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>

1 files changed, 12 insertions, 13 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 5dd56f6efdbd..7162c58355b1 100644
--- 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;
 }