[01/14] vrange: Add basic data structure and functions

diff --git a/include/linux/vrange.h b/include/linux/vrange.h
new file mode 100644
index 0000000..0d378a5
--- /dev/null
+++ b/include/linux/vrange.h
@@ -0,0 +1,48 @@ 
+#ifndef _LINUX_VRANGE_H
+#define _LINUX_VRANGE_H
+
+#include <linux/vrange_types.h>
+#include <linux/mm.h>
+
+#define vrange_from_node(node_ptr) \
+	container_of(node_ptr, struct vrange, node)
+
+#define vrange_entry(ptr) \
+	container_of(ptr, struct vrange, node.rb)
+
+#ifdef CONFIG_MMU
+
+static inline void vrange_root_init(struct vrange_root *vroot, int type,
+								void *object)
+{
+	vroot->type = type;
+	vroot->v_rb = RB_ROOT;
+	mutex_init(&vroot->v_lock);
+	vroot->object = object;
+}
+
+static inline void vrange_lock(struct vrange_root *vroot)
+{
+	mutex_lock(&vroot->v_lock);
+}
+
+static inline void vrange_unlock(struct vrange_root *vroot)
+{
+	mutex_unlock(&vroot->v_lock);
+}
+
+static inline int vrange_type(struct vrange *vrange)
+{
+	return vrange->owner->type;
+}
+
+extern void vrange_root_cleanup(struct vrange_root *vroot);
+
+#else
+
+static inline void vrange_root_init(struct vrange_root *vroot,
+					int type, void *object) {};
+static inline void vrange_root_cleanup(struct vrange_root *vroot) {};
+
+#endif
+#endif /* _LINIUX_VRANGE_H */
diff --git a/include/linux/vrange_types.h b/include/linux/vrange_types.h
new file mode 100644
index 0000000..0d48b42
--- /dev/null
+++ b/include/linux/vrange_types.h
@@ -0,0 +1,25 @@ 
+#ifndef _LINUX_VRANGE_TYPES_H
+#define _LINUX_VRANGE_TYPES_H
+
+#include <linux/mutex.h>
+#include <linux/interval_tree.h>
+
+enum vrange_type {
+	VRANGE_MM,
+	VRANGE_FILE,
+};
+
+struct vrange_root {
+	struct rb_root v_rb;		/* vrange rb tree */
+	struct mutex v_lock;		/* Protect v_rb */
+	enum vrange_type type;		/* range root type */
+	void *object;			/* pointer to mm_struct or mapping */
+};
+
+struct vrange {
+	struct interval_tree_node node;
+	struct vrange_root *owner;
+	int purged;
+};
+#endif
+
diff --git a/lib/Makefile b/lib/Makefile
index 7baccfd..c8739ee 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -13,7 +13,7 @@  lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
 	 proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
-	 earlycpio.o percpu-refcount.o
+	 earlycpio.o percpu-refcount.o interval_tree.o
 
 obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
 lib-$(CONFIG_MMU) += ioremap.o
diff --git a/mm/Makefile b/mm/Makefile
index f008033..54928af 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -5,7 +5,7 @@ 
 mmu-y			:= nommu.o
 mmu-$(CONFIG_MMU)	:= fremap.o highmem.o madvise.o memory.o mincore.o \
 			   mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
-			   vmalloc.o pagewalk.o pgtable-generic.o
+			   vmalloc.o pagewalk.o pgtable-generic.o vrange.o
 
