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, 16 insertions, 4 deletions

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 9aebb4c93b60..bb0df6a18443 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -263,12 +263,25 @@ static int raid0_mergeable_bvec(struct request_queue *q,
                 return max;
 }
 
+static sector_t raid0_size(mddev_t *mddev, sector_t sectors, int raid_disks)
+{
+        sector_t array_sectors = 0;
+        mdk_rdev_t *rdev;
+
+        WARN_ONCE(sectors || raid_disks,
+                  "%s does not support generic reshape\n", __func__);
+
+        list_for_each_entry(rdev, &mddev->disks, same_set)
+                array_sectors += rdev->sectors;
+
+        return array_sectors;
+}
+
 static int raid0_run (mddev_t *mddev)
 {
         unsigned  cur=0, i=0, nb_zone;
         s64 sectors;
         raid0_conf_t *conf;
-        mdk_rdev_t *rdev;
 
         if (mddev->chunk_size == 0) {
                 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
@@ -293,9 +306,7 @@ static int raid0_run (mddev_t *mddev)
                 goto out_free_conf;
 
         /* calculate array device size */
-        mddev->array_sectors = 0;
-        list_for_each_entry(rdev, &mddev->disks, same_set)
-                mddev->array_sectors += rdev->sectors;
+        mddev->array_sectors = raid0_size(mddev, 0, 0);
 
         printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
                 (unsigned long long)mddev->array_sectors);
@@ -511,6 +522,7 @@ static struct mdk_personality raid0_personality=
         .run            = raid0_run,
         .stop           = raid0_stop,
         .status         = raid0_status,
+        .size           = raid0_size,
 };
 
 static int __init raid0_init (void)