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block/create: Make x-blockdev-create a job

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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.

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 more than very
basic progress yet (total-progress is 1 and current-progress advances
from 0 to 1 when the driver callbacks returns). These features can be
added later without breaking compatibility.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
This commit is contained in:
Kevin Wolf 2018-01-18 14:33:04 +01:00
parent 1266c9b9f5
commit e5ab4347f9
4 changed files with 66 additions and 33 deletions
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67
block/create.c
View file

@ -24,28 +24,51 @@
#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;
job_progress_set_remaining(&s->common, 1);
s->ret = s->drv->bdrv_co_create(s->opts, &s->err);
job_progress_update(&s->common, 1);
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. */
@ -55,22 +78,24 @@ void qmp_x_blockdev_create(BlockdevCreateOptions *options, Error **errp)
return;
}
/* Call callback if it exists */
/* Error out if the driver doesn't support .bdrv_co_create */
if (!drv->bdrv_co_create) {
error_setg(errp, "Driver does not support blockdev-create");
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 */
/* TODO Running in the main context. Block drivers need to error out or add
* locking when they use a BDS in a different AioContext. */
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);
}