1nbd_aio_cache(3)                    LIBNBD                    nbd_aio_cache(3)
2
3
4

NAME

6       nbd_aio_cache - send cache (prefetch) command to the NBD server
7

SYNOPSIS

9        #include <libnbd.h>
10
11        typedef struct {
12          int (*callback) (void *user_data, int *error);
13          void *user_data;
14          void (*free) (void *user_data);
15        } nbd_completion_callback;
16
17        int64_t nbd_aio_cache (struct nbd_handle *h,
18                               uint64_t count, uint64_t offset,
19                               nbd_completion_callback completion_callback,
20                               uint32_t flags);
21

DESCRIPTION

23       Issue the cache (prefetch) command to the NBD server.
24
25       To check if the command completed, call nbd_aio_command_completed(3).
26       Or supply the optional "completion_callback" which will be invoked as
27       described in "Completion callbacks" in libnbd(3).
28
29       Other parameters behave as documented in nbd_cache(3).
30

RETURN VALUE

32       This call returns the 64 bit cookie of the command.  The cookie is ≥ 1.
33       Cookies are unique (per libnbd handle, not globally).
34

ERRORS

36       On error "-1" is returned.
37
38       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
39       of the error.
40

HANDLE STATE

42       The handle must be connected and finished handshaking with the server,
43       otherwise this call will return an error.
44

VERSION

46       This function first appeared in libnbd 1.0.
47
48       If you need to test if this function is available at compile time check
49       if the following macro is defined:
50
51        #define LIBNBD_HAVE_NBD_AIO_CACHE 1
52

SEE ALSO

54       nbd_aio_command_completed(3), nbd_cache(3), nbd_can_cache(3),
55       nbd_create(3), "Issuing asynchronous commands" in libnbd(3), libnbd(3).
56

AUTHORS

58       Eric Blake
59
60       Richard W.M. Jones
61

63       Copyright (C) 2019 Red Hat Inc.
64

LICENSE

66       This library is free software; you can redistribute it and/or modify it
67       under the terms of the GNU Lesser General Public License as published
68       by the Free Software Foundation; either version 2 of the License, or
69       (at your option) any later version.
70
71       This library is distributed in the hope that it will be useful, but
72       WITHOUT ANY WARRANTY; without even the implied warranty of
73       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
74       Lesser General Public License for more details.
75
76       You should have received a copy of the GNU Lesser General Public
77       License along with this library; if not, write to the Free Software
78       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
79       02110-1301 USA
80
81
82
83libnbd-1.3.7                      2020-04-23                  nbd_aio_cache(3)
Impressum