mds: open import bounding dirfrags in batch

Fixes: http://tracker.ceph.com/issues/38679
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
(cherry picked from commit 07de3126a8f14f668b3f24a32f3062196e14805d)
(cherry picked from commit 1f0dcf2b7f43e93212d56739a9d9d2db771b327f)

Note:
        the first "(cherry picked from . . .)" line is present in the master
        commit 1f0dcf2b7f43e93212d56739a9d9d2db771b327f

Conflicts:
	src/mds/Migrator.cc
- no C_MDS_ExportPrepFactory in mimic

diff --git a/src/mds/Migrator.cc b/src/mds/Migrator.cc
index 093f38c3581c05c73636e31b8693b1396bb5ad2e..40a8de544bbfe859fdee45485637e6813e48a018 100644 (file)
--- a/src/mds/Migrator.cc
+++ b/src/mds/Migrator.cc
@@ -2614,6 +2614,8 @@ void Migrator::handle_export_prep(MExportDirPrep *m)
     dout(7) << " not doing assim on " << *dir << dendl;
   }
 
+  MDSGatherBuilder gather(g_ceph_context);
+
   if (!finished.empty())
     mds->queue_waiters(finished);
 
@@ -2640,9 +2642,8 @@ void Migrator::handle_export_prep(MExportDirPrep *m)
        CDir *bound = cache->get_dirfrag(dirfrag_t(p->first, *q));
        if (!bound) {
          dout(7) << "  opening bounding dirfrag " << *q << " on " << *in << dendl;
-         cache->open_remote_dirfrag(in, *q,
-             new C_MDS_RetryMessage(mds, m));
-         return;
+         cache->open_remote_dirfrag(in, *q, gather.new_sub());
+         continue;
        }
 
        if (!bound->state_test(CDir::STATE_IMPORTBOUND)) {
@@ -2656,6 +2657,12 @@ void Migrator::handle_export_prep(MExportDirPrep *m)
       }
     }
 
+    if (gather.has_subs()) {
+      gather.set_finisher(new C_MDS_RetryMessage(mds, m));
+      gather.activate();
+      return;
+    }
+
     dout(7) << " all ready, noting auth and freezing import region" << dendl;
 
     if (!mds->mdcache->is_readonly() &&