On Fri, May 25, 2018 at 06:33:17PM +0200, Kevin Wolf wrote:
> This changes the x-blockdev-create QMP command so that it doesn't block
> the monitor and the main loop any more, but starts a background job that
> performs the image creation.
>
This comes down to "user error", but now that the monitor and main loop are
not blocked (which is good), should we try at all to catch/prevent a
blockdev-add that is issued before a blockdev-create completion?
> The basic job as implemented here is all that is necessary to make image
> creation asynchronous and to provide a QMP interface that can be marked
> stable, but it still lacks a few features that jobs usually provide: The
> job will ignore pause commands and it doesn't publish progress yet (so
> both current-progress and total-progress stay at 0). These features can
> be added later without breaking compatibility.
>
> Signed-off-by: Kevin Wolf <kw...@redhat.com>
> ---
> qapi/block-core.json | 14 +++++++----
> qapi/job.json | 4 +++-
> block/create.c | 61
> ++++++++++++++++++++++++++++++++----------------
> tests/qemu-iotests/group | 14 ++++++-----
> 4 files changed, 61 insertions(+), 32 deletions(-)
>
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 7dfa77a05c..1ed3a82373 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -4013,14 +4013,18 @@
> ##
> # @x-blockdev-create:
> #
> -# Create an image format on a given node.
> -# TODO Replace with something asynchronous (block job?)
> +# Starts a job to create an image format on a given node. The job is
> +# automatically finalized, but a manual job-dismiss is required.
> #
> -# Since: 2.12
> +# @job-id: Identifier for the newly created job.
> +#
> +# @options: Options for the image creation.
> +#
> +# Since: 3.0
> ##
> { 'command': 'x-blockdev-create',
> - 'data': 'BlockdevCreateOptions',
> - 'boxed': true }
> + 'data': { 'job-id': 'str',
> + 'options': 'BlockdevCreateOptions' } }
>
> ##
> # @blockdev-open-tray:
> diff --git a/qapi/job.json b/qapi/job.json
> index 970124de76..69c1970a58 100644
> --- a/qapi/job.json
> +++ b/qapi/job.json
> @@ -17,10 +17,12 @@
> #
> # @backup: drive backup job type, see "drive-backup"
> #
> +# @create: image creation job type, see "x-blockdev-create" (since 3.0)
> +#
> # Since: 1.7
> ##
> { 'enum': 'JobType',
> - 'data': ['commit', 'stream', 'mirror', 'backup'] }
> + 'data': ['commit', 'stream', 'mirror', 'backup', 'create'] }
>
> ##
> # @JobStatus:
> diff --git a/block/create.c b/block/create.c
> index 8bd8a03719..87fdab3b72 100644
> --- a/block/create.c
> +++ b/block/create.c
> @@ -24,28 +24,49 @@
>
> #include "qemu/osdep.h"
> #include "block/block_int.h"
> +#include "qemu/job.h"
> #include "qapi/qapi-commands-block-core.h"
> +#include "qapi/qapi-visit-block-core.h"
> +#include "qapi/clone-visitor.h"
> #include "qapi/error.h"
>
> -typedef struct BlockdevCreateCo {
> +typedef struct BlockdevCreateJob {
> + Job common;
> BlockDriver *drv;
> BlockdevCreateOptions *opts;
> int ret;
> - Error **errp;
> -} BlockdevCreateCo;
> + Error *err;
> +} BlockdevCreateJob;
>
> -static void coroutine_fn bdrv_co_create_co_entry(void *opaque)
> +static void blockdev_create_complete(Job *job, void *opaque)
> {
> - BlockdevCreateCo *cco = opaque;
> - cco->ret = cco->drv->bdrv_co_create(cco->opts, cco->errp);
> + BlockdevCreateJob *s = container_of(job, BlockdevCreateJob, common);
> +
> + job_completed(job, s->ret, s->err);
> }
>
> -void qmp_x_blockdev_create(BlockdevCreateOptions *options, Error **errp)
> +static void coroutine_fn blockdev_create_run(void *opaque)
> {
> + BlockdevCreateJob *s = opaque;
> +
> + s->ret = s->drv->bdrv_co_create(s->opts, &s->err);
> +
> + qapi_free_BlockdevCreateOptions(s->opts);
> + job_defer_to_main_loop(&s->common, blockdev_create_complete, NULL);
> +}
> +
> +static const JobDriver blockdev_create_job_driver = {
> + .instance_size = sizeof(BlockdevCreateJob),
> + .job_type = JOB_TYPE_CREATE,
> + .start = blockdev_create_run,
> +};
> +
> +void qmp_x_blockdev_create(const char *job_id, BlockdevCreateOptions
> *options,
> + Error **errp)
> +{
> + BlockdevCreateJob *s;
> const char *fmt = BlockdevDriver_str(options->driver);
> BlockDriver *drv = bdrv_find_format(fmt);
> - Coroutine *co;
> - BlockdevCreateCo cco;
>
> /* If the driver is in the schema, we know that it exists. But it may not
> * be whitelisted. */
> @@ -61,16 +82,16 @@ void qmp_x_blockdev_create(BlockdevCreateOptions
> *options, Error **errp)
> return;
> }
>
> - cco = (BlockdevCreateCo) {
> - .drv = drv,
> - .opts = options,
> - .ret = -EINPROGRESS,
> - .errp = errp,
> - };
> -
> - co = qemu_coroutine_create(bdrv_co_create_co_entry, &cco);
> - qemu_coroutine_enter(co);
> - while (cco.ret == -EINPROGRESS) {
> - aio_poll(qemu_get_aio_context(), true);
> + /* Create the block job */
> + s = job_create(job_id, &blockdev_create_job_driver, NULL,
> + qemu_get_aio_context(), JOB_DEFAULT | JOB_MANUAL_DISMISS,
> + NULL, NULL, errp);
> + if (!s) {
> + return;
> }
> +
> + s->drv = drv,
> + s->opts = QAPI_CLONE(BlockdevCreateOptions, options),
> +
> + job_start(&s->common);
> }
> diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
> index 93f93d71ba..22b0082db3 100644
> --- a/tests/qemu-iotests/group
> +++ b/tests/qemu-iotests/group
> @@ -204,14 +204,16 @@
> 203 rw auto migration
> 204 rw auto quick
> 205 rw auto quick
> -206 rw auto
> -207 rw auto
> +# TODO The following commented out tests need to be reworked to work
> +# with the x-blockdev-create job
> +#206 rw auto
> +#207 rw auto
> 208 rw auto quick
> 209 rw auto quick
> -210 rw auto
> -211 rw auto quick
> -212 rw auto quick
> -213 rw auto quick
> +#210 rw auto
> +#211 rw auto quick
> +#212 rw auto quick
> +#213 rw auto quick
> 214 rw auto
> 215 rw auto quick
> 216 rw auto quick
> --
> 2.13.6
>
>
