nbd_aio_disconnect3

Usage

 #include <libnbd.h>
 int nbd_aio_disconnect (
       struct nbd_handle *h, uint32_t flags
     );

Overview

Issue the disconnect command to the NBD server. This is not a normal command because NBD servers are not obliged to send a reply. Instead you should wait for nbd_aio_is_closed(3) to become true on the connection. Once this command is issued, you cannot issue any further commands.

Although libnbd does not prevent you from issuing this command while still waiting on the replies to previous commands, the NBD protocol recommends that you wait until there are no other commands in flight (see nbd_aio_in_flight(3)), to give the server a better chance at a clean shutdown.

The "flags" parameter must be 0 for now (it exists for future NBD protocol extensions). There is no direct synchronous counterpart; however, nbd_shutdown(3) will call this function if appropriate.

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_aio_disconnect 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_AIO_DISCONNECT 1