Re: [PATCH] jbd2: fix ocfs2 corrupt when updating journal superblock fails

["Theodore Ts'o" <tytso@mit.edu>]

This patch caused test ext4/306 to fail, because it caused resize2fs
to fail.  The problem is that jbd2_cleanup_journal_tail() will return
1 if there is nothing to cleanup, and a negative error number if there
is an error.  Unfortunately, this patch hunk:

On Mon, Jun 08, 2015 at 09:31:12AM +0800, Joseph Qi wrote:
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index b96bd80..6b33a42 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1950,7 +1966,13 @@ int jbd2_journal_flush(journal_t *journal)
>  		return -EIO;
> 
>  	mutex_lock(&journal->j_checkpoint_mutex);
> -	jbd2_cleanup_journal_tail(journal);
> +	if (!err) {
> +		err = jbd2_cleanup_journal_tail(journal);
> +		if (err < 0) {
> +			mutex_unlock(&journal->j_checkpoint_mutex);
> +			goto out;
> +		}
> +	}

... would let the non-negative return value leak out to
jbd2_journal_flush(), and its callers are *not* prepared to handle the
non-negative return value (since jbd2_journal_flush wasn't doing this
before.)

I've fixed this by adding a "err = 0;" after the if statement.

          	   	   	    	 - Ted