Re: [PATCH -next v3 6/7] md: factor out a helper rdev_addable() from remove_and_add_spares()

[Yu Kuai]

Hi,

在 2023/08/22 10:17, Yu Kuai 写道:
> Hi,
>
> 在 2023/08/22 7:22, Song Liu 写道:
> > On Sun, Aug 20, 2023 at 2:13 AM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
> > > From: Yu Kuai <yukuai3@xxxxxxxxxx>
> > >
> > > There are no functional changes, just to make the code simpler and
> > > prepare to delay remove_and_add_spares() to md_start_sync().
> > >
> > > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> > > ---
> > >   drivers/md/md.c | 28 ++++++++++++++++------------
> > >   1 file changed, 16 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/drivers/md/md.c b/drivers/md/md.c
> > > index 11d27c934fdd..cdc361c521d4 100644
> > > --- a/drivers/md/md.c
> > > +++ b/drivers/md/md.c
> > > @@ -9177,6 +9177,20 @@ static bool rdev_is_spare(struct md_rdev *rdev)
> > >                 !test_bit(Faulty, &rdev->flags);
> > >   }
> > >
> > > +static bool rdev_addable(struct md_rdev *rdev)
> > > +{
> > > +       if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 ||
> > > +           test_bit(Faulty, &rdev->flags))
> > > +               return false;
> > > +
> > > +       if (!test_bit(Journal, &rdev->flags) && 
> > > !md_is_rdwr(rdev->mddev) &&
> >
> > Instead of straightforward refactoring, I hope we can make these rdev_*
> > helpers more meaningful, and hopefullly reusable. For example, let's 
> > define
> > the meaning of "addable", and write the function to match that 
> > meaning. In
> > this case, I think we shouldn't check md_is_rdwr() inside rdev_addable().
> >
> > Does this make sense?
>
> Yes, this make sense, rdev can be added to read-only array.
>
> There are total three callers of pers->hot_add_sisk, I'll try to find if
> they have common conditions.

Unfortunately, the conditions is quite different, and It's difficult to
factor out a common helper for them to use.

In this case, !md_is_rdwr() is one of the four conditions, which means
if the array is read-only, there is a special case that rdev can't be
added to the configuration. Perhaps it's okay to keep this?

Thanks,
Kuai
> Thanks,
> Kuai
>
> > Thanks,
> > Song
> >
> >
> > > +           !(rdev->saved_raid_disk >= 0 &&
> > > +             !test_bit(Bitmap_sync, &rdev->flags)))
> > > +               return false;
> > > +
> > > +       return true;
> > > +}
> > > +
> > >   static int remove_and_add_spares(struct mddev *mddev,
> > >                                   struct md_rdev *this)
> > >   {
> > > @@ -9227,20 +9241,10 @@ static int remove_and_add_spares(struct mddev 
> > > *mddev,
> > >                          continue;
> > >                  if (rdev_is_spare(rdev))
> > >                          spares++;
> > > -               if (test_bit(Candidate, &rdev->flags))
> > > +               if (!rdev_addable(rdev))
> > >                          continue;
> > > -               if (rdev->raid_disk >= 0)
> > > -                       continue;
> > > -               if (test_bit(Faulty, &rdev->flags))
> > > -                       continue;
> > > -               if (!test_bit(Journal, &rdev->flags)) {
> > > -                       if (!md_is_rdwr(mddev) &&
> > > -                           !(rdev->saved_raid_disk >= 0 &&
> > > -                             !test_bit(Bitmap_sync, &rdev->flags)))
> > > -                               continue;
> > > -
> > > +               if (!test_bit(Journal, &rdev->flags))
> > >                          rdev->recovery_offset = 0;
> > > -               }
> > >                  if (mddev->pers->hot_add_disk(mddev, rdev) == 0) {
> > >                          /* failure here is OK */
> > >                          sysfs_link_rdev(mddev, rdev);
> > > --
> > > 2.39.2
> > .
>
> .