diff --git a/fs/libfs.c b/fs/libfs.c
index 5523bde..2319415 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -583,8 +583,8 @@
 /* Simple attribute files */
 
 struct simple_attr {
-	u64 (*get)(void *);
-	void (*set)(void *, u64);
+	int (*get)(void *, u64 *);
+	int (*set)(void *, u64);
 	char get_buf[24];	/* enough to store a u64 and "\n\0" */
 	char set_buf[24];
 	void *data;
@@ -595,7 +595,7 @@
 /* simple_attr_open is called by an actual attribute open file operation
  * to set the attribute specific access operations. */
 int simple_attr_open(struct inode *inode, struct file *file,
-		     u64 (*get)(void *), void (*set)(void *, u64),
+		     int (*get)(void *, u64 *), int (*set)(void *, u64),
 		     const char *fmt)
 {
 	struct simple_attr *attr;
@@ -635,14 +635,20 @@
 		return -EACCES;
 
 	mutex_lock(&attr->mutex);
-	if (*ppos) /* continued read */
+	if (*ppos) {		/* continued read */
 		size = strlen(attr->get_buf);
-	else	  /* first read */
+	} else {		/* first read */
+		u64 val;
+		ret = attr->get(attr->data, &val);
+		if (ret)
+			goto out;
+
 		size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
-				 attr->fmt,
-				 (unsigned long long)attr->get(attr->data));
+				 attr->fmt, (unsigned long long)val);
+	}
 
 	ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
+out:
 	mutex_unlock(&attr->mutex);
 	return ret;
 }
@@ -657,7 +663,6 @@
 	ssize_t ret;
 
 	attr = file->private_data;
-
 	if (!attr->set)
 		return -EACCES;