[Qemu-devel] [RFC PATCH 1/3] block: add target-id option to drive-backup QMP command

[Fam Zheng]

Add target-id (optional) to drive-backup command, to make the target bs
a named drive so that we can operate on it (e.g. export with NBD).

Signed-off-by: Fam Zheng <address@hidden>
---
 blockdev.c       | 4 +++-
 qapi-schema.json | 7 +++++--
 qmp-commands.hx  | 3 ++-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index b3a57e0..5e694f3 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -935,6 +935,7 @@ static void drive_backup_prepare(BlkTransactionState 
*common, Error **errp)
     backup = common->action->drive_backup;
 
     qmp_drive_backup(backup->device, backup->target,
+                     backup->has_target_id, backup->target_id,
                      backup->has_format, backup->format,
                      backup->has_mode, backup->mode,
                      backup->has_speed, backup->speed,
@@ -1420,6 +1421,7 @@ void qmp_block_commit(const char *device,
 }
 
 void qmp_drive_backup(const char *device, const char *target,
+                      bool has_target_id, const char *target_id,
                       bool has_format, const char *format,
                       bool has_mode, enum NewImageMode mode,
                       bool has_speed, int64_t speed,
@@ -1494,7 +1496,7 @@ void qmp_drive_backup(const char *device, const char 
*target,
         return;
     }
 
-    target_bs = bdrv_new("");
+    target_bs = bdrv_new(has_target_id ? target_id : "");
     ret = bdrv_open(target_bs, target, NULL, flags, drv);
     if (ret < 0) {
         bdrv_delete(target_bs);
diff --git a/qapi-schema.json b/qapi-schema.json
index 30b1edb..abd29c3 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1646,7 +1646,8 @@
 # Since: 1.6
 ##
 { 'type': 'DriveBackup',
-  'data': { 'device': 'str', 'target': 'str', '*format': 'str',
+  'data': { 'device': 'str', 'target': 'str',
+            '*target-id': 'str', '*format': 'str',
             '*mode': 'NewImageMode', '*speed': 'int',
             '*on-source-error': 'BlockdevOnError',
             '*on-target-error': 'BlockdevOnError' } }
@@ -1799,6 +1800,7 @@
 #          is a device, the existing file/device will be used as the new
 #          destination.  If it does not exist, a new file will be created.
 #
+# @target-id: #optional the drive id of the target.
 # @format: #optional the format of the new destination, default is to
 #          probe if @mode is 'existing', else the format of the source
 #
@@ -1825,7 +1827,8 @@
 # Since 1.6
 ##
 { 'command': 'drive-backup',
-  'data': { 'device': 'str', 'target': 'str', '*format': 'str',
+  'data': { 'device': 'str', 'target': 'str',
+            '*target-id': 'str', '*format': 'str',
             '*mode': 'NewImageMode', '*speed': 'int',
             '*on-source-error': 'BlockdevOnError',
             '*on-target-error': 'BlockdevOnError' } }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 362f0e1..c90e132 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -913,7 +913,7 @@ EQMP
 
     {
         .name       = "drive-backup",
-        .args_type  = "device:B,target:s,speed:i?,mode:s?,format:s?,"
+        .args_type  = 
"device:B,target:s,target-id:s?,speed:i?,mode:s?,format:s?,"
                       "on-source-error:s?,on-target-error:s?",
         .mhandler.cmd_new = qmp_marshal_input_drive_backup,
     },
@@ -936,6 +936,7 @@ Arguments:
             device, the existing file/device will be used as the new
             destination.  If it does not exist, a new file will be created.
             (json-string)
+- "target_id": the drive id of the target image.
 - "format": the format of the new destination, default is to probe if 'mode' is
             'existing', else the format of the source
             (json-string, optional)
-- 
1.8.3.1