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

Carlos Maiolino
2013-03-14T20:21:15Z

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@suse.cz>
> ---
> 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@redhat.com>

--
Carlos