2 files changed, 46 insertions, 0 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 8f8c0b915fbb..219962c9517e 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -57,6 +57,41 @@ struct resv_map {
 	struct cgroup_subsys_state *css;
 #endif
 };
+
+/*
+ * Region tracking -- allows tracking of reservations and instantiated pages
+ *                    across the pages in a mapping.
+ *
+ * The region data structures are embedded into a resv_map and protected
+ * by a resv_map's lock.  The set of regions within the resv_map represent
+ * reservations for huge pages, or huge pages that have already been
+ * instantiated within the map.  The from and to elements are huge page
+ * indicies into the associated mapping.  from indicates the starting index
+ * of the region.  to represents the first index past the end of  the region.
+ *
+ * For example, a file region structure with from == 0 and to == 4 represents
+ * four huge pages in a mapping.  It is important to note that the to element
+ * represents the first element past the end of the region. This is used in
+ * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
+ *
+ * Interval notation of the form [from, to) will be used to indicate that
+ * the endpoint from is inclusive and to is exclusive.
+ */
+struct file_region {
+	struct list_head link;
+	long from;
+	long to;
+#ifdef CONFIG_CGROUP_HUGETLB
+	/*
+	 * On shared mappings, each reserved region appears as a struct
+	 * file_region in resv_map. These fields hold the info needed to
+	 * uncharge each reservation.
+	 */
+	struct page_counter *reservation_counter;
+	struct cgroup_subsys_state *css;
+#endif
+};
+
 extern struct resv_map *resv_map_alloc(void);
 void resv_map_release(struct kref *ref);
 
diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
index 0699cd26e3ec..2ad6e92f124a 100644
--- a/include/linux/hugetlb_cgroup.h
+++ b/include/linux/hugetlb_cgroup.h
@@ -19,6 +19,7 @@
 
 struct hugetlb_cgroup;
 struct resv_map;
+struct file_region;
 
 /*
  * Minimum page order trackable by hugetlb cgroup.
@@ -135,11 +136,21 @@ extern void hugetlb_cgroup_uncharge_counter(struct resv_map *resv,
 					    unsigned long start,
 					    unsigned long end);
 
+extern void hugetlb_cgroup_uncharge_file_region(struct resv_map *resv,
+						struct file_region *rg,
+						unsigned long nr_pages);
+
 extern void hugetlb_cgroup_file_init(void) __init;
 extern void hugetlb_cgroup_migrate(struct page *oldhpage,
 				   struct page *newhpage);
 
 #else
+static inline void hugetlb_cgroup_uncharge_file_region(struct resv_map *resv,
+						       struct file_region *rg,
+						       unsigned long nr_pages)
+{
+}
+
 static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
 {
 	return NULL;