Support snapshots-of-snapshots

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 lib/activate/activate.c    |    6 +++---
 lib/activate/activate.h    |    3 ++-
 lib/activate/dev_manager.c |   10 ++++++++--
 lib/activate/dev_manager.h |    1 +
 lib/metadata/lv_manip.c    |    9 +++++++--
 5 files changed, 21 insertions(+), 8 deletions(-)

Index: lvm2/lib/metadata/lv_manip.c
===================================================================
--- lvm2.orig/lib/metadata/lv_manip.c
+++ lvm2/lib/metadata/lv_manip.c
@@ -3052,6 +3052,7 @@ int lv_create_single(struct volume_group
 	struct logical_volume *lv, *org = NULL;
 	int origin_active = 0;
 	const char *lv_name;
+	const char *origin_snapid = NULL;
 	struct lvinfo info;
 
 again:
@@ -3136,12 +3137,16 @@ again:
 					  lp->origin);
 				return 0;
 			}
+			if (lv_is_multisnap_cow(org)) {
+				origin_snapid = first_seg(org)->snapid;
+				org = first_seg(org)->origin;
+			}
 			if (lv_is_virtual_origin(org)) {
 				log_error("Can't share virtual origins. "
 					  "Use --virtualsize.");
 				return 0;
 			}
-			if (lv_is_cow(org) || lv_is_multisnap_cow(org)) {
+			if (lv_is_cow(org)) {
 				log_error("Snapshots of snapshots are not "
 					  "supported yet.");
 				return 0;
@@ -3325,7 +3330,7 @@ again:
 			}
 		}
 
-		if (!lv_multisnap_prepare_create(cmd, org, &snapid)) {
+		if (!lv_multisnap_prepare_create(cmd, org, origin_snapid, &snapid)) {
 			log_error("Couldn't make new snapshot for origin LV %s", org->name);
 
 multisnapshot_error:
Index: lvm2/lib/activate/activate.c
===================================================================
--- lvm2.orig/lib/activate/activate.c
+++ lvm2/lib/activate/activate.c
@@ -209,7 +209,7 @@ int lv_activate_with_filter(struct cmd_c
 	return 1;
 }
 
-int lv_multisnap_prepare_create(struct cmd_context *cmd, struct logical_volume *lv, char **snapid)
+int lv_multisnap_prepare_create(struct cmd_context *cmd, struct logical_volume *lv, const char *origin_snapid, char **snapid)
 {
 	return 0;
 }
@@ -1167,7 +1167,7 @@ int lv_activate_with_filter(struct cmd_c
 	return 1;
 }
 
-int lv_multisnap_prepare_create(struct cmd_context *cmd, struct logical_volume *lv, char **snapid)
+int lv_multisnap_prepare_create(struct cmd_context *cmd, struct logical_volume *lv, const char *origin_snapid, char **snapid)
 {
 	struct dev_manager *dm;
 	int r;
@@ -1178,7 +1178,7 @@ int lv_multisnap_prepare_create(struct c
 	if (!(dm = dev_manager_create(cmd, lv->vg->name)))
 		return_0;
 
-	r = dev_manager_multisnap_prepare_create(dm, lv, snapid);
+	r = dev_manager_multisnap_prepare_create(dm, lv, origin_snapid, snapid);
 
 	dev_manager_destroy(dm);
 
Index: lvm2/lib/activate/activate.h
===================================================================
--- lvm2.orig/lib/activate/activate.h
+++ lvm2/lib/activate/activate.h
@@ -63,7 +63,8 @@ int lv_activate_with_filter(struct cmd_c
 int lv_deactivate(struct cmd_context *cmd, const char *lvid_s);
 
 int lv_multisnap_prepare_create(struct cmd_context *cmd,
-				struct logical_volume *lv, char **snapid);
+				struct logical_volume *lv,
+				const char *origin_snapid, char **snapid);
 int lv_multisnap_delete(struct cmd_context *cmd,
 			struct logical_volume *lv, const char *snapid);
 
Index: lvm2/lib/activate/dev_manager.c
===================================================================
--- lvm2.orig/lib/activate/dev_manager.c
+++ lvm2/lib/activate/dev_manager.c
@@ -741,6 +741,7 @@ static int _multisnapshot_status(struct 
 
 int dev_manager_multisnap_prepare_create(struct dev_manager *dm,
 					 struct logical_volume *lv,
+					 const char *origin_snapid,
 					 char **snapid)
 {
 	const char *dlid;
@@ -753,8 +754,13 @@ int dev_manager_multisnap_prepare_create
 
 	log_debug("Getting new snapshot id for %s", lv->name);
 
-	if (!_multisnap_message(dm, dlid, "create"))
-		return 0;
+	if (!origin_snapid) {
+		if (!_multisnap_message(dm, dlid, "create"))
+			return 0;
+	} else {
+		if (!_multisnap_message(dm, dlid, "create_subsnap %s", origin_snapid))
+			return 0;
+	}
 
 	if (!_multisnapshot_status(dm, dlid, &err, snapid, NULL, NULL, NULL))
 		return 0;
Index: lvm2/lib/activate/dev_manager.h
===================================================================
--- lvm2.orig/lib/activate/dev_manager.h
+++ lvm2/lib/activate/dev_manager.h
@@ -62,6 +62,7 @@ int dev_manager_mknodes(const struct log
 
 int dev_manager_multisnap_prepare_create(struct dev_manager *dm,
 					 struct logical_volume *lv,
+					 const char *origin_snapid,
 					 char **snapid);
 int dev_manager_multisnap_delete(struct dev_manager *dm,
 				 struct logical_volume *lv,