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From: Donald Douwsma <donaldd@sgi.com>
To: David Chinner <dgc@sgi.com>
Cc: Lachlan McIlroy <lachlan@sgi.com>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: Review: Fix dbflush panic in xfs_qm_sync
Date: Wed, 17 Oct 2007 11:54:28 +1000	[thread overview]
Message-ID: <47156B54.8070102@sgi.com> (raw)
In-Reply-To: <20071016060726.GR995458@sgi.com>

David Chinner wrote:
> On Tue, Oct 16, 2007 at 03:18:02PM +1000, Lachlan McIlroy wrote:
>> Could mp->m_quotainfo become NULL after this check but before we
>> lock the list with xfs_qm_mplist_lock()?  There doesn't seem to
>> be any locking to protect changes to this field?
> 
> Possible - in theory. Likely - no. We do the same unlocked check in a
> few places...
> 

The mplist lock doesnt prevent the quotainfo going away while its held.
It's just guarding a hashlist that lives in quotainfo structure.
So none of this code prevents a quotaoff race.

In the short term this change restores the original checks. But in the
longer term we should review the locking in the quota system, possibly
adding a quotaoff lock to xfs_mount_t.

Don

  reply	other threads:[~2007-10-17  1:54 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-15 23:29 Review: Fix dbflush panic in xfs_qm_sync Donald Douwsma
2007-10-16  5:18 ` Lachlan McIlroy
2007-10-16  6:07   ` David Chinner
2007-10-17  1:54     ` Donald Douwsma [this message]
2007-10-18 16:16 ` Christoph Hellwig

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