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[Qemu-devel] Re: [PATCH 2/3] Introduce do_snapshot_blkdev() and monitor
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] Re: [PATCH 2/3] Introduce do_snapshot_blkdev() and monitor command to handle it. |
Date: |
Thu, 16 Dec 2010 12:45:47 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.15) Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10 |
Am 16.12.2010 12:04, schrieb address@hidden:
> From: Jes Sorensen <address@hidden>
>
> The monitor command is:
> snapshot_blkdev <device> [snapshot-file] [format]
>
> Default format is qcow2. For now snapshots without a snapshot-file, eg
> internal snapshots, are not supported.
>
> Signed-off-by: Jes Sorensen <address@hidden>
> ---
> blockdev.c | 61
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> blockdev.h | 1 +
> hmp-commands.hx | 19 +++++++++++++++++
> 3 files changed, 81 insertions(+), 0 deletions(-)
>
> diff --git a/blockdev.c b/blockdev.c
> index 3b3b82d..9d6f72c 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -516,6 +516,67 @@ void do_commit(Monitor *mon, const QDict *qdict)
> }
> }
>
> +int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data)
> +{
> + const char *device = qdict_get_str(qdict, "device");
> + const char *filename = qdict_get_try_str(qdict, "snapshot_file");
> + const char *format = qdict_get_try_str(qdict, "format");
> + const char format_qcow2[] = "qcow2";
> + BlockDriverState *bs;
> + BlockDriver *drv, *proto_drv;
> + int ret = 0;
> + int flags;
> +
> + bs = bdrv_find(device);
> + if (!bs) {
> + qerror_report(QERR_DEVICE_NOT_FOUND, device);
> + ret = -1;
> + goto out;
> + }
> +
> + if (!format) {
> + format = format_qcow2;
Why introducing format_qcow2 instead of directly using the string
literal here?
> + }
> +
> + drv = bdrv_find_format(format);
> + if (!drv) {
> + qerror_report(QERR_INVALID_BLOCK_FORMAT, format);
> + ret = -1;
> + goto out;
> + }
> +
> + proto_drv = bdrv_find_protocol(filename);
> + if (!proto_drv) {
> + qerror_report(QERR_INVALID_BLOCK_FORMAT, format);
> + ret = -1;
> + goto out;
> + }
> +
> + ret = bdrv_img_create(filename, format, bs->filename,
> + bs->drv->format_name, NULL, -1, bs->open_flags);
> + if (ret) {
> + goto out;
> + }
> +
> + qemu_aio_flush();
> + bdrv_flush(bs);
> +
> + flags = bs->open_flags;
> + bdrv_close(bs);
> + ret = bdrv_open(bs, filename, flags, drv);
> + /*
> + * If reopening the image file we just created fails, we really
> + * are in trouble :(
> + */
> + assert(ret == 0);
bdrv_commit handles this case by setting bs->drv = NULL. After this the
device will fail all requests with -ENOMEDIUM, but at least you don't
lose your VM immediately.
Kevin