[PATCH 1/3] io_uring: don't use req->work.creds for inline requests

[Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>]

In io_init_req(), if uers requires a new credentials, currently we'll
save it in req->work.creds, but indeed io_wq_work is designed to describe
needed running environment for requests that will go to io-wq, if one
request is going to be submitted inline, we'd better not touch io_wq_work.
Here add a new 'const struct cred *creds' in io_kiocb, if uers requires a
new credentials, inline requests can use it.

This patch is also a preparation for later patch.

Signed-off-by: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>
---
 fs/io_uring.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 2af87f73848e..788d960abc69 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -635,6 +635,7 @@ struct io_kiocb {
 	unsigned int		flags;
 	refcount_t		refs;
 	struct task_struct	*task;
+	const struct cred	*creds;
 	unsigned long		fsize;
 	u64			user_data;
 	u32			result;
@@ -1035,8 +1036,10 @@ static inline void io_req_work_grab_env(struct io_kiocb *req,
 		mmgrab(current->mm);
 		req->work.mm = current->mm;
 	}
-	if (!req->work.creds)
+	if (!req->creds)
 		req->work.creds = get_current_cred();
+	else
+		req->work.creds = get_cred(req->creds);
 	if (!req->work.fs && def->needs_fs) {
 		spin_lock(&current->fs->lock);
 		if (!current->fs->in_exec) {
@@ -1368,6 +1371,9 @@ static void __io_req_aux_free(struct io_kiocb *req)
 	if (req->flags & REQ_F_NEED_CLEANUP)
 		io_cleanup_req(req);
 
+	if (req->creds)
+		put_cred(req->creds);
+
 	kfree(req->io);
 	if (req->file)
 		io_put_file(req, req->file, (req->flags & REQ_F_FIXED_FILE));
@@ -5673,13 +5679,13 @@ static void __io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 again:
 	linked_timeout = io_prep_linked_timeout(req);
 
-	if (req->work.creds && req->work.creds != current_cred()) {
+	if (req->creds && req->creds != current_cred()) {
 		if (old_creds)
 			revert_creds(old_creds);
-		if (old_creds == req->work.creds)
+		if (old_creds == req->creds)
 			old_creds = NULL; /* restored original creds */
 		else
-			old_creds = override_creds(req->work.creds);
+			old_creds = override_creds(req->creds);
 	}
 
 	ret = io_issue_sqe(req, sqe, true);
@@ -5970,11 +5976,12 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 
 	id = READ_ONCE(sqe->personality);
 	if (id) {
-		req->work.creds = idr_find(&ctx->personality_idr, id);
-		if (unlikely(!req->work.creds))
+		req->creds = idr_find(&ctx->personality_idr, id);
+		if (unlikely(!req->creds))
 			return -EINVAL;
-		get_cred(req->work.creds);
-	}
+		get_cred(req->creds);
+	} else
+		req->creds = NULL;
 
 	/* same numerical values with corresponding REQ_F_*, safe to copy */
 	req->flags |= sqe_flags;
-- 
2.17.2