blockdev: 'blockdev-add' QMP command

For examples see the changes to qmp-commands.hx.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

blockdev.c

@@ -38,6 +38,8 @@
 #include "qemu/option.h"
 #include "qemu/config-file.h"
 #include "qapi/qmp/types.h"
+#include "qapi-visit.h"
+#include "qapi/qmp-output-visitor.h"
 #include "sysemu/sysemu.h"
 #include "block/block_int.h"
 #include "qmp-commands.h"
@@ -2066,6 +2068,61 @@ void qmp_block_job_complete(const char *device, Error **errp)
     block_job_complete(job, errp);
 }
 
+void qmp_blockdev_add(BlockdevOptions *options, Error **errp)
+{
+    QmpOutputVisitor *ov = qmp_output_visitor_new();
+    QObject *obj;
+    QDict *qdict;
+    DriveInfo *dinfo;
+    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_init: Reject aio=native with
+     * cache.direct=false instead of silently switching to aio=threads, except
+     * if called from drive_init.
+     *
+     * For now, simply forbidding the combination for all drivers will do. */
+    if (options->has_aio && options->aio == BLOCKDEV_AIO_OPTIONS_NATIVE) {
+        bool direct = options->cache->has_direct && options->cache->direct;
+        if (!options->has_cache && !direct) {
+            error_setg(errp, "aio=native requires cache.direct=true");
+            goto fail;
+        }
+    }
+
+    visit_type_BlockdevOptions(qmp_output_get_visitor(ov),
+                               &options, NULL, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+        goto fail;
+    }
+
+    obj = qmp_output_get_qobject(ov);
+    qdict = qobject_to_qdict(obj);
+
+    qdict_flatten(qdict);
+
+    QemuOpts *opts = qemu_opts_from_qdict(&qemu_drive_opts, qdict, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+        goto fail;
+    }
+
+    dinfo = blockdev_init(opts, IF_NONE);
+    if (!dinfo) {
+        error_setg(errp, "Could not open image");
+        goto fail;
+    }
+
+fail:
+    qmp_output_visitor_cleanup(ov);
+}
+
 static void do_qmp_query_block_jobs_one(void *opaque, BlockDriverState *bs)
 {
     BlockJobInfoList **prev = opaque;

