io_uring_register_files(3) liburing Manual io_uring_register_files(3)
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_tags(struct io_uring *ring, const int *files, const __u64 *tags, unsigned nr); int io_uring_register_files_sparse(struct io_uring *ring, unsigned nr_files); int io_uring_register_files_update(struct io_uring *ring, unsigned off, const int *files, unsigned nr_files); int io_uring_register_files_update_tag(struct io_uring *ring, unsigned off, const int *files, const __u64 *tags, 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 io_uring_register_files_tags(3) function behaves the same as io_uring_register_files(3) function but additionally takes tags parameter. See IORING_REGISTER_BUFFERS2 for the resource tagging description. The io_uring_register_files_sparse(3) function registers an empty file table of nr_files number of file descriptors. These files must be updated before use, using eg io_uring_register_files_update_tag(3). 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. The io_uring_register_files_update(3) function updates existing registered files. The off is offset on which to start the update nr_files number of files defined by the array files belonging to the ring. The io_uring_register_files_update_tag(3) function behaves the same as io_uring_register_files_update(3) function but additionally takes tags parameter. See IORING_REGISTER_BUFFERS2 for the resource tagging description.
On success io_uring_register_files(3), io_uring_register_files_tags(3) and io_uring_register_files_sparse(3) return 0. io_uring_register_files_update(3) and io_uring_register_files_update_tag(3) return number of files updated. On failure they return -errno.
io_uring_register(2), io_uring_get_sqe(3), io_uring_unregister_files(3)
This page is part of the liburing (A library for io_uring) project. Information about the project can be found at ⟨https://github.com/axboe/liburing⟩. If you have a bug report for this manual page, send it to email@example.com. This page was obtained from the project's upstream Git repository ⟨https://github.com/axboe/liburing⟩ on 2023-06-23. (At that time, the date of the most recent commit that was found in the repository was 2023-06-22.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to firstname.lastname@example.org liburing-2.1 November 15, 2021 io_uring_register_files(3)
Pages that refer to this page: io_uring_prep_accept(3), io_uring_prep_accept_direct(3), io_uring_prep_multishot_accept(3), io_uring_prep_multishot_accept_direct(3), io_uring_register_file_alloc_range(3), io_uring_register_files(3), io_uring_register_files_sparse(3), io_uring_register_files_tags(3), io_uring_register_files_update(3), io_uring_register_files_update_tag(3)