1nbd_get_nr_meta_contexts(3)         LIBNBD         nbd_get_nr_meta_contexts(3)
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NAME

6       nbd_get_nr_meta_contexts - return the current number of requested meta
7       contexts
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SYNOPSIS

10        #include <libnbd.h>
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12        ssize_t nbd_get_nr_meta_contexts (struct nbd_handle *h);
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DESCRIPTION

15       During connection libnbd can negotiate zero or more metadata contexts
16       with the server.  Metadata contexts are features (such as
17       "base:allocation") which describe information returned by the
18       nbd_block_status(3) command (for "base:allocation" this is whether
19       blocks of data are allocated, zero or sparse).
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21       This command returns how many meta contexts have been added to the list
22       to request from the server via nbd_add_meta_context(3).  The server is
23       not obligated to honor all of the requests; to see what it actually
24       supports, see nbd_can_meta_context(3).
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RETURN VALUE

27       This call returns an integer size ≥ 0.
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ERRORS

30       On error "-1" is returned.
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32       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
33       of the error.
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35       The following parameters must not be NULL: "h".  For more information
36       see "Non-NULL parameters" in libnbd(3).
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VERSION

39       This function first appeared in libnbd 1.6.
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41       If you need to test if this function is available at compile time check
42       if the following macro is defined:
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44        #define LIBNBD_HAVE_NBD_GET_NR_META_CONTEXTS 1
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SEE ALSO

47       nbd_add_meta_context(3), nbd_block_status(3), nbd_can_meta_context(3),
48       nbd_clear_meta_contexts(3), nbd_create(3), nbd_get_meta_context(3),
49       libnbd(3).
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AUTHORS

52       Eric Blake
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54       Richard W.M. Jones
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57       Copyright (C) 2019-2021 Red Hat Inc.
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LICENSE

60       This library is free software; you can redistribute it and/or modify it
61       under the terms of the GNU Lesser General Public License as published
62       by the Free Software Foundation; either version 2 of the License, or
63       (at your option) any later version.
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65       This library is distributed in the hope that it will be useful, but
66       WITHOUT ANY WARRANTY; without even the implied warranty of
67       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
68       Lesser General Public License for more details.
69
70       You should have received a copy of the GNU Lesser General Public
71       License along with this library; if not, write to the Free Software
72       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
73       02110-1301 USA
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77libnbd-1.14.2                     2023-01-03       nbd_get_nr_meta_contexts(3)
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