llists: move llist_reverse_order from raid5 to llist.c

Make this useful helper available for other users.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/llist.c b/lib/llist.c
index 4a70d120138c..ef48b87247ec 100644
--- a/lib/llist.c
+++ b/lib/llist.c
@@ -81,3 +81,25 @@ struct llist_node *llist_del_first(struct llist_head *head)
         return entry;
 }
 EXPORT_SYMBOL_GPL(llist_del_first);
+
+/**
+ * llist_reverse_order - reverse order of a llist chain
+ * @head:       first item of the list to be reversed
+ *
+ * Reverse the oder of a chain of llist entries and return the
+ * new first entry.
+ */
+struct llist_node *llist_reverse_order(struct llist_node *head)
+{
+        struct llist_node *new_head = NULL;
+
+        while (head) {
+                struct llist_node *tmp = head;
+                head = head->next;
+                tmp->next = new_head;
+                new_head = tmp;
+        }
+
+        return new_head;
+}
+EXPORT_SYMBOL_GPL(llist_reverse_order);