Re: [PATCH v2 07/11] block: add x-blockdev-amend qmp command

[Max Reitz <mreitz@redhat.com>]

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On 13.09.19 00:30, Maxim Levitsky wrote:
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>  block/Makefile.objs       |   2 +-
>  block/amend.c             | 116 ++++++++++++++++++++++++++++++++++++++
>  include/block/block_int.h |  23 ++++++--
>  qapi/block-core.json      |  26 +++++++++
>  qapi/job.json             |   4 +-
>  5 files changed, 163 insertions(+), 8 deletions(-)
>  create mode 100644 block/amend.c

I think I’d move this (and everything to belongs to it) to a different
series.

> diff --git a/block/Makefile.objs b/block/Makefile.objs
> index 35f3bca4d9..10d0308792 100644
> --- a/block/Makefile.objs
> +++ b/block/Makefile.objs
> @@ -18,7 +18,7 @@ block-obj-y += block-backend.o snapshot.o qapi.o
>  block-obj-$(CONFIG_WIN32) += file-win32.o win32-aio.o
>  block-obj-$(CONFIG_POSIX) += file-posix.o
>  block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o
> -block-obj-y += null.o mirror.o commit.o io.o create.o
> +block-obj-y += null.o mirror.o commit.o io.o create.o amend.o
>  block-obj-y += throttle-groups.o
>  block-obj-$(CONFIG_LINUX) += nvme.o
>  
> diff --git a/block/amend.c b/block/amend.c
> new file mode 100644
> index 0000000000..9bd28e08e7
> --- /dev/null
> +++ b/block/amend.c
> @@ -0,0 +1,116 @@
> +/*
> + * Block layer code related to image options amend
> + *
> + * Copyright (c) 2018 Kevin Wolf <kwolf@redhat.com>
> + * Copyright (c) 2019 Maxim Levitsky <mlevitsk@redhat.com>
> + *
> + * Heavily based on create.c
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this software and associated documentation files (the "Software"), to deal
> + * in the Software without restriction, including without limitation the rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "block/block_int.h"
> +#include "qemu/job.h"
> +#include "qemu/main-loop.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 BlockdevAmendJob {
> +    Job common;
> +    BlockdevCreateOptions *opts;
> +    BlockDriverState *bs;
> +    bool force;
> +} BlockdevAmendJob;
> +
> +static int coroutine_fn blockdev_amend_run(Job *job, Error **errp)
> +{
> +    BlockdevAmendJob *s = container_of(job, BlockdevAmendJob, common);
> +    int ret;
> +
> +    job_progress_set_remaining(&s->common, 1);
> +    ret = s->bs->drv->bdrv_co_amend(s->bs, s->opts, s->force, errp);
> +    job_progress_update(&s->common, 1);

It would be nice if the amend job could make use of the progress
reporting that we have in place for amend.

> +
> +    qapi_free_BlockdevCreateOptions(s->opts);
> +
> +    return ret;
> +}
> +
> +static const JobDriver blockdev_amend_job_driver = {
> +    .instance_size = sizeof(BlockdevAmendJob),
> +    .job_type      = JOB_TYPE_AMEND,
> +    .run           = blockdev_amend_run,
> +};
> +
> +void qmp_x_blockdev_amend(const char *job_id,
> +                        const char *node_name,
> +                        BlockdevCreateOptions *options,
> +                        bool has_force,
> +                        bool force,
> +                        Error **errp)
> +{
> +    BlockdevAmendJob *s;
> +    const char *fmt = BlockdevDriver_str(options->driver);
> +    BlockDriver *drv = bdrv_find_format(fmt);
> +    BlockDriverState *bs = bdrv_find_node(node_name);
> +
> +    /*
> +     * If the driver is in the schema, we know that it exists. But it may not
> +     * be whitelisted.
> +     */
> +    assert(drv);
> +    if (bdrv_uses_whitelist() && !bdrv_is_whitelisted(drv, false)) {
> +        error_setg(errp, "Driver is not whitelisted");
> +        return;
> +    }
> +
> +    if (bs->drv != drv) {
> +        error_setg(errp,
> +                   "x-blockdev-amend doesn't support changing the block driver");
> +        return;
> +
> +    }
> +
> +    /* Error out if the driver doesn't support .bdrv_co_amend */
> +    if (!drv->bdrv_co_amend) {
> +        error_setg(errp, "Driver does not support x-blockdev-amend");
> +        return;
> +    }
> +
> +    /*
> +     * 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.

Why shouldn’t the job just run in the node’s context?

Max


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