nilfs2: convert nilfs_readdir to use a folio

Use the new folio APIs to remove calls to compound_head().

Link: https://lkml.kernel.org/r/20231127143036.2425-11-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

@@ -284,9 +284,9 @@ static int nilfs_readdir(struct file *file, struct dir_context *ctx)
 	for ( ; n < npages; n++, offset = 0) {
 		char *kaddr, *limit;
 		struct nilfs_dir_entry *de;
-		struct page *page;
+		struct folio *folio;
 
-		kaddr = nilfs_get_page(inode, n, &page);
+		kaddr = nilfs_get_folio(inode, n, &folio);
 		if (IS_ERR(kaddr)) {
 			nilfs_error(sb, "bad page in #%lu", inode->i_ino);
 			ctx->pos += PAGE_SIZE - offset;
@@ -298,7 +298,7 @@ static int nilfs_readdir(struct file *file, struct dir_context *ctx)
 		for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
 			if (de->rec_len == 0) {
 				nilfs_error(sb, "zero-length directory entry");
-				unmap_and_put_page(page, kaddr);
+				folio_release_kmap(folio, kaddr);
 				return -EIO;
 			}
 			if (de->inode) {
@@ -311,13 +311,13 @@ static int nilfs_readdir(struct file *file, struct dir_context *ctx)
 
 				if (!dir_emit(ctx, de->name, de->name_len,
 						le64_to_cpu(de->inode), t)) {
-					unmap_and_put_page(page, kaddr);
+					folio_release_kmap(folio, kaddr);
 					return 0;
 				}
 			}
 			ctx->pos += nilfs_rec_len_from_disk(de->rec_len);
 		}
-		unmap_and_put_page(page, kaddr);
+		folio_release_kmap(folio, kaddr);
 	}
 	return 0;
 }