nbd_aio_block_status_filter - send filtered block status command to the NBD server

       Eric Blake

       Richard W.M. Jones

       Copyright Red Hat

       Send a filtered block status command to the NBD server.

       To check if the command completed, call nbd_aio_command_completed(3).  Or supply the optional
       "completion_callback" which will be invoked as described in "Completion callbacks" in libnbd(3).

       Other parameters behave as documented in nbd_block_status_filter(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.

       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", "contexts".  For more information see "Non-NULL
       parameters" in libnbd(3).

       nbd_aio_block_status_filter 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                │
        └─────────────────────────────────────┴─────────────────────────┘

       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

libnbd-1.22.2                                      2025-06-16                     nbd_aio_block_status_filter(3)

       nbd_aio_block_status_filter - send filtered block status command to the NBD server

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

nbd_aio_block_status_64(3), nbd_aio_command_completed(3), nbd_block_status_filter(3),
       nbd_can_block_status_payload(3), nbd_can_meta_context(3), nbd_create(3), nbd_set_strict_mode(3), "Issuing
       asynchronous commands" in libnbd(3), libnbd(3).

        #include <libnbd.h>

        typedef struct {
          int (*callback) (void *user_data,
                           const char *metacontext,
                           uint64_t offset, nbd_extent *entries,
                           size_t nr_entries, int *error);
          void *user_data;
          void (*free) (void *user_data);
        } nbd_extent64_callback;

        typedef struct {
          int (*callback) (void *user_data, int *error);
          void *user_data;
          void (*free) (void *user_data);
        } nbd_completion_callback;

        int64_t nbd_aio_block_status_filter (
                  struct nbd_handle *h, uint64_t count,
                  uint64_t offset, char **contexts,
                  nbd_extent64_callback extent64_callback,
                  nbd_completion_callback completion_callback,
                  uint32_t flags
                );

       This function first appeared in libnbd 1.18.

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

        #define LIBNBD_HAVE_NBD_AIO_BLOCK_STATUS_FILTER 1