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, 5 insertions, 7 deletions

diff --git a/mm/nommu.c b/mm/nommu.c
index 12e84e69dd06..45131b41bcdb 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -698,7 +698,7 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 
                 mutex_lock(&mapping->i_mmap_mutex);
                 flush_dcache_mmap_lock(mapping);
-                vma_prio_tree_insert(vma, &mapping->i_mmap);
+                vma_interval_tree_insert(vma, &mapping->i_mmap);
                 flush_dcache_mmap_unlock(mapping);
                 mutex_unlock(&mapping->i_mmap_mutex);
         }
@@ -764,7 +764,7 @@ static void delete_vma_from_mm(struct vm_area_struct *vma)
 
                 mutex_lock(&mapping->i_mmap_mutex);
                 flush_dcache_mmap_lock(mapping);
-                vma_prio_tree_remove(vma, &mapping->i_mmap);
+                vma_interval_tree_remove(vma, &mapping->i_mmap);
                 flush_dcache_mmap_unlock(mapping);
                 mutex_unlock(&mapping->i_mmap_mutex);
         }
@@ -2044,7 +2044,6 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
                                 size_t newsize)
 {
         struct vm_area_struct *vma;
-        struct prio_tree_iter iter;
         struct vm_region *region;
         pgoff_t low, high;
         size_t r_size, r_top;
@@ -2056,8 +2055,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
         mutex_lock(&inode->i_mapping->i_mmap_mutex);
 
         /* search for VMAs that fall within the dead zone */
-        vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
-                              low, high) {
+        vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
                 /* found one - only interested if it's shared out of the page
                  * cache */
                 if (vma->vm_flags & VM_SHARED) {
@@ -2073,8 +2071,8 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
          * we don't check for any regions that start beyond the EOF as there
          * shouldn't be any
          */
-        vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
-                              0, ULONG_MAX) {
+        vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap,
+                                  0, ULONG_MAX) {
                 if (!(vma->vm_flags & VM_SHARED))
                         continue;