qapi-schema.json

@@ -3952,3 +3952,239 @@
 ##
 { 'command': 'query-rx-filter', 'data': { '*name': 'str' },
   'returns': ['RxFilterInfo'] }
+
+
+##
+# @BlockdevDiscardOptions
+#
+# Determines how to handle discard requests.
+#
+# @ignore:      Ignore the request
+# @unmap:       Forward as an unmap request
+#
+# Since: 1.7
+##
+{ 'enum': 'BlockdevDiscardOptions',
+  'data': [ 'ignore', 'unmap' ] }
+
+##
+# @BlockdevAioOptions
+#
+# Selects the AIO backend to handle I/O requests
+#
+# @threads:     Use qemu's thread pool
+# @native:      Use native AIO backend (only Linux and Windows)
+#
+# Since: 1.7
+##
+{ 'enum': 'BlockdevAioOptions',
+  'data': [ 'threads', 'native' ] }
+
+##
+# @BlockdevCacheOptions
+#
+# Includes cache-related options for block devices
+#
+# @writeback:   #optional enables writeback mode for any caches (default: true)
+# @direct:      #optional enables use of O_DIRECT (bypass the host page cache;
+#               default: false)
+# @no-flush:    #optional ignore any flush requests for the device (default:
+#               false)
+#
+# Since: 1.7
+##
+{ 'type': 'BlockdevCacheOptions',
+  'data': { '*writeback': 'bool',
+            '*direct': 'bool',
+            '*no-flush': 'bool' } }
+
+##
+# @BlockdevOptionsBase
+#
+# Options that are available for all block devices, independent of the block
+# driver.
+#
+# @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.
+# @discard:     #optional discard-related options (default: ignore)
+# @cache:       #optional cache-related options
+# @aio:         #optional AIO backend (default: threads)
+# @rerror:      #optional how to handle read errors on the device
+#               (default: report)
+# @werror:      #optional how to handle write errors on the device
+#               (default: enospc)
+# @read-only:   #optional whether the block device should be read-only
+#               (default: false)
+#
+# Since: 1.7
+##
+{ 'type': 'BlockdevOptionsBase',
+  'data': { 'driver': 'str',
+            '*id': 'str',
+            '*discard': 'BlockdevDiscardOptions',
+            '*cache': 'BlockdevCacheOptions',
+            '*aio': 'BlockdevAioOptions',
+            '*rerror': 'BlockdevOnError',
+            '*werror': 'BlockdevOnError',
+            '*read-only': 'bool' } }
+
+##
+# @BlockdevOptionsFile
+#
+# Driver specific block device options for the file backend and similar
+# protocols.
+#
+# @filename:    path to the image file
+#
+# Since: 1.7
+##
+{ 'type': 'BlockdevOptionsFile',
+  'data': { 'filename': 'str' } }
+
+##
+# @BlockdevOptionsVVFAT
+#
+# Driver specific block device options for the vvfat protocol.
+#
+# @dir:         directory to be exported as FAT image
+# @fat-type:    #optional FAT type: 12, 16 or 32
+# @floppy:      #optional whether to export a floppy image (true) or
+#               partitioned hard disk (false; default)
+# @rw:          #optional whether to allow write operations (default: false)
+#
+# Since: 1.7
+##
+{ 'type': 'BlockdevOptionsVVFAT',
+  'data': { 'dir': 'str', '*fat-type': 'int', '*floppy': 'bool',
+            '*rw': 'bool' } }
+
+##
+# @BlockdevOptionsGenericFormat
+#
+# Driver specific block device options for image format that have no option
+# besides their data source.
+#
+# @file:        reference to or definition of the data source block device
+#
+# Since: 1.7
+##
+{ 'type': 'BlockdevOptionsGenericFormat',
+  'data': { 'file': 'BlockdevRef' } }
+
+##
+# @BlockdevOptionsGenericCOWFormat
+#
+# Driver specific block device options for image format that have no option
+# besides their data source and an optional backing file.
+#
+# @backing:     #optional reference to or definition of the backing file block
+#               device (if missing, taken from the image file content). It is
+#               allowed to pass an empty string here in order to disable the
+#               default backing file.
+#
+# Since: 1.7
+##
+{ 'type': 'BlockdevOptionsGenericCOWFormat',
+  'base': 'BlockdevOptionsGenericFormat',
+  'data': { '*backing': 'BlockdevRef' } }
+
+##
+# @BlockdevOptionsQcow2
+#
+# Driver specific block device options for qcow2.
+#
+# @lazy-refcounts:        #optional whether to enable the lazy refcounts
+#                         feature (default is taken from the image file)
+#
+# @pass-discard-request:  #optional whether discard requests to the qcow2
+#                         device should be forwarded to the data source
+#
+# @pass-discard-snapshot: #optional whether discard requests for the data source
+#                         should be issued when a snapshot operation (e.g.
+#                         deleting a snapshot) frees clusters in the qcow2 file
+#
+# @pass-discard-other:    #optional whether discard requests for the data source
+#                         should be issued on other occasions where a cluster
+#                         gets freed
+#
+# Since: 1.7
+##
+{ 'type': 'BlockdevOptionsQcow2',
+  'base': 'BlockdevOptionsGenericCOWFormat',
+  'data': { '*lazy-refcounts': 'bool',
+            '*pass-discard-request': 'bool',
+            '*pass-discard-snapshot': 'bool',
+            '*pass-discard-other': 'bool' } }
+
+##
+# @BlockdevOptions
+#
+# Options for creating a block device.
+#
+# Since: 1.7
+##
+{ 'union': 'BlockdevOptions',
+  'base': 'BlockdevOptionsBase',
+  'discriminator': 'driver',
+  'data': {
+      'file':       'BlockdevOptionsFile',
+      'http':       'BlockdevOptionsFile',
+      'https':      'BlockdevOptionsFile',
+      'ftp':        'BlockdevOptionsFile',
+      'ftps':       'BlockdevOptionsFile',
+      'tftp':       'BlockdevOptionsFile',
+# TODO gluster: Wait for structured options
+# TODO iscsi: Wait for structured options
+# TODO nbd: Should take InetSocketAddress for 'host'?
+# TODO rbd: Wait for structured options
+# TODO sheepdog: Wait for structured options
+# TODO ssh: Should take InetSocketAddress for 'host'?
+      'vvfat':      'BlockdevOptionsVVFAT',
+
+# TODO blkdebug: Wait for structured options
+# TODO blkverify: Wait for structured options
+
+      'bochs':      'BlockdevOptionsGenericFormat',
+      'cloop':      'BlockdevOptionsGenericFormat',
+      'cow':        'BlockdevOptionsGenericCOWFormat',
+      'dmg':        'BlockdevOptionsGenericFormat',
+      'parallels':  'BlockdevOptionsGenericFormat',
+      'qcow':       'BlockdevOptionsGenericCOWFormat',
+      'qcow2':      'BlockdevOptionsQcow2',
+      'qed':        'BlockdevOptionsGenericCOWFormat',
+      'raw':        'BlockdevOptionsGenericFormat',
+      'vdi':        'BlockdevOptionsGenericFormat',
+      'vhdx':       'BlockdevOptionsGenericFormat',
+      'vmdk':       'BlockdevOptionsGenericCOWFormat',
+      'vpc':        'BlockdevOptionsGenericFormat'
+  } }
+
+##
+# @BlockdevRef
+#
+# Reference to a block device.
+#
+# @definition:      defines a new block device inline
+# @reference:       references the ID of an existing block device. An
+#                   empty string means that no block device should be
+#                   referenced.
+#
+# Since: 1.7
+##
+{ 'union': 'BlockdevRef',
+  'discriminator': {},
+  'data': { 'definition': 'BlockdevOptions',
+            'reference': 'str' } }
+
+##
+# @blockdev-add:
+#
+# Creates a new block device.
+#
+# @options: block device options for the new device
+#
+# Since: 1.7
+##
+{ 'command': 'blockdev-add', 'data': { 'options': 'BlockdevOptions' } }

