Add orphan-log-trees test and reclaim_skip_finalize trigger

Add a reclaim_skip_finalize trigger that prevents reclaim from
setting FINALIZED on log_trees entries.  The test arms this trigger,
force-unmounts a client to create an orphan, and verifies the log
merge succeeds without timeout and the orphan reclaim message
appears in dmesg.

Signed-off-by: Auke Kok <auke.kok@versity.com>

tests/tests/orphan-log-trees.sh

@@ -0,0 +1,52 @@
+#
+# Test that orphaned log_trees entries from unmounted rids are
+# finalized and merged.
+#
+# An orphan log_trees entry is one whose rid has no mounted_clients
+# entry.  This can happen from incomplete reclaim across server
+# failovers.  We simulate it with the reclaim_skip_finalize trigger
+# which makes reclaim_open_log_tree skip the finalization step.
+#
+
+t_require_commands touch scoutfs
+t_require_mounts 2
+
+TIMEOUT=90
+
+echo "== create orphan log_trees entry via trigger"
+sv=$(t_server_nr)
+cl=$(t_first_client_nr)
+rid=$(t_mount_rid $cl)
+
+touch "$T_D0/file" "$T_D1/file"
+sync
+
+# arm the trigger so reclaim skips finalization
+t_trigger_arm_silent reclaim_skip_finalize $sv
+
+# force unmount the client, server will fence and reclaim it
+# but the trigger makes reclaim leave log_trees unfinalized
+t_force_umount $cl
+
+# wait for fencing to run
+verify_fenced() {
+	grep -q "running rid '$rid'" "$T_FENCED_LOG" 2>/dev/null
+}
+t_wait_until_timeout $TIMEOUT verify_fenced
+
+# give the server time to complete reclaim after fence
+sleep 5
+
+# remount the client so t_force_log_merge can sync all mounts.
+# the client gets a new rid; the old rid's log_trees is the orphan.
+t_mount $cl
+
+echo "== verify orphan is reclaimed and merge completes"
+t_force_log_merge
+
+echo "== verify orphan reclaim was logged"
+if ! dmesg | grep -q "reclaiming orphan log trees for rid $rid"; then
+	t_fail "expected orphan reclaim message for rid $rid in dmesg"
+fi
+
+t_pass