On Thu, Jul 13, 2017 at 05:20:52PM +0800, Ming Lei wrote:
> On Thu, Jul 13, 2017 at 01:09:28PM +1000, NeilBrown wrote:
> > On Thu, Jul 13 2017, Ming Lei wrote:
> >
> > > On Thu, Jul 13, 2017 at 10:01:33AM +1000, NeilBrown wrote:
> > >> On Wed, Jul 12 2017, Ming Lei wrote:
> > >>
> > >> > We will support multipage bvec soon, so initialize bvec
> > >> > table using the standardy way instead of writing the
> > >> > talbe directly. Otherwise it won't work any more once
> > >> > multipage bvec is enabled.
> > >> >
> > >> > Acked-by: Guoqing Jiang <gqjiang@xxxxxxxx>
> > >> > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> > >> > ---
> > >> > drivers/md/md.c | 21 +++++++++++++++++++++
> > >> > drivers/md/md.h | 3 +++
> > >> > drivers/md/raid1.c | 16 ++--------------
> > >> > drivers/md/raid10.c | 4 ++--
> > >> > 4 files changed, 28 insertions(+), 16 deletions(-)
> > >> >
> > >> > diff --git a/drivers/md/md.c b/drivers/md/md.c
> > >> > index 8cdca0296749..cc8dcd928dde 100644
> > >> > --- a/drivers/md/md.c
> > >> > +++ b/drivers/md/md.c
> > >> > @@ -9130,6 +9130,27 @@ void md_reload_sb(struct mddev *mddev, int nr)
> > >> > }
> > >> > EXPORT_SYMBOL(md_reload_sb);
> > >> >
> > >> > +/* generally called after bio_reset() for reseting bvec */
> > >> > +void md_bio_reset_resync_pages(struct bio *bio, struct resync_pages *rp,
> > >> > + int size)
> > >> > +{
> > >> > + int idx = 0;
> > >> > +
> > >> > + /* initialize bvec table again */
> > >> > + do {
> > >> > + struct page *page = resync_fetch_page(rp, idx);
> > >> > + int len = min_t(int, size, PAGE_SIZE);
> > >> > +
> > >> > + /*
> > >> > + * won't fail because the vec table is big
> > >> > + * enough to hold all these pages
> > >> > + */
> > >> > + bio_add_page(bio, page, len, 0);
> > >> > + size -= len;
> > >> > + } while (idx++ < RESYNC_PAGES && size > 0);
> > >> > +}
> > >> > +EXPORT_SYMBOL(md_bio_reset_resync_pages);
> > >>
> > >> I really don't think this is a good idea.
> > >> This code is specific to raid1/raid10. It is not generic md code. So
> > >> it doesn't belong here.
> > >
> > > We already added 'struct resync_pages' in drivers/md/md.h, so I think
> > > it is reasonable to add this function into drivers/md/md.c
> >
> > Alternative perspective: it was unreasonable to add "resync_pages" to
> > md.h.
> >
> > >
> > >>
> > >> If you want to remove code duplication, then work on moving all raid1
> > >> functionality into raid10.c, then discard raid1.c
> > >
> > > This patch is for avoiding new code duplication, not for removing current
> > > duplication.
> > >
> > >>
> > >> Or at the very least, have a separate "raid1-10.c" file for the common
> > >> code.
> > >
> > > You suggested it last time, but looks too overkill to be taken. But if
> > > someone wants to refactor raid1 and raid10, I think it can be a good start,
> > > but still not belong to this patch.
> >
> > You are trying to create common code for raid1 and raid10. This does
> > not belong in md.c.
> > If you really want to have a single copy of common code, then it exactly
> > is the role of this patch to create a place to put it.
> > I'm not saying you should put all common code in raid1-10.c. Just the
> > function that you have identified.
>
> I really don't want to waste time on this kind of thing, I can do
> either one frankly.
>
> Shaohua, could you share me which way you like to merge? I can do it in
> either way.
I don't have strong preference, but Neil's suggestion does make the code a
little better. Of course, only put the function into the raid1-10.c right now.
Thanks,
Shaohua
