The Monday 03 Mar 2014 à 16:28:45 (+0100), Max Reitz wrote :
> Add a JSON protocol driver which allows supplying block driver options
> through the filename rather than separately. Other than that, it is a
> pure passthrough driver which identifies itself as a filter.
>
> This patch implements the functions bdrv_parse_filename(),
> bdrv_file_open(), bdrv_close(), bdrv_aio_readv(), bdrv_aio_writev(),
> bdrv_getlength(), bdrv_refresh_limits() and bdrv_get_info().
>
> Signed-off-by: Max Reitz <mre...@redhat.com>
> ---
> block/Makefile.objs | 2 +-
> block/json.c | 136
> ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 137 insertions(+), 1 deletion(-)
> create mode 100644 block/json.c
>
> diff --git a/block/Makefile.objs b/block/Makefile.objs
> index fd88c03..d4b70f4 100644
> --- a/block/Makefile.objs
> +++ b/block/Makefile.objs
> @@ -5,7 +5,7 @@ block-obj-y += qed-check.o
> block-obj-$(CONFIG_VHDX) += vhdx.o vhdx-endian.o vhdx-log.o
> block-obj-$(CONFIG_QUORUM) += quorum.o
> block-obj-y += parallels.o blkdebug.o blkverify.o
> -block-obj-y += snapshot.o qapi.o
> +block-obj-y += snapshot.o qapi.o json.o
> block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o
> block-obj-$(CONFIG_POSIX) += raw-posix.o
> block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o
> diff --git a/block/json.c b/block/json.c
> new file mode 100644
> index 0000000..6d63cf6
> --- /dev/null
> +++ b/block/json.c
> @@ -0,0 +1,136 @@
> +/*
> + * JSON filename wrapper protocol driver
> + *
> + * Copyright (c) 2014 Red Hat Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu-common.h"
> +#include "block/block_int.h"
> +#include "qapi/qmp/qdict.h"
> +#include "qapi/qmp/qjson.h"
> +
> +static void json_parse_filename(const char *filename, QDict *options,
> + Error **errp)
> +{
> + QObject *file_options_obj;
> + QDict *full_options;
> +
> + if (!strstart(filename, "json:", &filename)) {
> + error_setg(errp, "Unknown protocol prefix for JSON block driver");
> + return;
> + }
> +
> + file_options_obj = qobject_from_json(filename);
> + if (!file_options_obj) {
> + error_setg(errp, "Could not parse the JSON options");
> + return;
> + }
> +
> + if (qobject_type(file_options_obj) != QTYPE_QDICT) {
> + qobject_decref(file_options_obj);
> + error_setg(errp, "Invalid JSON object");
> + return;
> + }
> +
> + full_options = qdict_new();
> + qdict_put_obj(full_options, "x-options", file_options_obj);
> + qdict_flatten(full_options);
> +
> + qdict_join(options, full_options, true);
> + assert(qdict_size(full_options) == 0);
> + QDECREF(full_options);
> +}
> +
> +static int json_open(BlockDriverState *bs, QDict *options, int flags,
> + Error **errp)
> +{
> + int ret;
> +
> + assert(bs->file == NULL);
> + ret = bdrv_open_image(&bs->file, NULL, options, "x-options", flags,
> false,
> + errp);
> + if (ret < 0) {
> + return ret;
> + }
> +
> + return 0;
Why not ?
return ret;
}
Do you plan to enrich this code path later ?
> +}
> +
> +static void json_close(BlockDriverState *bs)
> +{
> +}
> +
> +static BlockDriverAIOCB *json_aio_readv(BlockDriverState *bs,
> + int64_t sector_num, QEMUIOVector
> *qiov,
> + int nb_sectors,
> + BlockDriverCompletionFunc *cb,
> + void *opaque)
> +{
> + return bdrv_aio_readv(bs->file, sector_num, qiov, nb_sectors, cb,
> opaque);
> +}
> +
> +static BlockDriverAIOCB *json_aio_writev(BlockDriverState *bs,
> + int64_t sector_num, QEMUIOVector
> *qiov,
> + int nb_sectors,
> + BlockDriverCompletionFunc *cb,
> + void *opaque)
> +{
> + return bdrv_aio_writev(bs->file, sector_num, qiov, nb_sectors, cb,
> opaque);
> +}
> +
> +static int64_t json_getlength(BlockDriverState *bs)
> +{
> + return bdrv_getlength(bs->file);
> +}
> +
> +static int json_refresh_limits(BlockDriverState *bs)
> +{
> + bs->bl = bs->file->bl;
> + return 0;
> +}
> +
> +static int json_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
> +{
> + return bdrv_get_info(bs->file, bdi);
> +}
> +
> +static BlockDriver bdrv_json = {
> + .format_name = "json",
> + .protocol_name = "json",
> + .instance_size = 0,
> +
> + .bdrv_parse_filename = json_parse_filename,
> + .bdrv_file_open = json_open,
> + .bdrv_close = json_close,
> +
> + .bdrv_aio_readv = json_aio_readv,
> + .bdrv_aio_writev = json_aio_writev,
> +
> + .has_variable_length = true,
> + .bdrv_getlength = json_getlength,
> +
> + .bdrv_refresh_limits = json_refresh_limits,
> + .bdrv_get_info = json_get_info,
> +
> + .authorizations = { true, true },
Paolo make rewrite the snapshot authorization code.
In the new version you need
.is_filter = true;
.bdrv_recurse_is_first_children = your_implementation;
I don't know when these patchset will be reviewed and merged so maybe this
version is correct.
> +};
> +
> +static void bdrv_json_init(void)
> +{
> + bdrv_register(&bdrv_json);
> +}
> +
> +block_init(bdrv_json_init);
> --
> 1.9.0
>
>
