imsm: improve getinfo_super when reshape is in progress.

If a reshape (migration) is happening, we might need to modify the information
with provide to md so that it can cope with the reshape.
For example, if a migration from 4-device RAID0 to 5-device RAID0 is
happening, we need to tell md that it is reshape from degraded
5-device RAID4 to degraded 6-device RAID4 so md doesn't handle direct
reshape of RAID0.

There may be other migrations supported by IMSM that need special
treatment here.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/super-intel.c b/super-intel.c
index 86e6bd4f1780a5608b9ff2a65b1e752a21817893..0091b2711aa66c4103a8c20f5d12938f261c4388 100644 (file)
--- a/super-intel.c
+++ b/super-intel.c
@@ -1756,14 +1756,47 @@ static void getinfo_super_imsm_volume(struct supertype *st, struct mdinfo *info,
        info->custom_array_size   = __le32_to_cpu(dev->size_high);
        info->custom_array_size   <<= 32;
        info->custom_array_size   |= __le32_to_cpu(dev->size_low);
-       if (prev_map) {
+       if (prev_map && map->map_state == prev_map->map_state) {
+               info->reshape_active = 1;
                info->new_level = get_imsm_raid_level(map);
                info->new_layout = imsm_level_to_layout(info->new_level);
                info->new_chunk = __le16_to_cpu(map->blocks_per_strip) << 9;
+               info->delta_disks = map->num_members - prev_map->num_members;
+               /* We shape information that we give to md might have to be
+                * modify to cope with md's requirement for reshaping arrays.
+                * For example, when reshaping a RAID0, md requires it to be
+                * presented as a degraded RAID4.
+                * Also if a RAID0 is migrating to a RAID5 we need to specify
+                * the array as already being RAID5, but the 'before' layout
+                * is a RAID4-like layout.
+                */
+               switch (info->array.level) {
+               case 0:
+                       switch(info->new_level) {
+                       case 0:
+                               /* conversion is happening as RAID4 */
+                               info->array.level = 4;
+                               info->array.raid_disks += 1;
+                               break;
+                       case 5:
+                               /* conversion is happening as RAID5 */
+                               info->array.level = 5;
+                               info->array.layout = ALGORITHM_PARITY_N;
+                               info->array.raid_disks += 1;
+                               info->delta_disks -= 1;
+                               break;
+                       default:
+                               /* FIXME error message */
+                               info->array.level = UnSet;
+                               break;
+                       }
+                       break;
+               }
        } else {
                info->new_level = UnSet;
                info->new_layout = UnSet;
                info->new_chunk = info->array.chunk_size;
+               info->delta_disks = 0;
        }
        info->disk.major = 0;
        info->disk.minor = 0;
@@ -1777,12 +1810,6 @@ static void getinfo_super_imsm_volume(struct supertype *st, struct mdinfo *info,
                __le32_to_cpu(map_to_analyse->blocks_per_member);
        memset(info->uuid, 0, sizeof(info->uuid));
        info->recovery_start = MaxSector;
-       info->reshape_active = (prev_map != NULL) &&
-                              (map->map_state == prev_map->map_state);
-       if (info->reshape_active)
-               info->delta_disks = map->num_members - prev_map->num_members;
-       else
-               info->delta_disks = 0;
 
        info->reshape_progress = 0;
        if (map_to_analyse->map_state == IMSM_T_STATE_UNINITIALIZED ||