[Qemu-devel] [PULL 21/44] block: add transactional properties

[Stefan Hajnoczi]

From: John Snow <address@hidden>

Add both transactional properties to the QMP transactional interface,
and add the BlockJobTxn that we create as a result of the err-cancel
property to the BlkActionState structure.

[split up from a patch originally by Stefan and Fam. --js]
Signed-off-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Fam Zheng <address@hidden>
Signed-off-by: John Snow <address@hidden>

Signed-off-by: John Snow <address@hidden>
Message-id: address@hidden
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
 blockdev.c       | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
 qapi-schema.json | 50 +++++++++++++++++++++++++++++++++---
 qmp-commands.hx  |  2 +-
 3 files changed, 122 insertions(+), 8 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 03b637b..9907822 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1131,7 +1131,7 @@ static void blockdev_do_action(TransactionActionKind 
type, void *data,
     action.u.data = data;
     list.value = &action;
     list.next = NULL;
-    qmp_transaction(&list, errp);
+    qmp_transaction(&list, false, NULL, errp);
 }
 
 void qmp_blockdev_snapshot_sync(bool has_device, const char *device,
@@ -1351,6 +1351,7 @@ typedef struct BlkActionOps {
  *
  * @action: QAPI-defined enum identifying which Action to perform.
  * @ops: Table of ActionOps this Action can perform.
+ * @block_job_txn: Transaction which this action belongs to.
  * @entry: List membership for all Actions in this Transaction.
  *
  * This structure must be arranged as first member in a subclassed type,
@@ -1360,6 +1361,8 @@ typedef struct BlkActionOps {
 struct BlkActionState {
     TransactionAction *action;
     const BlkActionOps *ops;
+    BlockJobTxn *block_job_txn;
+    TransactionProperties *txn_props;
     QSIMPLEQ_ENTRY(BlkActionState) entry;
 };
 
@@ -1372,6 +1375,20 @@ typedef struct InternalSnapshotState {
     bool created;
 } InternalSnapshotState;
 
+
+static int action_check_completion_mode(BlkActionState *s, Error **errp)
+{
+    if (s->txn_props->completion_mode != ACTION_COMPLETION_MODE_INDIVIDUAL) {
+        error_setg(errp,
+                   "Action '%s' does not support Transaction property "
+                   "completion-mode = %s",
+                   TransactionActionKind_lookup[s->action->type],
+                   ActionCompletionMode_lookup[s->txn_props->completion_mode]);
+        return -1;
+    }
+    return 0;
+}
+
 static void internal_snapshot_prepare(BlkActionState *common,
                                       Error **errp)
 {
@@ -1397,6 +1414,10 @@ static void internal_snapshot_prepare(BlkActionState 
*common,
     name = internal->name;
 
     /* 2. check for validation */
+    if (action_check_completion_mode(common, errp) < 0) {
+        return;
+    }
+
     blk = blk_by_name(device);
     if (!blk) {
         error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
@@ -1554,6 +1575,10 @@ static void external_snapshot_prepare(BlkActionState 
*common,
     }
 
     /* start processing */
+    if (action_check_completion_mode(common, errp) < 0) {
+        return;
+    }
+
     state->old_bs = bdrv_lookup_bs(has_device ? device : NULL,
                                    has_node_name ? node_name : NULL,
                                    &local_err);
@@ -1721,7 +1746,7 @@ static void drive_backup_prepare(BlkActionState *common, 
Error **errp)
                     backup->has_bitmap, backup->bitmap,
                     backup->has_on_source_error, backup->on_source_error,
                     backup->has_on_target_error, backup->on_target_error,
-                    NULL, &local_err);
+                    common->block_job_txn, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1810,7 +1835,7 @@ static void blockdev_backup_prepare(BlkActionState 
*common, Error **errp)
                        backup->has_speed, backup->speed,
                        backup->has_on_source_error, backup->on_source_error,
                        backup->has_on_target_error, backup->on_target_error,
-                       NULL, &local_err);
+                       common->block_job_txn, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1857,6 +1882,10 @@ static void 
block_dirty_bitmap_add_prepare(BlkActionState *common,
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
+    if (action_check_completion_mode(common, errp) < 0) {
+        return;
+    }
+
     action = common->action->u.block_dirty_bitmap_add;
     /* AIO context taken and released within qmp_block_dirty_bitmap_add */
     qmp_block_dirty_bitmap_add(action->node, action->name,
@@ -1892,6 +1921,10 @@ static void 
block_dirty_bitmap_clear_prepare(BlkActionState *common,
                                              common, common);
     BlockDirtyBitmap *action;
 
+    if (action_check_completion_mode(common, errp) < 0) {
+        return;
+    }
+
     action = common->action->u.block_dirty_bitmap_clear;
     state->bitmap = block_dirty_bitmap_lookup(action->node,
                                               action->name,
@@ -1995,19 +2028,50 @@ static const BlkActionOps actions[] = {
     }
 };
 
