metadata: use radix_tree for find_lv_in_vg

Since there is a group of commands that need to access 'lv_list'
while still need to search for LV by its name, make the whole
struct lv_list a member of logical_volume structure.
This makes it easy to return also 'lv_list' this list this LV
within VG.
Also the patch should not use more memory, since we were allocating
lv_list for each LV anyway when linkin LV to VG.

Since find_lv_by_name() is now using radix_tree(),
use the same 'search for /' in LV in name for both
find_lv() & find_lv_in_vg().

TODO: Possibly refactor code and use only dm_list
instead of lv_list and dereference LV with container_of()
(thus saving pointer within struct logical_volume) - but
we use 'lv_list' currently in many places...

lib/metadata/lv.h

@@ -21,7 +21,14 @@ union lvid;
 struct lv_segment;
 enum activation_change;
 
+struct lv_list {
+	struct dm_list list;
+	struct logical_volume *lv;
+};
+
 struct logical_volume {
+	/* NOTE: lvid must be the first structure member as it's used for
+	 * offsetof()  calculation in report.c  with columns.h */
 	union lvid lvid;
 	const char *name;
 
@@ -41,6 +48,7 @@ struct logical_volume {
 	struct dm_list snapshot_segs;
 	struct lv_segment *snapshot;
 
+	struct lv_list lvl;
 	struct dm_list segments;
 	struct dm_list tags;
 	struct dm_list segs_using_this_lv;

lib/metadata/metadata-exported.h

@@ -573,11 +573,6 @@ struct pv_list {
 	struct dm_list *pe_ranges;	/* Ranges of PEs e.g. for allocation */
 };
 
-struct lv_list {
-	struct dm_list list;
-	struct logical_volume *lv;
-};
-
 struct glv_list {
 	struct dm_list list;
 	struct generic_logical_volume *glv;

lib/metadata/metadata.c

@@ -1637,6 +1637,7 @@ struct pv_list *find_pv_in_vg_by_uuid(const struct volume_group *vg,
 struct lv_list *find_lv_in_vg(const struct volume_group *vg,
 			      const char *lv_name)
 {
+	struct logical_volume *lv;
 	struct lv_list *lvl;
 	const char *ptr;
 
@@ -1646,6 +1647,11 @@ struct lv_list *find_lv_in_vg(const struct volume_group *vg,
 	else
 		ptr = lv_name;
 
+	if (vg->lv_names) {
+		lv = radix_tree_lookup_ptr(vg->lv_names, ptr, strlen(ptr));
+		return (lv) ? &lv->lvl : NULL;
+	}
+
 	dm_list_iterate_items(lvl, &vg->lvs)
 		if (!strcmp(lvl->lv->name, ptr))
 			return lvl;
@@ -1671,12 +1677,8 @@ struct logical_volume *find_lv_in_vg_by_lvid(const struct volume_group *vg,
 struct logical_volume *find_lv(const struct volume_group *vg,
 			       const char *lv_name)
 {
-	if (!vg->lv_names) {
 	struct lv_list *lvl = find_lv_in_vg(vg, lv_name);
 	return lvl ? lvl->lv : NULL;
-	}
-
-	return radix_tree_lookup_ptr(vg->lv_names, lv_name, strlen(lv_name));
 }
 
 struct generic_logical_volume *find_historical_glv(const struct volume_group *vg,

lib/metadata/vg.c

@@ -116,9 +116,7 @@ int link_lv_to_vg(struct volume_group *vg, struct logical_volume *lv)
 	if (vg_max_lv_reached(vg))
 		stack;
 
-	if (!(lvl = dm_pool_zalloc(vg->vgmem, sizeof(*lvl))))
+	lvl = &lv->lvl;
-		return_0;
-
 	lvl->lv = lv;
 	lv->vg = vg;
 	dm_list_add(&vg->lvs, &lvl->list);