[PATCH 2/2] xfs: fix the buffer log format for contiguous buffers

[Christoph Hellwig]

Do we have proper test coverage for the xfs_buf_item_format_segment
changes?  Given that they change what gets written into the log I'd
prefer them separate from a big cleanup patch, and including test
coverage verifying everything works fine when hitting these corner
cases.

>  		chunk_num = byte >> XFS_BLF_SHIFT;
>  		word_num = chunk_num >> BIT_TO_WORD_SHIFT;
>  		bit_num = chunk_num & (NBWORD - 1);
> -		wordp = &(bip->bli_format.blf_data_map[word_num]);
> +		wordp = &(bip->bli_formats[0].blf_data_map[word_num]);

This change doesn't seem to be mentioned in the changelog?

> @@ -644,8 +652,14 @@ xfs_buf_item_unlock(
>  	 * If the buf item isn't tracking any data, free it, otherwise drop the
>  	 * reference we hold to it.
>  	 */
> -	if (xfs_bitmap_empty(bip->bli_format.blf_data_map,
> -			     bip->bli_format.blf_map_size))
> +	empty = 1;
> +	for (i = 0; i < bip->bli_format_count; i++)
> +		if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map,
> +			     bip->bli_formats[i].blf_map_size)) {
> +			empty = 0;
> +			break;
> +		}
> +	if (empty)
>  		xfs_buf_item_relse(bp);

This looks like a bug fix, not just a cleanup.  Again I'd prefer this to
be a patch on its own, with a good description.

Also as in the last patch should we rename bli_format to __bli_format
to catch accidental references to it?