NAME

       nbd_flush - send flush command to the NBD server

SYNOPSIS

        #include <libnbd.h>

        int nbd_flush (
              struct nbd_handle *h, uint32_t flags
            );

DESCRIPTION

       Issue the flush command to the NBD server.  The function should return when all write commands which have
       completed have been committed to permanent storage on the server.  Note this will generally return an
       error if nbd_can_flush(3) is false.

       The "flags" parameter must be 0 for now (it exists for future NBD protocol extensions).

       By default, libnbd will reject attempts to use this function with parameters that are likely to result in
       server failure, such as requesting an unknown command flag.  The nbd_set_strict_mode(3) function can be
       used to alter which scenarios should await a server reply rather than failing fast.

RETURN VALUE

       If the call is successful the function returns 0.

ERRORS

       On error -1 is returned.

       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details of the error.

       The following parameters must not be NULL: "h".  For more information see "Non-NULL parameters" in
       libnbd(3).

HANDLE STATE

       nbd_flush can be called when the handle is in the following state:

        ┌─────────────────────────────────────┬─────────────────────────┐
        │ Handle created, before connecting   │ ❌ error                │
        │ Connecting                          │ ❌ error                │
        │ Connecting & handshaking (opt_mode) │ ❌ error                │
        │ Connected to the server             │ ✅ allowed              │
        │ Connection shut down                │ ❌ error                │
        │ Handle dead                         │ ❌ error                │
        └─────────────────────────────────────┴─────────────────────────┘

VERSION

       This function first appeared in libnbd 1.0.

       If you need to test if this function is available at compile time check if the following macro is
       defined:

        #define LIBNBD_HAVE_NBD_FLUSH 1

SEE ALSO

       nbd_aio_flush(3), nbd_can_flush(3), nbd_create(3), nbd_set_strict_mode(3), libnbd(3).

AUTHORS

       Eric Blake

       Richard W.M. Jones

COPYRIGHT

       Copyright Red Hat

LICENSE

       This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser
       General Public License as published by the Free Software Foundation; either version 2 of the License, or
       (at your option) any later version.

       This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
       the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General
       Public License for more details.

       You should have received a copy of the GNU Lesser General Public License along with this library; if not,
       write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA