1 files changed, 127 insertions, 3 deletions

diff --git a/fs/seq_file.c b/fs/seq_file.c
index eae7d9dbf3ff..e1f437be6c3c 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -674,7 +674,6 @@ struct list_head *seq_list_start(struct list_head *head, loff_t pos)
 
 	return NULL;
 }
-
 EXPORT_SYMBOL(seq_list_start);
 
 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
@@ -684,7 +683,6 @@ struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
 
 	return seq_list_start(head, pos - 1);
 }
-
 EXPORT_SYMBOL(seq_list_start_head);
 
 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
@@ -695,5 +693,131 @@ struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
 	++*ppos;
 	return lh == head ? NULL : lh;
 }
-
 EXPORT_SYMBOL(seq_list_next);
+
+/**
+ * seq_hlist_start - start an iteration of a hlist
+ * @head: the head of the hlist
+ * @pos:  the start position of the sequence
+ *
+ * Called at seq_file->op->start().
+ */
+struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
+{
+	struct hlist_node *node;
+
+	hlist_for_each(node, head)
+		if (pos-- == 0)
+			return node;
+	return NULL;
+}
+EXPORT_SYMBOL(seq_hlist_start);
+
+/**
+ * seq_hlist_start_head - start an iteration of a hlist
+ * @head: the head of the hlist
+ * @pos:  the start position of the sequence
+ *
+ * Called at seq_file->op->start(). Call this function if you want to
+ * print a header at the top of the output.
+ */
+struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
+{
+	if (!pos)
+		return SEQ_START_TOKEN;
+
+	return seq_hlist_start(head, pos - 1);
+}
+EXPORT_SYMBOL(seq_hlist_start_head);
+
+/**
+ * seq_hlist_next - move to the next position of the hlist
+ * @v:    the current iterator
+ * @head: the head of the hlist
+ * @ppos: the current position
+ *
+ * Called at seq_file->op->next().
+ */
+struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
+				  loff_t *ppos)
+{
+	struct hlist_node *node = v;
+
+	++*ppos;
+	if (v == SEQ_START_TOKEN)
+		return head->first;
+	else
+		return node->next;
+}
+EXPORT_SYMBOL(seq_hlist_next);
+
+/**
+ * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
+ * @head: the head of the hlist
+ * @pos:  the start position of the sequence
+ *
+ * Called at seq_file->op->start().
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as hlist_add_head_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
+				       loff_t pos)
+{
+	struct hlist_node *node;
+
+	__hlist_for_each_rcu(node, head)
+		if (pos-- == 0)
+			return node;
+	return NULL;
+}
+EXPORT_SYMBOL(seq_hlist_start_rcu);
+
+/**
+ * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
+ * @head: the head of the hlist
+ * @pos:  the start position of the sequence
+ *
+ * Called at seq_file->op->start(). Call this function if you want to
+ * print a header at the top of the output.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as hlist_add_head_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
+					    loff_t pos)
+{
+	if (!pos)
+		return SEQ_START_TOKEN;
+
+	return seq_hlist_start_rcu(head, pos - 1);
+}
+EXPORT_SYMBOL(seq_hlist_start_head_rcu);
+
+/**
+ * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
+ * @v:    the current iterator
+ * @head: the head of the hlist
+ * @ppos: the current position
+ *
+ * Called at seq_file->op->next().
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as hlist_add_head_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+struct hlist_node *seq_hlist_next_rcu(void *v,
+				      struct hlist_head *head,
+				      loff_t *ppos)
+{
+	struct hlist_node *node = v;
+
+	++*ppos;
+	if (v == SEQ_START_TOKEN)
+		return rcu_dereference(head->first);
+	else
+		return rcu_dereference(node->next);
+}
+EXPORT_SYMBOL(seq_hlist_next_rcu);