mm: replace vma prio_tree with an interval tree

Implement an interval tree as a replacement for the VMA prio_tree.  The
algorithms are similar to lib/interval_tree.c; however that code can't be
directly reused as the interval endpoints are not explicitly stored in the
VMA.  So instead, the common algorithm is moved into a template and the
details (node type, how to get interval endpoints from the node, etc) are
filled in using the C preprocessor.

Once the interval tree functions are available, using them as a
replacement to the VMA prio tree is a relatively simple, mechanical job.

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 912ef48..1d9c0a9 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -735,7 +735,6 @@
 build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
 {
 	unsigned long pgoff = offset >> PAGE_SHIFT;
-	struct prio_tree_iter iter;
 	struct vm_area_struct *vma;
 	struct map_info *curr = NULL;
 	struct map_info *prev = NULL;
@@ -744,7 +743,7 @@
 
  again:
 	mutex_lock(&mapping->i_mmap_mutex);
-	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
+	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
 		if (!valid_vma(vma, is_register))
 			continue;
 
diff --git a/kernel/fork.c b/kernel/fork.c
index 972762e..90dace5 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -423,7 +423,7 @@
 				mapping->i_mmap_writable++;
 			flush_dcache_mmap_lock(mapping);
 			/* insert tmp into the share list, just after mpnt */
-			vma_prio_tree_add(tmp, mpnt);
+			vma_interval_tree_add(tmp, mpnt, mapping);
 			flush_dcache_mmap_unlock(mapping);
 			mutex_unlock(&mapping->i_mmap_mutex);
 		}