Re: [libvirt] [PATCH 2/3] qemu: special error code in case of no job on cancel block job

Special error code helps gracefully handle race conditions on blockjob cancelling. Consider for example pull backup. We want to stop it and in the process we cancel blockjob for some of the exported disks. But at the time this command reaches qemu blockjob fail for some reason and cancel result and result of stopping will be an error with quite unexpecte message - no such job (sort of). Instead we can detect this race and treat as correct cancelling and wait until fail event will arrive. Then we can report corect error message with some details from qemu probably. Users of domainBlockJobAbort can be affected as -2 is new possible return code. Not sure if I should stick to the original behaviour in this case. --- src/qemu/qemu_monitor.c | 5 +++++ src/qemu/qemu_monitor_json.c | 11 +++++++---- 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c index 4171914..944856d 100644 --- a/src/qemu/qemu_monitor.c +++ b/src/qemu/qemu_monitor.c @@ -3335,6 +3335,11 @@ qemuMonitorBlockStream(qemuMonitorPtr mon, } +/* return: + * 0 in case of success + * -1 in case of general error + * -2 in case there is no such job + */ int qemuMonitorBlockJobCancel(qemuMonitorPtr mon, const char *device, diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c index 7903b47..42b05c4 100644 --- a/src/qemu/qemu_monitor_json.c +++ b/src/qemu/qemu_monitor_json.c @@ -4351,6 +4351,7 @@ qemuMonitorJSONBlockJobError(virJSONValuePtr reply, if (qemuMonitorJSONErrorIsClass(error, "DeviceNotActive")) { virReportError(VIR_ERR_OPERATION_INVALID, _("No active operation on device: %s"), device); + return -2; } else if (qemuMonitorJSONErrorIsClass(error, "DeviceInUse")) { virReportError(VIR_ERR_OPERATION_FAILED, _("Device %s in use"), device); @@ -4408,6 +4409,11 @@ qemuMonitorJSONBlockStream(qemuMonitorPtr mon, } +/* return: + * 0 in case of success + * -1 in case of general error + * -2 in case there is no such job + */ int qemuMonitorJSONBlockJobCancel(qemuMonitorPtr mon, const char *device, @@ -4426,10 +4432,7 @@ qemuMonitorJSONBlockJobCancel(qemuMonitorPtr mon, if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0) goto cleanup; - if (qemuMonitorJSONBlockJobError(reply, cmd_name, device) < 0) - goto cleanup; - - ret = 0; + ret = qemuMonitorJSONBlockJobError(reply, cmd_name, device); cleanup: virJSONValueFree(cmd);