mm: shmem: use new radix tree iterator

In shmem_find_get_pages_and_swap(), use the faster radix tree iterator
construct from commit 78c1d78488a3 ("radix-tree: introduce bit-optimized
iterator").

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 5dd56f6..7162c58 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -335,19 +335,19 @@ static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
                                        pgoff_t start, unsigned int nr_pages,
                                        struct page **pages, pgoff_t *indices)
 {
-       unsigned int i;
-       unsigned int ret;
-       unsigned int nr_found;
+       void **slot;
+       unsigned int ret = 0;
+       struct radix_tree_iter iter;
+
+       if (!nr_pages)
+               return 0;
 
        rcu_read_lock();
 restart:
-       nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
-                               (void ***)pages, indices, start, nr_pages);
-       ret = 0;
-       for (i = 0; i < nr_found; i++) {
+       radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
                struct page *page;
 repeat:
-               page = radix_tree_deref_slot((void **)pages[i]);
+               page = radix_tree_deref_slot(slot);
                if (unlikely(!page))
                        continue;
                if (radix_tree_exception(page)) {
@@ -364,17 +364,16 @@ repeat:
                        goto repeat;
 
                /* Has the page moved? */
-               if (unlikely(page != *((void **)pages[i]))) {
+               if (unlikely(page != *slot)) {
                        page_cache_release(page);
                        goto repeat;
                }
 export:
-               indices[ret] = indices[i];
+               indices[ret] = iter.index;
                pages[ret] = page;
-               ret++;
+               if (++ret == nr_pages)
+                       break;
        }
-       if (unlikely(!ret && nr_found))
-               goto restart;
        rcu_read_unlock();
        return ret;
 }