nbd_clear_meta_contexts(3)          LIBNBD          nbd_clear_meta_contexts(3)


NAME
       nbd_clear_meta_contexts - reset the list of requested meta contexts

SYNOPSIS
        #include <libnbd.h>

        int nbd_clear_meta_contexts (
              struct nbd_handle *h
            );

DESCRIPTION
       During connection libnbd can negotiate zero or more metadata contexts
       with the server.  Metadata contexts are features (such as
       "base:allocation") which describe information returned by the
       nbd_block_status_64(3) command (for "base:allocation" this is whether
       blocks of data are allocated, zero or sparse).

       This command resets the list of meta contexts to request back to an
       empty list, for re-population by further use of
       nbd_add_meta_context(3).  It is primarily useful when option
       negotiation mode is selected (see nbd_set_opt_mode(3)), for altering
       the list of attempted contexts between subsequent export queries.

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_clear_meta_contexts 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 1.6.

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

        #define LIBNBD_HAVE_NBD_CLEAR_META_CONTEXTS 1

SEE ALSO
       nbd_add_meta_context(3), nbd_block_status_64(3),
       nbd_can_meta_context(3), nbd_create(3), nbd_get_meta_context(3),
       nbd_get_nr_meta_contexts(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

libnbd-1.20.0                     2024-05-31        nbd_clear_meta_contexts(3)