qemu: add rbd to whitelist of migration-safe formats

QEMU (and librbd) flush the cache on the source before the
destination starts, and the destination does not read any
changeable data before that, so live migration with rbd caching
is safe.

This makes 'virsh migrate' work with rbd and caching without the
--unsafe flag.

Reported-by: Vladimir Bashkirtsev <vladimir@bashkirtsev.com>
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
(cherry picked from commit 78290b1641)

.mailmap

@@ -28,7 +28,8 @@
 <supriyak@linux.vnet.ibm.com> <supriyak@in.ibm.com>
 <neil@aldur.co.uk> <neil@brightbox.co.uk>
 <stefanb@us.ibm.com> <stefanb@linux.vnet.ibm.com>
-<josh.durgin@dreamhost.com> <joshd@hq.newdream.net>
+<josh.durgin@inktank.com> <joshd@hq.newdream.net>
+<josh.durgin@inktank.com> <josh.durgin@dreamhost.com>
 
 # Name consolidation:
 # Preferred author spelling <preferred email>

AUTHORS

@@ -143,7 +143,7 @@ Patches have also been contributed by:
   Hu Tao               <hutao@cn.fujitsu.com>
   Laurent Léonard      <laurent@open-minds.org>
   MORITA Kazutaka      <morita.kazutaka@lab.ntt.co.jp>
-  Josh Durgin          <josh.durgin@dreamhost.com>
+  Josh Durgin          <josh.durgin@inktank.com>
   Roopa Prabhu         <roprabhu@cisco.com>
   Paweł Krześniak      <pawel.krzesniak@gmail.com>
   Kay Schubert         <kayegypt@web.de>

src/qemu/qemu_migration.c

@@ -846,6 +846,9 @@ qemuMigrationIsSafe(virDomainDefPtr def)
                     continue;
                 else if (cfs < 0)
                     return false;
+            } else if (disk->type == VIR_DOMAIN_DISK_TYPE_NETWORK &&
+                       disk->protocol == VIR_DOMAIN_DISK_PROTOCOL_RBD) {
+                continue;
             }
 
             qemuReportError(VIR_ERR_MIGRATE_UNSAFE, "%s",