ufs: Convert ufs_make_empty() to use a folio

Removes a few hidden calls to compound_head() and uses kmap_local
instead of kmap.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/ufs/dir.c

@@ -540,26 +540,25 @@ int ufs_make_empty(struct inode * inode, struct inode *dir)
 {
 	struct super_block * sb = dir->i_sb;
 	struct address_space *mapping = inode->i_mapping;
-	struct page *page = grab_cache_page(mapping, 0);
+	struct folio *folio = filemap_grab_folio(mapping, 0);
 	const unsigned int chunk_size = UFS_SB(sb)->s_uspi->s_dirblksize;
 	struct ufs_dir_entry * de;
-	char *base;
 	int err;
+	char *kaddr;
 
-	if (!page)
-		return -ENOMEM;
+	if (IS_ERR(folio))
+		return PTR_ERR(folio);
 
-	err = ufs_prepare_chunk(page, 0, chunk_size);
+	err = ufs_prepare_chunk(&folio->page, 0, chunk_size);
 	if (err) {
-		unlock_page(page);
+		folio_unlock(folio);
 		goto fail;
 	}
 
-	kmap(page);
-	base = (char*)page_address(page);
-	memset(base, 0, PAGE_SIZE);
+	kaddr = kmap_local_folio(folio, 0);
+	memset(kaddr, 0, folio_size(folio));
 
-	de = (struct ufs_dir_entry *) base;
+	de = (struct ufs_dir_entry *)kaddr;
 
 	de->d_ino = cpu_to_fs32(sb, inode->i_ino);
 	ufs_set_de_type(sb, de, inode->i_mode);
@@ -573,12 +572,12 @@ int ufs_make_empty(struct inode * inode, struct inode *dir)
 	de->d_reclen = cpu_to_fs16(sb, chunk_size - UFS_DIR_REC_LEN(1));
 	ufs_set_de_namlen(sb, de, 2);
 	strcpy (de->d_name, "..");
-	kunmap(page);
+	kunmap_local(kaddr);
 
-	ufs_commit_chunk(page, 0, chunk_size);
+	ufs_commit_chunk(&folio->page, 0, chunk_size);
 	err = ufs_handle_dirsync(inode);
 fail:
-	put_page(page);
+	folio_put(folio);
 	return err;
 }