btrfs-progs: tests: Add test case with valid orphan inode

Regression test for false alerts in lowmem mode.

Signed-off-by: Qu Wenruo <wqu@suse.com>
[ update test ]
Signed-off-by: David Sterba <dsterba@suse.com>

tests/fsck-tests/029-valid-orphan-item/test.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+# To check if btrfs check can handle valid orphan items.
+# Orphan item is a marker for deleted inodes that were open at the time of
+# deletion.  # Orphan inode/root will is not referenced and will have an orphan
+# item, which should not be reported as error.
+
+source "$TEST_TOP/common"
+
+check_prereq btrfs
+
+check_image() {
+	run_check "$TOP/btrfs" check "$1"
+}
+
+check_all_images