+ if (shmem_swaplist.next != &info->swaplist)
+ list_move_tail(&shmem_swaplist, &info->swaplist);
+ mutex_unlock(&shmem_swaplist_mutex);
+
+ error = 1;
+ if (!inode)
+ goto out;
+ /*
+ * Charge page using GFP_KERNEL while we can wait.
+ * Charged back to the user(not to caller) when swap account is used.
+ * add_to_page_cache() will be called with GFP_NOWAIT.
+ */
+ error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
+ if (error)
+ goto out;
+ error = radix_tree_preload(GFP_KERNEL);
+ if (error) {
+ mem_cgroup_uncharge_cache_page(page);
+ goto out;
+ }
+ error = 1;
+
+ spin_lock(&info->lock);
+ ptr = shmem_swp_entry(info, idx, NULL);
+ if (ptr && ptr->val == entry.val) {
+ error = add_to_page_cache_locked(page, inode->i_mapping,
+ idx, GFP_NOWAIT);
+ /* does mem_cgroup_uncharge_cache_page on error */
+ } else /* we must compensate for our precharge above */
+ mem_cgroup_uncharge_cache_page(page);
+
+ if (error == -EEXIST) {
+ struct page *filepage = find_get_page(inode->i_mapping, idx);
+ error = 1;
+ if (filepage) {
+ /*
+ * There might be a more uptodate page coming down
+ * from a stacked writepage: forget our swappage if so.
+ */
+ if (PageUptodate(filepage))
+ error = 0;
+ page_cache_release(filepage);
+ }
+ }
+ if (!error) {
+ delete_from_swap_cache(page);
+ set_page_dirty(page);
+ info->flags |= SHMEM_PAGEIN;
+ shmem_swp_set(info, ptr, 0);
+ swap_free(entry);
+ error = 1; /* not an error, but entry was found */
+ }
+ if (ptr)
+ shmem_swp_unmap(ptr);
+ spin_unlock(&info->lock);
+ radix_tree_preload_end();
+out:
+ unlock_page(page);
+ page_cache_release(page);
+ iput(inode); /* allows for NULL */
+ return error;