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

[Mark Tinguely <tinguely@xxxxxxx>]

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.