Re: [PATCH v2 3/6] block: Clarify that @bytes is no limit on *pnum

[Max Reitz]

On 28.06.21 21:10, Eric Blake wrote:
> > > > +++ b/include/block/block_int.h
> > > > @@ -347,6 +347,11 @@ struct BlockDriver {
> > > >         * clamped to bdrv_getlength() and aligned to request_alignment,
> > > >         * as well as non-NULL pnum, map, and file; in turn, the driver
> > > >         * must return an error or set pnum to an aligned non-zero value.
> > > > +     *
> > > > +     * Note that @bytes is just a hint on how big of a region the
> > > > +     * caller wants to inspect.  It is not a limit on *pnum.
> > > > +     * Implementations are free to return larger values of *pnum if
> > > > +     * doing so does not incur a performance penalty.
> > > Worth mention that the cache will benefit of it?
> > Oh, right, absolutely.  Like so:
> >
> > "block/io.c's bdrv_co_block_status() will clamp *pnum before returning it to
> > its caller, but it itself can still make use of the unclamped *pnum value.
> > Specifically, the block-status cache for protocol nodes will benefit from
> > storing as large a region as possible."
> How about this tweak to the wording to make it flow a little better:
>
> block/io.c's bdrv_co_block_status() will utilize an unclamped *pnum
> value for the block-status cache on protocol nodes, prior to clamping
> *pnum for return to its caller.

Sure, thanks!

Max