Re: [libvirt] [RFC] Add API to change qemu agent response timeout

Some layered products such as oVirt have requested a way to avoid being blocked by guest agent commands when querying a loaded vm. For example, many guest agent commands are polled periodically to monitor changes, and rather than blocking the calling process, they'd prefer to simply time out when an agent query is taking too long. This patch adds a way for the user to specify a custom agent timeout that is applied to all agent commands. One special case to note here is the 'guest-sync' command. 'guest-sync' is issued internally prior to calling any other command. (For example, when libvirt wants to call 'guest-get-fsinfo', we first call 'guest-sync' and then call 'guest-get-fsinfo'). Previously, the 'guest-sync' command used a 5-second timeout (VIR_DOMAIN_QEMU_AGENT_COMMAND_DEFAULT), whereas the actual command that followed always blocked indefinitely (VIR_DOMAIN_QEMU_AGENT_COMMAND_BLOCK). As part of this patch, if a custom timeout is specified that is shorter than 5 seconds, this new timeout also used for 'guest-sync'. If there is no custom timeout or if the custom timeout is longer than 5 seconds, we will continue to use the 5-second timeout. See https://bugzilla.redhat.com/show_bug.cgi?id=1705426 for additional details. Signed-off-by: Jonathon Jongsma <jjongsma(a)redhat.com&gt; --- include/libvirt/libvirt-qemu.h | 2 + src/driver-hypervisor.h | 5 +++ src/libvirt-qemu.c | 40 ++++++++++++++++++++ src/libvirt_qemu.syms | 4 ++ src/qemu/qemu_agent.c | 69 +++++++++++++++++++--------------- src/qemu/qemu_agent.h | 3 ++ src/qemu/qemu_driver.c | 24 ++++++++++++ src/qemu_protocol-structs | 8 ++++ src/remote/qemu_protocol.x | 18 ++++++++- src/remote/remote_driver.c | 1 + 10 files changed, 143 insertions(+), 31 deletions(-)

@@ -2737,3 +2730,19 @@ qemuAgentGetTimezone(qemuAgentPtr mon, return 0; } + +int +qemuAgentSetTimeout(qemuAgentPtr mon, + int timeout) +{ + if (timeout < VIR_DOMAIN_QEMU_AGENT_COMMAND_MIN) { + virReportError(VIR_ERR_INVALID_ARG, + _("guest agent timeout '%d' is " + "less than the minimum '%d'"), + timeout, VIR_DOMAIN_QEMU_AGENT_COMMAND_MIN);

+ return -1; + } + + mon->timeout = timeout; + return 0; +}

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 1e041a8bac..09251cc9e2 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -23434,6 +23434,29 @@ qemuDomainGetGuestInfo(virDomainPtr dom, return ret; } +static int +qemuDomainQemuAgentSetTimeout(virDomainPtr dom, + int timeout) +{ + virDomainObjPtr vm = NULL; + qemuAgentPtr agent; + int ret = -1; + + if (!(vm = qemuDomObjFromDomain(dom))) + goto cleanup; + + if (virDomainQemuAgentSetTimeoutEnsureACL(dom->conn, vm->def) < 0) + goto cleanup; + + agent = qemuDomainObjEnterAgent(vm);

+ ret = qemuAgentSetTimeout(agent, timeout); + qemuDomainObjExitAgent(vm, agent);