This is a note to let you know that I've just added the patch titled io_uring: do not recalculate ppos unnecessarily to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: io_uring-do-not-recalculate-ppos-unnecessarily.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 1bede82287bd73eb9e91510500259fa6cb6a4197 Author: Dylan Yudaken <dylany@xxxxxx> Date: Tue Feb 22 02:55:03 2022 -0800 io_uring: do not recalculate ppos unnecessarily commit b4aec40015953b65f2f114641e7fd7714c8df8e6 upstream. There is a slight optimisation to be had by calculating the correct pos pointer inside io_kiocb_update_pos and then using that later. It seems code size drops by a bit: 000000000000a1b0 0000000000000400 t io_read 000000000000a5b0 0000000000000319 t io_write vs 000000000000a1b0 00000000000003f6 t io_read 000000000000a5b0 0000000000000310 t io_write Signed-off-by: Dylan Yudaken <dylany@xxxxxx> Reviewed-by: Pavel Begunkov <asml.silence@xxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index eaf8463c9b14..d4e017b07371 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3000,18 +3000,22 @@ static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret) } } -static inline void io_kiocb_update_pos(struct io_kiocb *req) +static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req) { struct kiocb *kiocb = &req->rw.kiocb; + bool is_stream = req->file->f_mode & FMODE_STREAM; if (kiocb->ki_pos == -1) { - if (!(req->file->f_mode & FMODE_STREAM)) { + if (!is_stream) { req->flags |= REQ_F_CUR_POS; kiocb->ki_pos = req->file->f_pos; + return &kiocb->ki_pos; } else { kiocb->ki_pos = 0; + return NULL; } } + return is_stream ? NULL : &kiocb->ki_pos; } static void kiocb_done(struct kiocb *kiocb, ssize_t ret, @@ -3537,6 +3541,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags) bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; struct iov_iter_state __state, *state; ssize_t ret, ret2; + loff_t *ppos; if (rw) { iter = &rw->iter; @@ -3569,9 +3574,9 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags) return ret ?: -EAGAIN; } - io_kiocb_update_pos(req); + ppos = io_kiocb_update_pos(req); - ret = rw_verify_area(READ, req->file, io_kiocb_ppos(kiocb), req->result); + ret = rw_verify_area(READ, req->file, ppos, req->result); if (unlikely(ret)) { kfree(iovec); return ret; @@ -3675,6 +3680,7 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags) bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; struct iov_iter_state __state, *state; ssize_t ret, ret2; + loff_t *ppos; if (rw) { iter = &rw->iter; @@ -3705,9 +3711,9 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags) (req->flags & REQ_F_ISREG)) goto copy_iov; - io_kiocb_update_pos(req); + ppos = io_kiocb_update_pos(req); - ret = rw_verify_area(WRITE, req->file, io_kiocb_ppos(kiocb), req->result); + ret = rw_verify_area(WRITE, req->file, ppos, req->result); if (unlikely(ret)) goto out_free;