PM / Hibernate: Make snapshot_release() restore GFP mask

PM / Hibernate: Make snapshot_release() restore GFP mask

BugLink: http://bugs.launchpad.net/bugs/788691

commit 9744997a8a2280e67984d4bffd87221d24f3b6b1 upstream.

If the process using the hibernate user space interface closes
/dev/snapshot after creating a hibernation image without thawing
tasks, snapshot_release() should call pm_restore_gfp_mask() to
restore the GFP mask used before the creation of the image.  Make
that happen.

Tested-by: Alexandre Felipe Muller de Souza <alexandrefm@mandriva.com.br>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Steve Conklin <sconklin@canonical.com>