ext4: Fix WARN_ON from ext4_releasepage()

Submitted by Jan Kara on March 7, 2013, 2:52 p.m.

Details

Message ID 1362667969-19818-1-git-send-email-jack@suse.cz
State Accepted, archived
Headers show

Commit Message

Jan Kara March 7, 2013, 2:52 p.m.
ext4_releasepage() warns when it is passed a page with PageChecked set.
However this can correctly happen when invalidate_inode_pages2_range()
invalidates pages - and we should fail the release in that case. Since
the page was dirty anyway, it won't be discarded and no harm has
happened but it's good to be safe. Also remove bogus page_has_buffers()
check - we are guaranteed page has buffers in this function.

Reported-by: Zheng Liu <gnehzuil.liu@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/inode.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

Comments

Zheng Liu March 8, 2013, 12:45 p.m.
On Thu, Mar 07, 2013 at 03:52:49PM +0100, Jan Kara wrote:
> ext4_releasepage() warns when it is passed a page with PageChecked set.
> However this can correctly happen when invalidate_inode_pages2_range()
> invalidates pages - and we should fail the release in that case. Since
> the page was dirty anyway, it won't be discarded and no harm has
> happened but it's good to be safe. Also remove bogus page_has_buffers()
> check - we are guaranteed page has buffers in this function.
> 
> Reported-by: Zheng Liu <gnehzuil.liu@gmail.com>
> Signed-off-by: Jan Kara <jack@suse.cz>
Thanks for fixing it.  I can confirm that the warning disappears.
Tested-by: Zheng Liu <wenqing.lz@taobao.com>

Regards,
                                                - Zheng
> ---
>  fs/ext4/inode.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 9c4f4b1..34cc72d 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2912,8 +2912,8 @@ static int ext4_releasepage(struct page *page, gfp_t wait)
>  
>  	trace_ext4_releasepage(page);
>  
> -	WARN_ON(PageChecked(page));
> -	if (!page_has_buffers(page))
> +	/* Page has dirty journalled data -> cannot release */
> +	if (PageChecked(page))
>  		return 0;
>  	if (journal)
>  		return jbd2_journal_try_to_free_buffers(journal, page, wait);
> -- 
> 1.7.1
> 
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Theodore Ts'o March 11, 2013, 2:20 a.m.
Thanks, applied.

							- Ted
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diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9c4f4b1..34cc72d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2912,8 +2912,8 @@  static int ext4_releasepage(struct page *page, gfp_t wait)
 
 	trace_ext4_releasepage(page);
 
-	WARN_ON(PageChecked(page));
-	if (!page_has_buffers(page))
+	/* Page has dirty journalled data -> cannot release */
+	if (PageChecked(page))
 		return 0;
 	if (journal)
 		return jbd2_journal_try_to_free_buffers(journal, page, wait);