nbd_aio_block_status_64(3)

📦
version 1.25.8 · 16 versions
, in centos-stream 10

✨ nbd_aio_block_status_64(3) ✨

okay so bestie, welcome to the nbd_aio_block_status_64 page from the LIBNBD manual 💅 this is the one where you yeet a block status command at the server asynchronously, and get a fancy 64-bit callback situation going. it's giving main character energy for extent-hungry gorls only 🎀

🌸 NAME 🌸

nbd_aio_block_status_64 — send block status command, with 64-bit callback

like. that's literally it. you send the command, the callback gets 64-bit things. slay 🦋

⭐ SYNOPSIS ⭐

#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_64 (
          struct nbd_handle *h, uint64_t count,
          uint64_t offset,
          nbd_extent64_callback extent64_callback,
          nbd_completion_callback completion_callback,
          uint32_t flags
        );

two structs, one function, zero chill. copy it exactly, bestie, don't get creative with the types 🙈

💜 DESCRIPTION 💜

Send the block status command to the NBD server. that's the whole vibe fr fr 🔥

So how do you know it finished? Two ways, pick your fighter:

  • call nbd_aio_command_completed(3) — the classic, lowkey the responsible choice
  • or supply the optional completion_callback — which gets invoked exactly as described in "Completion callbacks" in libnbd(3)

and all the other parameters? they behave as documented in nbd_block_status_64(3). no cap, go read that one for the deets 🫶

🎀 RETURN VALUE 🎀

This call returns the 64 bit cookie of the command 🍪 and that cookie is ≥ 1.

like, cookies are unique — but per libnbd handle, not globally. so don't go comparing cookies across handles, that's not the vibe 😭

💀 ERRORS 💀

On error, -1 is returned. that's your "nope, didn't work" signal 🚩

Refer to "ERROR HANDLING" in libnbd(3) for how to get further details of the error — the manpage is literally telling you where the receipts live, iykyk.

⚠️ The following parameters must not be NULL: h. For more information see "Non-NULL parameters" in libnbd(3). like, do NOT pass NULL to h. that's a jump scare waiting to happen.

🧚 NOTES 🧚

🌈 Strict call 🌈

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 🙅‍♀️ it's giving "protective bestie".

The nbd_set_strict_mode(3) function can be used to alter which scenarios should await a server reply rather than failing fast. so if you really wanna live dangerously, that's the knob to turn. choose wisely tho 💅

👑 HANDLE STATE 👑

nbd_aio_block_status_64 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

so basically: connect first, then call it. that's the whole plot 🦋

🌸 VERSION 🌸

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_64 1

it's giving "are you on the right version or are you about to have a bad time" 🫶

🍓 SEE ALSO 🍓

go read them. all of them. that's the assignment 📚✨

💖 AUTHORS 💖

Eric Blake

Richard W.M. Jones

icons, legends, the whole thing 👑

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

and that's the page, bestie 🫶 this was libnbd-1.25.8, dated 2026-10-13 — catch you on the next one, mwah 💋✨

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