1nbd_set_request_block_size(3)       LIBNBD       nbd_set_request_block_size(3)
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NAME

6       nbd_set_request_block_size - control whether NBD_OPT_GO requests block
7       size
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SYNOPSIS

10        #include <libnbd.h>
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12        int nbd_set_request_block_size (struct nbd_handle *h,
13                                        bool request);
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DESCRIPTION

16       By default, when connecting to an export, libnbd requests that the
17       server report any block size restrictions.  The NBD protocol states
18       that a server may supply block sizes regardless of whether the client
19       requests them, and libnbd will report those block sizes (see
20       nbd_get_block_size(3)); conversely, if a client does not request block
21       sizes, the server may reject the connection instead of dealing with a
22       client sending unaligned requests.  This function makes it possible to
23       test server behavior by emulating older clients.
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25       Note that even when block size is requested, the server is not
26       obligated to provide any.  Furthermore, if block sizes are provided
27       (whether or not the client requested them), libnbd enforces alignment
28       to those sizes unless nbd_set_strict_mode(3) is used to bypass client-
29       side safety checks.
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RETURN VALUE

32       If the call is successful the function returns 0.
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ERRORS

35       On error "-1" is returned.
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37       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
38       of the error.
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40       The following parameters must not be NULL: "h".  For more information
41       see "Non-NULL parameters" in libnbd(3).
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HANDLE STATE

44       The handle must be newly created, or negotiating, otherwise this call
45       will return an error.
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VERSION

48       This function first appeared in libnbd 1.12.
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50       If you need to test if this function is available at compile time check
51       if the following macro is defined:
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53        #define LIBNBD_HAVE_NBD_SET_REQUEST_BLOCK_SIZE 1
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SEE ALSO

56       nbd_create(3), nbd_get_block_size(3), nbd_get_request_block_size(3),
57       nbd_set_full_info(3), nbd_set_strict_mode(3), libnbd(3).
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AUTHORS

60       Eric Blake
61
62       Richard W.M. Jones
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65       Copyright (C) 2019-2021 Red Hat Inc.
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LICENSE

68       This library is free software; you can redistribute it and/or modify it
69       under the terms of the GNU Lesser General Public License as published
70       by the Free Software Foundation; either version 2 of the License, or
71       (at your option) any later version.
72
73       This library is distributed in the hope that it will be useful, but
74       WITHOUT ANY WARRANTY; without even the implied warranty of
75       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
76       Lesser General Public License for more details.
77
78       You should have received a copy of the GNU Lesser General Public
79       License along with this library; if not, write to the Free Software
80       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
81       02110-1301 USA
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85libnbd-1.14.2                     2023-01-03     nbd_set_request_block_size(3)
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