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From:   Mike Christie <michael.christie@oracle.com>
To:     stefanha@redhat.com, jasowang@redhat.com, mst@redhat.com,
        sgarzare@redhat.com, virtualization@lists.linux-foundation.org,
        christian.brauner@ubuntu.com, axboe@kernel.dk,
        linux-kernel@vger.kernel.org
Cc:     Mike Christie <michael.christie@oracle.com>
Subject: [PATCH 5/8] io_uring: switch to kernel_copy_process
Date:   Thu, 16 Sep 2021 16:20:48 -0500
Message-Id: <20210916212051.6918-6-michael.christie@oracle.com>
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Convert io_uring and io-wq to use kernel_copy_process.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 fs/io-wq.c                 |  9 +++++++--
 fs/io_uring.c              |  5 ++++-
 include/linux/sched/task.h |  1 -
 kernel/fork.c              | 22 ----------------------
 4 files changed, 11 insertions(+), 26 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 6c55362c1f99..6fccba5bdc65 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -68,6 +68,9 @@ struct io_worker {
 
 #define IO_WQ_NR_HASH_BUCKETS	(1u << IO_WQ_HASH_ORDER)
 
+#define IO_WQ_CLONE_FLAGS	CLONE_FS|CLONE_FILES|CLONE_SIGHAND| \
+				CLONE_THREAD|CLONE_IO
+
 struct io_wqe_acct {
 	unsigned nr_workers;
 	unsigned max_workers;
@@ -687,7 +690,8 @@ static void create_worker_cont(struct callback_head *cb)
 	worker = container_of(cb, struct io_worker, create_work);
 	clear_bit_unlock(0, &worker->create_state);
 	wqe = worker->wqe;
-	tsk = create_io_thread(io_wqe_worker, worker, wqe->node);
+	tsk = kernel_copy_process(io_wqe_worker, worker, wqe->node,
+				  IO_WQ_CLONE_FLAGS, 1, 0);
 	if (!IS_ERR(tsk)) {
 		io_init_new_worker(wqe, worker, tsk);
 		io_worker_release(worker);
@@ -757,7 +761,8 @@ static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
 	if (index == IO_WQ_ACCT_BOUND)
 		worker->flags |= IO_WORKER_F_BOUND;
 
-	tsk = create_io_thread(io_wqe_worker, worker, wqe->node);
+	tsk = kernel_copy_process(io_wqe_worker, worker, wqe->node,
+				  IO_WQ_CLONE_FLAGS, 1, 0);
 	if (!IS_ERR(tsk)) {
 		io_init_new_worker(wqe, worker, tsk);
 	} else if (!io_should_retry_thread(PTR_ERR(tsk))) {
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 16fb7436043c..2493a78ddd7d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8519,6 +8519,8 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx,
 		fdput(f);
 	}
 	if (ctx->flags & IORING_SETUP_SQPOLL) {
+		unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|
+					CLONE_THREAD|CLONE_IO;
 		struct task_struct *tsk;
 		struct io_sq_data *sqd;
 		bool attached;
@@ -8560,7 +8562,8 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx,
 
 		sqd->task_pid = current->pid;
 		sqd->task_tgid = current->tgid;
-		tsk = create_io_thread(io_sq_thread, sqd, NUMA_NO_NODE);
+		tsk = kernel_copy_process(io_sq_thread, sqd, NUMA_NO_NODE,
+					  flags, 1, 0);
 		if (IS_ERR(tsk)) {
 			ret = PTR_ERR(tsk);
 			goto err_sqpoll;
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 4a6100a24894..f43e81c907e1 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -85,7 +85,6 @@ extern void exit_files(struct task_struct *);
 extern void exit_itimers(struct signal_struct *);
 
 extern pid_t kernel_clone(struct kernel_clone_args *kargs);
-struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
 struct task_struct *kernel_copy_process(int (*fn)(void *), void *arg, int node,
 					unsigned long clone_flags,
 					int io_thread, int no_files);
diff --git a/kernel/fork.c b/kernel/fork.c
index 1dda1d4ea77b..9011cbe83fe8 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2518,28 +2518,6 @@ struct mm_struct *copy_init_mm(void)
 	return dup_mm(NULL, &init_mm);
 }
 
-/*
- * This is like kernel_clone(), but shaved down and tailored to just
- * creating io_uring workers. It returns a created task, or an error pointer.
- * The returned task is inactive, and the caller must fire it up through
- * wake_up_new_task(p). All signals are blocked in the created task.
- */
-struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
-{
-	unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
-				CLONE_IO;
-	struct kernel_clone_args args = {
-		.flags		= ((lower_32_bits(flags) | CLONE_VM |
-				    CLONE_UNTRACED) & ~CSIGNAL),
-		.exit_signal	= (lower_32_bits(flags) & CSIGNAL),
-		.stack		= (unsigned long)fn,
-		.stack_size	= (unsigned long)arg,
-		.io_thread	= 1,
-	};
-
-	return copy_process(NULL, 0, node, &args);
-}
-
 /**
  * kernel_copy_process - create a copy of a process to be used by the kernel
  * @fn: thread stack
-- 
2.25.1