qmp-commands.hx

@@ -3239,4 +3239,59 @@ Example:
       ]
    }
 
+EQMP
+
+    {
+        .name       = "blockdev-add",
+        .args_type  = "options:q",
+        .mhandler.cmd_new = qmp_marshal_input_blockdev_add,
+    },
+
+SQMP
+blockdev-add
+------------
+
+Add a block device.
+
+Arguments:
+
+- "options": block driver options
+
+Example (1):
+
+-> { "execute": "blockdev-add",
+    "arguments": { "options" : { "driver": "qcow2",
+                                 "file": { "driver": "file",
+                                           "filename": "test.qcow2" } } } }
+<- { "return": {} }
+
+Example (2):
+
+-> { "execute": "blockdev-add",
+     "arguments": {
+         "options": {
+           "driver": "qcow2",
+           "id": "my_disk",
+           "discard": "unmap",
+           "cache": {
+               "direct": true,
+               "writeback": true
+           },
+           "file": {
+               "driver": "file",
+               "filename": "/tmp/test.qcow2"
+           },
+           "backing": {
+               "driver": "raw",
+               "file": {
+                   "driver": "file",
+                   "filename": "/dev/fdset/4"
+               }
+           }
+         }
+       }
+     }
+
+<- { "return": {} }
+
 EQMP