
>
> I have to say I'm still not very easy with iolock nesting, even if it's
> a trylock.
>
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).
Brian
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next prev parent reply other threads:[~2014-05-27 12:18 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 [this message]
2014-05-27 21:26 ` Dave Chinner
2014-05-28 5:30 ` Christoph Hellwig
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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