diff --git a/mm/truncate.c b/mm/truncate.c
index 8d8c62d..9c809e7 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -753,7 +753,7 @@ EXPORT_SYMBOL(truncate_setsize);
  */
 void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
 {
-	int bsize = 1 << inode->i_blkbits;
+	int bsize = i_blocksize(inode);
 	loff_t rounded_from;
 	struct page *page;
 	pgoff_t index;