Re: [libvirt] [PATCHv3 09/10] threshold: add threshold event handling in qemu

With this patch, block write threshold events delivered by qemu are converted into libvirt events. This patch takes the easy road, and only reports events if the node name is still cached by libvirtd (true in the common case when libvirtd is not restarted, since you can't get an event if you didn't register a threshold). A followup patch will be needed to properly handle grabbing the job lock and getting the node name when the cache lookup fails, using code similar to how we update domain XML after a block job completes. But for getting the initial API in place, I figured this was a good enough start. * src/qemu/qemu_monitor_json.c (qemuMonitorJSONHandleBlockWriteThreshold): New function. * src/qemu/qemu_monitor.c (qemuMonitorEmitBlockThreshold): Likewise. * src/qemu/qemu_monitor.h (qemuMonitorEmitBlockThreshold): Likewise. * src/qemu/qemu_process.c (qemuProcessHandleBlockThreshold): Likewise. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- src/qemu/qemu_monitor.c | 14 ++++++++++++++ src/qemu/qemu_monitor.h | 11 +++++++++++ src/qemu/qemu_monitor_json.c | 31 +++++++++++++++++++++++++++++++ src/qemu/qemu_process.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 100 insertions(+)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index ba84182..5f582e5 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -1037,6 +1037,49 @@ qemuProcessHandleBlockJob(qemuMonitorPtr mon ATTRIBUTE_UNUSED, static int +qemuProcessHandleBlockThreshold(qemuMonitorPtr mon ATTRIBUTE_UNUSED, + virDomainObjPtr vm, + const char *node, + unsigned long long threshold, + unsigned long long length, + void *opaque) +{ + virQEMUDriverPtr driver = opaque; + virDomainDiskDefPtr disk; + virObjectEventPtr event = NULL; + const char *path = NULL; + + virObjectLock(vm); + + VIR_DEBUG("Block threshold for node %s (domain: %p,%s) threshold %llu " + "length %llu", node, vm, vm->def->name, threshold, length); + + /* TODO: If the node name is not found in the current domain XML, + * we need to grab a job lock and query the monitor to repopulate + * the node name cache. For now, if that happens, we just discard + * the event. */

+ if (!(disk = qemuDomainDiskResolveAllocationNode(driver, vm, node, + false))) { + VIR_WARN("failed to locate disk matching node '%s'", node); + goto cleanup; + } + if (virStorageSourceIsLocalStorage(disk->src)) + path = disk->src->path; + + /* TODO: Once we support node names for more than just the active + * layer, we will need to map this into 'vda[1]' notation. */ + event = virDomainEventWriteThresholdNewFromObj(vm, disk->dst, path, + threshold, length); +