io_uring: remove io_identity

We are no longer grabbing state, so no need to maintain an IO identity
that we COW if there are changes.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 26 insertions, 0 deletions

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 41042119bf0f..acc67ed3a52c 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -53,6 +53,9 @@ struct io_worker {
 	struct io_wq_work *cur_work;
 	spinlock_t lock;
 
+	const struct cred *cur_creds;
+	const struct cred *saved_creds;
+
 	struct rcu_head rcu;
 };
 
@@ -171,6 +174,11 @@ static void io_worker_exit(struct io_worker *worker)
 	worker->flags = 0;
 	preempt_enable();
 
+	if (worker->saved_creds) {
+		revert_creds(worker->saved_creds);
+		worker->cur_creds = worker->saved_creds = NULL;
+	}
+
 	raw_spin_lock_irq(&wqe->lock);
 	hlist_nulls_del_rcu(&worker->nulls_node);
 	list_del_rcu(&worker->all_list);
@@ -312,6 +320,10 @@ static void __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker)
 		worker->flags |= IO_WORKER_F_FREE;
 		hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
 	}
+	if (worker->saved_creds) {
+		revert_creds(worker->saved_creds);
+		worker->cur_creds = worker->saved_creds = NULL;
+	}
 }
 
 static inline unsigned int io_get_work_hash(struct io_wq_work *work)
@@ -359,6 +371,18 @@ static void io_flush_signals(void)
 	}
 }
 
+static void io_wq_switch_creds(struct io_worker *worker,
+			       struct io_wq_work *work)
+{
+	const struct cred *old_creds = override_creds(work->creds);
+
+	worker->cur_creds = work->creds;
+	if (worker->saved_creds)
+		put_cred(old_creds); /* creds set by previous switch */
+	else
+		worker->saved_creds = old_creds;
+}
+
 static void io_assign_current_work(struct io_worker *worker,
 				   struct io_wq_work *work)
 {
@@ -407,6 +431,8 @@ get_next:
 			unsigned int hash = io_get_work_hash(work);
 
 			next_hashed = wq_next_work(work);
+			if (work->creds && worker->cur_creds != work->creds)
+				io_wq_switch_creds(worker, work);
 			wq->do_work(work);
 			io_assign_current_work(worker, NULL);