nbd_aio_block_status_filter - Man Page

​ #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
​         );

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.

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

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 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

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).

Eric Blake

Richard W.M. Jones

Copyright Red Hat

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