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

[Mark Tinguely]

On 11/21/12 03:54, Christoph Hellwig wrote:
> 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.
>

The bli_format -> bli_formats changes are bug fixes - the description 
should say this is a bug fix not just a cleanup.

Eric's test 291 created a buffer with 4 mapped segments. It found most 
of the issues in the buffer map and in the buffer log format. Dave 
pointed out the xfs_bitmap_empty() error.

--Mark.