δΊ 2013-1-9 20:44, Stefan Hajnoczi ει:
On Mon, Jan 07, 2013 at 03:28:06PM +0800, Wenchao Xia wrote:
This patch switch to internal common API to take group external
snapshots from qmp_transaction interface. qmp layer simply does
a translation from user input.
Signed-off-by: Wenchao Xia <xiaw...@linux.vnet.ibm.com>
---
blockdev.c | 215 ++++++++++++++++++++++++------------------------------------
1 files changed, 87 insertions(+), 128 deletions(-)
An internal API for snapshots is not necessary. qmp_transaction() is
already usable both from the monitor and C code.
The QAPI code generator creates structs that can be accessed directly
from C. qmp_transaction(), BlockdevAction, and BlockdevActionList *is*
the snapshot API. It just doesn't support internal snapshots yet, which
is what you are trying to add.
To add internal snapshot support, define a BlockdevInternalSnapshot type
in qapi-schema.json and add internal snapshot support in
qmp_transaction().
qmp_transaction() was designed with this in mind from the beginning and
dispatches based on BlockdevAction->kind.
The patch series will become much smaller while still adding internal
snapshot support.
Stefan
As API, qmp_transaction have following disadvantages:
1) interface is based on string not data type inside qemu, that means
other function calling it result in: bdrv->string->bdrv
2) all capability are forced to be exposed.
3) need structure to record each transaction state, such as
BlkTransactionStates. Extending it is equal to add an internal layer.
Actually I started up by use qmp_transaction as API, but soon
found that work is almost done around BlkTransactionStates, so
added a layer around it clearly.
--
Best Regards
Wenchao Xia
