[Qemu-devel] [Qemu-devel [RFC] [WIP] v1] Keeping the Source side alive incase of network failure (Migration recover from network failure)

[Md Haris Iqbal <haris.phnx@gmail.com>]

---
 include/migration/migration.h |  1 +
 migration/migration.c         | 41 ++++++++++++++++++++++++++++++++++++-----
 vl.c                          |  4 ++++
 3 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/include/migration/migration.h b/include/migration/migration.h
index ac2c12c..33da695 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -325,6 +325,7 @@ void global_state_store_running(void);
 void flush_page_queue(MigrationState *ms);
 int ram_save_queue_pages(MigrationState *ms, const char *rbname,
                          ram_addr_t start, ram_addr_t len);
+int qemu_migrate_postcopy_outgoing_recovery(MigrationState *ms);
 
 PostcopyState postcopy_state_get(void);
 /* Set the state and return the old state */
diff --git a/migration/migration.c b/migration/migration.c
index 991313a..ee0c2a8 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -539,6 +539,7 @@ static bool migration_is_setup_or_active(int state)
     case MIGRATION_STATUS_ACTIVE:
     case MIGRATION_STATUS_POSTCOPY_ACTIVE:
     case MIGRATION_STATUS_SETUP:
+    case MIGRATION_STATUS_POSTCOPY_RECOVERY:
         return true;
 
     default:
@@ -1634,6 +1635,8 @@ static void *migration_thread(void *opaque)
     /* The active state we expect to be in; ACTIVE or POSTCOPY_ACTIVE */
     enum MigrationStatus current_active_state = MIGRATION_STATUS_ACTIVE;
 
+    int32_t ret;
+
     rcu_register_thread();
 
     qemu_savevm_state_header(s->to_dst_file);
@@ -1700,11 +1703,26 @@ static void *migration_thread(void *opaque)
             }
         }
 
-        if (qemu_file_get_error(s->to_dst_file)) {
-            migrate_set_state(&s->state, current_active_state,
-                              MIGRATION_STATUS_FAILED);
-            trace_migration_thread_file_err();
-            break;
+        if ((ret = qemu_file_get_error(s->to_dst_file))) {
+            fprintf(stderr, "1 : Error %s %d\n", strerror(-ret), -ret);
+            if(ret != -EIO && s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
+                /* Network Failure during postcopy */
+
+                current_active_state = MIGRATION_STATUS_POSTCOPY_RECOVERY;
+                runstate_set(RUN_STATE_POSTMIGRATE_RECOVERY);
+                fprintf(stderr, "1.1 : Error %s %d\n", strerror(-ret), -ret);
+                ret = qemu_migrate_postcopy_outgoing_recovery(s);
+                if(ret < 0) {
+                    break;
+                }
+
+            } else {
+                migrate_set_state(&s->state, current_active_state,
+                                             MIGRATION_STATUS_FAILED);
+                fprintf(stderr, "1.2 : Error %s %d\n", strerror(-ret), -ret);
+                trace_migration_thread_file_err();
+                break;
+            }
         }
         current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
         if (current_time >= initial_time + BUFFER_DELAY) {
@@ -1797,6 +1815,19 @@ void migrate_fd_connect(MigrationState *s)
     s->migration_thread_running = true;
 }
 
+int qemu_migrate_postcopy_outgoing_recovery(MigrationState* ms)
+{
+    migrate_set_state(&ms->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
+                                  MIGRATION_STATUS_POSTCOPY_RECOVERY);
+
+    /* Code for network recovery to be added here */
+    while(1) {
+        fprintf(stderr, "Not letting it fail\n");
+        sleep(2);
+    }
+
+}
+
 PostcopyState  postcopy_state_get(void)
 {
     return atomic_mb_read(&incoming_postcopy_state);
diff --git a/vl.c b/vl.c
index 5fd22cb..c237140 100644
--- a/vl.c
+++ b/vl.c
@@ -618,6 +618,10 @@ static const RunStateTransition runstate_transitions_def[] = {
     { RUN_STATE_FINISH_MIGRATE, RUN_STATE_RUNNING },
     { RUN_STATE_FINISH_MIGRATE, RUN_STATE_POSTMIGRATE },
     { RUN_STATE_FINISH_MIGRATE, RUN_STATE_PRELAUNCH },
+    { RUN_STATE_FINISH_MIGRATE, RUN_STATE_POSTMIGRATE_RECOVERY },
+
+    { RUN_STATE_POSTMIGRATE_RECOVERY, RUN_STATE_FINISH_MIGRATE },
+    { RUN_STATE_POSTMIGRATE_RECOVERY, RUN_STATE_SHUTDOWN },
 
     { RUN_STATE_RESTORE_VM, RUN_STATE_RUNNING },
     { RUN_STATE_RESTORE_VM, RUN_STATE_PRELAUNCH },
-- 
2.7.4