[dm-devel] [PATCH v3 04/26] block: Refactor blk_update_request()

[Kent Overstreet]

On Tue, Oct 02, 2012 at 02:59:55PM -0400, Vivek Goyal wrote:
> On Mon, Sep 24, 2012 at 03:34:44PM -0700, Kent Overstreet wrote:
> > Converts it to use bio_advance(), simplifying it quite a bit in the
> > process.
> > 
> > Note that req_bio_endio() now always calls bio_advance() - which means
> > it always loops over the biovec, not just on partial completions. Don't
> > expect it to affect performance, but worth noting.
> > 
> > Tested it by forcing partial updates, and dumping before and after on
> > various bio/bvec fields when doing a partial update.
> 
> Kent,
> 
> In general, have you tested all these changes with FLUSH and DISCARD 
> bios/requests. Some of the code paths tend to break down because of these
> special bios don't have payload.

Believe so, I should double check - also, I changed the bio_advance()
patch since the one I posted to make it handle DISCARD and WRITE_SAME
requests more explicitly.

(At this level, discards do (sometimes) have payloads, it's just always
a single page)