io\_uring\_register\_file\_alloc\_range(3) liburing Manual io\_uring\_register\_file\_alloc\_range(3)

# [NAME](#NAME)

io\_uring\_register\_file\_alloc\_range - set range for fixed file allocations

# [SYNOPSIS](#SYNOPSIS)

```
#include <liburing.h>
```

```
int io_uring_register_file_alloc_range(struct io_uring *ring,
                                       unsigned off,
                                       unsigned len);
```

# [DESCRIPTION](#DESCRIPTION)

The [**io\_uring\_register\_file\_alloc\_range**(3)](/man/os/liburing/io_uring_register_file_alloc_range.3) function sets the allowable range for fixed file index allocations within the kernel. When requests that can instantiate a new fixed file are used with **IORING\_FILE\_INDEX\_ALLOC ,** the application is asking the kernel to allocate a new fixed file descriptor rather than pass in a specific value for one. By default, the kernel will pick any available fixed file descriptor within the range available. Calling this function with *off* set to the starting offset and *len* set to the number of descriptors, the application can limit the allocated descriptors to that particular range. This effectively allows the application to set aside a range just for dynamic allocations, with the remainder being used for specific values.

The application must have registered a fixed file table upfront, e.g. through [**io\_uring\_register\_files**(3)](/man/os/liburing/io_uring_register_files.3) or [**io\_uring\_register\_files\_sparse**(3)](/man/os/liburing/io_uring_register_files_sparse.3)**.**

Available since 6.0.

# [RETURN VALUE](#RETURN_VALUE)

On success [**io\_uring\_register\_file\_alloc\_range**(3)](/man/os/liburing/io_uring_register_file_alloc_range.3) returns 0. On failure it returns **-errno**.

# [SEE ALSO](#SEE_ALSO)

[**io\_uring\_register\_files**(3)](/man/os/liburing/io_uring_register_files.3) [**io\_uring\_prep\_accept\_direct**(3)](/man/os/liburing/io_uring_prep_accept_direct.3) [**io\_uring\_prep\_openat\_direct**(3)](/man/os/liburing/io_uring_prep_openat_direct.3) [**io\_uring\_prep\_socket\_direct**(3)](/man/os/liburing/io_uring_prep_socket_direct.3)

October 21, 2022 liburing-2.3

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Document: io_uring_register_file_alloc_range(3) from liburing 2.15-r5 (Chainguard OS)
Source: https://github.com/axboe/liburing.git