Re: [PATCH V6 00/30] block: support multipage bvec

Ming Lei
2018-06-14T01:19:24Z

On Wed, Jun 13, 2018 at 07:42:53AM -0700, Christoph Hellwig wrote:
> On Tue, Jun 12, 2018 at 11:42:49AM +0800, Ming Lei wrote:
> > On Mon, Jun 11, 2018 at 09:48:06AM -0700, Christoph Hellwig wrote:
> > > І think the new naming scheme in this series is a nightmare. It
> > > confuses the heck out of me, and that is despite knowing many bits of
> > > the block layer inside out, and reviewing previous series.
> >
> > In V5, there isn't such issue, since bio_for_each_segment* is renamed
> > into bio_for_each_page* first before doing the change.
>
> But now we are at V6 where that isn't the case..
>
> > Seems Jens isn't fine with the big renaming, then I follow the suggestion
> > of taking 'chunk' for representing multipage bvec in V6.
>
> Please don't use chunk. We are iterating over bio_vec structures, while
> we have the concept of a chunk size for something else in the block layer,
> so this just creates confusion. Nevermind names like
> bio_for_each_chunk_segment_all which just double the confusion.

We may keep the name of bio_for_each_segment_all(), and just change
the prototype in one single big patch.

>
> So assuming that bio_for_each_segment is set to stay as-is for now,
> here is a proposal for sanity by using the vec name.
>
> OLD: bio_for_each_segment
> NEW(page): bio_for_each_segment, to be renamed bio_for_each_page later
> NEW(bvec): bio_for_each_bvec
>
> OLD: __bio_for_each_segment
> NEW(page): __bio_for_each_segment, to be renamed __bio_for_each_page later
> NEW(bvec): (no bvec version needed)

For the above two, basically similar with V6, just V6 takes chunk, :-)

>
> OLD: bio_for_each_segment_all
> NEW(page): bio_for_each_page_all (needs updated prototype anyway)
> NEW(bvec): (no bvec version needed once bcache is fixed up)

This one may cause confusing, since we iterate over pages via
bio_for_each_segment(), but the _all version takes another name
of page, still iterate over pages.

So could we change it in the following way?

OLD: bio_for_each_segment_all
NEW(page): bio_for_each_segment_all (update prototype in one tree-wide &
big patch, to be renamed bio_for_each_page_all)
NEW(bvec): (no bvec version needed once bcache is fixed up)

Thanks,
Ming