[Devel] [PATCH RHEL9 COMMIT] fs/fuse kio: refactor code related to the 'krpc_send' kthread

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.0-427.44.1.vz9.80.x-ovz" and will appear at git at bitbucket.org:openvz/vzkernel.git
after rh9-5.14.0-427.44.1.vz9.80.24
------>
commit 79d0b81cf496e6037f8fe88b3233987b48cd0cee
Author: Liu Kui <kui.liu at virtuozzo.com>
Date:   Sat Apr 5 10:22:03 2025 +0800

    fs/fuse kio: refactor code related to the 'krpc_send' kthread
    
    This patch is purely for code beautification patch that won't
    affect any functionality.
    
    Signed-off-by: Liu Kui <kui.liu at virtuozzo.com>
    Acked-by: Alexey Kuznetsov <kuznet at virtuozzo.com>
    
    Feature: fuse: kRPC - single RPC for kernel and userspace
---
 fs/fuse/kio/pcs/pcs_krpc.c | 66 ++++++++++++++++++++++++----------------------
 1 file changed, 35 insertions(+), 31 deletions(-)

diff --git a/fs/fuse/kio/pcs/pcs_krpc.c b/fs/fuse/kio/pcs/pcs_krpc.c
index 78180bdb4993..087d1d966e0d 100644
--- a/fs/fuse/kio/pcs/pcs_krpc.c
+++ b/fs/fuse/kio/pcs/pcs_krpc.c
@@ -632,18 +632,18 @@ static void kreq_submit(struct krpc_req *kreq)
 static int krpc_threadfn(void *data)
 {
 	struct pcs_krpc_set *krpcs = data;
+	struct llist_node *ll;
+	struct krpc_req *kreq, *kreq_next;
 
 	kthread_use_mm(krpcs->mm);
 
 	for (;;) {
-		struct llist_node *ll;
-
 		set_current_state(TASK_INTERRUPTIBLE);
 
 		ll = llist_del_all(&krpcs->req_llist);
 
-		if (ll == NULL) {
-			if (kthread_should_stop()) {
+		if (!ll) {
+			if (unlikely(kthread_should_stop())) {
 				__set_current_state(TASK_RUNNING);
 				break;
 			}
@@ -654,52 +654,56 @@ static int krpc_threadfn(void *data)
 		__set_current_state(TASK_RUNNING);
 
 		ll = llist_reverse_order(ll);
-		while (ll) {
-			struct llist_node *next = ll->next;
-			struct krpc_req *kreq = container_of(ll, struct krpc_req, llist_link);
-
+		llist_for_each_entry_safe(kreq, kreq_next, ll, llist_link)
 			kreq_submit(kreq);
-
-			ll = next;
-		}
 	}
 
 	kthread_unuse_mm(krpcs->mm);
 	return 0;
 }
 
+static struct task_struct *pcs_krpc_task_create(struct pcs_krpc_set *krpcs)
+{
+	struct task_struct *tsk;
+	struct mm_struct *mm;
+
+	WARN_ON_ONCE(krpcs->krpc_task);
+
+	mm = get_task_mm(current);
+	if (!mm)
+		return NULL;
+
+	tsk = kthread_create(krpc_threadfn, krpcs, "krpc_send");
+	if (!tsk || IS_ERR(tsk)) {
+		mmput(mm);
+		return NULL;
+	}
+
+	krpcs->krpc_task = get_task_struct(tsk);
+	krpcs->mm = mm;
+	atomic_inc(&current->files->count);
+	tsk->files = current->files;
+
+	return tsk;
+}
+
 static int pcs_krpc_ioctl_send_msg(struct krpc_req *kreq)
 {
 	struct task_struct *tsk;
-	struct pcs_cluster_core *cc;
+	struct pcs_krpc_set *krpcs = kreq->krpc->krpcs;
 
 	if (pcs_krpc_use_thread) {
-		cc = container_of(kreq->krpc->krpcs, struct pcs_cluster_core, krpcs);
-		tsk = cc->krpcs.krpc_task;
-		if (unlikely(tsk == NULL)) {
-			cc->krpcs.mm = get_task_mm(current);
-			if (cc->krpcs.mm) {
-				tsk = kthread_create(krpc_threadfn, &cc->krpcs, "krpc_send");
-				if (tsk && !IS_ERR(tsk)) {
-					cc->krpcs.krpc_task = get_task_struct(tsk);
-					atomic_inc(&current->files->count);
-					tsk->files = current->files;
-				} else {
-					mmput(cc->krpcs.mm);
-					cc->krpcs.mm = NULL;
-				}
-			}
-		}
+		tsk = krpcs->krpc_task;
+		if (unlikely(!tsk))
+			tsk = pcs_krpc_task_create(krpcs);
 
 		if (likely(tsk)) {
-			llist_add(&kreq->llist_link, &kreq->krpc->krpcs->req_llist);
+			llist_add(&kreq->llist_link, &krpcs->req_llist);
 			wake_up_process(tsk);
 			return 0;
 		}
 	}
-
 	kreq_submit(kreq);
-
 	return 0;
 }