diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index e6b764a..437affe 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -347,6 +347,11 @@
 	fatent->fat_inode = NULL;
 }
 
+static inline bool fat_valid_entry(struct msdos_sb_info *sbi, int entry)
+{
+	return FAT_START_ENT <= entry && entry < sbi->max_cluster;
+}
+
 extern void fat_ent_access_init(struct super_block *sb);
 extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent,
 			int entry);