[Qemu-devel] [RFC V3 7/7] qmp: Allow to take external snapshots on bs graphs node.

[Benoît Canet]

Signed-off-by: Benoit Canet <address@hidden>
---
 blockdev.c       | 49 +++++++++++++++++++++++++++++++++++++++++--------
 hmp.c            |  4 +++-
 qapi-schema.json | 13 ++++++++++---
 qmp-commands.hx  | 11 ++++++++++-
 4 files changed, 64 insertions(+), 13 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index e314d62..68d4ad1 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -940,14 +940,22 @@ static void blockdev_do_action(int kind, void *data, 
Error **errp)
     qmp_transaction(&list, errp);
 }
 
-void qmp_blockdev_snapshot_sync(const char *device, const char *snapshot_file,
-                                bool has_format, const char *format,
-                                bool has_mode, enum NewImageMode mode,
-                                Error **errp)
+void qmp_blockdev_snapshot_sync(bool has_device, const char * device,
+                                bool has_node_name, const char * node_name,
+                                const char * snapshot_file,
+                                bool has_snapshot_node_name,
+                                const char * snapshot_node_name,
+                                bool has_format, const char * format,
+                                bool has_mode, NewImageMode mode, Error **errp)
 {
     BlockdevSnapshot snapshot = {
+        .has_device = has_device,
         .device = (char *) device,
+        .has_node_name = has_node_name,
+        .node_name = (char *) node_name,
         .snapshot_file = (char *) snapshot_file,
+        .has_snapshot_node_name = has_snapshot_node_name,
+        .snapshot_node_name = (char *) snapshot_node_name,
         .has_format = has_format,
         .format = (char *) format,
         .has_mode = has_mode,
@@ -1186,7 +1194,12 @@ static void 
external_snapshot_prepare(BlkTransactionState *common,
     BlockDriver *drv;
     int flags, ret;
     Error *local_err = NULL;
+    bool has_device = false;
     const char *device;
+    bool has_node_name = false;
+    const char *node_name;
+    bool has_snapshot_node_name = false;
+    const char *snapshot_node_name;
     const char *new_image_file;
     const char *format = "qcow2";
     enum NewImageMode mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
@@ -1197,7 +1210,14 @@ static void 
external_snapshot_prepare(BlkTransactionState *common,
     /* get parameters */
     g_assert(action->kind == TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC);
 
+    has_device = action->blockdev_snapshot_sync->has_device;
     device = action->blockdev_snapshot_sync->device;
+    has_node_name = action->blockdev_snapshot_sync->has_node_name;
+    node_name = action->blockdev_snapshot_sync->node_name;
+    has_snapshot_node_name =
+        action->blockdev_snapshot_sync->has_snapshot_node_name;
+    snapshot_node_name = action->blockdev_snapshot_sync->snapshot_node_name;
+
     new_image_file = action->blockdev_snapshot_sync->snapshot_file;
     if (action->blockdev_snapshot_sync->has_format) {
         format = action->blockdev_snapshot_sync->format;
@@ -1213,9 +1233,21 @@ static void 
external_snapshot_prepare(BlkTransactionState *common,
         return;
     }
 
-    state->old_bs = bdrv_find(device);
-    if (!state->old_bs) {
-        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+    state->old_bs = bdrv_lookup_bs(has_device, device,
+                                   has_node_name, node_name,
+                                   &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    if (has_node_name && !has_snapshot_node_name) {
+        error_setg(errp, "New snapshot node name missing");
+        return;
+    }
+
+    if (has_snapshot_node_name && bdrv_find_node(snapshot_node_name)) {
+        error_setg(errp, "New snapshot node name already existing");
         return;
     }
 
@@ -1256,7 +1288,8 @@ static void external_snapshot_prepare(BlkTransactionState 
*common,
     }
 
