io_uring: remove duplicated calls to io_kiocb_ppos

io_kiocb_ppos is called in both branches, and it seems that the compiler
does not fuse this. Fusing removes a few bytes from loop_rw_iter.

Before:
$ nm -S fs/io_uring.o | grep loop_rw_iter
0000000000002430 0000000000000124 t loop_rw_iter

After:
$ nm -S fs/io_uring.o | grep loop_rw_iter
0000000000002430 000000000000010d t loop_rw_iter
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -3420,6 +3420,7 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
 	struct kiocb *kiocb = &req->rw.kiocb;
 	struct file *file = req->file;
 	ssize_t ret = 0;
+	loff_t *ppos;
 
 	/*
 	 * Don't support polled IO through this interface, and we can't
@@ -3432,6 +3433,8 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
 	    !(kiocb->ki_filp->f_flags & O_NONBLOCK))
 		return -EAGAIN;
 
+	ppos = io_kiocb_ppos(kiocb);
+
 	while (iov_iter_count(iter)) {
 		struct iovec iovec;
 		ssize_t nr;
@@ -3445,10 +3448,10 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
 
 		if (rw == READ) {
 			nr = file->f_op->read(file, iovec.iov_base,
-					      iovec.iov_len, io_kiocb_ppos(kiocb));
+					      iovec.iov_len, ppos);
 		} else {
 			nr = file->f_op->write(file, iovec.iov_base,
-					       iovec.iov_len, io_kiocb_ppos(kiocb));
+					       iovec.iov_len, ppos);
 		}
 
 		if (nr < 0) {