UPSTREAM: 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

Change-Id: I19d8cdb6ea88d8fc4625e521363d5a8f638dfdcb
Signed-off-by: Dylan Yudaken <[email protected]>
Reviewed-by: Pavel Begunkov <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Bug: 268174392
(cherry picked from commit e90cfb96999454b6d3f469f3a9414cf7f9df62fe)
Signed-off-by: Greg Kroah-Hartman <[email protected]>
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index ad58603..a494126 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3010,18 +3010,22 @@ 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,
@@ -3547,6 +3551,7 @@ 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;
@@ -3579,9 +3584,9 @@ 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;
@@ -3685,6 +3690,7 @@ 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;
@@ -3715,9 +3721,9 @@ 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;