     /* We will manually add the backing_hd field to the bs later */
-    state->new_bs = bdrv_new("", "");
+    state->new_bs = bdrv_new("",
+                             has_snapshot_node_name ? snapshot_node_name : "");
     /* TODO Inherit bs->options or only take explicit options with an
      * extended QMP command? */
     ret = bdrv_open(state->new_bs, new_image_file, NULL,
diff --git a/hmp.c b/hmp.c
index 906ddb7..47dcf0c 100644
--- a/hmp.c
+++ b/hmp.c
@@ -971,7 +971,9 @@ void hmp_snapshot_blkdev(Monitor *mon, const QDict *qdict)
     }
 
     mode = reuse ? NEW_IMAGE_MODE_EXISTING : NEW_IMAGE_MODE_ABSOLUTE_PATHS;
-    qmp_blockdev_snapshot_sync(device, filename, !!format, format,
+    qmp_blockdev_snapshot_sync(true, device, false, NULL,
+                               filename, false, NULL,
+                               !!format, format,
                                true, mode, &errp);
     hmp_handle_error(mon, &errp);
 }
diff --git a/qapi-schema.json b/qapi-schema.json
index 92a7768..8d3ff1a 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1758,18 +1758,25 @@
 ##
 # @BlockdevSnapshot
 #
-# @device:  the name of the device to generate the snapshot from.
+# Either @device or @node-name must be set but not both.
+#
+# @device: #optional the name of the device to generate the snapshot from.
+#
+# @node-name: #optional graph node name to generate the snapshot from (Since 
1.8)
 #
 # @snapshot-file: the target of the new image. A new file will be created.
 #
+# @snapshot-node-name: the graph node name of the new image (Since 1.8)
+#
 # @format: #optional the format of the snapshot image, default is 'qcow2'.
 #
 # @mode: #optional whether and how QEMU should create a new image, default is
 #        'absolute-paths'.
 ##
 { 'type': 'BlockdevSnapshot',
-  'data': { 'device': 'str', 'snapshot-file': 'str', '*format': 'str',
-            '*mode': 'NewImageMode' } }
+  'data': { '*device': 'str', '*node-name': 'str',
+            'snapshot-file': 'str', '*snapshot-node-name': 'str',
+            '*format': 'str', '*mode': 'NewImageMode' } }
 
 ##
 # @BlockdevSnapshotInternal
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 6b309a1..853cc67 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1038,7 +1038,9 @@ actions array:
     - "data": a dictionary.  The contents depend on the value
       of "type".  When "type" is "blockdev-snapshot-sync":
       - "device": device name to snapshot (json-string)
+      - "node-name": graph node name to snapshot (json-string)
       - "snapshot-file": name of new image file (json-string)
+      - "snapshot-node-name": graph node name of the new snapshot (json-string)
       - "format": format of new image (json-string, optional)
       - "mode": whether and how QEMU should create the snapshot file
         (NewImageMode, optional, default "absolute-paths")
@@ -1053,6 +1055,11 @@ Example:
          { 'type': 'blockdev-snapshot-sync', 'data' : { "device": "ide-hd0",
                                          "snapshot-file": 
"/some/place/my-image",
                                          "format": "qcow2" } },
+         { 'type': 'blockdev-snapshot-sync', 'data' : { "node-name": "myfile",
+                                         "snapshot-file": 
"/some/place/my-image2",
+                                         "snapshot-node-name": "node3432",
+                                         "mode": "existing",
+                                         "format": "qcow2" } },
          { 'type': 'blockdev-snapshot-sync', 'data' : { "device": "ide-hd1",
                                          "snapshot-file": 
"/some/place/my-image2",
                                          "mode": "existing",
@@ -1066,7 +1073,7 @@ EQMP
 
     {
         .name       = "blockdev-snapshot-sync",
-        .args_type  = "device:B,snapshot-file:s,format:s?,mode:s?",
+        .args_type  = 
"device:s?,node-name:s?,snapshot-file:s,snapshot-node-name:s?,format:s?,mode:s?",
         .mhandler.cmd_new = qmp_marshal_input_blockdev_snapshot_sync,
     },
 
@@ -1083,7 +1090,9 @@ snapshot image, default is qcow2.
 Arguments:
 
 - "device": device name to snapshot (json-string)
+- "node-name": graph node name to snapshot (json-string)
 - "snapshot-file": name of new image file (json-string)
+- "snapshot-node-name": graph node name of the new snapshot (json-string)
 - "mode": whether and how QEMU should create the snapshot file
   (NewImageMode, optional, default "absolute-paths")
 - "format": format of new image (json-string, optional)
-- 
1.8.3.2