io_uring_register_files - register file descriptors
#include <liburing.h>
int io_uring_register_files(struct io_uring *ring,
const int *files,
unsigned nr_files);
int io_uring_register_files_sparse(struct io_uring *ring,
unsigned nr_files);
The
io_uring_register_files(3) function registers
nr_files number
of file descriptors defined by the array
files belonging to the
ring for subsequent operations.
The function registers an empty file
table of
nr_files number of file descriptors. The sparse variant is
available in kernels 5.19 and later.
Registering a file table is a prerequisite for using any request that uses
direct descriptors.
Registered files have less overhead per operation than normal files. This is due
to the kernel grabbing a reference count on a file when an operation begins,
and dropping it when it's done. When the process file table is shared, for
example if the process has ever created any threads, then this cost goes up
even more. Using registered files reduces the overhead of file reference
management across requests that operate on a file.
On success
io_uring_register_files(3) and
return 0. On failure they return
-errno.
io_uring_get_sqe(3),
io_uring_unregister_files(3)