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Re: [PATCH] xfs: Fix WARN_ON(delalloc) in xfs_vm_releasepage()

To: Jan Kara <jack@xxxxxxx>
Subject: Re: [PATCH] xfs: Fix WARN_ON(delalloc) in xfs_vm_releasepage()
From: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
Date: Thu, 14 Mar 2013 17:21:09 -0300
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1363267854-25602-1-git-send-email-jack@xxxxxxx>
References: <1363267854-25602-1-git-send-email-jack@xxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Thu, Mar 14, 2013 at 02:30:54PM +0100, Jan Kara wrote:
> When a dirty page is truncated from a file but reclaim gets to it before
> truncate_inode_pages(), we hit WARN_ON(delalloc) in
> xfs_vm_releasepage(). This is because reclaim tries to write the page,
> xfs_vm_writepage() just bails out (leaving page clean) and thus reclaim
> thinks it can continue and calls xfs_vm_releasepage() on page with dirty
> buffers.
> 
> Fix the issue by redirtying the page in xfs_vm_writepage(). This makes
> reclaim stop reclaiming the page and also logically it keeps page in a
> more consistent state where page with dirty buffers has PageDirty set.
> 
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
>  fs/xfs/xfs_aops.c |   12 ++++++------
>  1 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 5f707e5..3244c98 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -953,13 +953,13 @@ xfs_vm_writepage(
>               unsigned offset_into_page = offset & (PAGE_CACHE_SIZE - 1);
>  
>               /*
> -              * Just skip the page if it is fully outside i_size, e.g. due
> -              * to a truncate operation that is in progress.
> +              * Skip the page if it is fully outside i_size, e.g. due to a
> +              * truncate operation that is in progress. We must redirty the
> +              * page so that reclaim stops reclaiming it. Otherwise
> +              * xfs_vm_releasepage() is called on it and gets confused.
>                */
> -             if (page->index >= end_index + 1 || offset_into_page == 0) {
> -                     unlock_page(page);
> -                     return 0;
> -             }
> +             if (page->index >= end_index + 1 || offset_into_page == 0)
> +                     goto redirty;
>  
>               /*
>                * The page straddles i_size.  It must be zeroed out on each
> -- 
> 1.7.1
> 
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Looks Good,
Reviewed-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>

-- 
Carlos

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