ext3: Don't warn from writepage when readonly inode is spotted after error

WARN_ON_ONCE(IS_RDONLY(inode)) tends to trip when filesystem hits error and is
remounted read-only. This unnecessarily scares users (well, they should be
scared because of filesystem error, but the stack trace distracts them from the
right source of their fear ;-). We could as well just remove the WARN_ON but
it's not hard to fix it to not trip on filesystem with errors and not use more
cycles in the common case so that's what we do.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext3/inode.c |   18 +++++++++++++++---
 1 files changed, 15 insertions(+), 3 deletions(-)

  I carry this patch in my tree and will merge it with Linus in the next merge
window if noone objects.

On 12/22/11 9:56 AM, Jan Kara wrote:
> WARN_ON_ONCE(IS_RDONLY(inode)) tends to trip when filesystem hits error and is
> remounted read-only. This unnecessarily scares users (well, they should be
> scared because of filesystem error, but the stack trace distracts them from the
> right source of their fear ;-). We could as well just remove the WARN_ON but
> it's not hard to fix it to not trip on filesystem with errors and not use more
> cycles in the common case so that's what we do.

I've seen that too and it is distracting.

Looks good to me, aside from the rather long lines ;)

-Eric


> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/ext3/inode.c |   18 +++++++++++++++---
>  1 files changed, 15 insertions(+), 3 deletions(-)
> 
>   I carry this patch in my tree and will merge it with Linus in the next merge
> window if noone objects.
> 
> diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
> index a8d3217..91ac85b 100644
> --- a/fs/ext3/inode.c
> +++ b/fs/ext3/inode.c
> @@ -1623,7 +1623,11 @@ static int ext3_ordered_writepage(struct page *page,
>  	int err;
>  
>  	J_ASSERT(PageLocked(page));
> -	WARN_ON_ONCE(IS_RDONLY(inode));
> +	/*
> +	 * We don't want to warn for emergency remount. The condition is ordered to avoid
> +	 * dereferencing inode->i_sb in non-error case to avoid slow-downs.
> +	 */
> +	WARN_ON_ONCE(IS_RDONLY(inode) && !(EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ERROR_FS));
>  
>  	/*
>  	 * We give up here if we're reentered, because it might be for a
> @@ -1698,7 +1702,11 @@ static int ext3_writeback_writepage(struct page *page,
>  	int err;
>  
>  	J_ASSERT(PageLocked(page));
> -	WARN_ON_ONCE(IS_RDONLY(inode));
> +	/*
> +	 * We don't want to warn for emergency remount. The condition is ordered to avoid
> +	 * dereferencing inode->i_sb in non-error case to avoid slow-downs.
> +	 */
> +	WARN_ON_ONCE(IS_RDONLY(inode) && !(EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ERROR_FS));
>  
>  	if (ext3_journal_current_handle())
>  		goto out_fail;
> @@ -1741,7 +1749,11 @@ static int ext3_journalled_writepage(struct page *page,
>  	int err;
>  
>  	J_ASSERT(PageLocked(page));
> -	WARN_ON_ONCE(IS_RDONLY(inode));
> +	/*
> +	 * We don't want to warn for emergency remount. The condition is ordered to avoid
> +	 * dereferencing inode->i_sb in non-error case to avoid slow-downs.
> +	 */
> +	WARN_ON_ONCE(IS_RDONLY(inode) && !(EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ERROR_FS));
>  
>  	if (ext3_journal_current_handle())
>  		goto no_write;

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