Re: fr1-2.16 patch for 2.6.10 kernel

In article <[email protected]> you wrote:
> > You might want to try the obvious changes (- 1 -> - 2, twice).
> 
> Ok, It works, Although not really clean?

Well, if you can figure out the event stamping algorithm, you are a
better man than I! 

If it only shows up on preempt and/or smp machines, I'd suspect a race
between tamping and ejecting from the array..  Heck - it may even be a
race anyway.

> > 
> > Wel, that certainly doesn't show it.  I wanted to know if the
> > bitmap->stop(bitmap) call makes any difference.  If it doesn't, you can
> > try
> > 
> >    remove_bitmap(conf); create_bitmap(conf);
> 
> Changed it too, but remanence is still there.

Isn't that imposible? Urrrrrrrr ... maybe the bitmap_destr routine
needs to _actually_ destroy the pages (hangs head in shame - I don't
turn the bitmap off, ever ..). Hang on and I'll vamp the "remove" bit
of the bitmap code. You need  an extra "print stats" routine anyway.

> It's strange, as normally the bitmap is cleared for any successful write 
>   during resync, but it seems that it remains untouched from a cycle to 
> another one. Maybe a cache effect ?

No - it'll be something more subtle or more obvious. It's good that
it's constant. I should be able to reproduce it.


> Anyway, normally it's here :
> 
> 
> (raid1.c)
> 
>         * on writes, clear the bitmap if all disks were written
>           */
>          int uptodate = test_bit(R1BIO_Uptodate, &r1_bio->state);
>         conf_t *conf = mddev_to_conf(r1_bio->mddev);
> 
>          /* if we should mark the bitmap clean, do so */
>          if (uptodate && bio_data_dir(bio) == WRITE
>                       && r1_bio->nonoperational <= 0) {
>                  struct bitmap * bitmap = conf->bitmap;
>                  if (bitmap && bitmap->active(bitmap)) {
>                          bitmap->clearbits(bitmap,
>                                  bio->bi_sector >> 1, bio->bi_size >> 10);
>                  }
>          }
> 
> I'm going to add some printks here...

OK - but it should show the calls being made!

Peter