[PATCH 04/11] fsverity: start consolidating pagecache code

Christoph Hellwig
2026-01-22T08:22:52Z

ext4 and f2fs are largely using the same code to read a page full
of Merkle tree blocks from the page cache, and the upcoming xfs
fsverity support would add another copy.

Move the ext4 code to fs/verity/ and use it in f2fs as well. For f2fs
this removes the previous f2fs-specific error injection, but otherwise
the behavior remains unchanged.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/ext4/verity.c | 17 +----------------
fs/f2fs/verity.c | 17 +----------------
fs/verity/pagecache.c | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/fsverity.h | 3 +++
4 files changed, 43 insertions(+), 32 deletions(-)
create mode 100644 fs/verity/pagecache.c

diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c
index 2ce4cf8a1e31..a071860ad36a 100644
--- a/fs/ext4/verity.c
+++ b/fs/ext4/verity.c
@@ -361,23 +361,8 @@ static struct page *ext4_read_merkle_tree_page(struct inode *inode,
pgoff_t index,
unsigned long num_ra_pages)
{
- struct folio *folio;
-
index += ext4_verity_metadata_pos(inode) >> PAGE_SHIFT;
-
- folio = __filemap_get_folio(inode->i_mapping, index, FGP_ACCESSED, 0);
- if (IS_ERR(folio) || !folio_test_uptodate(folio)) {
- DEFINE_READAHEAD(ractl, NULL, NULL, inode->i_mapping, index);
-
- if (!IS_ERR(folio))
- folio_put(folio);
- else if (num_ra_pages > 1)
- page_cache_ra_unbounded(&ractl, num_ra_pages, 0);
- folio = read_mapping_folio(inode->i_mapping, index, NULL);
- if (IS_ERR(folio))
- return ERR_CAST(folio);
- }
- return folio_file_page(folio, index);
+ return generic_read_merkle_tree_page(inode, index, num_ra_pages);
}

static int ext4_write_merkle_tree_block(struct file *file, const void *buf,
diff --git a/fs/f2fs/verity.c b/fs/f2fs/verity.c
index c1c4d8044681..d37e584423af 100644
--- a/fs/f2fs/verity.c
+++ b/fs/f2fs/verity.c
@@ -259,23 +259,8 @@ static struct page *f2fs_read_merkle_tree_page(struct inode *inode,
pgoff_t index,
unsigned long num_ra_pages)
{
- struct folio *folio;
-
index += f2fs_verity_metadata_pos(inode) >> PAGE_SHIFT;
-
- folio = f2fs_filemap_get_folio(inode->i_mapping, index, FGP_ACCESSED, 0);
- if (IS_ERR(folio) || !folio_test_uptodate(folio)) {
- DEFINE_READAHEAD(ractl, NULL, NULL, inode->i_mapping, index);
-
- if (!IS_ERR(folio))
- folio_put(folio);
- else if (num_ra_pages > 1)
- page_cache_ra_unbounded(&ractl, num_ra_pages, 0);
- folio = read_mapping_folio(inode->i_mapping, index, NULL);
- if (IS_ERR(folio))
- return ERR_CAST(folio);
- }
- return folio_file_page(folio, index);
+ return generic_read_merkle_tree_page(inode, index, num_ra_pages);
}

static int f2fs_write_merkle_tree_block(struct file *file, const void *buf,
diff --git a/fs/verity/pagecache.c b/fs/verity/pagecache.c
new file mode 100644
index 000000000000..1efcdde20b73
--- /dev/null
+++ b/fs/verity/pagecache.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 Google LLC
+ */
+
+#include <linux/fsverity.h>
+#include <linux/pagemap.h>
+
+/**
+ * generic_read_merkle_tree_page - generic ->read_merkle_tree_page helper
+ * @inode: inode containing the Merkle tree
+ * @index: 0-based index of the page in the inode
+ * @num_ra_pages: The number of Merkle tree pages that should be prefetched.
+ *
+ * The caller needs to adjust @index from the Merkle-tree relative index passed
+ * to ->read_merkle_tree_page to the actual index where the Merkle tree is
+ * stored in the page cache for @inode.
+ */
+struct page *generic_read_merkle_tree_page(struct inode *inode, pgoff_t index,
+ unsigned long num_ra_pages)
+{
+ struct folio *folio;
+
+ folio = __filemap_get_folio(inode->i_mapping, index, FGP_ACCESSED, 0);
+ if (IS_ERR(folio) || !folio_test_uptodate(folio)) {
+ DEFINE_READAHEAD(ractl, NULL, NULL, inode->i_mapping, index);
+
+ if (!IS_ERR(folio))
+ folio_put(folio);
+ else if (num_ra_pages > 1)
+ page_cache_ra_unbounded(&ractl, num_ra_pages, 0);
+ folio = read_mapping_folio(inode->i_mapping, index, NULL);
+ if (IS_ERR(folio))
+ return ERR_CAST(folio);
+ }
+ return folio_file_page(folio, index);
+}
+EXPORT_SYMBOL_GPL(generic_read_merkle_tree_page);
diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h
index e22cf84fe83a..121703625cc8 100644
--- a/include/linux/fsverity.h
+++ b/include/linux/fsverity.h
@@ -309,4 +309,7 @@ static inline int fsverity_file_open(struct inode *inode, struct file *filp)

void fsverity_cleanup_inode(struct inode *inode);

+struct page *generic_read_merkle_tree_page(struct inode *inode, pgoff_t index,
+ unsigned long num_ra_pages);
+
#endif /* _LINUX_FSVERITY_H */
--
2.47.3