On 01/20/14 17:27, Daniel P. Berrange wrote:
On Fri, Dec 20, 2013 at 11:03:53PM -0500, Adam Walters wrote:
This patchset adds a driver named 'config' that allows access to configuration data, such as secret and storage definitions. This is a pre-requisite for my next patchset which resolves the race condition on libvirtd startup and the circular dependencies between QEMU and the storage driver.
I vaguely recall something being mentioned in the past, but not the details. Can you explain the details of the circular dependancy problem that you're currently facing ?
The problem is that when we are re-starting with running VMs that have storage placed on RBD volumes with secrets stored in the secret driver we encounter the following dependancy: 1) the qemu driver depends on the storage driver to be started so that disk type="volume" can be resolved to the actual volumes 2) the storage driver depends on requesting credentials from the secret driver and thus needs a connection to do so. For some strange reason the storage driver opens "qemu:///system" for this purpose: static void storageDriverAutostart(virStorageDriverStatePtr driver) { size_t i; virConnectPtr conn = NULL; /* XXX Remove hardcoding of QEMU URI */ if (driverState->privileged) conn = virConnectOpen("qemu:///system"); else conn = virConnectOpen("qemu:///session"); /* Ignoring NULL conn - let backends decide */ This works if the drivers are initialized, but breaks in the case we use RBD volumes with secrets that and <disk type=volume, where we need to initialize the storage driver before the qemu driver. Peter