[PATCH 6/8] nbd: don't copy kernel creds

[Christian Brauner <brauner@kernel.org>]

No need to copy kernel credentials.

Link: https://patch.msgid.link/20251031-work-creds-init_cred-v1-4-cbf0400d6e0e@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 drivers/block/nbd.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index a853c65ac65d..1f0d89e21ec8 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -52,7 +52,6 @@
 static DEFINE_IDR(nbd_index_idr);
 static DEFINE_MUTEX(nbd_index_mutex);
 static struct workqueue_struct *nbd_del_wq;
-static struct cred *nbd_cred;
 static int nbd_total_devices = 0;
 
 struct nbd_sock {
@@ -555,7 +554,6 @@ static int __sock_xmit(struct nbd_device *nbd, struct socket *sock, int send,
 	int result;
 	struct msghdr msg = {} ;
 	unsigned int noreclaim_flag;
-	const struct cred *old_cred;
 
 	if (unlikely(!sock)) {
 		dev_err_ratelimited(disk_to_dev(nbd->disk),
@@ -564,10 +562,10 @@ static int __sock_xmit(struct nbd_device *nbd, struct socket *sock, int send,
 		return -EINVAL;
 	}
 
-	old_cred = override_creds(nbd_cred);
-
 	msg.msg_iter = *iter;
 
+	with_kernel_creds();
+
 	noreclaim_flag = memalloc_noreclaim_save();
 	do {
 		sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
@@ -590,8 +588,6 @@ static int __sock_xmit(struct nbd_device *nbd, struct socket *sock, int send,
 
 	memalloc_noreclaim_restore(noreclaim_flag);
 
-	revert_creds(old_cred);
-
 	return result;
 }
 
@@ -2683,15 +2679,7 @@ static int __init nbd_init(void)
 		return -ENOMEM;
 	}
 
-	nbd_cred = prepare_kernel_cred(&init_task);
-	if (!nbd_cred) {
-		destroy_workqueue(nbd_del_wq);
-		unregister_blkdev(NBD_MAJOR, "nbd");
-		return -ENOMEM;
-	}
-
 	if (genl_register_family(&nbd_genl_family)) {
-		put_cred(nbd_cred);
 		destroy_workqueue(nbd_del_wq);
 		unregister_blkdev(NBD_MAJOR, "nbd");
 		return -EINVAL;
@@ -2746,7 +2734,6 @@ static void __exit nbd_cleanup(void)
 	/* Also wait for nbd_dev_remove_work() completes */
 	destroy_workqueue(nbd_del_wq);
 
-	put_cred(nbd_cred);
 	idr_destroy(&nbd_index_idr);
 	unregister_blkdev(NBD_MAJOR, "nbd");
 }

-- 
2.47.3