diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index f16948e..980c034 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -218,6 +218,13 @@
 		+ sbi->data_start;
 }
 
+static inline void fat_get_blknr_offset(struct msdos_sb_info *sbi,
+				loff_t i_pos, sector_t *blknr, int *offset)
+{
+	*blknr = i_pos >> sbi->dir_per_block_bits;
+	*offset = i_pos & (sbi->dir_per_block - 1);
+}
+
 static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
 					struct inode *inode)
 {