page cache: Convert page deletion to XArray

The code is slightly shorter and simpler.

Signed-off-by: Matthew Wilcox <willy@infradead.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index b63caebd13675ea3d1fd10271cae7eb717061f88..414efbdc95df8a1c1974b674a99b9c77e32774a9 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -111,31 +111,26 @@
  *   ->tasklist_lock            (memory_failure, collect_procs_ao)
  */
 
-static void page_cache_tree_delete(struct address_space *mapping,
+static void page_cache_delete(struct address_space *mapping,
                                   struct page *page, void *shadow)
 {
-       int i, nr;
+       XA_STATE(xas, &mapping->i_pages, page->index);
+       unsigned int nr = 1;
 
-       /* hugetlb pages are represented by one entry in the radix tree */
-       nr = PageHuge(page) ? 1 : hpage_nr_pages(page);
+       mapping_set_update(&xas, mapping);
+
+       /* hugetlb pages are represented by a single entry in the xarray */
+       if (!PageHuge(page)) {
+               xas_set_order(&xas, page->index, compound_order(page));
+               nr = 1U << compound_order(page);
+       }
 
        VM_BUG_ON_PAGE(!PageLocked(page), page);
        VM_BUG_ON_PAGE(PageTail(page), page);
        VM_BUG_ON_PAGE(nr != 1 && shadow, page);
 
-       for (i = 0; i < nr; i++) {
-               struct radix_tree_node *node;
-               void **slot;
-
-               __radix_tree_lookup(&mapping->i_pages, page->index + i,
-                                   &node, &slot);
-
-               VM_BUG_ON_PAGE(!node && nr != 1, page);
-
-               radix_tree_clear_tags(&mapping->i_pages, node, slot);
-               __radix_tree_replace(&mapping->i_pages, node, slot, shadow,
-                               workingset_lookup_update(mapping));
-       }
+       xas_store(&xas, shadow);
+       xas_init_marks(&xas);
 
        page->mapping = NULL;
        /* Leave page->index set: truncation lookup relies upon it */
@@ -234,7 +229,7 @@ void __delete_from_page_cache(struct page *page, void *shadow)
        trace_mm_filemap_delete_from_page_cache(page);
 
        unaccount_page_cache_page(mapping, page);
-       page_cache_tree_delete(mapping, page, shadow);
+       page_cache_delete(mapping, page, shadow);
 }
 
 static void page_cache_free_page(struct address_space *mapping,