search for: nbd_clear_meta_contexts

...st to be negotiated. You can call it as many times as needed. The list is initially -empty when the handle is created. +empty when the handle is created; you can check the contents of +the list with L<nbd_get_nr_meta_contexts(3)> and +L<nbd_get_meta_context(3)>, or clear it with +L<nbd_clear_meta_contexts(3)>. The NBD protocol limits meta context names to 4096 bytes, but servers may not support the full length. The encoding of meta @@ -991,9 +994,73 @@ C<LIBNBD_CONTEXT_> for some well-known contexts, but you are free to pass in other contexts. Other metadata contexts are server-speci...

I'm posting this now, as I'm at the end of a workday and I got things working for manual experimentation. Still to do: - write interop tests for qemu-nbd and nbdkit (including my proposed patch addition of qemu-nbd -A to show qemu:allocation-depth) - figure out if we can make 'nbdinfo --map' use the new API to automatically select all contexts advertised by the server Eric Blake

...enabled option mode. + +The NBD protocol allows a client to decide how many queries to ask +the server. Rather than taking that list of queries as a parameter +to this function, libnbd reuses the current list of requested meta +contexts as set by L<nbd_add_meta_context(3)>; you can use +L<nbd_clear_meta_contexts(3)> to set up a different list of queries. +When the list is empty, a server will typically reply with all +contexts that it supports; when the list is non-empty, the server +will reply only with supported contexts that match the client's +request. Note that a reply by the server might be e...

In v2: ack'ed preliminary patches have been pushed, and I've added a lot of testsuite coverage as well as putting the new API to use in nbdinfo. Eric Blake (2): api: Add nbd_opt_list_meta_context info: List available meta-contexts lib/internal.h | 1 + generator/API.ml | 84 ++++++++-