Description of problem:
Upstream NBD is considering an extension to add 64-bit commands. While read and write will still be bounded at qemu's 32M limit for payload size, other commands without large payloads (block status, trim, and write-zero) benefit from being able to request an action over more than just 32 bits of length from a given 64-bit offset. Supporting 64-bit lengths in the NBD protocol requires opt-in from both client and server, both of which are utilized in qemu.

Version-Release number of selected component (if applicable):

How reproducible:
100%

Steps to Reproduce:
1. Create a 5G image, serve it over qemu-nbd (or qemu-storage-daemon), then use qemu-io to query block status or perform a 'write -z' to the entire image. Watching --trace=nbd_* output can show whether the requests had to be broken up at 32-bit boundaries or done in one go.
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Actual results:

Expected results:

Additional info:
See also https://lists.debian.org/nbd/2022/11/msg00008.html