Re: [Libguestfs] [libnbd PATCH v2] api: Add set_request_block_size

Our testsuite coverage of nbd_get_block_size() is pretty sparse (the recent commit 6f5fec2ea uses them in errors-server-unaligned.c for debug purposes, and even that requires recent patches in nbdkit). But in the process of adding an interop test with qemu-nbd, I also noticed that qemu-nbd (at least version 6.2) fails NBD_OPT_INFO for older clients that don't request block size, and fudges the value to 1 for NBD_OPT_GO for back-compat reasons. We still want to request by default, but now we need a knob, similar to the existing set_full_info(), for overriding our defaults for testing purposes. --- In v2: - drop RFC - fix bugs in implementation (the RFC version passed a wrong size over the wire, causing 'nbdkit nbd' to deadlock) - actually implement interop-qemu-block-size.sh - add test coverage of language bindings