page cache: Convert find_get_entry to XArray

Slightly shorter and simpler code.

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

1 files changed, 28 insertions, 35 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 414efbdc95df..2bf9f0742082 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1382,47 +1382,40 @@ EXPORT_SYMBOL(page_cache_prev_miss);
  */
 struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
 {
-        void **pagep;
+        XA_STATE(xas, &mapping->i_pages, offset);
         struct page *head, *page;
 
         rcu_read_lock();
 repeat:
-        page = NULL;
-        pagep = radix_tree_lookup_slot(&mapping->i_pages, offset);
-        if (pagep) {
-                page = radix_tree_deref_slot(pagep);
-                if (unlikely(!page))
-                        goto out;
-                if (radix_tree_exception(page)) {
-                        if (radix_tree_deref_retry(page))
-                                goto repeat;
-                        /*
-                         * A shadow entry of a recently evicted page,
-                         * or a swap entry from shmem/tmpfs.  Return
-                         * it without attempting to raise page count.
-                         */
-                        goto out;
-                }
+        xas_reset(&xas);
+        page = xas_load(&xas);
+        if (xas_retry(&xas, page))
+                goto repeat;
+        /*
+         * A shadow entry of a recently evicted page, or a swap entry from
+         * shmem/tmpfs.  Return it without attempting to raise page count.
+         */
+        if (!page || xa_is_value(page))
+                goto out;
 
-                head = compound_head(page);
-                if (!page_cache_get_speculative(head))
-                        goto repeat;
+        head = compound_head(page);
+        if (!page_cache_get_speculative(head))
+                goto repeat;
 
-                /* The page was split under us? */
-                if (compound_head(page) != head) {
-                        put_page(head);
-                        goto repeat;
-                }
+        /* The page was split under us? */
+        if (compound_head(page) != head) {
+                put_page(head);
+                goto repeat;
+        }
 
-                /*
-                 * Has the page moved?
-                 * This is part of the lockless pagecache protocol. See
-                 * include/linux/pagemap.h for details.
-                 */
-                if (unlikely(page != *pagep)) {
-                        put_page(head);
-                        goto repeat;
-                }
+        /*
+         * Has the page moved?
+         * This is part of the lockless pagecache protocol. See
+         * include/linux/pagemap.h for details.
+         */
+        if (unlikely(page != xas_reload(&xas))) {
+                put_page(head);
+                goto repeat;
         }
 out:
         rcu_read_unlock();
@@ -1453,7 +1446,7 @@ struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset)
 
 repeat:
         page = find_get_entry(mapping, offset);
-        if (page && !radix_tree_exception(page)) {
+        if (page && !xa_is_value(page)) {
                 lock_page(page);
                 /* Has the page been truncated? */
                 if (unlikely(page_mapping(page) != mapping)) {