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Re: [Qemu-devel] [PATCH 2/3] qapi: Introduce blockdev-group-snapshot-syn
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] qapi: Introduce blockdev-group-snapshot-sync command |
Date: |
Mon, 20 Feb 2012 10:41:44 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120209 Thunderbird/10.0.1 |
On 02/20/2012 10:31 AM, Jeff Cody wrote:
> This is a QAPI/QMP only command to take a snapshot of a group of
> devices. This is simlar to the blockdev-snapshot-sync command, except
s/simlar/similar/
> blockdev-group-snapshot-sync accepts a list devices, filenames, and
> formats.
>
> It is attempted to keep the snapshot of the group atomic; if
> any snapshot of a device in a given group fails, then the whole group
> is reverted back to its original image, and error is reported.
>
> This allows the group of disks to remain consistent with each other,
> even across snapshot failures.
>
> Signed-off-by: Jeff Cody <address@hidden>
> ---
> blockdev.c | 130
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> qapi-schema.json | 45 +++++++++++++++++++
> qmp-commands.hx | 39 ++++++++++++++++
> 3 files changed, 214 insertions(+), 0 deletions(-)
> +
> +error_rollback:
> + /* failure, undo everything as much as we can */
> + QSIMPLEQ_FOREACH(snap_entry, &gsnp_list, entry) {
> + if (snap_entry->has_pivoted) {
> + ret = bdrv_open(snap_entry->bs, snap_entry->old_filename,
> + snap_entry->flags, snap_entry->old_drv);
> + if (ret != 0) {
> + /* This is very very bad */
> + error_set(errp, QERR_OPEN_FILE_FAILED,
> + snap_entry->old_filename);
Is there any way to reduce the likelihood of a rollback failure?
> +SQMP
> +blockdev-group-snapshot-sync
> +----------------------
> +
> +Synchronous snapshot of one or more block devices. A list array input
> +is accepted, that contains the device, snapshot-file to be create as the
> +target of the new image. If the file exists, or if it is a device, the
> +snapshot will be created in the existing file/device. If does not
> +exist, a new file will be created. format specifies the format of the
> +snapshot image, default is qcow2. On failure of any device, it is
> +attempted to reopen the original image for all the devices that were
> +specified.
> +
> +Arguments:
> +
> +- "device": device name to snapshot (json-string)
> +- "snapshot-file": name of new image file (json-string)
> +- "format": format of new image (json-string, optional)
Shouldn't this mention that the arguments is a JSON list, rather than a
single argument?
> +
> +Example:
> +
> +-> { "execute": "blockdev-group-snapshot-sync", "arguments": [{ "device":
> "ide-hd0",
> +
> "snapshot-file":
> +
> "/some/place/my-image",
> + "format":
> "qcow2" },
> + { "device":
> "ide-hd1",
> +
> "snapshot-file":
> +
> "/some/place/my-image2",
> + "format":
> "qcow2" } }
Are you missing a ']' before the final '}' here?
--
Eric Blake address@hidden +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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[Qemu-devel] [PATCH 3/3] qapi: Introduce blockdev-query-group-snapshot-failure, Jeff Cody, 2012/02/20
[Qemu-devel] [PATCH 2/3] qapi: Introduce blockdev-group-snapshot-sync command, Jeff Cody, 2012/02/20
- Re: [Qemu-devel] [PATCH 2/3] qapi: Introduce blockdev-group-snapshot-sync command,
Eric Blake <=