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From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Brian Foster <bfoster@redhat.com>, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 10/10] xfs: cache unlinked pointers in an rhashtable
Date: Tue, 5 Feb 2019 10:17:33 -0800	[thread overview]
Message-ID: <20190205181733.GK7991@magnolia> (raw)
In-Reply-To: <20190205175702.GA5951@infradead.org>

On Tue, Feb 05, 2019 at 09:57:02AM -0800, Christoph Hellwig wrote:
> On Tue, Feb 05, 2019 at 09:53:09AM -0800, Darrick J. Wong wrote:
> > Good point, we could be much more resilient to backref cache failures
> > since we do have the option of doing it the slow way.
> 
> I don't think there is any failure that can happen during normal
> operation as long as we use KM_SLEEP..

I dug even deeper into the rhashtable code it looks like it can fail a
GFP_ATOMIC allocation for new buckets, which will bubble ENOMEM up to
the caller, so Brian's right that we have to handle various errors, and
should do so in a manner that doesn't kill the filesystem.

Seeing as it's a backref cache and not critical to correct operation, I
think I can change add_backref to ignore errors other than EEXIST
(because having duplicate entries is a sign that we've screwed something
up).  change_backref can absorb all the error codes, though it'll have
to handle the case that lookup_fast returns ENOENT.

--D

  reply	other threads:[~2019-02-05 18:17 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-04 17:58 [PATCH v2 00/10] xfs: incore unlinked list Darrick J. Wong
2019-02-04 17:59 ` [PATCH 01/10] xfs: clean up iunlink functions Darrick J. Wong
2019-02-04 19:24   ` Brian Foster
2019-02-04 20:51   ` Christoph Hellwig
2019-02-04 17:59 ` [PATCH 02/10] xfs: track unlinked inode counts in per-ag data Darrick J. Wong
2019-02-04 19:24   ` Brian Foster
2019-02-04 20:53     ` Christoph Hellwig
2019-02-05  0:26       ` Darrick J. Wong
2019-02-05  6:55         ` Christoph Hellwig
2019-02-05  7:07           ` Darrick J. Wong
2019-02-05  0:42     ` Darrick J. Wong
2019-02-04 17:59 ` [PATCH 03/10] xfs: add xfs_verify_agino_or_null helper Darrick J. Wong
2019-02-04 19:24   ` Brian Foster
2019-02-04 20:53   ` Christoph Hellwig
2019-02-04 17:59 ` [PATCH 04/10] xfs: refactor AGI unlinked bucket updates Darrick J. Wong
2019-02-04 19:25   ` Brian Foster
2019-02-04 20:54   ` Christoph Hellwig
2019-02-04 17:59 ` [PATCH 05/10] xfs: strengthen AGI unlinked inode bucket pointer checks Darrick J. Wong
2019-02-04 17:59 ` [PATCH 06/10] xfs: refactor inode unlinked pointer update functions Darrick J. Wong
2019-02-04 20:56   ` Christoph Hellwig
2019-02-04 21:49     ` Darrick J. Wong
2019-02-05 14:23   ` Brian Foster
2019-02-04 17:59 ` [PATCH 07/10] xfs: refactor unlinked list search and mapping to a separate function Darrick J. Wong
2019-02-04 20:58   ` Christoph Hellwig
2019-02-04 22:23     ` Darrick J. Wong
2019-02-04 17:59 ` [PATCH 08/10] xfs: refactor inode update in iunlink_remove Darrick J. Wong
2019-02-04 20:58   ` Christoph Hellwig
2019-02-05 14:23   ` Brian Foster
2019-02-04 17:59 ` [PATCH 09/10] xfs: add tracepoints for high level iunlink operations Darrick J. Wong
2019-02-04 20:59   ` Christoph Hellwig
2019-02-05 14:24   ` Brian Foster
2019-02-04 18:00 ` [PATCH 10/10] xfs: cache unlinked pointers in an rhashtable Darrick J. Wong
2019-02-04 21:08   ` Christoph Hellwig
2019-02-05  1:02     ` Darrick J. Wong
2019-02-05 14:24   ` Brian Foster
2019-02-05 17:53     ` Darrick J. Wong
2019-02-05 17:57       ` Christoph Hellwig
2019-02-05 18:17         ` Darrick J. Wong [this message]
2019-02-05 19:06       ` Brian Foster
2019-02-05 19:20         ` Darrick J. Wong
2019-02-05 20:59       ` Dave Chinner
2019-02-06 18:25         ` Darrick J. Wong

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