Function io_uring_register_file_alloc_range 

pub unsafe extern "C" fn io_uring_register_file_alloc_range(
    ring: *mut io_uring,
    off: c_uint,
    len: c_uint,
) -> c_int

Set range for fixed file allocations

DESCRIPTION

The io_uring_register_file_alloc_range 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 or io_uring_register_files_sparse.

Available since 6.0.

RETURN VALUE

On success io_uring_register_file_alloc_range returns 0. On failure it returns -errno.

SEE ALSO

io_uring_register_files io_uring_prep_accept_direct io_uring_prep_openat_direct io_uring_prep_socket_direct