Revert "kernfs: remove KERNFS_REMOVED"

This reverts commit ae34372eb8408b3d07e870f1939f99007a730d28.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 231a171..bdd3885 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -856,13 +856,9 @@
 	if (ops->mmap)
 		kn->flags |= KERNFS_HAS_MMAP;
 
-	rc = -ENOENT;
-	if (kernfs_get_active(parent)) {
-		kernfs_addrm_start(&acxt);
-		rc = kernfs_add_one(&acxt, kn, parent);
-		kernfs_addrm_finish(&acxt);
-		kernfs_put_active(parent);
-	}
+	kernfs_addrm_start(&acxt);
+	rc = kernfs_add_one(&acxt, kn, parent);
+	kernfs_addrm_finish(&acxt);
 
 	if (rc) {
 		kernfs_put(kn);