Re: [PATCH v3 28/49] dm zoned: dynamically allocate the dm-zoned-meta shrinker

[Qi Zheng]

On 2023/7/27 18:20, Damien Le Moal wrote:
> On 7/27/23 17:55, Qi Zheng wrote:
> > > >            goto err;
> > > >        }
> > > >    +    zmd->mblk_shrinker->count_objects = dmz_mblock_shrinker_count;
> > > > +    zmd->mblk_shrinker->scan_objects = dmz_mblock_shrinker_scan;
> > > > +    zmd->mblk_shrinker->seeks = DEFAULT_SEEKS;
> > > > +    zmd->mblk_shrinker->private_data = zmd;
> > > > +
> > > > +    shrinker_register(zmd->mblk_shrinker);
> > >
> > > I fail to see how this new shrinker API is better... Why isn't there a
> > > shrinker_alloc_and_register() function ? That would avoid adding all this code
> > > all over the place as the new API call would be very similar to the current
> > > shrinker_register() call with static allocation.
> >
> > In some registration scenarios, memory needs to be allocated in advance.
> > So we continue to use the previous prealloc/register_prepared()
> > algorithm. The shrinker_alloc_and_register() is just a helper function
> > that combines the two, and this increases the number of APIs that
> > shrinker exposes to the outside, so I choose not to add this helper.
>
> And that results in more code in many places instead of less code + a simple
> inline helper in the shrinker header file... So not adding that super simple

It also needs to be exported to the driver for use.

> helper is not exactly the best choice in my opinion.

Hm, either one is fine for me. If no one else objects, I can add this
helper. ;)

>