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@fb.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index d9396cfaa4f3f79b1310903849c693030645273e..73d261004c4a0e26742705a461744a94342dddee 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3003,18 +3003,22 @@ 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,
@@ -3540,6 +3544,7 @@ 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;
@@ -3572,9 +3577,9 @@ 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;
@@ -3678,6 +3683,7 @@ 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;
@@ -3708,9 +3714,9 @@ 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;