md: add 'size' as a personality method

In preparation for giving userspace control over ->array_sectors we need
to be able to retrieve the 'default' size, and the 'anticipated' size
when a reshape is requested.  For personalities that do not reshape emit
a warning if anything but the default size is requested.

In the raid5 case we need to update ->previous_raid_disks to make the
new 'default' size available.

Reviewed-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 8034f62a9d28..d2c50da1ae7f 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -312,6 +312,7 @@ struct mdk_personality
         int (*spare_active) (mddev_t *mddev);
         sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);
         int (*resize) (mddev_t *mddev, sector_t sectors);
+        sector_t (*size) (mddev_t *mddev, sector_t sectors, int raid_disks);
         int (*check_reshape) (mddev_t *mddev);
         int (*start_reshape) (mddev_t *mddev);
         int (*reconfig) (mddev_t *mddev, int layout, int chunk_size);