[PATCH 5/6] io_uring: add __io_open_prep() helper

[Thomas Bertschinger <tahbertschinger@xxxxxxxxx>]

This adds a helper, __io_open_prep(), which does the part of preparing
for an open that is shared between openat*() and open_by_handle_at().

It excludes reading in the user path or file handle--this will be done
by functions specific to the kind of open().

Signed-off-by: Thomas Bertschinger <tahbertschinger@xxxxxxxxx>
---
 io_uring/openclose.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/io_uring/openclose.c b/io_uring/openclose.c
index f15a9307f811..8be061783207 100644
--- a/io_uring/openclose.c
+++ b/io_uring/openclose.c
@@ -58,11 +58,10 @@ static bool io_openat_force_async(struct io_open *open)
 	return open->how.flags & (O_TRUNC | O_CREAT | __O_TMPFILE);
 }
 
-static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+/* Prep for open that is common to both openat*() and open_by_handle_at() */
+static int __io_open_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct io_open *open = io_kiocb_to_cmd(req, struct io_open);
-	const char __user *fname;
-	int ret;
 
 	if (unlikely(sqe->buf_index))
 		return -EINVAL;
@@ -74,6 +73,26 @@ static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 		open->how.flags |= O_LARGEFILE;
 
 	open->dfd = READ_ONCE(sqe->fd);
+
+	open->file_slot = READ_ONCE(sqe->file_index);
+	if (open->file_slot && (open->how.flags & O_CLOEXEC))
+		return -EINVAL;
+
+	open->nofile = rlimit(RLIMIT_NOFILE);
+
+	return 0;
+}
+
+static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_open *open = io_kiocb_to_cmd(req, struct io_open);
+	const char __user *fname;
+	int ret;
+
+	ret = __io_open_prep(req, sqe);
+	if (ret)
+		return ret;
+
 	fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
 	open->filename = getname(fname);
 	if (IS_ERR(open->filename)) {
@@ -82,11 +101,6 @@ static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 		return ret;
 	}
 
-	open->file_slot = READ_ONCE(sqe->file_index);
-	if (open->file_slot && (open->how.flags & O_CLOEXEC))
-		return -EINVAL;
-
-	open->nofile = rlimit(RLIMIT_NOFILE);
 	req->flags |= REQ_F_NEED_CLEANUP;
 	if (io_openat_force_async(open))
 		req->flags |= REQ_F_FORCE_ASYNC;
-- 
2.50.1