erofs: convert z_erofs_pcluster_readmore() to folios

Unlike `pagecache_get_page()`, `__filemap_get_folio()` returns error
pointers instead of NULL, thus switching to `IS_ERR_OR_NULL`.

Apart from that, it's just a straightforward conversion.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240703120051.3653452-1-hsiangkao@linux.alibaba.com

fs/erofs/internal.h

@@ -312,17 +312,13 @@ static inline unsigned int erofs_inode_datalayout(unsigned int ifmt)
 	return (ifmt >> EROFS_I_DATALAYOUT_BIT) & EROFS_I_DATALAYOUT_MASK;
 }
 
-/*
- * Different from grab_cache_page_nowait(), reclaiming is never triggered
- * when allocating new pages.
- */
-static inline
-struct page *erofs_grab_cache_page_nowait(struct address_space *mapping,
-					  pgoff_t index)
+/* reclaiming is never triggered when allocating new folios. */
+static inline struct folio *erofs_grab_folio_nowait(struct address_space *as,
+						    pgoff_t index)
 {
-	return pagecache_get_page(mapping, index,
+	return __filemap_get_folio(as, index,
 			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
-			readahead_gfp_mask(mapping) & ~__GFP_RECLAIM);
+			readahead_gfp_mask(as) & ~__GFP_RECLAIM);
 }
 
 /* Has a disk mapping */

fs/erofs/zdata.c

@@ -1767,7 +1767,6 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
 		end = round_up(end, PAGE_SIZE);
 	} else {
 		end = round_up(map->m_la, PAGE_SIZE);
-
 		if (!map->m_llen)
 			return;
 	}
@@ -1775,15 +1774,15 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
 	cur = map->m_la + map->m_llen - 1;
 	while ((cur >= end) && (cur < i_size_read(inode))) {
 		pgoff_t index = cur >> PAGE_SHIFT;
-		struct page *page;
+		struct folio *folio;
 
-		page = erofs_grab_cache_page_nowait(inode->i_mapping, index);
-		if (page) {
-			if (PageUptodate(page))
-				unlock_page(page);
+		folio = erofs_grab_folio_nowait(inode->i_mapping, index);
+		if (!IS_ERR_OR_NULL(folio)) {
+			if (folio_test_uptodate(folio))
+				folio_unlock(folio);
 			else
-				z_erofs_scan_folio(f, page_folio(page), !!rac);
-			put_page(page);
+				z_erofs_scan_folio(f, folio, !!rac);
+			folio_put(folio);
 		}
 
 		if (cur < PAGE_SIZE)