NAME

       nbd_set_request_meta_context - control whether connect automatically requests meta
       contexts

SYNOPSIS

        #include <libnbd.h>

        int nbd_set_request_meta_context (
              struct nbd_handle *h, bool request
            );

DESCRIPTION

       This function controls whether the act of connecting to an export (all "nbd_connect_*"
       calls when nbd_set_opt_mode(3) is false, or nbd_opt_go(3) and nbd_opt_info(3) when option
       mode is enabled) will also try to issue NBD_OPT_SET_META_CONTEXT when the server supports
       structured replies or extended headers and any contexts were registered by
       nbd_add_meta_context(3).  The default setting is true; however the extra step of
       negotiating meta contexts is not always desirable: performing both info and go on the same
       export works without needing to re-negotiate contexts on the second call; integration
       testing of other servers may benefit from manual invocation of nbd_opt_set_meta_context(3)
       at other times in the negotiation sequence; and even when using just nbd_opt_info(3), it
       can be faster to collect the server's results by relying on the callback function passed
       to nbd_opt_list_meta_context(3) than a series of post-process calls to
       nbd_can_meta_context(3).

       Note that this control has no effect if the server does not negotiate structured replies
       or extended headers, or if the client did not request any contexts via
       nbd_add_meta_context(3).  Setting this control to false may cause nbd_block_status(3) to
       fail.

RETURN VALUE

       If the call is successful the function returns 0.

ERRORS

       On error -1 is returned.

       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details of the error.

       The following parameters must not be NULL: "h".  For more information see "Non-NULL
       parameters" in libnbd(3).

HANDLE STATE

       nbd_set_request_meta_context can be called when the handle is in the following states:

        ┌─────────────────────────────────────┬─────────────────────────┐
        │ Handle created, before connecting   │ ✅ allowed              │
        │ Connecting                          │ ❌ error                │
        │ Connecting & handshaking (opt_mode) │ ✅ allowed              │
        │ Connected to the server             │ ❌ error                │
        │ Connection shut down                │ ❌ error                │
        │ Handle dead                         │ ❌ error                │
        └─────────────────────────────────────┴─────────────────────────┘

VERSION

       This function first appeared in libnbd 1.16.

       If you need to test if this function is available at compile time check if the following
       macro is defined:

        #define LIBNBD_HAVE_NBD_SET_REQUEST_META_CONTEXT 1

SEE ALSO

       nbd_add_meta_context(3), nbd_block_status(3), nbd_can_meta_context(3), nbd_create(3),
       nbd_get_request_meta_context(3), nbd_get_structured_replies_negotiated(3), nbd_opt_go(3),
       nbd_opt_info(3), nbd_opt_list_meta_context(3), nbd_opt_set_meta_context(3),
       nbd_set_opt_mode(3), libnbd(3).

AUTHORS

       Eric Blake

       Richard W.M. Jones

COPYRIGHT

       Copyright Red Hat

LICENSE

       This library is free software; you can redistribute it and/or modify it under the terms of
       the GNU Lesser General Public License as published by the Free Software Foundation; either
       version 2 of the License, or (at your option) any later version.

       This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
       without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
       See the GNU Lesser General Public License for more details.

       You should have received a copy of the GNU Lesser General Public License along with this
       library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
       Floor, Boston, MA 02110-1301 USA