jammy (3) nbd_zero.3.gz

Provided by: libnbd-dev_1.10.5-1_amd64 bug

NAME
       nbd_zero - send write zeroes command to the NBD server


SYNOPSIS
        #include <libnbd.h>

        int nbd_zero (struct nbd_handle *h, uint64_t count,
                      uint64_t offset, uint32_t flags);


DESCRIPTION
       Issue a write zeroes command to the NBD server, which if supported by the server causes a zeroes to be
       written efficiently starting at "offset" and ending at "offset" + "count" - 1.  The call returns when the
       command has been acknowledged by the server, or there is an error.  Note this will generally return an
       error if nbd_can_zero(3) is false or nbd_is_read_only(3) is true.

       The "flags" parameter may be 0 for no flags, or may contain "LIBNBD_CMD_FLAG_FUA" meaning that the server
       should not return until the data has been committed to permanent storage (if that is supported - some
       servers cannot do this, see nbd_can_fua(3)), "LIBNBD_CMD_FLAG_NO_HOLE" meaning that the server should
       favor writing actual allocated zeroes over punching a hole, and/or "LIBNBD_CMD_FLAG_FAST_ZERO" meaning
       that the server must fail quickly if writing zeroes is no faster than a normal write (if that is
       supported - some servers cannot do this, see nbd_can_fast_zero(3)).

       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.


HANDLE STATE
       The handle must be connected with the server, otherwise this call will return an 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_ZERO 1


SEE ALSO
       nbd_aio_zero(3), nbd_can_fast_zero(3), nbd_can_fua(3), nbd_can_zero(3), nbd_create(3),
       nbd_is_read_only(3), nbd_set_strict_mode(3), libnbd(3).


AUTHORS
       Eric Blake

       Richard W.M. Jones


       Copyright (C) 2019-2021 Red Hat Inc.


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