Re: assertion failed in xfs_reclaim_inodes_ag()

[Lachlan McIlroy <lachlan@sgi.com>]

Christoph Hellwig wrote:
> On Tue, Nov 18, 2008 at 08:38:44AM -0500, Christoph Hellwig wrote:
>> On Tue, Nov 18, 2008 at 12:42:27PM +1100, Lachlan McIlroy wrote:
>>> Hit this while running stress tests.  Looks like an inode is tagged with
>>> XFS_ICI_RECLAIM_TAG but not XFS_IRECLAIMABLE|XFS_IRECLAIM.  I can't see
>>> how that can happen.
>> Looks it's xfs_iget_cache_hit when the inode is marked XFS_IRECLAIMABLE,
>> in that case we first clear XFS_IRECLAIMABLE and then call
>> __xfs_inode_clear_reclaim_tag, and all that under
>> read_lock(&pag->pag_ici_lock) only, so no protection against the assert
>> in xfs_reclaim_inodes_ag.
Oh, of course.  I thought I found the problem but then saw the pag_ici_lock
was held in xfs_iget_cache_hit - I didn't realise it was only in read mode.
I assumed that if we are changing the state of the inode we would at least
have some lock exclusive.

> 
> And the easiest fix is to just remove the assert, xfs_reclaim_inode does
> the right thing (bail out) if XFS_IRECLAIMABLE is not set, and it does
> so with the correct locks.  The more complicated fix would be to take
> the pag_ici_lock in write more from the very beginning in
> xfs_reclaim_inodes_ag, and open-code a variant of xfs_reclaim_inode
> there.
> 
Thanks.  I'll just remove the assert.

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