+/**
+ * Allocate a TransactionProperties structure if necessary, and fill
+ * that structure with desired defaults if they are unset.
+ */
+static TransactionProperties *get_transaction_properties(
+    TransactionProperties *props)
+{
+    if (!props) {
+        props = g_new0(TransactionProperties, 1);
+    }
+
+    if (!props->has_completion_mode) {
+        props->has_completion_mode = true;
+        props->completion_mode = ACTION_COMPLETION_MODE_INDIVIDUAL;
+    }
+
+    return props;
+}
+
 /*
  * 'Atomic' group operations.  The operations are performed as a set, and if
  * any fail then we roll back all operations in the group.
  */
-void qmp_transaction(TransactionActionList *dev_list, Error **errp)
+void qmp_transaction(TransactionActionList *dev_list,
+                     bool has_props,
+                     struct TransactionProperties *props,
+                     Error **errp)
 {
     TransactionActionList *dev_entry = dev_list;
+    BlockJobTxn *block_job_txn = NULL;
     BlkActionState *state, *next;
     Error *local_err = NULL;
 
     QSIMPLEQ_HEAD(snap_bdrv_states, BlkActionState) snap_bdrv_states;
     QSIMPLEQ_INIT(&snap_bdrv_states);
 
+    /* Does this transaction get canceled as a group on failure?
+     * If not, we don't really need to make a BlockJobTxn.
+     */
+    props = get_transaction_properties(props);
+    if (props->completion_mode != ACTION_COMPLETION_MODE_INDIVIDUAL) {
+        block_job_txn = block_job_txn_new();
+    }
+
     /* drain all i/o before any operations */
     bdrv_drain_all();
 
@@ -2027,6 +2091,8 @@ void qmp_transaction(TransactionActionList *dev_list, 
Error **errp)
         state = g_malloc0(ops->instance_size);
         state->ops = ops;
         state->action = dev_info;
+        state->block_job_txn = block_job_txn;
+        state->txn_props = props;
         QSIMPLEQ_INSERT_TAIL(&snap_bdrv_states, state, entry);
 
         state->ops->prepare(state, &local_err);
@@ -2059,6 +2125,10 @@ exit:
         }
         g_free(state);
     }
+    if (!has_props) {
+        qapi_free_TransactionProperties(props);
+    }
+    block_job_txn_unref(block_job_txn);
 }
 
 
diff --git a/qapi-schema.json b/qapi-schema.json
index dbab843..b9d02f4 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1520,6 +1520,26 @@
   'data': { } }
 
 ##
+# @ActionCompletionMode
+#
+# An enumeration of Transactional completion modes.
+#
+# @individual: Do not attempt to cancel any other Actions if any Actions fail
+#              after the Transaction request succeeds. All Actions that
+#              can complete successfully will do so without waiting on others.
+#              This is the default.
+#
+# @grouped: If any Action fails after the Transaction succeeds, cancel all
+#           Actions. Actions do not complete until all Actions are ready to
+#           complete. May be rejected by Actions that do not support this
+#           completion mode.
+#
+# Since: 2.5
+##
+{ 'enum': 'ActionCompletionMode',
+  'data': [ 'individual', 'grouped' ] }
+
+##
 # @TransactionAction
 #
 # A discriminated record of operations that can be performed with
@@ -1546,14 +1566,35 @@
    } }
 
 ##
+# @TransactionProperties
+#
+# Optional arguments to modify the behavior of a Transaction.
+#
+# @completion-mode: #optional Controls how jobs launched asynchronously by
+#                   Actions will complete or fail as a group.
+#                   See @ActionCompletionMode for details.
+#
+# Since: 2.5
+##
+{ 'struct': 'TransactionProperties',
+  'data': {
+       '*completion-mode': 'ActionCompletionMode'
+  }
+}
+
+##
 # @transaction
 #
 # Executes a number of transactionable QMP commands atomically. If any
 # operation fails, then the entire set of actions will be abandoned and the
 # appropriate error returned.
 #
-#  List of:
-#  @TransactionAction: information needed for the respective operation
+# @actions: List of @TransactionAction;
+#           information needed for the respective operations.
+#
+# @properties: #optional structure of additional options to control the
+#              execution of the transaction. See @TransactionProperties
+#              for additional detail.
 #
 # Returns: nothing on success
 #          Errors depend on the operations of the transaction
@@ -1565,7 +1606,10 @@
 # Since 1.1
 ##
 { 'command': 'transaction',
-  'data': { 'actions': [ 'TransactionAction' ] } }
+  'data': { 'actions': [ 'TransactionAction' ],
+            '*properties': 'TransactionProperties'
+          }
+}
 
 ##
 # @human-monitor-command:
diff --git a/qmp-commands.hx b/qmp-commands.hx
index d7cf0ff..7ba693a 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1262,7 +1262,7 @@ EQMP
     },
     {
         .name       = "transaction",
-        .args_type  = "actions:q",
+        .args_type  = "actions:q,properties:q?",
         .mhandler.cmd_new = qmp_marshal_transaction,
     },
 
-- 
2.5.0