device-dax: add resize support

Make the device-dax 'size' attribute writable to allow capacity to be
split between multiple instances in a region.  The intended consumers of
this capability are users that want to split a scarce memory resource
between device-dax and System-RAM access, or users that want to have
multiple security domains for a large region.

By default the hmem instance provider allocates an entire region to the
first instance.  The process of creating a new instance (assuming a
region-id of 0) is find the region and trigger the 'create' attribute
which yields an empty instance to configure.  For example:

    cd /sys/bus/dax/devices
    echo dax0.0 > dax0.0/driver/unbind
    echo $new_size > dax0.0/size
    echo 1 > $(readlink -f dax0.0)../dax_region/create
    seed=$(cat $(readlink -f dax0.0)../dax_region/seed)
    echo $new_size > $seed/size
    echo dax0.0 > ../drivers/{device_dax,kmem}/bind
    echo dax0.1 > ../drivers/{device_dax,kmem}/bind

Instances can be destroyed by:

    echo $device > $(readlink -f $device)../dax_region/delete

Signed-off-by: Dan Williams <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Brice Goglin <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: Jia He <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Ben Skeggs <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Hulk Robot <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jason Yan <[email protected]>
Cc: Jeff Moyer <[email protected]>
Cc: "Jérôme Glisse" <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Pavel Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Vivek Goyal <[email protected]>
Cc: Wei Yang <[email protected]>
Cc: Will Deacon <[email protected]>
Link: https://lkml.kernel.org/r/159643102625.4062302.7431838945566033852.stgit@dwillia2-desk3.amr.corp.intel.com
Link: https://lkml.kernel.org/r/160106115239.30709.9850106928133493138.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions