On Tue, Mar 15, 2022 at 01:14:41PM +0000, Richard W.M. Jones wrote: > The patches seem OK to me, but I don't really know enough about the > internals of qemu-nbd to give a line-by-line review. I did however > build and test qemu-nbd with the patches: > > $ ./build/qemu-nbd /var/tmp/test.qcow2 > $ nbdinfo nbd://localhost > ... > can_multi_conn: false > > > $ ./build/qemu-nbd -e 2 /var/tmp/test.qcow2 > $ nbdinfo nbd://localhost > ... > can_multi_conn: false > > ^^^ Is this expected? It also happens with -e 0.
Yes, because qemu-nbd defaults to read-write connections, but to be conservative, this patch defaults '-m auto' to NOT advertise multi-conn for read-write; you need to be explicit: > > > $ ./build/qemu-nbd -e 2 -m on /var/tmp/test.qcow2 > $ nbdinfo nbd://localhost > ... > can_multi_conn: true either with '-m on' as you did here, or with build/qemu-nbd -r -e 2 /var/tmp/test.qcow2 where the '-m auto' default exposes multi-conn for a readonly client. > > > $ ./build/qemu-nbd -e 2 -m off /var/tmp/test.qcow2 > $ nbdinfo nbd://localhost > ... > can_multi_conn: false > > > Rich. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
