mds: Add fragment to scrub

Add dirfrag split and merge to scrub process.

Fixes: https://tracker.ceph.com/issues/57481
Signed-off-by: Christopher Hoffman <choffman@redhat.com>

Author: chrisphoffman

src/mds/MDCache.cc

@@ -12511,6 +12511,9 @@ void MDCache::force_readonly()
   mds->mdlog->flush();
 }
 
+void MDCache::maybe_fragment(CDir *dir) {
+  mds->balancer->maybe_fragment(dir, false);
+}
 
 // ==============================================================
 // debug crap

src/mds/MDCache.h

@@ -269,6 +269,8 @@ class MDCache {
   bool is_readonly() { return readonly; }
   void force_readonly();
 
+  void maybe_fragment(CDir* dir);
+
   static file_layout_t gen_default_file_layout(const MDSMap &mdsmap);
   static file_layout_t gen_default_log_layout(const MDSMap &mdsmap);
 

src/mds/ScrubStack.cc

@@ -471,6 +471,7 @@ void ScrubStack::scrub_dirfrag(CDir *dir, bool *done)
                  << " log and `damage ls` output for details";
   }
 
+  mdcache->maybe_fragment(dir);
   dir->scrub_finished();
   dir->auth_unpin(this);