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| From: | Max Reitz |
| Subject: | Re: [Qemu-devel] [PATCH 02/10] block/json: Add JSON protocol driver |
| Date: | Wed, 05 Mar 2014 21:21:46 +0100 |
| User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 |
On 05.03.2014 21:20, Benoît Canet wrote:
The Wednesday 05 Mar 2014 à 20:58:12 (+0100), Max Reitz wrote :On 05.03.2014 17:04, Benoît Canet wrote: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 <address@hidden> --- 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 ?You're right, that'd be shorter. It's just that I'm so in the habit of writing "ret = foo(); if (ret < 0) { return ret; / goto fail; }" that I didn't notice. ;-)+} + +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.I'll just rebase on top of Paolo's series then.It's a sugestion made by Paolo. I wrote the actual code. The series is : "[PATCH] Rewrite block filter snapshot authorization mechanism"
Okay, thank you again. :-) Max
Thanks, Max+}; + +static void bdrv_json_init(void) +{ + bdrv_register(&bdrv_json); +} + +block_init(bdrv_json_init); -- 1.9.0
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