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

WIP: I need to finish writing the actual interop-qemu-block-size.sh to demonstrate scenarios where qemu-nbd advertises a block size > 1 to clients that request it, but sticks to 1 otherwise (see https://gitlab.com/qemu-project/qemu/-/blob/master/nbd/server.c#L660). Our testsuite coverage of nbd_get_block_size() is pretty sparse (a single line in tests/errors.c, which was skipping until patches to nbdkit finally made it possible to utilize). But in the process of adding an interop test with qemu-nbd, I also noticed that qemu-nbd (at least version 6.2) exposes different block sizes to older clients that don't request block size than it does to newer clients which promise to obey block sizes. We still want to request by default, but now we need a knob, similar to the existing set_full_info(), for overriding that default for testing purposes.

@@ -20,6 +20,7 @@ include $(top_srcdir)/subdir-rules.mk EXTRA_DIST = \ dirty-bitmap.sh \ interop-qemu-storage-daemon.sh \ + interop-qemu-block-size.sh \ list-exports-nbd-config \ list-exports-test-dir/disk1 \ list-exports-test-dir/disk2 \ @@ -141,6 +142,7 @@ TESTS += \ socket-activation-qemu-nbd \ dirty-bitmap.sh \ structured-read.sh \ + interop-qemu-block-size.sh \ $(NULL)