[PATCH 6.18.y 1/6] fuse-uring: refactor io-uring header copying to ring

[Sasha Levin <sashal@kernel.org>]

From: Joanne Koong <joannelkoong@gmail.com>

[ Upstream commit 6582f8a06698403dccf8a01b7eef176b2c6dd7ff ]

Move header copying to ring logic into a new copy_header_to_ring()
function. This makes the copy_to_user() logic more clear and centralizes
error handling / rate-limited logging.

Reviewed-by: Bernd Schubert <bschubert@ddn.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Baokun Li <libaokun@linux.alibaba.com>
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Stable-dep-of: fd10f40af314 ("fuse: copy request headers via a stack buffer for io-uring")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/fuse/dev_uring.c | 39 +++++++++++++++++++++------------------
 1 file changed, 21 insertions(+), 18 deletions(-)

diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index 6f74c345080f4..e4c912c4f5e56 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -579,6 +579,18 @@ static int fuse_uring_out_header_has_err(struct fuse_out_header *oh,
 	return err;
 }
 
+static __always_inline int copy_header_to_ring(void __user *ring,
+					       const void *header,
+					       size_t header_size)
+{
+	if (copy_to_user(ring, header, header_size)) {
+		pr_info_ratelimited("Copying header to ring failed.\n");
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
 static int fuse_uring_copy_from_ring(struct fuse_ring *ring,
 				     struct fuse_req *req,
 				     struct fuse_ring_ent *ent)
@@ -641,13 +653,11 @@ static int fuse_uring_args_to_ring(struct fuse_ring *ring, struct fuse_req *req,
 		 * Some op code have that as zero size.
 		 */
 		if (args->in_args[0].size > 0) {
-			err = copy_to_user(&ent->headers->op_in, in_args->value,
-					   in_args->size);
-			if (err) {
-				pr_info_ratelimited(
-					"Copying the header failed.\n");
-				return -EFAULT;
-			}
+			err = copy_header_to_ring(&ent->headers->op_in,
+						  in_args->value,
+						  in_args->size);
+			if (err)
+				return err;
 		}
 		in_args++;
 		num_args--;
@@ -663,9 +673,8 @@ static int fuse_uring_args_to_ring(struct fuse_ring *ring, struct fuse_req *req,
 	}
 
 	ent_in_out.payload_sz = cs.ring.copied_sz;
-	err = copy_to_user(&ent->headers->ring_ent_in_out, &ent_in_out,
-			   sizeof(ent_in_out));
-	return err ? -EFAULT : 0;
+	return copy_header_to_ring(&ent->headers->ring_ent_in_out, &ent_in_out,
+				   sizeof(ent_in_out));
 }
 
 static int fuse_uring_copy_to_ring(struct fuse_ring_ent *ent,
@@ -694,14 +703,8 @@ static int fuse_uring_copy_to_ring(struct fuse_ring_ent *ent,
 	}
 
 	/* copy fuse_in_header */
-	err = copy_to_user(&ent->headers->in_out, &req->in.h,
-			   sizeof(req->in.h));
-	if (err) {
-		err = -EFAULT;
-		return err;
-	}
-
-	return 0;
+	return copy_header_to_ring(&ent->headers->in_out, &req->in.h,
+				   sizeof(req->in.h));
 }
 
 static int fuse_uring_prepare_send(struct fuse_ring_ent *ent,
-- 
2.53.0