We forget to release page references we acquire in
ext4_da_block_invalidatepages.  Luckily, this function gets called only if we
are not able to allocate blocks for delay-allocated data so that function
should better never be called.
Also cleanup handling of index variable.
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
                        break;
                for (i = 0; i < nr_pages; i++) {
                        struct page *page = pvec.pages[i];
-                       index = page->index;
-                       if (index > end)
+                       if (page->index > end)
                                break;
-                       index++;
-
                        BUG_ON(!PageLocked(page));
                        BUG_ON(PageWriteback(page));
                        block_invalidatepage(page, 0);
                        ClearPageUptodate(page);
                        unlock_page(page);
                }
+               index = pvec.pages[nr_pages - 1]->index + 1;
+               pagevec_release(&pvec);
        }
        return;
 }