thin: fix merge of old snaphost

Fix merging of old snapshot into thinvolume origin.
Add also internal error for the error case when
merging requests activation of merged LV.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.02.106 - 
 ====================================
+  Fix merging of old snapshot into thin volume origin.
   Use --ignoreskippedcluster in lvm2-monitor initscript/systemd unit.
   Do not use VG read/write state for LV read/write state.
   Use --ignoreskippedcluster in activation systemd units if use_lvmetad=0.

lib/metadata/snapshot_manip.c

@@ -15,6 +15,7 @@
 
 #include "lib.h"
 #include "metadata.h"
+#include "segtype.h"
 #include "locking.h"
 #include "toolcontext.h"
 #include "lv_alloc.h"
@@ -151,7 +152,7 @@ void init_snapshot_merge(struct lv_segment *snap_seg,
 	origin->snapshot = snap_seg;
 	origin->status |= MERGING;
 
-	if (lv_is_thin_volume(origin)) {
+	if (seg_is_thin_volume(snap_seg)) {
 		snap_seg->merge_lv = origin;
 		/* Making thin LV inivisible with regular log */
 		lv_set_hidden(snap_seg->lv);

lib/thin/thin.c

@@ -542,18 +542,19 @@ static int _thin_add_target_line(struct dev_manager *dm,
 	}
 
 	if (!laopts->no_merging) {
+		if (seg->merge_lv) {
+			log_error(INTERNAL_ERROR "Failed to add merged segment of %s.",
+				  seg->lv->name);
+			return 0;
+		}
 		/*
 		 * merge support for thinp snapshots is implemented by
 		 * simply swapping the thinp device_id of the snapshot
 		 * and origin.
 		 */
-		if (seg->merge_lv) {
+		if (lv_is_merging_origin(seg->lv) && seg_is_thin_volume(find_snapshot(seg->lv)))
-			/* snapshot, use merging lv's device_id */
-			device_id = first_seg(seg->merge_lv)->device_id;
-		} else if (lv_is_merging_origin(seg->lv)) {
 			/* origin, use merging snapshot's device_id */
 			device_id = find_snapshot(seg->lv)->device_id;
-		}
 	}
 
 	if (!dm_tree_node_add_thin_target(node, len, pool_dlid, device_id))

test/shell/thin-merge.sh

@@ -13,7 +13,8 @@
 
 . lib/test
 
-which mkfs.ext2 || skip
+MKFS=mkfs.ext2
+which $MKFS  || skip
 which fsck || skip
 
 #
@@ -27,13 +28,13 @@ lvcreate -T -L8M $vg/pool -V10M -n $lv1
 lvchange --addtag tagL $vg/$lv1
 
 mkdir mnt
-mkfs.ext2 $DM_DEV_DIR/$vg/$lv1
+$MKFS $DM_DEV_DIR/$vg/$lv1
 mount $DM_DEV_DIR/$vg/$lv1 mnt
 touch mnt/test
 
 lvcreate -K -s -n snap --addtag tagS $vg/$lv1
 mkdir mntsnap
-mkfs.ext2 $DM_DEV_DIR/$vg/snap
+$MKFS $DM_DEV_DIR/$vg/snap
 mount $DM_DEV_DIR/$vg/snap mntsnap
 touch mntsnap/test_snap
 
@@ -82,7 +83,7 @@ lvchange -ay $vg/$lv1
 check lv_exists $vg $lv1
 check lv_field  $vg/$lv1 thin_id "2"
 check lv_field $vg/$lv1 tags "tagL"
-not check lv_exists $vg snap
+check lv_not_exists $vg snap
 
 fsck -n $DM_DEV_DIR/$vg/$lv1
 mount $DM_DEV_DIR/$vg/$lv1 mnt
@@ -97,8 +98,10 @@ lvcreate -s -n snap $vg/$lv1
 # Also add old snapshot to thin origin
 lvcreate -s -L10 -n oldsnapof_${lv1} $vg/$lv1
 not lvconvert --merge $vg/snap
-lvremove -f $vg/oldsnapof_${lv1}
+$MKFS $DM_DEV_DIR/$vg/oldsnapof_${lv1}
-
+lvconvert --merge $vg/oldsnapof_${lv1}
+fsck -n $DM_DEV_DIR/$vg/$lv1
+check lv_not_exists $vg oldsnapof_${lv1}
 # Add old snapshot to thin snapshot
 lvcreate -s -L10 -n oldsnapof_snap $vg/snap
 lvconvert --merge $vg/snap

tools/lvconvert.c

@@ -897,7 +897,7 @@ int lvconvert_poll(struct cmd_context *cmd, struct logical_volume *lv,
 
 	if (lv_is_merging_origin(lv))
 		return poll_daemon(cmd, lv_full_name, uuid, background, 0,
-				   lv_is_thin_volume(lv) ?
+				   seg_is_thin_volume(find_snapshot(lv)) ?
 				   &_lvconvert_thin_merge_fns : &_lvconvert_merge_fns,
 				   "Merged");