mds: fix dump dir indicate dir is not cached

Example output:
$ ceph daemon mds.a dump dir /test-dir
[
    {
        "value/bits": "0/0",
        "status": "dirfrag not in cache"
    }
]

Fixes: https://tracker.ceph.com/issues/63093
Signed-off-by: Jos Collin <[email protected]>

Author: joscollin

src/mds/MDSRank.cc

@@ -3393,8 +3393,14 @@ void MDSRank::command_dump_dir(Formatter *f, const cmdmap_t &cmdmap, std::ostrea
   in->dirfragtree.get_leaves_under(frag_t(), leaves);
   for (const auto& leaf : leaves) {
     CDir *dir = in->get_dirfrag(leaf);
-    if (dir)
+    if (dir) {
       mdcache->dump_dir(f, dir, dentry_dump);
+    } else {
+      f->open_object_section("frag");
+      f->dump_stream("frag") << leaf;
+      f->dump_string("status", "dirfrag not in cache");
+      f->close_section();
+    }
   }
   f->close_section();
 }