Re: [Qemu-devel] [PATCH V3 11/11] hmp: show snapshot on single block device

[Luiz Capitulino <lcapitulino@redhat.com>]

On Mon, 14 Jan 2013 15:09:47 +0800
Wenchao Xia <xiawenc@linux.vnet.ibm.com> wrote:

>   This patch use block layer API to qmp snapshot info on a block
> device, then use the same code dumping vm snapshot info, to print
> in monitor.
> 
> Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
> ---
> Note:
>   This patch need previous hmp extention patch which enable
> info sub command take qdict * as paramter.
> 
> ---
>  monitor.c |    6 +++---
>  savevm.c  |   43 ++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 45 insertions(+), 4 deletions(-)
> 
> diff --git a/monitor.c b/monitor.c
> index d186532..cba75a2 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -2583,9 +2583,9 @@ static mon_cmd_t info_cmds[] = {
>      },
>      {
>          .name       = "snapshots",
> -        .args_type  = "",
> -        .params     = "",
> -        .help       = "show the currently saved VM snapshots",
> +        .args_type  = "device:B?",
> +        .params     = "[device]",
> +        .help       = "show snapshots of whole vm or a single device",
>          .mhandler.cmd = do_info_snapshots,
>      },
>      {
> diff --git a/savevm.c b/savevm.c
> index cabdcb6..cd474e9 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -2354,9 +2354,50 @@ static void do_info_snapshots_vm(Monitor *mon)
>      return;
>  }
>  
> +static void do_info_snapshots_blk(Monitor *mon, const char *device)
> +{
> +    Error *err = NULL;
> +    SnapshotInfoList *list;
> +    BlockDriverState *bs;
> +
> +    /* find the target bs */
> +    bs = bdrv_find(device);
> +    if (!bs) {
> +        monitor_printf(mon, "Device '%s' not found.\n", device);
> +        return ;
> +    }
> +
> +    if (!bdrv_can_snapshot(bs)) {
> +        monitor_printf(mon, "Device '%s' can't have snapshot.\n", device);
> +        return ;
> +    }
> +
> +    list = bdrv_query_snapshot_infolist(bs, NULL, NULL, &err);
> +    if (error_is_set(&err)) {
> +        hmp_handle_error(mon, &err);
> +        return;
> +    }

We try to restrict hmp.c to use the QMP API only (see Pavel's comment on
moving this to hmp.c).

If this can't be implemented using qmp_query_snapshots(), then I'd suggest
to add this capability to qmp_query_snapshots() or add a new QMP command.

> +
> +    if (list == NULL) {
> +        monitor_printf(mon, "There is no snapshot available.\n");
> +        return;
> +    }
> +
> +    monitor_printf(mon, "Device '%s':\n", device);
> +    monitor_dump_snapshotinfolist(mon, list);
> +    qapi_free_SnapshotInfoList(list);
> +    return;
> +}
> +
>  void do_info_snapshots(Monitor *mon, const QDict *qdict)
>  {
> -    do_info_snapshots_vm(mon);
> +    const char *device = qdict_get_try_str(qdict, "device");
> +    if (!device) {
> +        do_info_snapshots_vm(mon);
> +    } else {
> +        do_info_snapshots_blk(mon, device);
> +    }
> +    return;
>  }
>  
>  void vmstate_register_ram(MemoryRegion *mr, DeviceState *dev)