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From: Mark Tinguely <tinguely@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Ben Myers <bpm@sgi.com>, xfs@oss.sgi.com
Subject: Re: [PATCH 3/8] xfs: initialise xfssync work before running quotachecks
Date: Fri, 23 Mar 2012 08:34:31 -0500	[thread overview]
Message-ID: <4F6C7BE7.3060100@sgi.com> (raw)
In-Reply-To: <20120322210723.GC5091@dastard>

On 03/22/12 16:07, Dave Chinner wrote:
> On Thu, Mar 22, 2012 at 10:15:48AM -0500, Ben Myers wrote:
>> On Thu, Mar 22, 2012 at 04:15:08PM +1100, Dave Chinner wrote:
>>> From: Dave Chinner<dchinner@redhat.com>
>>>
>>> Because the mount process can run a quotacheck and consume lots of
>>> inodes, we need to be able to run periodic inode reclaim during the
>>> mount process. This will prevent running the system out of memory
>>> during quota checks.
>>>
>>> This essentially reverts 2bcf6e97, but that is safe to do now that
>>> the quota sync code that was causing problems during long quotacheck
>>> executions is now gone.
>>
>> Dave, I've held off on #s 3 and 4 because they appear to be racy.  Being
>
> What race?
>
> Cheers,
>
> Dave


2 of the sync workers use iterators
  xfs_inode_ag_iterator()
   xfs_perag_get()
    radix_tree_lookup(&mp->m_perag_tree, agno)

The race I was worried about was in xfs_mount() to initialize the
mp->m_perag_lock, and the radix tree initialization:
  INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC)).

There is a lock and 2 or 3 unbuffered I/O are performed in xfs_mountfs()
before the mp->m_perag_tree is initialized.

I was also looking at the xfs_perag_t being allocated in mountfs() and 
being deallocated in umountfs(), but it turns out that is not important, 
xfs_perag_get() will return NULL if these have not been allocated yet or 
have been removed for the required ag.

Mark Tinguely.

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  reply	other threads:[~2012-03-23 13:34 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-22  5:15 [PATH 0/8] xfs: outstanding patches for 3.4 merge window Dave Chinner
2012-03-22  5:15 ` [PATCH 1/8] xfs: Fix open flag handling in open_by_handle code Dave Chinner
2012-03-22  5:15 ` [PATCH 2/8] xfs: introduce an allocation workqueue Dave Chinner
2012-03-22  5:15 ` [PATCH 3/8] xfs: initialise xfssync work before running quotachecks Dave Chinner
2012-03-22 15:15   ` Ben Myers
2012-03-22 21:07     ` Dave Chinner
2012-03-23 13:34       ` Mark Tinguely [this message]
2012-03-25 23:22         ` Dave Chinner
2012-03-26 15:10           ` Mark Tinguely
2012-03-26 21:57             ` Dave Chinner
2012-03-28 19:40               ` Ben Myers
2012-03-29  0:29                 ` Dave Chinner
2012-03-29  6:30                   ` [PATCH v2] xfs: Ensure inode reclaim can run during quotacheck Dave Chinner
2012-03-28 17:38   ` [PATCH 3/8] xfs: initialise xfssync work before running quotachecks Ben Myers
2012-03-28 18:02     ` Christoph Hellwig
2012-03-28 18:43       ` Ben Myers
2012-03-22  5:15 ` [PATCH 4/8] xfs: remove MS_ACTIVE guard from inode reclaim work Dave Chinner
2012-03-22  5:15 ` [PATCH 5/8] xfs: don't cache inodes read through bulkstat Dave Chinner
2012-03-22  5:15 ` [PATCH 6/8] xfs: Account log unmount transaction correctly Dave Chinner
2012-03-24  8:27   ` Christoph Hellwig
2012-03-24 22:49     ` Dave Chinner
2012-03-26 22:28   ` Ben Myers
2012-03-22  5:15 ` [PATCH 7/8] xfs: fix fstrim offset calculations Dave Chinner
2012-03-24 13:36   ` Christoph Hellwig
2012-03-27 20:48   ` Ben Myers
2012-03-27 21:42     ` Dave Chinner
2012-03-22  5:15 ` [PATCH 8/8] xfs: add lots of attribute trace points Dave Chinner
2012-03-24 13:42   ` Christoph Hellwig
2012-03-27 21:18   ` Ben Myers
2012-03-27 21:45     ` Dave Chinner
2012-03-27 22:01       ` Ben Myers

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