nilfs2: convert nilfs_make_empty() to use a folio

Remove two calls to compound_head() and switch from kmap_atomic to
kmap_local.

Link: https://lkml.kernel.org/r/20231127143036.2425-16-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

@@ -559,21 +559,21 @@ int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct folio *folio)
 int nilfs_make_empty(struct inode *inode, struct inode *parent)
 {
 	struct address_space *mapping = inode->i_mapping;
-	struct page *page = grab_cache_page(mapping, 0);
+	struct folio *folio = filemap_grab_folio(mapping, 0);
 	unsigned int chunk_size = nilfs_chunk_size(inode);
 	struct nilfs_dir_entry *de;
 	int err;
 	void *kaddr;
 
-	if (!page)
-		return -ENOMEM;
+	if (IS_ERR(folio))
+		return PTR_ERR(folio);
 
-	err = nilfs_prepare_chunk(page, 0, chunk_size);
+	err = nilfs_prepare_chunk(&folio->page, 0, chunk_size);
 	if (unlikely(err)) {
-		unlock_page(page);
+		folio_unlock(folio);
 		goto fail;
 	}
-	kaddr = kmap_atomic(page);
+	kaddr = kmap_local_folio(folio, 0);
 	memset(kaddr, 0, chunk_size);
 	de = (struct nilfs_dir_entry *)kaddr;
 	de->name_len = 1;
@@ -588,10 +588,10 @@ int nilfs_make_empty(struct inode *inode, struct inode *parent)
 	de->inode = cpu_to_le64(parent->i_ino);
 	memcpy(de->name, "..\0", 4);
 	nilfs_set_de_type(de, inode);
-	kunmap_atomic(kaddr);
-	nilfs_commit_chunk(page, mapping, 0, chunk_size);
+	kunmap_local(kaddr);
+	nilfs_commit_chunk(&folio->page, mapping, 0, chunk_size);
 fail:
-	put_page(page);
+	folio_put(folio);
 	return err;
 }