Re: [libvirt] [RFC PATCH 03/12] lib: Introduce event for tracking disk backing file write threshold

When using thin provisioning, management tools need to resize the disk in certain cases. To avoid having them to poll disk fillng introduce an

event whic will be fired when a given offset of the storage is written

by the hypervisor. Together with the API which will be added later, it will allow to register thresholds for given storage backing volumes and

this event will then notify management if the threshold is exceeded. --- daemon/remote.c | 43 ++++++++++++++++ examples/object-events/event-test.c | 19 ++++++++ include/libvirt/libvirt-domain.h | 31 ++++++++++++ src/conf/domain_event.c | 97 +++++++++++++++++++++++++++++++++++++ src/conf/domain_event.h | 15 ++++++ src/libvirt_private.syms | 2 + src/remote/remote_driver.c | 33 +++++++++++++ src/remote/remote_protocol.x | 18 ++++++- src/remote_protocol-structs | 9 ++++ tools/virsh-domain.c | 21 ++++++++ 10 files changed, 287 insertions(+), 1 deletion(-)

+++ b/include/libvirt/libvirt-domain.h @@ -4175,6 +4175,36 @@ typedef void (*virConnectDomainEventAgentLifecycleCallback)(virConnectPtr conn, /** + * virConnectDomainEventBlockThresholdCallback: + * @conn: connection object + * @dom: domain on which the event occurred + * @dev: name associated with the affected disk or storage backing chain + * element + * @path: for local storage, the path of the backing chain element + * @threshold: threshold + * @excess: WTF

+ * @opaque: application specified data + * + * The callback occurs when the hypervisor detects that the given storage + * element was written beyond the point specified by @threshold. The excess + * data size written beyond @threshold is reported by @excess (if supported + * by the hypervisor, 0 otherwise). The event is useful for thin-provisioned + * storage.

+ * + * The threshold size can be set via the virDomainSetBlockThreshold API.