 ifdef CONFIG_CROSS_MEMORY_ATTACH
 mmu-$(CONFIG_MMU)	+= process_vm_access.o
diff --git a/mm/vrange.c b/mm/vrange.c
new file mode 100644
index 0000000..866566c
--- /dev/null
+++ b/mm/vrange.c
@@ -0,0 +1,183 @@ 
+/*
+ * mm/vrange.c
+ */
+
+#include <linux/vrange.h>
+#include <linux/slab.h>
+
+static struct kmem_cache *vrange_cachep;
+
+static int __init vrange_init(void)
+{
+	vrange_cachep = KMEM_CACHE(vrange, SLAB_PANIC);
+	return 0;
+}
+module_init(vrange_init);
+
+static struct vrange *__vrange_alloc(gfp_t flags)
+{
+	struct vrange *vrange = kmem_cache_alloc(vrange_cachep, flags);
+	if (!vrange)
+		return vrange;
+	vrange->owner = NULL;
+	return vrange;
+}
+
+static void __vrange_free(struct vrange *range)
+{
+	WARN_ON(range->owner);
+	kmem_cache_free(vrange_cachep, range);
+}
+
+static void __vrange_add(struct vrange *range, struct vrange_root *vroot)
+{
+	range->owner = vroot;
+	interval_tree_insert(&range->node, &vroot->v_rb);
+}
+
+static void __vrange_remove(struct vrange *range)
+{
+	interval_tree_remove(&range->node, &range->owner->v_rb);
+	range->owner = NULL;
+}
+
+static inline void __vrange_set(struct vrange *range,
+		unsigned long start_idx, unsigned long end_idx,
+		bool purged)
+{
+	range->node.start = start_idx;
+	range->node.last = end_idx;
+	range->purged = purged;
+}
+
+static inline void __vrange_resize(struct vrange *range,
+		unsigned long start_idx, unsigned long end_idx)
+{
+	struct vrange_root *vroot = range->owner;
+	bool purged = range->purged;
+
+	__vrange_remove(range);
+	__vrange_set(range, start_idx, end_idx, purged);
+	__vrange_add(range, vroot);
+}
+
+static int vrange_add(struct vrange_root *vroot,
+			unsigned long start_idx, unsigned long end_idx)
+{
+	struct vrange *new_range, *range;
+	struct interval_tree_node *node, *next;
+	int purged = 0;
+
+	new_range = __vrange_alloc(GFP_KERNEL);
+	if (!new_range)
+		return -ENOMEM;
+
+	vrange_lock(vroot);
+
+	node = interval_tree_iter_first(&vroot->v_rb, start_idx, end_idx);
+	while (node) {
+		next = interval_tree_iter_next(node, start_idx, end_idx);
+		range = vrange_from_node(node);
+		/* old range covers new range fully */
+		if (node->start <= start_idx && node->last >= end_idx) {
+			__vrange_free(new_range);
+			goto out;
+		}
+
+		start_idx = min_t(unsigned long, start_idx, node->start);
+		end_idx = max_t(unsigned long, end_idx, node->last);
+		purged |= range->purged;
+
+		__vrange_remove(range);
+		__vrange_free(range);
+
+		node = next;
+	}
+
+	__vrange_set(new_range, start_idx, end_idx, purged);
+	__vrange_add(new_range, vroot);
+out:
+	vrange_unlock(vroot);
+	return 0;
+}
+
+static int vrange_remove(struct vrange_root *vroot,
+				unsigned long start_idx, unsigned long end_idx,
+				int *purged)
+{
+	struct vrange *new_range, *range;
+	struct interval_tree_node *node, *next;
+	bool used_new = false;
+
+	if (!purged)
+		return -EINVAL;
+
+	*purged = 0;
+
+	new_range = __vrange_alloc(GFP_KERNEL);
+	if (!new_range)
+		return -ENOMEM;
+
+	vrange_lock(vroot);
+
+	node = interval_tree_iter_first(&vroot->v_rb, start_idx, end_idx);
+	while (node) {
+		next = interval_tree_iter_next(node, start_idx, end_idx);
+		range = vrange_from_node(node);
+
+		*purged |= range->purged;
+
+		if (start_idx <= node->start && end_idx >= node->last) {
+			/* argumented range covers the range fully */
+			__vrange_remove(range);
+			__vrange_free(range);
+		} else if (node->start >= start_idx) {
+			/*
+			 * Argumented range covers over the left of the
+			 * range
+			 */
+			__vrange_resize(range, end_idx + 1, node->last);
+		} else if (node->last <= end_idx) {
+			/*
+			 * Argumented range covers over the right of the
+			 * range
+			 */
+			__vrange_resize(range, node->start, start_idx - 1);
+		} else {
+			/*
+			 * Argumented range is middle of the range
+			 */
+			unsigned long last = node->last;
+			used_new = true;
+			__vrange_resize(range, node->start, start_idx - 1);
+			__vrange_set(new_range, end_idx + 1, last,
+					range->purged);
+			__vrange_add(new_range, vroot);
+			break;
+		}
+
+		node = next;
+	}
+	vrange_unlock(vroot);
+
+	if (!used_new)
+		__vrange_free(new_range);
+
+	return 0;
+}
+
+void vrange_root_cleanup(struct vrange_root *vroot)
+{
+	struct vrange *range;
+	struct rb_node *node;
+
+	vrange_lock(vroot);
+	/* We should remove node by post-order traversal */
+	while ((node = rb_first(&vroot->v_rb))) {
+		range = vrange_entry(node);
+		__vrange_remove(range);
+		__vrange_free(range);
+	}
+	vrange_unlock(vroot);
+}
+