[v3,02/11] block: Accept node-name for block-commit

Commit Message

Kevin Wolf July 7, 2016, 12:11 p.m. UTC

In order to remove the necessity to use BlockBackend names in the
external API, we want to allow node-names everywhere. This converts
block-commit to accept a node-name without lifting the restriction that
we're operating at a root node.

As libvirt makes use of the DeviceNotFound error class, we must add
explicit code to retain this behaviour because qmp_get_root_bs() only
returns GenericErrors.

Signed-off-by: Kevin Wolf <[e-mail]>
---
 blockdev.c           | 23 +++++++++++------------
 qapi/block-core.json |  5 ++---
 qmp-commands.hx      |  2 +-
 3 files changed, 14 insertions(+), 16 deletions(-)

Comments

Eric Blake July 7, 2016, 10:52 p.m. UTC | #1

On 07/07/2016 06:11 AM, Kevin Wolf wrote:
> In order to remove the necessity to use BlockBackend names in the
> external API, we want to allow node-names everywhere. This converts
> block-commit to accept a node-name without lifting the restriction that
> we're operating at a root node.
> 
> As libvirt makes use of the DeviceNotFound error class, we must add
> explicit code to retain this behaviour because qmp_get_root_bs() only
> returns GenericErrors.

Indeed, and good thing we had the comment in the code to remind us.

> 
> Signed-off-by: Kevin Wolf <[e-mail]>
> ---
>  blockdev.c           | 23 +++++++++++------------
>  qapi/block-core.json |  5 ++---
>  qmp-commands.hx      |  2 +-
>  3 files changed, 14 insertions(+), 16 deletions(-)
> 

> +++ b/qapi/block-core.json
> @@ -1004,7 +1004,7 @@
>  # Live commit of data from overlay image nodes into backing nodes - i.e.,
>  # writes data between 'top' and 'base' into 'base'.
>  #
> -# @device:  the name of the device
> +# @device:  the device name or node-name of a root node
>  #
>  # @base:   #optional The file name of the backing image to write data into.
>  #                    If not specified, this is the deepest backing image
> @@ -1046,9 +1046,8 @@
>  #
>  # Returns: Nothing on success
>  #          If commit or stream is already active on this device, DeviceInUse
> -#          If @device does not exist, DeviceNotFound

Except deleting this line is at odds with the special casing you added.

>  #          If image commit is not supported by this device, NotSupported
> -#          If @base or @top is invalid, a generic error is returned
> +#          If @device, @base or @top is invalid, a generic error is returned
>  #          If @speed is invalid, InvalidParameter
>  #

Patch

diff --git a/blockdev.c b/blockdev.c
index 01e57c9..e3586f7 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3091,7 +3091,6 @@  void qmp_block_commit(const char *device,
                       bool has_speed, int64_t speed,
                       Error **errp)
 {
-    BlockBackend *blk;
     BlockDriverState *bs;
     BlockDriverState *base_bs, *top_bs;
     AioContext *aio_context;
@@ -3110,22 +3109,22 @@  void qmp_block_commit(const char *device,
      *  live commit feature versions; for this to work, we must make sure to
      *  perform the device lookup before any generic errors that may occur in a
      *  scenario in which all optional arguments are omitted. */
-    blk = blk_by_name(device);
-    if (!blk) {
-        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
-                  "Device '%s' not found", device);
+    bs = qmp_get_root_bs(device, &local_err);
+    if (!bs) {
+        bs = bdrv_lookup_bs(device, device, NULL);
+        if (!bs) {
+            error_free(local_err);
+            error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
+                      "Device '%s' not found", device);
+        } else {
+            error_propagate(errp, local_err);
+        }
         return;
     }
 
-    aio_context = blk_get_aio_context(blk);
+    aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
-    if (!blk_is_available(blk)) {
-        error_setg(errp, "Device '%s' has no medium", device);
-        goto out;
-    }
-    bs = blk_bs(blk);
-
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, errp)) {
         goto out;
     }
diff --git a/qapi/block-core.json b/qapi/block-core.json
index f069e40..6baf6cc 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1004,7 +1004,7 @@ 
 # Live commit of data from overlay image nodes into backing nodes - i.e.,
 # writes data between 'top' and 'base' into 'base'.
 #
-# @device:  the name of the device
+# @device:  the device name or node-name of a root node
 #
 # @base:   #optional The file name of the backing image to write data into.
 #                    If not specified, this is the deepest backing image
@@ -1046,9 +1046,8 @@ 
 #
 # Returns: Nothing on success
 #          If commit or stream is already active on this device, DeviceInUse
-#          If @device does not exist, DeviceNotFound
 #          If image commit is not supported by this device, NotSupported
-#          If @base or @top is invalid, a generic error is returned
+#          If @device, @base or @top is invalid, a generic error is returned
 #          If @speed is invalid, InvalidParameter
 #
 # Since: 1.3
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 0588fd6..c6df92c 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1162,7 +1162,7 @@  data between 'top' and 'base' into 'base'.
 
 Arguments:
 
-- "device": The device's ID, must be unique (json-string)
+- "device": The device name or node-name of a root node (json-string)
 - "base": The file name of the backing image to write data into.
           If not specified, this is the deepest backing image
           (json-string, optional)