fsverity: pass pos and size to ->write_merkle_tree_block

fsverity_operations::write_merkle_tree_block is passed the index of the
block to write and the log base 2 of the block size.  However, all
implementations of it use these parameters only to calculate the
position and the size of the block, in bytes.

Therefore, make ->write_merkle_tree_block take 'pos' and 'size'
parameters instead of 'index' and 'log_blocksize'.

Suggested-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20221214224304.145712-5-ebiggers@kernel.org

fs/btrfs/verity.c

@@ -784,29 +784,24 @@ static struct page *btrfs_read_merkle_tree_page(struct inode *inode,
  * fsverity op that writes a Merkle tree block into the btree.
  *
  * @inode:	inode to write a Merkle tree block for
- * @buf:            Merkle tree data block to write
+ * @buf:	Merkle tree block to write
- * @index:          index of the block in the Merkle tree
+ * @pos:	the position of the block in the Merkle tree (in bytes)
- * @log_blocksize:  log base 2 of the Merkle tree block size
+ * @size:	the Merkle tree block size (in bytes)
- *
- * Note that the block size could be different from the page size, so it is not
- * safe to assume that index is a page index.
  *
  * Returns 0 on success or negative error code on failure
  */
 static int btrfs_write_merkle_tree_block(struct inode *inode, const void *buf,
-					u64 index, int log_blocksize)
+					 u64 pos, unsigned int size)
 {
-	u64 off = index << log_blocksize;
-	u64 len = 1ULL << log_blocksize;
 	loff_t merkle_pos = merkle_file_pos(inode);
 
 	if (merkle_pos < 0)
 		return merkle_pos;
-	if (merkle_pos > inode->i_sb->s_maxbytes - off - len)
+	if (merkle_pos > inode->i_sb->s_maxbytes - pos - size)
 		return -EFBIG;
 
 	return write_key_bytes(BTRFS_I(inode), BTRFS_VERITY_MERKLE_ITEM_KEY,
-			       off, buf, len);
+			       pos, buf, size);
 }
 
 const struct fsverity_operations btrfs_verityops = {

fs/ext4/verity.c

@@ -381,11 +381,11 @@ static struct page *ext4_read_merkle_tree_page(struct inode *inode,
 }
 
 static int ext4_write_merkle_tree_block(struct inode *inode, const void *buf,
-					u64 index, int log_blocksize)
+					u64 pos, unsigned int size)
 {
-	loff_t pos = ext4_verity_metadata_pos(inode) + (index << log_blocksize);
+	pos += ext4_verity_metadata_pos(inode);
 
-	return pagecache_write(inode, buf, 1 << log_blocksize, pos);
+	return pagecache_write(inode, buf, size, pos);
 }
 
 const struct fsverity_operations ext4_verityops = {

fs/f2fs/verity.c

@@ -276,11 +276,11 @@ static struct page *f2fs_read_merkle_tree_page(struct inode *inode,
 }
 
 static int f2fs_write_merkle_tree_block(struct inode *inode, const void *buf,
-					u64 index, int log_blocksize)
+					u64 pos, unsigned int size)
 {
-	loff_t pos = f2fs_verity_metadata_pos(inode) + (index << log_blocksize);
+	pos += f2fs_verity_metadata_pos(inode);
 
-	return pagecache_write(inode, buf, 1 << log_blocksize, pos);
+	return pagecache_write(inode, buf, size, pos);
 }
 
 const struct fsverity_operations f2fs_verityops = {

fs/verity/enable.c

@@ -120,8 +120,8 @@ static int build_merkle_tree_level(struct file *filp, unsigned int level,
 			       params->block_size - pending_size);
 			err = vops->write_merkle_tree_block(inode,
 					pending_hashes,
-					dst_block_num,
+					dst_block_num << params->log_blocksize,
-					params->log_blocksize);
+					params->block_size);
 			if (err) {
 				fsverity_err(inode,
 					     "Error %d writing Merkle tree block %llu",

include/linux/fsverity.h

@@ -109,9 +109,9 @@ struct fsverity_operations {
 	 * Write a Merkle tree block to the given inode.
 	 *
 	 * @inode: the inode for which the Merkle tree is being built
-	 * @buf: block to write
+	 * @buf: the Merkle tree block to write
-	 * @index: 0-based index of the block within the Merkle tree
+	 * @pos: the position of the block in the Merkle tree (in bytes)
-	 * @log_blocksize: log base 2 of the Merkle tree block size
+	 * @size: the Merkle tree block size (in bytes)
 	 *
 	 * This is only called between ->begin_enable_verity() and
 	 * ->end_enable_verity().
@@ -119,7 +119,7 @@ struct fsverity_operations {
 	 * Return: 0 on success, -errno on failure
 	 */
 	int (*write_merkle_tree_block)(struct inode *inode, const void *buf,
-				       u64 index, int log_blocksize);
+				       u64 pos, unsigned int size);
 };
 
 #ifdef CONFIG_FS_VERITY