From fa40e65622352012dccd435147f28161375a6815 Mon Sep 17 00:00:00 2001 From: Jeff Cody Date: Tue, 1 Jul 2014 09:52:16 +0200 Subject: block: add QAPI command to allow live backing file change This allows a user to make a live change to the backing file recorded in an open image. The image file to modify can be specified 2 ways: 1) image filename 2) image node-name Note: this does not cause the backing file itself to be reopened; it merely changes the backing filename in the image file structure, and in internal BDS structures. It is the responsibility of the user to pass a filename string that can be resolved when the image chain is reopened, and the filename string is not validated. A good analogy for this command is that it is a live version of 'qemu-img rebase -u', with respect to changing the backing file string. [Jeff is offline so I respun this patch in his absence. Dropped image filename since using node-name is preferred and this is a new command. No need to introduce the limitations of finding images by filename. --Stefan] Reviewed-by: Eric Blake Reviewed-by: Kevin Wolf Signed-off-by: Jeff Cody Signed-off-by: Stefan Hajnoczi --- qmp-commands.hx | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) (limited to 'qmp-commands.hx') diff --git a/qmp-commands.hx b/qmp-commands.hx index 8c5fdb5ca1..8534948e3f 100644 --- a/qmp-commands.hx +++ b/qmp-commands.hx @@ -1350,6 +1350,45 @@ Example: "format": "qcow2" } } <- { "return": {} } +EQMP + + { + .name = "change-backing-file", + .args_type = "device:s,image-node-name:s,backing-file:s", + .mhandler.cmd_new = qmp_marshal_input_change_backing_file, + }, + +SQMP +change-backing-file +------------------- +Since: 2.1 + +Change the backing file in the image file metadata. This does not cause +QEMU to reopen the image file to reparse the backing filename (it may, +however, perform a reopen to change permissions from r/o -> r/w -> r/o, +if needed). The new backing file string is written into the image file +metadata, and the QEMU internal strings are updated. + +Arguments: + +- "image-node-name": The name of the block driver state node of the + image to modify. The "device" is argument is used to + verify "image-node-name" is in the chain described by + "device". + (json-string, optional) + +- "device": The name of the device. + (json-string) + +- "backing-file": The string to write as the backing file. This string is + not validated, so care should be taken when specifying + the string or the image chain may not be able to be + reopened again. + (json-string) + +Returns: Nothing on success + If "device" does not exist or cannot be determined, DeviceNotFound + EQMP { -- cgit v1.2.1