page cache: Convert find_get_entries_tag to XArray

Slightly shorter and simpler code.

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

1 files changed, 24 insertions, 30 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 0df28aa6411c..35ae011971e1 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1866,57 +1866,51 @@ EXPORT_SYMBOL(find_get_pages_range_tag);
  * @tag.
  */
 unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
-                        int tag, unsigned int nr_entries,
+                        xa_mark_t tag, unsigned int nr_entries,
                         struct page **entries, pgoff_t *indices)
 {
-        void **slot;
+        XA_STATE(xas, &mapping->i_pages, start);
+        struct page *page;
         unsigned int ret = 0;
-        struct radix_tree_iter iter;
 
         if (!nr_entries)
                 return 0;
 
         rcu_read_lock();
-        radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, start, tag) {
-                struct page *head, *page;
-repeat:
-                page = radix_tree_deref_slot(slot);
-                if (unlikely(!page))
+        xas_for_each_marked(&xas, page, ULONG_MAX, tag) {
+                struct page *head;
+                if (xas_retry(&xas, page))
                         continue;
-                if (radix_tree_exception(page)) {
-                        if (radix_tree_deref_retry(page)) {
-                                slot = radix_tree_iter_retry(&iter);
-                                continue;
-                        }
-
-                        /*
-                         * A shadow entry of a recently evicted page, a swap
-                         * entry from shmem/tmpfs or a DAX entry.  Return it
-                         * without attempting to raise page count.
-                         */
+                /*
+                 * A shadow entry of a recently evicted page, a swap
+                 * entry from shmem/tmpfs or a DAX entry.  Return it
+                 * without attempting to raise page count.
+                 */
+                if (xa_is_value(page))
                         goto export;
-                }
 
                 head = compound_head(page);
                 if (!page_cache_get_speculative(head))
-                        goto repeat;
+                        goto retry;
 
                 /* The page was split under us? */
-                if (compound_head(page) != head) {
-                        put_page(head);
-                        goto repeat;
-                }
+                if (compound_head(page) != head)
+                        goto put_page;
 
                 /* Has the page moved? */
-                if (unlikely(page != *slot)) {
-                        put_page(head);
-                        goto repeat;
-                }
+                if (unlikely(page != xas_reload(&xas)))
+                        goto put_page;
+
 export:
-                indices[ret] = iter.index;
+                indices[ret] = xas.xa_index;
                 entries[ret] = page;
                 if (++ret == nr_entries)
                         break;
+                continue;
+put_page:
+                put_page(head);
+retry:
+                xas_reset(&xas);
         }
         rcu_read_unlock();
         return ret;