From: Patrick Donnelly <pdonnell@redhat.com>
Date: Sat, 7 Mar 2020 03:19:49 +0000 (-0800)
Subject: mds: skip export of empty directories
X-Git-Tag: v15.2.5~172^2~16
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=b860823d70a7c6081d73e46be8dda454f30669ad;p=ceph.git

mds: skip export of empty directories

Note: empty as in no cached sub-entries.

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
(cherry picked from commit 570e6cfbcfc98f877a0e21cf536dfc826a4f9d15)
---

diff --git a/src/mds/MDBalancer.cc b/src/mds/MDBalancer.cc
index 89f4040fa2c..c3bac659ecf 100644
--- a/src/mds/MDBalancer.cc
+++ b/src/mds/MDBalancer.cc
@@ -145,7 +145,12 @@ void MDBalancer::handle_export_pins(void)
 	  dir->state_set(CDir::STATE_AUXSUBTREE);
 	}
       } else {
-	mds->mdcache->migrator->export_dir(dir, export_pin);
+        /* Only export a directory if it's non-empty. An empty directory will
+         * be sent back by the importer.
+         */
+        if (dir->get_num_head_items() > 0) {
+	  mds->mdcache->migrator->export_dir(dir, export_pin);
+        }
 	remove = false;
       }
     }