1 files changed, 20 insertions, 6 deletions

diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index ffa4565c275a..a6c692cac616 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -483,9 +483,11 @@ static int kernfs_fop_mmap(struct file *file, struct vm_area_struct *vma)
 		goto out_put;
 
 	rc = 0;
-	of->mmapped = true;
-	of_on(of)->nr_mmapped++;
-	of->vm_ops = vma->vm_ops;
+	if (!of->mmapped) {
+		of->mmapped = true;
+		of_on(of)->nr_mmapped++;
+		of->vm_ops = vma->vm_ops;
+	}
 	vma->vm_ops = &kernfs_vm_ops;
 out_put:
 	kernfs_put_active(of->kn);
@@ -634,11 +636,18 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
 	 * each file a separate locking class.  Let's differentiate on
 	 * whether the file has mmap or not for now.
 	 *
-	 * Both paths of the branch look the same.  They're supposed to
+	 * For similar reasons, writable and readonly files are given different
+	 * lockdep key, because the writable file /sys/power/resume may call vfs
+	 * lookup helpers for arbitrary paths and readonly files can be read by
+	 * overlayfs from vfs helpers when sysfs is a lower layer of overalyfs.
+	 *
+	 * All three cases look the same.  They're supposed to
 	 * look that way and give @of->mutex different static lockdep keys.
 	 */
 	if (has_mmap)
 		mutex_init(&of->mutex);
+	else if (file->f_mode & FMODE_WRITE)
+		mutex_init(&of->mutex);
 	else
 		mutex_init(&of->mutex);
 
@@ -769,8 +778,9 @@ bool kernfs_should_drain_open_files(struct kernfs_node *kn)
 	/*
 	 * @kn being deactivated guarantees that @kn->attr.open can't change
 	 * beneath us making the lockless test below safe.
+	 * Callers post kernfs_unbreak_active_protection may be counted in
+	 * kn->active by now, do not WARN_ON because of them.
 	 */
-	WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS);
 
 	rcu_read_lock();
 	on = rcu_dereference(kn->attr.open);
@@ -902,9 +912,11 @@ repeat:
 	/* kick fsnotify */
 
 	down_read(&root->kernfs_supers_rwsem);
+	down_read(&root->kernfs_rwsem);
 	list_for_each_entry(info, &kernfs_root(kn)->supers, node) {
 		struct kernfs_node *parent;
 		struct inode *p_inode = NULL;
+		const char *kn_name;
 		struct inode *inode;
 		struct qstr name;
 
@@ -918,7 +930,8 @@ repeat:
 		if (!inode)
 			continue;
 
-		name = (struct qstr)QSTR_INIT(kn->name, strlen(kn->name));
+		kn_name = kernfs_rcu_name(kn);
+		name = QSTR(kn_name);
 		parent = kernfs_get_parent(kn);
 		if (parent) {
 			p_inode = ilookup(info->sb, kernfs_ino(parent));
@@ -938,6 +951,7 @@ repeat:
 		iput(inode);
 	}
 
+	up_read(&root->kernfs_rwsem);
 	up_read(&root->kernfs_supers_rwsem);
 	kernfs_put(kn);
 	goto repeat;