[tip: sched/psi] kernfs: Factor out kernfs_activate_one()

[tip-bot2 for Tejun Heo]

The following commit has been merged into the sched/psi branch of tip:

Commit-ID:     f8eb145eb946d543e8c8df3d2db39fcd5c80dacb
Gitweb:        https://git.kernel.org/tip/f8eb145eb946d543e8c8df3d2db39fcd5c80dacb
Author:        Tejun Heo <tj@xxxxxxxxxx>
AuthorDate:    Sat, 27 Aug 2022 19:04:38 -10:00
Committer:     Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
CommitterDate: Thu, 01 Sep 2022 18:08:44 +02:00

kernfs: Factor out kernfs_activate_one()

Factor out kernfs_activate_one() from kernfs_activate() and reorder
operations so that KERNFS_ACTIVATED now simply indicates whether activation
was attempted on the node ignoring whether activation took place. As the
flag doesn't have a reader, the refactoring and reordering shouldn't cause
any behavior difference.

Tested-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Reviewed-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220828050440.734579-8-tj@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/kernfs/dir.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index f8cbd05..c932395 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -1305,6 +1305,21 @@ static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
 	return pos->parent;
 }
 
+static void kernfs_activate_one(struct kernfs_node *kn)
+{
+	lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem);
+
+	kn->flags |= KERNFS_ACTIVATED;
+
+	if (kernfs_active(kn) || (kn->flags & KERNFS_REMOVING))
+		return;
+
+	WARN_ON_ONCE(kn->parent && RB_EMPTY_NODE(&kn->rb));
+	WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS);
+
+	atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);
+}
+
 /**
  * kernfs_activate - activate a node which started deactivated
  * @kn: kernfs_node whose subtree is to be activated
@@ -1326,16 +1341,8 @@ void kernfs_activate(struct kernfs_node *kn)
 	down_write(&root->kernfs_rwsem);
 
 	pos = NULL;
-	while ((pos = kernfs_next_descendant_post(pos, kn))) {
-		if (kernfs_active(pos) || (pos->flags & KERNFS_REMOVING))
-			continue;
-
-		WARN_ON_ONCE(pos->parent && RB_EMPTY_NODE(&pos->rb));
-		WARN_ON_ONCE(atomic_read(&pos->active) != KN_DEACTIVATED_BIAS);
-
-		atomic_sub(KN_DEACTIVATED_BIAS, &pos->active);
-		pos->flags |= KERNFS_ACTIVATED;
-	}
+	while ((pos = kernfs_next_descendant_post(pos, kn)))
+		kernfs_activate_one(pos);
 
 	up_write(&root->kernfs_rwsem);
 }