nilfs2: remove page_address() from nilfs_delete_entry

In preparation for removing kmap from directory handling, mask the
directory entry pointer to discover the start address of the page. 
Matches ext2.

Link: https://lkml.kernel.org/r/20231127143036.2425-6-konishi.ryusuke@gmail.comSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/nilfs2/dir.c

@@ -531,7 +531,7 @@ int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
 {
 	struct address_space *mapping = page->mapping;
 	struct inode *inode = mapping->host;
-	char *kaddr = page_address(page);
+	char *kaddr = (char *)((unsigned long)dir & PAGE_MASK);
 	unsigned int from, to;
 	struct nilfs_dir_entry *de, *pde = NULL;
 	int err;
@@ -551,7 +551,7 @@ int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
 		de = nilfs_next_entry(de);
 	}
 	if (pde)
-		from = (char *)pde - (char *)page_address(page);
+		from = (char *)pde - kaddr;
 	lock_page(page);
 	err = nilfs_prepare_chunk(page, from, to);
 	BUG_ON(err);