1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright 2019 Google LLC 4 */ 5 6 #include <linux/fsverity.h> 7 #include <linux/pagemap.h> 8 9 /** 10 * generic_read_merkle_tree_page - generic ->read_merkle_tree_page helper 11 * @inode: inode containing the Merkle tree 12 * @index: 0-based index of the Merkle tree page in the inode 13 * @num_ra_pages: The number of Merkle tree pages that should be prefetched. 14 * 15 * The caller needs to adjust @index from the Merkle-tree relative index passed 16 * to ->read_merkle_tree_page to the actual index where the Merkle tree is 17 * stored in the page cache for @inode. 18 */ 19 struct page *generic_read_merkle_tree_page(struct inode *inode, pgoff_t index, 20 unsigned long num_ra_pages) 21 { 22 struct folio *folio; 23 24 folio = __filemap_get_folio(inode->i_mapping, index, FGP_ACCESSED, 0); 25 if (folio == ERR_PTR(-ENOENT) || 26 (!IS_ERR(folio) && !folio_test_uptodate(folio))) { 27 DEFINE_READAHEAD(ractl, NULL, NULL, inode->i_mapping, index); 28 29 if (!IS_ERR(folio)) 30 folio_put(folio); 31 else if (num_ra_pages > 1) 32 page_cache_ra_unbounded(&ractl, num_ra_pages, 0); 33 folio = read_mapping_folio(inode->i_mapping, index, NULL); 34 } 35 if (IS_ERR(folio)) 36 return ERR_CAST(folio); 37 return folio_file_page(folio, index); 38 } 39 EXPORT_SYMBOL_GPL(generic_read_merkle_tree_page); 40