Add an optional feature to open/accept directly into io_uring's fixed file table bypassing the normal file table. Same behaviour if as the snippet below, but in one operation: sqe = io_uring_[open|accept]_prep(); io_uring_submit(sqe); // ... once we get a CQE back io_uring_register_files_update(uring_idx, (fd = cqe->res)); close((fd = cqe->res)); The idea is old, and was brough up and implemented a year ago by Josh Triplett, though haven't sought the light. The behaviour is controlled by setting sqe->file_index, where 0 implies the old behaviour using normal file tables. If non-zero value is specified, then it will behave as described and place the file into a fixed file slot sqe->file_index - 1. A file table should be already created, the slot should be valid and empty, otherwise the operation will fail. note: IOSQE_FIXED_FILE can't be used as a mode switch, because accept takes a file, and it already uses the flag with a different meaning. v2, since RFC: - added attribution - updated descriptions - rebased v3: - EBADF if slot is already used (Josh Triplett) - alias index with splice_fd_in (Josh Triplett) - fix a bound check bug v4: - separate u32 fields to internally store indexes (Jens, Josh) Pavel Begunkov (4): net: add accept helper not installing fd io_uring: openat directly into fixed fd table io_uring: hand code io_accept() fd installing io_uring: accept directly into fixed file table fs/io_uring.c | 115 +++++++++++++++++++++++++++++----- include/linux/socket.h | 3 + include/uapi/linux/io_uring.h | 5 +- net/socket.c | 71 +++++++++++---------- 4 files changed, 143 insertions(+), 51 deletions(-) -- 2.32.0
