I'm currently helping with work on adding extensions to the upstream NBD protocol to allow more efficient handling of sparse files, and wanted to get my feet wet in the qemu NBD code (both client and server), to actually implement those proposals to see how well they work. In the process, I found a flaw where we were silently ignoring bad client flags; the same flaw was just recently patched in upstream NBD: https://github.com/yoe/nbd/commit/ab22e0820
I didn't go quite as far as upstream (that is, I still silently permit FLAG_FUA in combination with CMD_TRIM, which does not have defined semantics upstream, and where our current implementation might be too weak compared to the actual semantics that upstream wants to propose, because we aren't actually flushing in that case), but this at least gets rid of the worst offenses and starts to document some anomolies that may need later fixing. Eric Blake (3): nbd: Treat flags vs. command type as separate fields nbd: Fix poor debug message nbd: Reject unknown request flags include/block/nbd.h | 17 +++++++++++------ block/nbd-client.c | 11 ++++------- nbd/client.c | 19 +++++++++++-------- nbd/server.c | 32 ++++++++++++++++++++------------ 4 files changed, 46 insertions(+), 33 deletions(-) -- 2.5.5
