Re: [PATCH] ext3: Don't warn from writepage when readonly inode is spotted after error

Eric Sandeen
2011-12-22T16:12:03Z

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;