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 --- qapi/block-core.json | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'qapi/block-core.json') diff --git a/qapi/block-core.json b/qapi/block-core.json index 6a697f1458..aa1252778c 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -679,6 +679,32 @@ { 'command': 'blockdev-snapshot-sync', 'data': 'BlockdevSnapshot' } +## +# @change-backing-file +# +# 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. +# +# @image-node-name: The name of the block driver state node of the +# image to modify. +# +# @device: The name of the device that owns image-node-name. +# +# @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. +# +# Since: 2.1 +## +{ 'command': 'change-backing-file', + 'data': { 'device': 'str', 'image-node-name': 'str', + 'backing-file': 'str' } } + ## # @block-commit # -- cgit v1.2.3