nilfs2: convert nilfs_find_entry to use a folio

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

[konishi.ryusuke: resolved a conflict due to style warning correction]
Link: https://lkml.kernel.org/r/20231127143036.2425-12-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

@@ -339,7 +339,7 @@ nilfs_find_entry(struct inode *dir, const struct qstr *qstr,
 	unsigned int reclen = NILFS_DIR_REC_LEN(namelen);
 	unsigned long start, n;
 	unsigned long npages = dir_pages(dir);
-	struct page *page = NULL;
+	struct folio *folio = NULL;
 	struct nilfs_inode_info *ei = NILFS_I(dir);
 	struct nilfs_dir_entry *de;
 
@@ -354,7 +354,7 @@ nilfs_find_entry(struct inode *dir, const struct qstr *qstr,
 		start = 0;
 	n = start;
 	do {
-		char *kaddr = nilfs_get_page(dir, n, &page);
+		char *kaddr = nilfs_get_folio(dir, n, &folio);
 
 		if (!IS_ERR(kaddr)) {
 			de = (struct nilfs_dir_entry *)kaddr;
@@ -363,18 +363,18 @@ nilfs_find_entry(struct inode *dir, const struct qstr *qstr,
 				if (de->rec_len == 0) {
 					nilfs_error(dir->i_sb,
 						"zero-length directory entry");
-					unmap_and_put_page(page, kaddr);
+					folio_release_kmap(folio, kaddr);
 					goto out;
 				}
 				if (nilfs_match(namelen, name, de))
 					goto found;
 				de = nilfs_next_entry(de);
 			}
-			unmap_and_put_page(page, kaddr);
+			folio_release_kmap(folio, kaddr);
 		}
 		if (++n >= npages)
 			n = 0;
-		/* next page is past the blocks we've got */
+		/* next folio is past the blocks we've got */
 		if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
 			nilfs_error(dir->i_sb,
 			       "dir %lu size %lld exceeds block count %llu",
@@ -387,7 +387,7 @@ nilfs_find_entry(struct inode *dir, const struct qstr *qstr,
 	return NULL;
 
 found:
-	*res_page = page;
+	*res_page = &folio->page;
 	ei->i_dir_start_lookup = n;
 	return de;
 }