[RFC][PATCH -mm 0/2] Additional function in swapfile.c (needed for swap suspend)

["Rafael J. Wysocki" <rjw@sisk.pl>]

Hi,

To implement the image-writing part of swsusp in the user space and maintain
the compatibility with the in-kernel implementation we need to be able to
ask the kernel to allocate a swap page from specific swap partition.  For this
purpose we need a function allowing us to specify the swap partition to
allocate from.

Moreover, if we had such a function, we could change the in-kernel
implementation of swsusp to avoid locking of the swap devices that
are not used for suspend and this would allow us to simplify the code
quite a bit.

The first of the following two patches adds such a function, and the second
of them shows what can be done in swsusp if that function is available.

All of your comments and/or suggestions will be appreciated.

Greetings,
Rafael