Re: [Libguestfs] [libnbd PATCH v2 04/12] api: Add nbd_set_request_meta_context()

On Thu, Sep 01, 2022 at 05:29:21PM +0100, Richard W.M. Jones wrote: > On Wed, Aug 31, 2022 at 09:39:20AM -0500, Eric Blake wrote: > > Add a new control knob nbd_set_request_meta_context(), modeled after > > the existing nbd_set_request_structured_replies(), to make it possible > > to skip the NBD_OPT_SET_META_CONTEXT half of the two-command sequence > > currently performed in nbd_opt_go() and nbd_opt_info(). Also add a > > counterpart nbd_get_request_meta_context() for symmetry. > > > > This really needs an example. Will do. Sounds like I have enough incremental things to improve that it will be worth a v3 series, although I'll continue to let more reviews come on in the rest of the series before I post that.

I'm wondering whether it is easier to modify the existing examples/list-exports.c, or to write a second example. Over the course of this series, as more and more APIs are added, the example can cover more steps. By the end of the series, it would look something like: // error checking omitted here for brevity, but I'll probably add it in the example nbd = nbd_create (); nbd_set_tls (nbd, LIBNBD_TLS_DISABLE); // we'll manually enable tls later nbd_set_request_structured_reply (nbd, false); // we'll manually request SR later nbd_set_request_meta_context (nbd, false); // we'll do this ourselves nbd_set_opt_mode (nbd, true); nbd_connect_...(); if (!nbd_aio_is_negotiating (nbd)) fatal ("server does not support listing"); // Determine which exports (if any) are exposed without TLS printf ("unencrypted exports:\n"); nbd_opt_list (nbd, callback_exports); // Now enable TLS, and try again if (nbd_opt_starttls (nbd) != 0) fatal ("server does not support TLS"); printf ("encrypted exports:\n"); nbd_opt_list (nbd, callback_exports); printf ("which export to learn more about?"); get user's choice... nbd_set_export_name (nbd, name); if (nbd_opt_structured_reply (nbd) == 1) { printf ("metacontexts available:"); nbd_opt_list_meta_context (nbd, callback_contexts); while (1) { printf ("which context to request, or -1 to finish connecting"); get user's choice if (choice == -1) break; nbd_add_meta_context (nbd, choice); } nbd_opt_set_meta_context (nbd, callback_silent); } else printf ("metacontexts not available\n"); nbd_opt_go (nbd);

> > @@ -3246,6 +3299,10 @@ let first_version = > > "set_request_block_size", (1, 12); > > "get_request_block_size", (1, 12); > > > > + (* Added in 1.13.x development cycle, will be stable and supported in 1.14. *) > > + "set_request_meta_context", (1, 14); > > + "get_request_meta_context", (1, 14); > > I think this should be 1.15.x .. 1.16, since 1.14 is already out. You're right. Fixed for the nbd_supports_vsock() patch, since that one will beat this series in.