[PATCH RFC 07/11] migration/block: Apply the migration_block_* API to postcopy

[Peter Xu <peterx@redhat.com>]

Postcopy also has similar error handling for re-activation of block
devices.  Use the same API as precopy to do the re-activation, for both src
& dst sides.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/migration.c | 22 +++-------------------
 migration/savevm.c    | 10 ++++------
 2 files changed, 7 insertions(+), 25 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index e01264168f..1a1c570c5b 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2544,7 +2544,6 @@ static int postcopy_start(MigrationState *ms, Error **errp)
     QIOChannelBuffer *bioc;
     QEMUFile *fb;
     uint64_t bandwidth = migrate_max_postcopy_bandwidth();
-    bool restart_block = false;
     int cur_state = MIGRATION_STATUS_ACTIVE;
 
     if (migrate_postcopy_preempt()) {
@@ -2580,13 +2579,10 @@ static int postcopy_start(MigrationState *ms, Error **errp)
         goto fail;
     }
 
-    ret = bdrv_inactivate_all();
-    if (ret < 0) {
-        error_setg_errno(errp, -ret, "%s: Failed in bdrv_inactivate_all()",
-                         __func__);
+    if (!migration_block_inactivate(ms)) {
+        error_setg(errp, "%s: Failed in bdrv_inactivate_all()", __func__);
         goto fail;
     }
-    restart_block = true;
 
     /*
      * Cause any non-postcopiable, but iterative devices to
@@ -2656,8 +2652,6 @@ static int postcopy_start(MigrationState *ms, Error **errp)
         goto fail_closefb;
     }
 
-    restart_block = false;
-
     /* Now send that blob */
     if (qemu_savevm_send_packaged(ms->to_dst_file, bioc->data, bioc->usage)) {
         error_setg(errp, "%s: Failed to send packaged data", __func__);
@@ -2702,17 +2696,7 @@ fail_closefb:
 fail:
     migrate_set_state(&ms->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
                           MIGRATION_STATUS_FAILED);
-    if (restart_block) {
-        /* A failure happened early enough that we know the destination hasn't
-         * accessed block devices, so we're safe to recover.
-         */
-        Error *local_err = NULL;
-
-        bdrv_activate_all(&local_err);
-        if (local_err) {
-            error_report_err(local_err);
-        }
-    }
+    migration_block_activate(ms);
     migration_call_notifiers(ms, MIG_EVENT_PRECOPY_FAILED, NULL);
     bql_unlock();
     return -1;
diff --git a/migration/savevm.c b/migration/savevm.c
index a335344c75..2ce5064efc 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2120,7 +2120,6 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
 
 static void loadvm_postcopy_handle_run_bh(void *opaque)
 {
-    Error *local_err = NULL;
     MigrationIncomingState *mis = opaque;
 
     trace_vmstate_downtime_checkpoint("dst-postcopy-bh-enter");
@@ -2141,12 +2140,11 @@ static void loadvm_postcopy_handle_run_bh(void *opaque)
     if (autostart) {
         /* Make sure all file formats throw away their mutable metadata.
          * If we get an error here, just don't restart the VM yet. */
-        bdrv_activate_all(&local_err);
+        bool success = migration_block_activate(migrate_get_current());
+
         trace_vmstate_downtime_checkpoint("dst-postcopy-bh-cache-invalidated");
-        if (local_err) {
-            error_report_err(local_err);
-            local_err = NULL;
-        } else {
+
+        if (success) {
             vm_start();
         }
     } else {
-- 
2.47.0