1nbd_cache(3)                        LIBNBD                        nbd_cache(3)
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NAME

6       nbd_cache - send cache (prefetch) command to the NBD server
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SYNOPSIS

9        #include <libnbd.h>
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11        int nbd_cache (struct nbd_handle *h, uint64_t count,
12                       uint64_t offset, uint32_t flags);
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DESCRIPTION

15       Issue the cache (prefetch) command to the NBD server, which if
16       supported by the server causes data to be prefetched into faster
17       storage by the server, speeding up a subsequent nbd_pread(3) call.  The
18       server can also silently ignore this command.  Note this will return an
19       error if nbd_can_cache(3) is false.
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21       The "flags" parameter must be 0 for now (it exists for future NBD
22       protocol extensions).
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RETURN VALUE

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

28       On error "-1" is returned.
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30       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
31       of the error.
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HANDLE STATE

34       The handle must be connected and finished handshaking with the server,
35       otherwise this call will return an error.
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VERSION

38       This function first appeared in libnbd 1.0.
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40       If you need to test if this function is available at compile time check
41       if the following macro is defined:
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43        #define LIBNBD_HAVE_NBD_CACHE 1
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SEE ALSO

46       nbd_aio_cache(3), nbd_can_cache(3), nbd_create(3), nbd_pread(3),
47       libnbd(3).
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AUTHORS

50       Eric Blake
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52       Richard W.M. Jones
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55       Copyright (C) 2019 Red Hat Inc.
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LICENSE

58       This library is free software; you can redistribute it and/or modify it
59       under the terms of the GNU Lesser General Public License as published
60       by the Free Software Foundation; either version 2 of the License, or
61       (at your option) any later version.
62
63       This library is distributed in the hope that it will be useful, but
64       WITHOUT ANY WARRANTY; without even the implied warranty of
65       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
66       Lesser General Public License for more details.
67
68       You should have received a copy of the GNU Lesser General Public
69       License along with this library; if not, write to the Free Software
70       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
71       02110-1301 USA
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75libnbd-1.3.7                      2020-04-23                      nbd_cache(3)
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