[Libguestfs] Re: [nbdkit PATCH 0/4] RFC: Better handling of extents alignment

This is in response to https://gitlab.com/nbdkit/libnbd/-/issues/12 where nbdinfo is having a hard time because nbdkit is outputting data that is not in compliance with the current NBD spec (which states that if client and server agreed on a minimum blocksize, then extents must be aligned to that). I still have more to write: - add a unit test for the server change at 4G (in addition to the unit test I got working for blocksize-policy tripping on the same problem with a much smaller unaligned-size data image) - libnbd: patch nbdinfo to tolerate unaligned extents from the server. Even if the spec says its wrong, existing servers in the wild do it, so we should be tolerant. - upstream NBD spec: propose weakening the standard from SHALL to SHOULD provide aligned extents - blocksize-policy: Consider patches to allow aligned offset but unaligned length IF the length extends from offset to the end of the unaligned-size disk. Document that an unaligned tail is hard to read, and suggest use of the truncate filter to deal with it.

But as this has taken me the better part of today, I wanted to put out what I have so far. Eric Blake (4): human-size: Add human_size_parse_substr data: Allow scaling suffixes on @decimal blocksize-policy: Round extents to match minimum alignment server: Align the truncation of large block_status results plugins/data/nbdkit-data-plugin.pod | 3 +- tests/Makefile.am | 2 + common/include/human-size-test-cases.h | 83 ++++++++++-------- common/include/human-size.h | 57 ++++++++---- common/include/test-human-size.c | 52 +++++++++-- server/protocol.c | 12 ++- server/test-public.c | 13 +-- plugins/data/format.c | 115 ++++++++++++------------- filters/blocksize-policy/policy.c | 15 +++- tests/test-data-format.sh | 8 +- tests/test-eval-extents.sh | 6 +- 11 files changed, 230 insertions(+), 136 deletions(-)