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>

1 files changed, 2 insertions, 17 deletions

diff --git a/lib/prio_tree.c b/lib/prio_tree.c
index 4e0d2edff2b4..bba37148c15e 100644
--- a/lib/prio_tree.c
+++ b/lib/prio_tree.c
@@ -44,27 +44,12 @@
  * The following macros are used for implementing prio_tree for i_mmap
  */
 
-#define RADIX_INDEX(vma)  ((vma)->vm_pgoff)
-#define VMA_SIZE(vma)     (((vma)->vm_end - (vma)->vm_start) >> PAGE_SHIFT)
-/* avoid overflow */
-#define HEAP_INDEX(vma)   ((vma)->vm_pgoff + (VMA_SIZE(vma) - 1))
-
-
 static void get_index(const struct prio_tree_root *root,
     const struct prio_tree_node *node,
     unsigned long *radix, unsigned long *heap)
 {
-        if (root->raw) {
-                struct vm_area_struct *vma = prio_tree_entry(
-                    node, struct vm_area_struct, shared.prio_tree_node);
-
-                *radix = RADIX_INDEX(vma);
-                *heap = HEAP_INDEX(vma);
-        }
-        else {
-                *radix = node->start;
-                *heap = node->last;
-        }
+        *radix = node->start;
+        *heap = node->last;
 }
 
 static unsigned long index_bits_to_maxindex[BITS_PER_LONG];