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SubjectRe: [PATCH] zram: clear disk io accounting when reset zram device
Hello guys,

On Fri, May 29, 2015 at 12:41:41PM +0900, Sergey Senozhatsky wrote:
> On (05/29/15 11:23), Weijie Yang wrote:
> > This patch clears zram disk io accounting when reset the zram device,
> > if don't do this, the residual io accounting stat will affect the
> > diskstat in the next zram active cycle.

Thanks for the fix.

> >
>
> thanks. my bad.
>
> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>

I give my acked-by because it's surely fix so there is no reason to
hesitate.

In future, I hope to change it like below.

I think the problem is caused from weired feature "reset" of zram.
Until a while ago, we didn't have hot_add/del feature so we should
use custom reset function but now we have hot/add feature.
So reset is logically same feature(ie, reset = hot_remove+hot_add
but remains same device id).

If we reuse zram_remove/add for reset, finally it calls del_gendisk
which will do part_stat_set_all for us so we didn't have this kinds
of problems.

It needs more churns and some tweaks of zram_[remove|add] but
it's more clean and consistent between reset and hot_remove.

Just my two cents.

>
> -ss
>
> > Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
> > ---
> > drivers/block/zram/zram_drv.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> > index 8dcbced..6e134f4 100644
> > --- a/drivers/block/zram/zram_drv.c
> > +++ b/drivers/block/zram/zram_drv.c
> > @@ -805,7 +805,9 @@ static void zram_reset_device(struct zram *zram)
> > memset(&zram->stats, 0, sizeof(zram->stats));
> > zram->disksize = 0;
> > zram->max_comp_streams = 1;
> > +
> > set_capacity(zram->disk, 0);
> > + part_stat_set_all(&zram->disk->part0, 0);
> >
> > up_write(&zram->init_lock);
> > /* I/O operation under all of CPU are done so let's free */
> > --
> > 1.7.10.4
> >
> >

--
Kind regards,
Minchan Kim


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