diff --git a/fs/attr.c b/fs/attr.c
index 1f6a895..aeac826 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -237,13 +237,10 @@
 	if (ia_valid & ATTR_SIZE)
 		down_write(&dentry->d_inode->i_alloc_sem);
 
-	if (inode->i_op && inode->i_op->setattr) {
+	if (inode->i_op->setattr)
 		error = inode->i_op->setattr(dentry, attr);
-	} else {
-		error = inode_change_ok(inode, attr);
-		if (!error)
-			error = inode_setattr(inode, attr);
-	}
+	else
+		error = simple_setattr(dentry, attr);
 
 	if (ia_valid & ATTR_SIZE)
 		up_write(&dentry->d_inode->i_alloc_sem);
diff --git a/fs/libfs.c b/fs/libfs.c
index 861a887..4056222 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -370,21 +370,26 @@
 EXPORT_SYMBOL(simple_setsize);
 
 /**
- * simple_setattr - setattr for simple in-memory filesystem
+ * simple_setattr - setattr for simple filesystem
  * @dentry: dentry
  * @iattr: iattr structure
  *
  * Returns 0 on success, -error on failure.
  *
- * simple_setattr implements setattr for an in-memory filesystem which
- * does not store its own file data or metadata (eg. uses the page cache
- * and inode cache as its data store).
+ * simple_setattr is a simple ->setattr implementation without a proper
+ * implementation of size changes.
+ *
+ * It can either be used for in-memory filesystems or special files
+ * on simple regular filesystems.  Anything that needs to change on-disk
+ * or wire state on size changes needs its own setattr method.
  */
 int simple_setattr(struct dentry *dentry, struct iattr *iattr)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
 
+	WARN_ON_ONCE(inode->i_op->truncate);
+
 	error = inode_change_ok(inode, iattr);
 	if (error)
 		return error;
@@ -396,7 +401,8 @@
 	}
 
 	setattr_copy(inode, iattr);
-	return error;
+	mark_inode_dirty(inode);
+	return 0;
 }
 EXPORT_SYMBOL(simple_setattr);