Re: [PATCH 02/10] Remove need for explicit device initialization

Pekka Enberg
2010-08-09T18:36:54Z

On Mon, Aug 9, 2010 at 8:26 PM, Nitin Gupta <ngupta@vflare.org> wrote:
> Currently, the user has to explicitly write a positive value to
> initstate sysfs node before the device can be used. This event
> triggers allocation of per-device metadata like memory pool,
> table array and so on.
>
> We do not pre-initialize all zram devices since the 'table' array,
> mapping disk blocks to compressed chunks, takes considerable amount
> of memory (8 bytes per page). So, pre-initializing all devices will
> be quite wasteful if only few or none of the devices are actually
> used.
>
> This explicit device initialization from user is an odd requirement and
> can be easily avoided. We now initialize the device when first write is
> done to the device.
>
> Signed-off-by: Nitin Gupta <ngupta@vflare.org>

AFAICT, most hardware block device drivers do things like this in the
probe function. Why can't we do that for zram as well and drop the
->init_done and ->init_lock parts?