From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-xfs@vger.kernel.org, david@fromorbit.com
Subject: Re: [PATCH 1/2] xfs: log new intent items created as part of finishing recovered intent items
Date: Thu, 17 Sep 2020 10:07:42 +0100 [thread overview]
Message-ID: <20200917090742.GC13366@infradead.org> (raw)
In-Reply-To: <160031332982.3624373.6230830770363563010.stgit@magnolia>
On Wed, Sep 16, 2020 at 08:28:49PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> During a code inspection, I found a serious bug in the log intent item
> recovery code when an intent item cannot complete all the work and
> decides to requeue itself to get that done. When this happens, the
> item recovery creates a new incore deferred op representing the
> remaining work and attaches it to the transaction that it allocated. At
> the end of _item_recover, it moves the entire chain of deferred ops to
> the dummy parent_tp that xlog_recover_process_intents passed to it, but
> fail to log a new intent item for the remaining work before committing
> the transaction for the single unit of work.
>
> xlog_finish_defer_ops logs those new intent items once recovery has
> finished dealing with the intent items that it recovered, but this isn't
> sufficient. If the log is forced to disk after a recovered log item
> decides to requeue itself and the system goes down before we call
> xlog_finish_defer_ops, the second log recovery will never see the new
> intent item and therefore has no idea that there was more work to do.
> It will finish recovery leaving the filesystem in a corrupted state.
>
> The same logic applies to /any/ deferred ops added during intent item
> recovery, not just the one handling the remaining work.
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
I wonder how we could come up with a reliable reproducer for this,
though..
next prev parent reply other threads:[~2020-09-17 9:07 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-17 3:28 [PATCH 0/2] xfs: fix simple problems with log intent recovery Darrick J. Wong
2020-09-17 3:28 ` [PATCH 1/2] xfs: log new intent items created as part of finishing recovered intent items Darrick J. Wong
2020-09-17 4:58 ` Dave Chinner
2020-09-17 9:07 ` Christoph Hellwig [this message]
2020-09-17 17:45 ` Darrick J. Wong
2020-09-17 3:28 ` [PATCH 2/2] xfs: attach inode to dquot in xfs_bui_item_recover Darrick J. Wong
2020-09-17 4:54 ` Dave Chinner
2020-09-17 6:36 ` Darrick J. Wong
2020-09-17 7:01 ` [PATCH v2 " Darrick J. Wong
2020-09-17 8:03 ` Dave Chinner
2020-09-17 9:04 ` Christoph Hellwig
2020-09-17 7:01 ` [PATCH 3/2] xfs: free the intent item when allocating recovery transaction fails Darrick J. Wong
2020-09-17 8:05 ` Dave Chinner
2020-09-17 9:06 ` Christoph Hellwig
2020-09-18 1:48 ` Darrick J. Wong
2020-09-18 2:17 ` [PATCH v2 3/2] xfs: fix simple problems with log intent recovery Darrick J. Wong
2020-09-18 2:19 ` [PATCH v3 3/2] xfs: don't release log intent items when recovery fails Darrick J. Wong
2020-09-19 5:49 ` Christoph Hellwig
2020-09-21 6:49 ` Dave Chinner
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