On Mon, Jun 22, 2015 at 17:06:42 -0600, Eric Blake wrote:
> Implement the QMP side of asking qemu what node name it assigned
> to an arbitrary top-level device node. Assumes that the caller
> will have already validated that the device is qcow2 backed by
> a block device, and that qemu auto-assigns node names.
>
> * src/qemu/qemu_monitor.h (qemuMonitorNodeNameLookup): New function.
> * src/qemu/qemu_monitor.c (qemuMonitorNodeNameLookup): Likewise.
> * src/qemu/qemu_monitor_json.h (qemuMonitorJSONNodeNameLookup):
> Likewise.
> * src/qemu/qemu_monitor_json.c (qemuMonitorJSONNodeNameLookup):
> Likewise.
>
> Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
> ---
> src/qemu/qemu_monitor.c | 15 ++++++++-
> src/qemu/qemu_monitor.h | 3 ++
> src/qemu/qemu_monitor_json.c | 77 ++++++++++++++++++++++++++++++++++++++++++++
> src/qemu/qemu_monitor_json.h | 3 ++
> 4 files changed, 97 insertions(+), 1 deletion(-)
>
...
> @@ -3900,6 +3902,81 @@ qemuMonitorJSONDiskNameLookup(qemuMonitorPtr mon,
> }
>
>
> +/* Look up the node name of the file underneath a qcow2 image. */
> +char *
> +qemuMonitorJSONNodeNameLookup(qemuMonitorPtr mon,
> + const char *device)
> +{
> + char *ret = NULL;
> + virJSONValuePtr cmd = NULL;
> + virJSONValuePtr reply = NULL;
> + virJSONValuePtr devices;
> + size_t i;
> +
> + cmd = qemuMonitorJSONMakeCommand("query-blockstats", NULL);
Since this is yet another function that would call query-blockstats ...
> + if (!cmd)
> + return NULL;
> + if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
> + goto cleanup;
> +
> + if (!(devices = virJSONValueObjectGetArray(reply, "return"))) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("blockstats reply was missing device list"));
> + goto cleanup;
> + }
> +
> + for (i = 0; i < virJSONValueArraySize(devices); i++) {
> + virJSONValuePtr dev = virJSONValueArrayGet(devices, i);
> + virJSONValuePtr parent;
> + const char *thisdev;
> + const char *node;
> +
> + if (!dev || dev->type != VIR_JSON_TYPE_OBJECT) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("blockstats entry was not in expected format"));
> + goto cleanup;
> + }
> +
> + if (!(thisdev = virJSONValueObjectGetString(dev, "device"))) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("blockstats entry was not in expected format"));
> + goto cleanup;
> + }
> +
> + if (STRPREFIX(thisdev, QEMU_DRIVE_HOST_PREFIX))
> + thisdev += strlen(QEMU_DRIVE_HOST_PREFIX);
> + if (STRNEQ(thisdev, device))
> + continue;
> +
> + if (!(parent = virJSONValueObjectGetObject(dev, "parent"))) {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("blockstats device %s missing parent node"),
> + device);
> + goto cleanup;
> + }
> +
> + if (!(node = virJSONValueObjectGetString(parent, "node-name"))) {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("node name missing for device %s"), device);
> + goto cleanup;
> + }
> + ignore_value(VIR_STRDUP(ret, node));
> + goto cleanup;
> + }
> +
> + /* If we get here, we didn't find the device. */
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("unable to find node name for device %s"),
> + device);
... and works only on one device and thus needs to be re-called for
every single disk I'd rather see us fold this code into
qemuMonitorJSONGetOneBlockStatsInfo so that all the info can be returned
via qemuMonitorJSONGetAllBlockStatsInfo.
I'll post a series that kills qemuMonitorJSONGetBlockExtent since it's
basically the same instance.
Peter
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