On 12/16/10 12:45, Kevin Wolf wrote:
> Am 16.12.2010 12:04, schrieb jes.soren...@redhat.com:
>> From: Jes Sorensen <jes.soren...@redhat.com>
>>
>> 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 <jes.soren...@redhat.com>
>> ---
>> 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?
It should generate the same code - I kinda liked my style better, but
I'll change it.
>> + 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.
Well if we hit this situation something catastrophic happened. I don't
see how we can continue beyond this point really. The old image was
dropped in the swap and the new one is not accessible ... we're dead :(
Cheers,
Jes
