v4.19.13 snapshot.
diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h
new file mode 100644
index 0000000..b94fa61
--- /dev/null
+++ b/include/linux/flex_array.h
@@ -0,0 +1,149 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _FLEX_ARRAY_H
+#define _FLEX_ARRAY_H
+
+#include <linux/types.h>
+#include <linux/reciprocal_div.h>
+#include <asm/page.h>
+
+#define FLEX_ARRAY_PART_SIZE PAGE_SIZE
+#define FLEX_ARRAY_BASE_SIZE PAGE_SIZE
+
+struct flex_array_part;
+
+/*
+ * This is meant to replace cases where an array-like
+ * structure has gotten too big to fit into kmalloc()
+ * and the developer is getting tempted to use
+ * vmalloc().
+ */
+
+struct flex_array {
+ union {
+ struct {
+ int element_size;
+ int total_nr_elements;
+ int elems_per_part;
+ struct reciprocal_value reciprocal_elems;
+ struct flex_array_part *parts[];
+ };
+ /*
+ * This little trick makes sure that
+ * sizeof(flex_array) == PAGE_SIZE
+ */
+ char padding[FLEX_ARRAY_BASE_SIZE];
+ };
+};
+
+/* Number of bytes left in base struct flex_array, excluding metadata */
+#define FLEX_ARRAY_BASE_BYTES_LEFT \
+ (FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts))
+
+/* Number of pointers in base to struct flex_array_part pages */
+#define FLEX_ARRAY_NR_BASE_PTRS \
+ (FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *))
+
+/* Number of elements of size that fit in struct flex_array_part */
+#define FLEX_ARRAY_ELEMENTS_PER_PART(size) \
+ (FLEX_ARRAY_PART_SIZE / size)
+
+/*
+ * Defines a statically allocated flex array and ensures its parameters are
+ * valid.
+ */
+#define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total) \
+ struct flex_array __arrayname = { { { \
+ .element_size = (__element_size), \
+ .total_nr_elements = (__total), \
+ } } }; \
+ static inline void __arrayname##_invalid_parameter(void) \
+ { \
+ BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS * \
+ FLEX_ARRAY_ELEMENTS_PER_PART(__element_size)); \
+ }
+
+/**
+ * flex_array_alloc() - Creates a flexible array.
+ * @element_size: individual object size.
+ * @total: maximum number of objects which can be stored.
+ * @flags: GFP flags
+ *
+ * Return: Returns an object of structure flex_array.
+ */
+struct flex_array *flex_array_alloc(int element_size, unsigned int total,
+ gfp_t flags);
+
+/**
+ * flex_array_prealloc() - Ensures that memory for the elements indexed in the
+ * range defined by start and nr_elements has been allocated.
+ * @fa: array to allocate memory to.
+ * @start: start address
+ * @nr_elements: number of elements to be allocated.
+ * @flags: GFP flags
+ *
+ */
+int flex_array_prealloc(struct flex_array *fa, unsigned int start,
+ unsigned int nr_elements, gfp_t flags);
+
+/**
+ * flex_array_free() - Removes all elements of a flexible array.
+ * @fa: array to be freed.
+ */
+void flex_array_free(struct flex_array *fa);
+
+/**
+ * flex_array_free_parts() - Removes all elements of a flexible array, but
+ * leaves the array itself in place.
+ * @fa: array to be emptied.
+ */
+void flex_array_free_parts(struct flex_array *fa);
+
+/**
+ * flex_array_put() - Stores data into a flexible array.
+ * @fa: array where element is to be stored.
+ * @element_nr: position to copy, must be less than the maximum specified when
+ * the array was created.
+ * @src: data source to be copied into the array.
+ * @flags: GFP flags
+ *
+ * Return: Returns zero on success, a negative error code otherwise.
+ */
+int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
+ gfp_t flags);
+
+/**
+ * flex_array_clear() - Clears an individual element in the array, sets the
+ * given element to FLEX_ARRAY_FREE.
+ * @element_nr: element position to clear.
+ * @fa: array to which element to be cleared belongs.
+ *
+ * Return: Returns zero on success, -EINVAL otherwise.
+ */
+int flex_array_clear(struct flex_array *fa, unsigned int element_nr);
+
+/**
+ * flex_array_get() - Retrieves data into a flexible array.
+ *
+ * @element_nr: Element position to retrieve data from.
+ * @fa: array from which data is to be retrieved.
+ *
+ * Return: Returns a pointer to the data element, or NULL if that
+ * particular element has never been allocated.
+ */
+void *flex_array_get(struct flex_array *fa, unsigned int element_nr);
+
+/**
+ * flex_array_shrink() - Reduces the allocated size of an array.
+ * @fa: array to shrink.
+ *
+ * Return: Returns number of pages of memory actually freed.
+ *
+ */
+int flex_array_shrink(struct flex_array *fa);
+
+#define flex_array_put_ptr(fa, nr, src, gfp) \
+ flex_array_put(fa, nr, (void *)&(src), gfp)
+
+void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr);
+
+#endif /* _FLEX_ARRAY_H */