blockdev: Allow creation of BDS trees without BB
If the "id" field is missing from the options given to blockdev-add,
just omit the BlockBackend and create the BlockDriverState tree alone.
However, if "id" is missing, "node-name" must be specified; otherwise,
the BDS tree would no longer be accessible.
Many BDS options which are not parsed by bdrv_open() (like caching)
cannot be specified for these BB-less BDS trees yet. A future patch will
remove this limitation.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/blockdev.c b/blockdev.c
index 27398b1..07855575 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3026,17 +3026,12 @@
void qmp_blockdev_add(BlockdevOptions *options, Error **errp)
{
QmpOutputVisitor *ov = qmp_output_visitor_new();
- BlockBackend *blk;
+ BlockDriverState *bs;
+ BlockBackend *blk = NULL;
QObject *obj;
QDict *qdict;
Error *local_err = NULL;
- /* Require an ID in the top level */
- if (!options->has_id) {
- error_setg(errp, "Block device needs an ID");
- goto fail;
- }
-
/* TODO Sort it out in raw-posix and drive_new(): Reject aio=native with
* cache.direct=false instead of silently switching to aio=threads, except
* when called from drive_new().
@@ -3064,14 +3059,37 @@
qdict_flatten(qdict);
- blk = blockdev_init(NULL, qdict, &local_err);
- if (local_err) {
- error_propagate(errp, local_err);
- goto fail;
+ if (options->has_id) {
+ blk = blockdev_init(NULL, qdict, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ goto fail;
+ }
+
+ bs = blk_bs(blk);
+ } else {
+ int ret;
+
+ if (!qdict_get_try_str(qdict, "node-name")) {
+ error_setg(errp, "'id' and/or 'node-name' need to be specified for "
+ "the root node");
+ goto fail;
+ }
+
+ bs = NULL;
+ ret = bdrv_open(&bs, NULL, NULL, qdict, BDRV_O_RDWR | BDRV_O_CACHE_WB,
+ errp);
+ if (ret < 0) {
+ goto fail;
+ }
}
- if (bdrv_key_required(blk_bs(blk))) {
- blk_unref(blk);
+ if (bs && bdrv_key_required(bs)) {
+ if (blk) {
+ blk_unref(blk);
+ } else {
+ bdrv_unref(bs);
+ }
error_setg(errp, "blockdev-add doesn't support encrypted devices");
goto fail;
}
diff --git a/qapi/block-core.json b/qapi/block-core.json
index c042561..425fdab 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1393,9 +1393,12 @@
#
# @driver: block driver name
# @id: #optional id by which the new block device can be referred to.
-# This is a required option on the top level of blockdev-add, and
-# currently not allowed on any other level.
-# @node-name: #optional the name of a block driver state node (Since 2.0)
+# This option is only allowed on the top level of blockdev-add.
+# A BlockBackend will be created by blockdev-add if and only if
+# this option is given.
+# @node-name: #optional the name of a block driver state node (Since 2.0).
+# This option is required on the top level of blockdev-add if
+# the @id option is not given there.
# @discard: #optional discard-related options (default: ignore)
# @cache: #optional cache-related options
# @aio: #optional AIO backend (default: threads)
@@ -1859,7 +1862,9 @@
##
# @blockdev-add:
#
-# Creates a new block device.
+# Creates a new block device. If the @id option is given at the top level, a
+# BlockBackend will be created; otherwise, @node-name is mandatory at the top
+# level and no BlockBackend will be created.
#
# This command is still a work in progress. It doesn't support all
# block drivers, it lacks a matching blockdev-del, and more. Stay
diff --git a/tests/qemu-iotests/087 b/tests/qemu-iotests/087
index 8694749..af44299 100755
--- a/tests/qemu-iotests/087
+++ b/tests/qemu-iotests/087
@@ -54,7 +54,7 @@
_make_test_img $size
echo
-echo === Missing ID ===
+echo === Missing ID and node-name ===
echo
run_qemu <<EOF
diff --git a/tests/qemu-iotests/087.out b/tests/qemu-iotests/087.out
index c509a40..7d62cd5 100644
--- a/tests/qemu-iotests/087.out
+++ b/tests/qemu-iotests/087.out
@@ -1,12 +1,12 @@
QA output created by 087
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-=== Missing ID ===
+=== Missing ID and node-name ===
Testing:
QMP_VERSION
{"return": {}}
-{"error": {"class": "GenericError", "desc": "Block device needs an ID"}}
+{"error": {"class": "GenericError", "desc": "'id' and/or 'node-name' need to be specified for the root node"}}
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "SHUTDOWN"}
