nbd\_clear\_meta\_contexts(3) LIBNBD nbd\_clear\_meta\_contexts(3)

# [NAME](#NAME)

nbd\_clear\_meta\_contexts - reset the list of requested meta contexts

# [SYNOPSIS](#SYNOPSIS)

```
 #include <libnbd.h>
 int nbd_clear_meta_contexts (
       struct nbd_handle *h
     );
```

# [DESCRIPTION](#DESCRIPTION)

During connection libnbd can negotiate zero or more metadata contexts with the server. Metadata contexts are features (such as "base:allocation") which describe information returned by the [**nbd\_block\_status\_64**(3)](/man/os/libnbd/nbd_block_status_64.3) command (for "base:allocation" this is whether blocks of data are allocated, zero or sparse).

This command resets the list of meta contexts to request back to an empty list, for re-population by further use of [**nbd\_add\_meta\_context**(3)](/man/os/libnbd/nbd_add_meta_context.3). It is primarily useful when option negotiation mode is selected (see [**nbd\_set\_opt\_mode**(3)](/man/os/libnbd/nbd_set_opt_mode.3)), for altering the list of attempted contexts between subsequent export queries.

# [RETURN VALUE](#RETURN_VALUE)

If the call is successful the function returns 0.

# [ERRORS](#ERRORS)

On error -1 is returned.

Refer to "ERROR HANDLING" in [**libnbd**(3)](/man/os/libnbd/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)](/man/os/libnbd/libnbd.3).

# [HANDLE STATE](#HANDLE_STATE)

nbd\_clear\_meta\_contexts can be called when the handle is in the following states:

```
 ┌─────────────────────────────────────┬─────────────────────────┐
 │ Handle created, before connecting   │ ✅ allowed              │
 │ Connecting                          │ ❌ error                │
 │ Connecting & handshaking (opt_mode) │ ✅ allowed              │
 │ Connected to the server             │ ❌ error                │
 │ Connection shut down                │ ❌ error                │
 │ Handle dead                         │ ❌ error                │
 └─────────────────────────────────────┴─────────────────────────┘
```

# [VERSION](#VERSION)

This function first appeared in libnbd 1.6.

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

```
 #define LIBNBD_HAVE_NBD_CLEAR_META_CONTEXTS 1
```

# [SEE ALSO](#SEE_ALSO)

[**nbd\_add\_meta\_context**(3)](/man/os/libnbd/nbd_add_meta_context.3), [**nbd\_block\_status\_64**(3)](/man/os/libnbd/nbd_block_status_64.3), [**nbd\_can\_meta\_context**(3)](/man/os/libnbd/nbd_can_meta_context.3), [**nbd\_create**(3)](/man/os/libnbd/nbd_create.3), [**nbd\_get\_meta\_context**(3)](/man/os/libnbd/nbd_get_meta_context.3), [**nbd\_get\_nr\_meta\_contexts**(3)](/man/os/libnbd/nbd_get_nr_meta_contexts.3), [**nbd\_set\_opt\_mode**(3)](/man/os/libnbd/nbd_set_opt_mode.3), [**libnbd**(3)](/man/os/libnbd/libnbd.3).

# [AUTHORS](#AUTHORS)

Eric Blake

Richard W.M. Jones

# [COPYRIGHT](#COPYRIGHT)

Copyright Red Hat

# [LICENSE](#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

2026-09-11 libnbd-1.25.7

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Document: nbd_clear_meta_contexts(3) from libnbd 1.25.7-r2 (Chainguard OS)