add mode field to blockdev-snapshot-sync transaction item
The mode field lets a management application create the snapshot
destination outside QEMU.
Right now, the only modes are "existing" and "absolute-paths". Mirroring
introduces "no-backing-file". In the future "relative-paths" could be
implemented too.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/qmp-commands.hx b/qmp-commands.hx
index fb4f1df..7c03b62 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -705,6 +705,13 @@
For snapshots this is the device, the file to use for the new snapshot,
and the format. The default format, if not specified, is qcow2.
+Each new snapshot defaults to being created by QEMU (wiping any
+contents if the file already exists), but it is also possible to reuse
+an externally-created file. In the latter case, you should ensure that
+the new image file has the same contents as the current one; QEMU cannot
+perform any meaningful check. Typically this is achieved by using the
+current image file as the backing file for the new image.
+
Arguments:
actions array:
@@ -715,6 +722,8 @@
- "device": device name to snapshot (json-string)
- "snapshot-file": name of new image file (json-string)
- "format": format of new image (json-string, optional)
+ - "mode": whether and how QEMU should create the snapshot file
+ (NewImageMode, optional, default "absolute-paths")
Example:
@@ -725,6 +734,7 @@
"format": "qcow2" } },
{ 'type': 'blockdev-snapshot-sync', 'data' : { "device": "ide-hd1",
"snapshot-file": "/some/place/my-image2",
+ "mode": "existing",
"format": "qcow2" } } ] } }
<- { "return": {} }