From: Dave Chinner <david@fromorbit.com>
To: xfs@oss.sgi.com
Subject: Re: [PATCH 0/6] XFS: Fix growfs deadlocks and per-AG use after free V2
Date: Tue, 15 Dec 2009 16:14:55 +1100 [thread overview]
Message-ID: <20091215051455.GB4850@discord.disaster> (raw)
In-Reply-To: <1260832270-14762-1-git-send-email-david@fromorbit.com>
On Tue, Dec 15, 2009 at 10:11:04AM +1100, Dave Chinner wrote:
> The use of an array for the xfs_perag structures results in growfs having
> to realocate the array. This requires exclusion to prevent use-after-free
> situations. The current locking is prone to deadlocks when growing under
> load, and the xfssyncd currently has no protection against the array being
> reallocated that can lead to panics.
>
> This series abstracts the per-ag structure access and then removes the array
> to replace it with individual xfs_perag structures indexed by a radix tree.
> The only locking required is for the radix tree, hence the deadlocks go away
> as the tree lock is always the innermost lock. The use after frees go away
> as well as growfs does not need to reallocate structures fo pre-existing
> allocation groups - it only needs to allocate the structures for the new
> AGs and insert them into the tree.
>
> This series also adds reference counting to the xfs-perag structure to
> ensure that we balance get/put accesses to the structures and provide the
> infrastructure to determine if the structure is in use or not.
>
> Version 2: Fix review comments from Christoph.
This series needs updating after the trace patches were merged. I'll
post it again soon...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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prev parent reply other threads:[~2009-12-15 5:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-14 23:11 [PATCH 0/6] XFS: Fix growfs deadlocks and per-AG use after free V2 Dave Chinner
2009-12-14 23:11 ` [PATCH 1/6] XFS: rename xfs_get_perag Dave Chinner
2009-12-14 23:11 ` [PATCH 2/6] XFS: Don't directly reference m_perag in allocation code Dave Chinner
2009-12-14 23:11 ` [PATCH 3/6] XFS: Convert filestreams code to use per-ag get/put routines Dave Chinner
2009-12-14 23:11 ` [PATCH 4/6] XFS: convert remaining direct references to m_perag Dave Chinner
2009-12-14 23:11 ` [PATCH 5/6] XFS: Replace per-ag array with a radix tree Dave Chinner
2009-12-14 23:11 ` [PATCH 6/6] XFS: Reference count per-ag structures Dave Chinner
2009-12-15 5:14 ` Dave Chinner [this message]
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