Il 16/09/2014 14:52, Kevin Wolf ha scritto: > Yes, that's true. We can't fix this problem in qcow2, though, because > it's a more general one. I think we must make sure that > bdrv_invalidate_cache() doesn't yield. > > Either by forbidding to run bdrv_invalidate_cache() in a coroutine and > moving the problem to the caller (where and why is it even called from a > coroutine?), or possibly by creating a new coroutine for the driver > callback and running that in a nested event loop that only handles > bdrv_invalidate_cache() callbacks, so that the NBD server doesn't get a > chance to process new requests in this thread.
Incoming migration runs in a coroutine (the coroutine entry point is process_incoming_migration_co). But everything after qemu_fclose() can probably be moved into a separate bottom half, so that it gets out of coroutine context. Paolo
