io_uring: deduplicate io_openat{,2}_prep()

to #28736503

commit ec65fea5a8d7a82d3137dd2a44197eb577da111f upstream

io_openat_prep() and io_openat2_prep() are identical except for how
struct open_how is built. Deduplicate it with a helper.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

fs/io_uring.c

@@ -2981,26 +2981,21 @@ static int io_fallocate(struct io_kiocb *req, bool force_nonblock)
 	return 0;
 }
 
-static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	const char __user *fname;
-	u64 flags, mode;
 	int ret;
 
 	if (unlikely(req->ctx->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_SQPOLL)))
 		return -EINVAL;
-	if (sqe->ioprio || sqe->buf_index)
+	if (unlikely(sqe->ioprio || sqe->buf_index))
 		return -EINVAL;
-	if (req->flags & REQ_F_FIXED_FILE)
+	if (unlikely(req->flags & REQ_F_FIXED_FILE))
 		return -EBADF;
-	if (req->flags & REQ_F_NEED_CLEANUP)
-		return 0;
 
-	mode = READ_ONCE(sqe->len);
-	flags = READ_ONCE(sqe->open_flags);
-	if (force_o_largefile())
-		flags |= O_LARGEFILE;
-	req->open.how = build_open_how(flags, mode);
+	/* open.how should be already initialised */
+	if (!(req->open.how.flags & O_PATH) && force_o_largefile())
+		req->open.how.flags |= O_LARGEFILE;
 
 	req->open.dfd = READ_ONCE(sqe->fd);
 	fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
@@ -3010,33 +3005,33 @@ static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		req->open.filename = NULL;
 		return ret;
 	}
-
 	req->open.nofile = rlimit(RLIMIT_NOFILE);
 	req->flags |= REQ_F_NEED_CLEANUP;
 	return 0;
 }
 
+static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	u64 flags, mode;
+
+	if (req->flags & REQ_F_NEED_CLEANUP)
+		return 0;
+	mode = READ_ONCE(sqe->len);
+	flags = READ_ONCE(sqe->open_flags);
+	req->open.how = build_open_how(flags, mode);
+	return __io_openat_prep(req, sqe);
+}
+
 static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct open_how __user *how;
-	const char __user *fname;
 	size_t len;
 	int ret;
 
-	if (unlikely(req->ctx->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_SQPOLL)))
-		return -EINVAL;
-	if (sqe->ioprio || sqe->buf_index)
-		return -EINVAL;
-	if (req->flags & REQ_F_FIXED_FILE)
-		return -EBADF;
 	if (req->flags & REQ_F_NEED_CLEANUP)
 		return 0;
-
-	req->open.dfd = READ_ONCE(sqe->fd);
-	fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
 	how = u64_to_user_ptr(READ_ONCE(sqe->addr2));
 	len = READ_ONCE(sqe->len);
-
 	if (len < OPEN_HOW_SIZE_VER0)
 		return -EINVAL;
 
@@ -3045,19 +3040,7 @@ static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if (ret)
 		return ret;
 
-	if (!(req->open.how.flags & O_PATH) && force_o_largefile())
-		req->open.how.flags |= O_LARGEFILE;
-
-	req->open.filename = getname(fname);
-	if (IS_ERR(req->open.filename)) {
-		ret = PTR_ERR(req->open.filename);
-		req->open.filename = NULL;
-		return ret;
-	}
-
-	req->open.nofile = rlimit(RLIMIT_NOFILE);
-	req->flags |= REQ_F_NEED_CLEANUP;
-	return 0;
+	return __io_openat_prep(req, sqe);
 }
 
 static int io_openat2(struct io_kiocb *req, bool force_nonblock)