1nbd_block_status_filter(3)          LIBNBD          nbd_block_status_filter(3)
2
3
4

NAME

6       nbd_block_status_filter - send filtered block status command, with
7       64-bit callback
8

SYNOPSIS

10        #include <libnbd.h>
11
12        typedef struct {
13          int (*callback) (void *user_data,
14                           const char *metacontext,
15                           uint64_t offset, nbd_extent *entries,
16                           size_t nr_entries, int *error);
17          void *user_data;
18          void (*free) (void *user_data);
19        } nbd_extent64_callback;
20
21        int nbd_block_status_filter (
22              struct nbd_handle *h, uint64_t count,
23              uint64_t offset, char **contexts,
24              nbd_extent64_callback extent64_callback,
25              uint32_t flags
26            );
27

DESCRIPTION

29       Issue a filtered block status command to the NBD server.  If supported
30       by the server (see nbd_can_block_status_payload(3)), this causes
31       metadata context information about blocks beginning from the specified
32       offset to be returned, and with the result limited to just the contexts
33       specified in "filter".  Note that all strings in "filter" must be
34       supported by nbd_can_meta_context(3).
35
36       All other parameters to this function have the same semantics as in
37       nbd_block_status_64(3); except that for convenience, unless
38       <nbd_set_strict_flags(3)> was used to disable
39       "LIBNBD_STRICT_AUTO_FLAG", libnbd ignores the presence or absence of
40       the flag "LIBNBD_CMD_FLAG_PAYLOAD_LEN" in "flags", while correctly
41       using the flag over the wire.
42
43       By default, libnbd will reject attempts to use this function with
44       parameters that are likely to result in server failure, such as
45       requesting an unknown command flag.  The nbd_set_strict_mode(3)
46       function can be used to alter which scenarios should await a server
47       reply rather than failing fast.
48

RETURN VALUE

50       If the call is successful the function returns 0.
51

ERRORS

53       On error -1 is returned.
54
55       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
56       of the error.
57
58       The following parameters must not be NULL: "h", "contexts".  For more
59       information see "Non-NULL parameters" in libnbd(3).
60

HANDLE STATE

62       The handle must be connected with the server, otherwise this call will
63       return an error.
64

VERSION

66       This function first appeared in libnbd 1.18.
67
68       If you need to test if this function is available at compile time check
69       if the following macro is defined:
70
71        #define LIBNBD_HAVE_NBD_BLOCK_STATUS_FILTER 1
72

SEE ALSO

74       nbd_aio_block_status_filter(3), nbd_block_status_64(3),
75       nbd_can_block_status_payload(3), nbd_can_meta_context(3),
76       nbd_create(3), nbd_set_strict_mode(3), libnbd(3).
77

AUTHORS

79       Eric Blake
80
81       Richard W.M. Jones
82

84       Copyright Red Hat
85

LICENSE

87       This library is free software; you can redistribute it and/or modify it
88       under the terms of the GNU Lesser General Public License as published
89       by the Free Software Foundation; either version 2 of the License, or
90       (at your option) any later version.
91
92       This library is distributed in the hope that it will be useful, but
93       WITHOUT ANY WARRANTY; without even the implied warranty of
94       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
95       Lesser General Public License for more details.
96
97       You should have received a copy of the GNU Lesser General Public
98       License along with this library; if not, write to the Free Software
99       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
100       02110-1301 USA
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104libnbd-1.18.1                     2023-10-31        nbd_block_status_filter(3)
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