Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20180410a' into staging

Migration reversion pull for 2.12

One to revert after we decided it needs some more thinking.

# gpg: Signature made Tue 10 Apr 2018 16:02:17 BST
# gpg:                using RSA key 0516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>"
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-migration-20180410a:
  Revert "migration: Don't activate block devices if using -S"
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

migration/migration.c

@@ -306,21 +306,13 @@ static void process_incoming_migration_bh(void *opaque)
     Error *local_err = NULL;
     MigrationIncomingState *mis = opaque;
 
-    /* Only fire up the block code now if we're going to restart the
-     * VM, else 'cont' will do it.
-     * This causes file locking to happen; so we don't want it to happen
-     * unless we really are starting the VM.
-     */
-    if (autostart && (!global_state_received() ||
-        global_state_get_runstate() == RUN_STATE_RUNNING)) {
-        /* Make sure all file formats flush their mutable metadata.
-         * If we get an error here, just don't restart the VM yet. */
-        bdrv_invalidate_cache_all(&local_err);
-        if (local_err) {
-            error_report_err(local_err);
-            local_err = NULL;
-            autostart = false;
-        }
+    /* Make sure all file formats flush their mutable metadata.
+     * If we get an error here, just don't restart the VM yet. */
+    bdrv_invalidate_cache_all(&local_err);
+    if (local_err) {
+        error_report_err(local_err);
+        local_err = NULL;
+        autostart = false;
     }
 
     /*