[linux-mm-cc] [PATCH 2/4] send callback when swap slot is freed

[Pekka Enberg]

Hi Hugh,

On Mon, Sep 21, 2009 at 2:55 PM, Hugh Dickins
<hugh.dickins at tiscali.co.uk> wrote:
> Though exporting the swap_info_struct still bothers me, and it
> seems convoluted that the block device should have a method, so
> swapon can call the block device, so the block device can call
> swapfile.c to install a callout, so that swapfile.c can call the
> block device when freeing swap.  I'm not saying there is a better
> way, just that I'd be glad of a better way.

I guess we can combine my ->swapon() hook in struct
block_device_operations with Nitin's set_swap_free_notify() function
to avoid exporting struct swap_info_struct. Alternatively, we could
add the ->swap_free() hook too struct block_device_operations. In any
case, I don't think we can do the setup at sys_open() if we keep
Nitin's hook as struct swap_info_struct is not set up until
sys_swapon().

                        Pekka