linux-kernel - Re: [PATCH] xfs: call xfs_idestroy_fork() in xfs

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Date:	Thu, 23 Apr 2015 13:14:40 -0400
From:	Waiman Long <waiman.long@...com>
To:	Dave Chinner <david@...morbit.com>
CC:	xfs@....sgi.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xfs: call xfs_idestroy_fork() in xfs_ilock() critical
 section

On 04/22/2015 07:17 PM, Dave Chinner wrote:
> -- 
> Dave Chinner
> david@...morbit.com
>
> xfs: xfs_attr_inactive leaves inconsistent attr fork state behind
>
> From: Dave Chinner<dchinner@...hat.com>
>
> xfs_attr_inactive() is supposed to clean up the attribute fork when
> the inode is being freed. While it removes attribute fork extents,
> it completely ignores attributes in local format, which means that
> there can still be active attributes on the inode after
> xfs_attr_inactive() has run.
>
> This leads to problems with concurrent inode writeback - the in-core
> inode attribute fork is removed without locking on the assumption
> that nothing will be attempting to access the attribute fork after a
> call to xfs_attr_inactive() because it isn't supposed to exist on
> disk any more.
>
> To fix this, make xfs_attr_inactive() completely remove all traces
> of the attribute fork from the inode, regardless of it's state.
> Further, also remove the in-core attribute fork structure safely so
> that there is nothing further that needs to be done by callers to
> clean up the attribute fork. This means we can remove the in-core
> and on-disk attribute forks atomically.
>
> Also, on error simply remove the in-memory attribute fork. There's
> nothing that can be done with it once we have failed to remove the
> on-disk attribute fork, so we may as well just blow it away here
> anyway.
>
> cc:<stable@...r.kernel.org>  # 3.12 to 4.0
> Reported-by: Waiman Long<waiman.long@...com>
> Signed-off-by: Dave Chinner<dchinner@...hat.com>
> ---
>   fs/xfs/libxfs/xfs_attr_leaf.c |  2 +-
>   fs/xfs/libxfs/xfs_attr_leaf.h |  2 +-
>   fs/xfs/xfs_attr_inactive.c    | 81 ++++++++++++++++++++++++++-----------------
>   fs/xfs/xfs_inode.c            | 12 +++----
>   4 files changed, 55 insertions(+), 42 deletions(-)

Thanks for figuring out a better way to fix the underlying problem. I 
tested it in my test machine and it did fix the errors that I had seen 
in my test case.

Tested-by: Waiman Long<Waiman.Long@...com>

Cheers,
Longman

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