Re: [Qemu-devel] [PATCH] Disk image shared and exclusive locks.

[Chris Webb]

"Daniel P. Berrange" <address@hidden> writes:

> The only other alternative would be for the destination to open the disks,
> but not immediately acquire the locks. In the final stage of migration have
> the source release its lock & signal to the dest that it can now acquire
> the lock. The assumption being that the lock acquisition is far less likely
> to fail than the open(), so we focus on making sure we can properly handle
> open() failure.

This is what we've implemented as a prototype for sheepdog, with bdrv_claim
(happens on vm_start) and bdrv_release (happens on exit/vm_stop) hooks
available to block drivers.

Cheers,

Chris.