lvconvert: add infrastructure for RaidLV reshaping support

In order to support striped raid5/6/10 LV reshaping (change
of LV type, stripesize or number of legs), this patch
introduces infrastructure prerequisites to be used
by raid_manip.c extensions in followup patches.

This base is needed for allocation of out-of-place
reshape space required by the MD raid personalities to
avoid writing over data in-place when reading off the
current RAID layout or number of legs and writing out
the new layout or to a different number of legs
(i.e. restripe)

Changes:
- add members reshape_len to 'struct lv_segment' to store
  out-of-place reshape length per component rimage
- add member data_copies to struct lv_segment
  to support more than 2 raid10 data copies
- make alloc_lv_segment() aware of both reshape_len and data_copies
- adjust all alloc_lv_segment() callers to the new API
- add functions to retrieve the current data offset (needed for
  out-of-place reshaping space allocation) and the devices count
  from the kernel
- make libdm deptree code aware of reshape_len
- add LV flags for disk add/remove reshaping
- support import/export of the new 'struct lv_segment' members
- enhance lv_extend/_lv_reduce to cope with reshape_len
- add seg_is_*/segtype_is_* macros related to reshaping
- add target version check for reshaping
- grow rebuilds/writemostly bitmaps to 246 bit to support kernel maximal
- enhance libdm deptree code to support data_offset (out-of-place reshaping)
  and delta_disk (legs add/remove reshaping) target arguments

Related: rhbz834579
Related: rhbz1191935
Related: rhbz1191978

1 files changed, 18 insertions, 0 deletions

diff --git a/libdm/libdm-targets.c b/libdm/libdm-targets.c
index c94e05753..6b8337234 100644
--- a/libdm/libdm-targets.c
+++ b/libdm/libdm-targets.c
@@ -89,6 +89,8 @@ static unsigned _count_fields(const char *p)
  *   <raid_type> <#devs> <health_str> <sync_ratio>
  * Versions 1.5.0+  (6 fields):
  *   <raid_type> <#devs> <health_str> <sync_ratio> <sync_action> <mismatch_cnt>
+ * Versions 1.9.0+  (7 fields):
+ *   <raid_type> <#devs> <health_str> <sync_ratio> <sync_action> <mismatch_cnt> <data_offset>
  */
 int dm_get_status_raid(struct dm_pool *mem, const char *params,
 		       struct dm_status_raid **status)
@@ -147,6 +149,22 @@ int dm_get_status_raid(struct dm_pool *mem, const char *params,
 	if (sscanf(p, "%s %" PRIu64, s->sync_action, &s->mismatch_count) != 2)
 		goto_bad;
 
+	if (num_fields < 7)
+		goto out;
+
+	/*
+	 * All pre-1.9.0 version parameters are read.  Now we check
+	 * for additional 1.9.0+ parameters (i.e. nr_fields at least 7).
+	 *
+	 * Note that data_offset will be 0 if the
+	 * kernel returns a pre-1.9.0 status.
+	 */
+	msg_fields = "<data_offset>";
+	if (!(p = _skip_fields(params, 6))) /* skip pre-1.9.0 params */
+		goto bad;
+	if (sscanf(p, "%" PRIu64, &s->data_offset) != 1)
+		goto bad;
+
 out:
 	*status = s;