On Mon, Jun 22, 2015 at 17:06:46 -0600, Eric Blake wrote:
> Time to wire up the new API to call into the QMP command for setting
> a write threshold.
>
> For now, the API only allows setting the threshold on the active
> layer. But I left TODOs in the series for places that need
> touching to find and support node names of backing files, so that
> we can use "vda[1]" notation to register for a threshold on the
> backing image during an active commit operation.
>
> * src/qemu/qemu_driver.c (qemuDomainBlockSetWriteThreshold): New
> function.
> * src/qemu/qemu_monitor.c (qemuMonitorBlockSetWriteThreshold):
> Likewise.
> * src/qemu/qemu_monitor.h (qemuMonitorBlockSetWriteThreshold):
> Likewise.
> * src/qemu/qemu_monitor_json.c
> (qemuMonitorJSONBlockSetWriteThreshold): Likewise.
> * src/qemu/qemu_monitor_json.h
> (qemuMonitorJSONBlockSetWriteThreshold): Likewise.
>
> Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
> ---
> src/qemu/qemu_driver.c | 95 ++++++++++++++++++++++++++++++++++++++++++++
> src/qemu/qemu_monitor.c | 13 ++++++
> src/qemu/qemu_monitor.h | 5 +++
> src/qemu/qemu_monitor_json.c | 30 ++++++++++++++
> src/qemu/qemu_monitor_json.h | 3 ++
> 5 files changed, 146 insertions(+)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 72e256b..732f102 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -17906,6 +17906,100 @@ qemuDomainGetBlockIoTune(virDomainPtr dom,
> return ret;
> }
>
> +
> +static int
> +qemuDomainBlockSetWriteThreshold(virDomainPtr dom,
> + const char *path,
> + unsigned long long threshold,
> + unsigned int flags)
> +{
> + virQEMUDriverPtr driver = dom->conn->privateData;
> + virDomainObjPtr vm = NULL;
> + qemuDomainObjPrivatePtr priv;
> + virDomainDiskDefPtr disk = NULL;
> + virCapsPtr caps = NULL;
> + virQEMUDriverConfigPtr cfg = NULL;
> + const char *node = NULL;
> + int ret = -1;
> +
> + virCheckFlags(VIR_DOMAIN_BLOCK_SET_WRITE_THRESHOLD_PROPORTION, -1);
> +
> + if (!(vm = qemuDomObjFromDomain(dom)))
> + return -1;
> + priv = vm->privateData;
> +
> + if (virDomainBlockSetWriteThresholdEnsureACL(dom->conn, vm->def) < 0)
> + goto cleanup;
> +
> + if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
> + goto cleanup;
> + if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCK_WRITE_THRESHOLD) ||
> + !virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_AUTO_NODE_NAMES)) {
> + virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
> + _("block write threshold not supported by this "
> + "qemu binary"));
> + goto cleanup;
> + }
> +
> + if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
> + goto cleanup;
> +
> + if (!virDomainObjIsActive(vm)) {
> + virReportError(VIR_ERR_OPERATION_INVALID,
> + "%s", _("domain is not running"));
> + goto endjob;
> + }
> +
> + if (!(disk = virDomainDiskByName(vm->def, path, false))) {
> + virReportError(VIR_ERR_INVALID_ARG,
> + _("invalid path %s not assigned to domain"), path);
> + goto endjob;
> + }
> +
> + if (!(node = qemuDomainDiskGetAllocationNode(driver, vm, disk))) {
> + virReportError(VIR_ERR_INVALID_ARG,
> + _("cannot track threshold events on disk '%s'"),
> + path);
> + goto endjob;
> + }
> +
> + cfg = virQEMUDriverGetConfig(driver);
> + if (qemuStorageLimitsRefresh(driver, cfg, vm, disk->src) < 0)
This function begins with a rather long comment explaining that it's not
entirely a good idea to use it on online VMs and especially on
write-enabled disk sources. Shouldn't we query the monitor rather than
use that?
> + goto endjob;
> +
> + if (flags & VIR_DOMAIN_BLOCK_SET_WRITE_THRESHOLD_PROPORTION) {
> + /* Caller already sanitized max value to 1000000. Use of
> + * floating point intermediary reduces (but does not
> + * eliminate) rounding error, but since we already document a
> + * granularity of parts per million, it shouldn't matter too
> + * much if the answer is a few bytes off. */
> + threshold *= disk->src->physical / 1e6;
> + } else {
> + if (threshold > disk->src->physical) {
> + virReportError(VIR_ERR_INVALID_ARG,
> + _("threshold %llu exceeds disk size %llu"),
> + threshold, disk->src->physical);
> + goto endjob;
> + }
> + }
> +
> + qemuDomainObjEnterMonitor(driver, vm);
> + ret = qemuMonitorBlockSetWriteThreshold(priv->mon, node, threshold);
> + if (qemuDomainObjExitMonitor(driver, vm) < 0)
> + ret = -1;
> +
> +
> + endjob:
> + qemuDomainObjEndJob(driver, vm);
> +
> + cleanup:
> + virDomainObjEndAPI(&vm);
> + virObjectUnref(caps);
> + virObjectUnref(cfg);
> + return ret;
> +}
> +
> +
> static int
> qemuDomainGetDiskErrors(virDomainPtr dom,
> virDomainDiskErrorPtr errors,
> @@ -20037,6 +20131,7 @@ static virHypervisorDriver qemuHypervisorDriver = {
> .nodeSuspendForDuration = qemuNodeSuspendForDuration, /* 0.9.8 */
> .domainSetBlockIoTune = qemuDomainSetBlockIoTune, /* 0.9.8 */
> .domainGetBlockIoTune = qemuDomainGetBlockIoTune, /* 0.9.8 */
> + .domainBlockSetWriteThreshold = qemuDomainBlockSetWriteThreshold, /* 1.3.0 */
> .domainSetNumaParameters = qemuDomainSetNumaParameters, /* 0.9.9 */
> .domainGetNumaParameters = qemuDomainGetNumaParameters, /* 0.9.9 */
> .domainGetInterfaceParameters = qemuDomainGetInterfaceParameters, /* 0.9.9 */
> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> index c4b6073..2ff34e2 100644
> --- a/src/qemu/qemu_monitor.c
> +++ b/src/qemu/qemu_monitor.c
> @@ -1866,6 +1866,19 @@ qemuMonitorBlockStatsUpdateThreshold(qemuMonitorPtr mon,
>
>
> int
> +qemuMonitorBlockSetWriteThreshold(qemuMonitorPtr mon,
> + const char *dev_name,
This function needs a node name passed so it should also be called that
way to avoid confusion since the function lacks docs.
> + unsigned long long threshold)
> +{
> + VIR_DEBUG("dev_name=%s, threshold=%llu", dev_name, threshold);
> +
> + QEMU_CHECK_MONITOR_JSON(mon);
> +
> + return qemuMonitorJSONBlockSetWriteThreshold(mon, dev_name, threshold);
> +}
> +
> +
> +int
> qemuMonitorGetBlockExtent(qemuMonitorPtr mon,
> const char *dev_name,
> unsigned long long *extent)
Peter
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