e56cc4f439
Nova so far applied a retry loop that tried to periodically detach the device from libvirt while the device was visible in the domain xml. This could lead to an issue where an already progressing detach on the libvirt side is interrupted by nova re-sending the detach request for the same device. See bug #1882521 for more information. Also if there was both a persistent and a live domain the nova tried the detach from both at the same call. This lead to confusion about the result when such call failed. Was the detach failed partially? We can do better, at least for the live detach case. Based on the libvirt developers detaching from the persistent domain always succeeds and it is a synchronous process. Detaching from the live domain can be both synchronous or asynchronous depending on the guest OS and the load on the hypervisor. But for live detach libvirt always sends an event [1] nova can wait for. So this patch does two things. 1) Separates the detach from the persistent domain from the detach from the live domain to make the error cases clearer. 2) Changes the retry mechanism. Detaching from the persistent domain is not retried. If libvirt reports device not found, while both persistent and live detach is needed, the error is ignored, and the process continues with the live detach. In any other case the error considered as fatal. Detaching from the live domain is changed to always wait for the libvirt event. In case of timeout, the live detach is retried. But a failure event from libvirt considered fatal, based on the information from the libvirt developers, so in this case the detach is not retried. Related-Bug: #1882521 [1]https://libvirt.org/html/libvirt-libvirt-domain.html#virConnectDomainEventDeviceRemovedCallback Change-Id: I7f2b6330decb92e2838aa7cee47fb228f00f47da |
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