Il 09/03/2013 23:22, Stefan Hajnoczi ha scritto:
> @block-backup
>
> Start a point-in-time copy of a block device to a new destination.
>
> @device: the name of the device whose writes should be mirrored.
>
> @target: the target of the new image. If the file exists, or if it
> is a device, the existing file/device will be used as the new
> destination. If it does not exist, a new file will be created.
>
> @format: #optional the format of the new destination, default is to
> probe if @mode is 'existing', else the format of the source
>
> @mode: #optional whether and how QEMU should create a new image, default is
> 'absolute-paths'.
>
> @speed: #optional the maximum speed, in bytes per second
>
> Returns: nothing on success
> If @device is not a valid block device, DeviceNotFound
Two features that would be nice to have:
1) a sync mode (full/top/none) like drive-mirror;
2) transaction support to start multiple backups live without stopping
the VM (for use cases that do not include migration)
Thanks,
Paolo
> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
> ---
> blockdev.c | 92
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> qapi-schema.json | 28 +++++++++++++++++
> qmp-commands.hx | 6 ++++
> 3 files changed, 126 insertions(+)
>
> diff --git a/blockdev.c b/blockdev.c
> index 0e67d06..95a72de 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1208,6 +1208,98 @@ void qmp_block_commit(const char *device,
> drive_get_ref(drive_get_by_blockdev(bs));
> }
>
> +void qmp_block_backup(const char *device, const char *target,
> + bool has_format, const char *format,
> + bool has_mode, enum NewImageMode mode,
> + bool has_speed, int64_t speed,
> + Error **errp)
> +{
> + BlockDriverState *bs;
> + BlockDriverState *target_bs;
> + BlockDriver *proto_drv;
> + BlockDriver *drv = NULL;
> + Error *local_err = NULL;
> + int flags;
> + uint64_t size;
> + int ret;
> +
> + if (!has_speed) {
> + speed = 0;
> + }
> + if (!has_mode) {
> + mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
> + }
> +
> + bs = bdrv_find(device);
> + if (!bs) {
> + error_set(errp, QERR_DEVICE_NOT_FOUND, device);
> + return;
> + }
> +
> + if (!bdrv_is_inserted(bs)) {
> + error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
> + return;
> + }
> +
> + if (!has_format) {
> + format = mode == NEW_IMAGE_MODE_EXISTING ? NULL :
> bs->drv->format_name;
> + }
> + if (format) {
> + drv = bdrv_find_format(format);
> + if (!drv) {
> + error_set(errp, QERR_INVALID_BLOCK_FORMAT, format);
> + return;
> + }
> + }
> +
> + if (bdrv_in_use(bs)) {
> + error_set(errp, QERR_DEVICE_IN_USE, device);
> + return;
> + }
> +
> + flags = bs->open_flags | BDRV_O_RDWR;
> +
> + proto_drv = bdrv_find_protocol(target);
> + if (!proto_drv) {
> + error_set(errp, QERR_INVALID_BLOCK_FORMAT, format);
> + return;
> + }
> +
> + bdrv_get_geometry(bs, &size);
> + size *= 512;
> + if (mode != NEW_IMAGE_MODE_EXISTING) {
> + assert(format && drv);
> + bdrv_img_create(target, format,
> + NULL, NULL, NULL, size, flags, &local_err, false);
> + }
> +
> + if (error_is_set(&local_err)) {
> + error_propagate(errp, local_err);
> + return;
> + }
> +
> + target_bs = bdrv_new("");
> + ret = bdrv_open(target_bs, target, flags, drv);
> +
> + if (ret < 0) {
> + bdrv_delete(target_bs);
> + error_set(errp, QERR_OPEN_FILE_FAILED, target);
> + return;
> + }
> +
> + backup_start(bs, target_bs, speed, block_job_cb, bs, &local_err);
> + if (local_err != NULL) {
> + bdrv_delete(target_bs);
> + error_propagate(errp, local_err);
> + return;
> + }
> +
> + /* Grab a reference so hotplug does not delete the BlockDriverState from
> + * underneath us.
> + */
> + drive_get_ref(drive_get_by_blockdev(bs));
> +}
> +
> #define DEFAULT_MIRROR_BUF_SIZE (10 << 20)
>
> void qmp_drive_mirror(const char *device, const char *target,
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 6b64aec..1dbf7b5 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -1716,6 +1716,34 @@
> '*speed': 'int' } }
>
> ##
> +# @block-backup
> +#
> +# Start a point-in-time copy of a block device to a new destination.
> +#
> +# @device: the name of the device whose writes should be mirrored.
> +#
> +# @target: the target of the new image. If the file exists, or if it
> +# is a device, the existing file/device will be used as the new
> +# destination. If it does not exist, a new file will be created.
> +#
> +# @format: #optional the format of the new destination, default is to
> +# probe if @mode is 'existing', else the format of the source
> +#
> +# @mode: #optional whether and how QEMU should create a new image, default is
> +# 'absolute-paths'.
> +#
> +# @speed: #optional the maximum speed, in bytes per second
> +#
> +# Returns: nothing on success
> +# If @device is not a valid block device, DeviceNotFound
> +#
> +# Since 1.5
> +##
> +{ 'command': 'block-backup',
> + 'data': { 'device': 'str', 'target': 'str', '*format': 'str',
> + '*mode': 'NewImageMode', '*speed': 'int' } }
> +
> +##
> # @drive-mirror
> #
> # Start mirroring a block device's writes to a new destination.
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index 95022e2..bda8eb4 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -889,6 +889,12 @@ EQMP
> },
>
> {
> + .name = "block-backup",
> + .args_type = "device:B,target:s,speed:i?,mode:s?,format:s?",
> + .mhandler.cmd_new = qmp_marshal_input_block_backup,
> + },
> +
> + {
> .name = "block-job-set-speed",
> .args_type = "device:B,speed:o",
> .mhandler.cmd_new = qmp_marshal_input_block_job_set_speed,
>
