cleanup: consolidate lv_layout and lv_role reporting

This patch makes the keyword combinations found in "lv_layout" and
"lv_role" much more understandable - there were some ambiguities
for some of the combinations which lead to confusion before.

Now, the scheme used is:

LAYOUTS ("how the LV is laid out"):
===================================
[linear] (all segments have number of stripes = 1)

[striped] (all segments have number of stripes > 1)

[linear,striped] (mixed linear and striped)

raid (raid layout always reported together with raid level, raid layout == image + metadata LVs underneath that make up raid LV)
  [raid,raid1]
  [raid,raid10]
  [raid,raid4]
  [raid,raid5] (exact sublayout not specified during creation - default one used - raid5_ls)
    [raid,raid5,raid5_ls]
    [raid,raid5,raid6_rs]
    [raid,raid5,raid5_la]
    [raid,raid5,raid5_ra]
  [raid6,raid] (exact sublayout not specified during creation - default one used - raid6_zr)
    [raid,raid6,raid6_zr]
    [raid,raid6,raid6_nc]
    [raid,raid6,raid6_ns]

[mirror] (mirror layout == log + image LVs underneath that make up mirror LV)

thin (thin layout always reported together with sublayout)
  [thin,sparse] (thin layout == allocated out of thin pool)
  [thin,pool] (thin pool layout == data + metadata volumes underneath that make up thin pool LV, not supposed to be used for direct use!!!)

[cache] (cache layout == allocated out of cache pool in conjunction with cache origin)
  [cache,pool] (cache pool layout == data + metadata volumes underneath that make up cache pool LV, not supposed to be used for direct use!!!)

[virtual] (virtual layout == not hitting disk underneath, currently this layout denotes only 'zero' device used for origin,thickorigin role)

[unknown] (either error state or missing recognition for such layout)

ROLES ("what's the purpose or use of the LV - what is its role"):
=================================================================
- each LV has either of these two roles at least:  [public] (public LV that users may use freely to write their data to)

  [public] (public LV that users may use freely to write their data to)
  [private] (private LV that LVM maintains; not supposed to be directly used by user to write his data to)

- and then some special-purpose roles in addition to that:

  [origin,thickorigin] (origin for thick-style snapshot; "thick" as opposed to "thin")
  [origin,multithickorigin] (there are more than 2 thick-style snapshots for this origin)
  [origin,thinorigin] (origin for thin snapshot)
  [origin,multithinorigin] (there are more than 2 thin snapshots for this origin)
  [origin,extorigin] (external origin for thin snapshot)
  [origin,multiextoriginl (there are more than 2 thin snapshots using this external origin)
  [origin,cacheorigin] (cache origin)

  [snapshot,thicksnapshot] (thick-style snapshot; "thick" as opposed to "thin")
  [snapshot,thinsnapshot] (thin-style snapshot)

  [raid,metadata] (raid metadata LV)
  [raid,image] (raid image LV)

  [mirror,image] (mirror image LV)
  [mirror,log] (mirror log LV)
  [pvmove] (pvmove LV)

  [thin,pool,data] (thin pool data LV)
  [thin,pool,metadata] (thin pool metadata LV)

  [cache,pool,data] (cache pool data LV)
  [cache,pool,metadata] (cache pool metadata LV)

  [pool,spare] (pool spare LV - common role of LV that makes it used for both thin and cache repairs)

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/datastruct/str_list.h b/lib/datastruct/str_list.h
index a052df602..0046fe42a 100644
--- a/lib/datastruct/str_list.h
+++ b/lib/datastruct/str_list.h
@@ -22,6 +22,7 @@ struct dm_pool;
 struct dm_list *str_list_create(struct dm_pool *mem);
 int str_list_add(struct dm_pool *mem, struct dm_list *sll, const char *str);
 int str_list_add_no_dup_check(struct dm_pool *mem, struct dm_list *sll, const char *str);
+int str_list_add_h_no_dup_check(struct dm_pool *mem, struct dm_list *sll, const char *str);
 void str_list_del(struct dm_list *sll, const char *str);
 int str_list_match_item(const struct dm_list *sll, const char *str);
 int str_list_match_list(const struct dm_list *sll, const struct dm_list *sll2, const char **tag_matched);