diff options
| -rw-r--r-- | blockdev.c | 79 | ||||
| -rw-r--r-- | qapi/block-core.json | 26 | ||||
| -rw-r--r-- | qmp-commands.hx | 39 |
3 files changed, 144 insertions, 0 deletions
diff --git a/blockdev.c b/blockdev.c index 79ce52b58b..57373d3661 100644 --- a/blockdev.c +++ b/blockdev.c @@ -2367,6 +2367,85 @@ void qmp_block_job_complete(const char *device, Error **errp) block_job_complete(job, errp); } +void qmp_change_backing_file(const char *device, + const char *image_node_name, + const char *backing_file, + Error **errp) +{ + BlockDriverState *bs = NULL; + BlockDriverState *image_bs = NULL; + Error *local_err = NULL; + bool ro; + int open_flags; + int ret; + + /* find the top layer BDS of the chain */ + bs = bdrv_find(device); + if (!bs) { + error_set(errp, QERR_DEVICE_NOT_FOUND, device); + return; + } + + image_bs = bdrv_lookup_bs(NULL, image_node_name, &local_err); + if (local_err) { + error_propagate(errp, local_err); + return; + } + + if (!image_bs) { + error_setg(errp, "image file not found"); + return; + } + + if (bdrv_find_base(image_bs) == image_bs) { + error_setg(errp, "not allowing backing file change on an image " + "without a backing file"); + return; + } + + /* even though we are not necessarily operating on bs, we need it to + * determine if block ops are currently prohibited on the chain */ + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_CHANGE, errp)) { + return; + } + + /* final sanity check */ + if (!bdrv_chain_contains(bs, image_bs)) { + error_setg(errp, "'%s' and image file are not in the same chain", + device); + return; + } + + /* if not r/w, reopen to make r/w */ + open_flags = image_bs->open_flags; + ro = bdrv_is_read_only(image_bs); + + if (ro) { + bdrv_reopen(image_bs, open_flags | BDRV_O_RDWR, &local_err); + if (local_err) { + error_propagate(errp, local_err); + return; + } + } + + ret = bdrv_change_backing_file(image_bs, backing_file, + image_bs->drv ? image_bs->drv->format_name : ""); + + if (ret < 0) { + error_setg_errno(errp, -ret, "Could not change backing file to '%s'", + backing_file); + /* don't exit here, so we can try to restore open flags if + * appropriate */ + } + + if (ro) { + bdrv_reopen(image_bs, open_flags, &local_err); + if (local_err) { + error_propagate(errp, local_err); /* will preserve prior errp */ + } + } +} + void qmp_blockdev_add(BlockdevOptions *options, Error **errp) { QmpOutputVisitor *ov = qmp_output_visitor_new(); 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 @@ -680,6 +680,32 @@ '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 # # Live commit of data from overlay image nodes into backing nodes - i.e., diff --git a/qmp-commands.hx b/qmp-commands.hx index 8c5fdb5ca1..8534948e3f 100644 --- a/qmp-commands.hx +++ b/qmp-commands.hx @@ -1353,6 +1353,45 @@ Example: 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 + + { .name = "balloon", .args_type = "value:M", .mhandler.cmd_new = qmp_marshal_input_balloon, |