Basic support for "snapshot-merge" target.

Adds new function dm_tree_node_add_snapshot_merge_target

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

---
 lib/.exported_symbols |    1 +
 lib/libdevmapper.h    |    5 +++++
 lib/libdm-deptree.c   |   49 +++++++++++++++++++++++++++++++++++++++++--------
 3 files changed, 47 insertions(+), 8 deletions(-)

Index: device-mapper.1.02.27/lib/.exported_symbols
===================================================================
--- device-mapper.1.02.27.orig/lib/.exported_symbols	2008-07-08 19:44:12.000000000 +0200
+++ device-mapper.1.02.27/lib/.exported_symbols	2008-07-08 19:45:02.000000000 +0200
@@ -62,6 +62,7 @@ dm_tree_suspend_children
 dm_tree_children_use_uuid
 dm_tree_node_add_snapshot_origin_target
 dm_tree_node_add_snapshot_target
+dm_tree_node_add_snapshot_merge_target
 dm_tree_node_add_error_target
 dm_tree_node_add_zero_target
 dm_tree_node_add_linear_target
Index: device-mapper.1.02.27/lib/libdevmapper.h
===================================================================
--- device-mapper.1.02.27.orig/lib/libdevmapper.h	2008-07-08 19:44:13.000000000 +0200
+++ device-mapper.1.02.27/lib/libdevmapper.h	2008-07-08 19:45:02.000000000 +0200
@@ -363,6 +363,11 @@ int dm_tree_node_add_snapshot_target(str
 					const char *cow_uuid,
 					int persistent,
 					uint32_t chunk_size);
+int dm_tree_node_add_snapshot_merge_target(struct dm_tree_node *node,
+					     uint64_t size,
+					     const char *origin_uuid,
+					     const char *cow_uuid,
+					     uint32_t chunk_size);
 int dm_tree_node_add_error_target(struct dm_tree_node *node,
 				     uint64_t size);
 int dm_tree_node_add_zero_target(struct dm_tree_node *node,
Index: device-mapper.1.02.27/lib/libdm-deptree.c
===================================================================
--- device-mapper.1.02.27.orig/lib/libdm-deptree.c	2008-07-08 19:44:13.000000000 +0200
+++ device-mapper.1.02.27/lib/libdm-deptree.c	2008-07-08 19:45:02.000000000 +0200
@@ -35,6 +35,7 @@ enum {
 	SEG_MIRRORED,
 	SEG_SNAPSHOT,
 	SEG_SNAPSHOT_ORIGIN,
+	SEG_SNAPSHOT_MERGE,
 	SEG_STRIPED,
 	SEG_ZERO,
 };
@@ -50,6 +51,7 @@ struct {
 	{ SEG_MIRRORED, "mirror" },
 	{ SEG_SNAPSHOT, "snapshot" },
 	{ SEG_SNAPSHOT_ORIGIN, "snapshot-origin" },
+	{ SEG_SNAPSHOT_MERGE, "snapshot-merge" },
 	{ SEG_STRIPED, "striped" },
 	{ SEG_ZERO, "zero"},
 };
@@ -76,6 +78,7 @@ struct load_segment {
 
 	uint32_t stripe_size;		/* Striped */
 
+	int merge;			/* Snapshot */
 	int persistent;			/* Snapshot */
 	uint32_t chunk_size;		/* Snapshot */
 	struct dm_tree_node *cow;	/* Snapshot */
@@ -1362,6 +1365,7 @@ static int _emit_segment_line(struct dm_
 
 		break;
 	case SEG_SNAPSHOT:
+	case SEG_SNAPSHOT_MERGE:
 		if (!_build_dev_string(originbuf, sizeof(originbuf), seg->origin))
 			return_0;
 		if (!_build_dev_string(cowbuf, sizeof(cowbuf), seg->cow))
@@ -1397,6 +1401,7 @@ static int _emit_segment_line(struct dm_
 	case SEG_ERROR:
 	case SEG_SNAPSHOT:
 	case SEG_SNAPSHOT_ORIGIN:
+	case SEG_SNAPSHOT_MERGE:
 	case SEG_ZERO:
 		break;
 	case SEG_LINEAR:
@@ -1609,6 +1614,7 @@ static struct load_segment *_add_segment
 	seg->area_count = 0;
 	list_init(&seg->areas);
 	seg->stripe_size = 0;
+	seg->merge = 0;
 	seg->persistent = 0;
 	seg->chunk_size = 0;
 	seg->cow = NULL;
@@ -1645,17 +1651,21 @@ int dm_tree_node_add_snapshot_origin_tar
 	return 1;
 }
 
-int dm_tree_node_add_snapshot_target(struct dm_tree_node *node,
-                                        uint64_t size,
-                                        const char *origin_uuid,
-                                        const char *cow_uuid,
-                                        int persistent,
-                                        uint32_t chunk_size)
+static int _add_snapshot_target(struct dm_tree_node *node,
+				   uint64_t size,
+				   const char *origin_uuid,
+				   const char *cow_uuid,
+				   int merge,
+				   int persistent,
+				   uint32_t chunk_size)
 {
 	struct load_segment *seg;
 	struct dm_tree_node *origin_node, *cow_node;
+	unsigned seg_type;
+
+	seg_type = !merge ? SEG_SNAPSHOT : SEG_SNAPSHOT_MERGE;
 
-	if (!(seg = _add_segment(node, SEG_SNAPSHOT, size)))
+	if (!(seg = _add_segment(node, seg_type, size)))
 		return_0;
 
 	if (!(origin_node = dm_tree_find_node_by_uuid(node->dtree, origin_uuid))) {
@@ -1668,7 +1678,7 @@ int dm_tree_node_add_snapshot_target(str
 		return_0;
 
 	if (!(cow_node = dm_tree_find_node_by_uuid(node->dtree, cow_uuid))) {
-		log_error("Couldn't find snapshot origin uuid %s.", cow_uuid);
+		log_error("Couldn't find snapshot COW device uuid %s.", cow_uuid);
 		return 0;
 	}
 
@@ -1676,12 +1686,35 @@ int dm_tree_node_add_snapshot_target(str
 	if (!_link_tree_nodes(node, cow_node))
 		return_0;
 
+	seg->merge = merge ? 1 : 0;
 	seg->persistent = persistent ? 1 : 0;
 	seg->chunk_size = chunk_size;
 
 	return 1;
 }
 
+
+int dm_tree_node_add_snapshot_target(struct dm_tree_node *node,
+                                        uint64_t size,
+                                        const char *origin_uuid,
+                                        const char *cow_uuid,
+                                        int persistent,
+                                        uint32_t chunk_size)
+{
+	return _add_snapshot_target(node, size, origin_uuid, cow_uuid, 0,
+				    persistent, chunk_size);
+}
+
+int dm_tree_node_add_snapshot_merge_target(struct dm_tree_node *node,
+					     uint64_t size,
+					     const char *origin_uuid,
+					     const char *cow_uuid,
+					     uint32_t chunk_size
+					     )
+{
+	return _add_snapshot_target(node, size, origin_uuid, cow_uuid, 1, 1, chunk_size);
+}
+
 int dm_tree_node_add_error_target(struct dm_tree_node *node,
                                      uint64_t size)
 {