exfat: fix overflow for large capacity partition

Using int type for sector index, there will be overflow in a large
capacity partition.

For example, if storage with sector size of 512 bytes and partition
capacity is larger than 2TB, there will be overflow.

Fixes: 1b6138385499 ("exfat: reduce block requests when zeroing a cluster")

Signed-off-by: Yuezhang Mo <[email protected]>
Reviewed-by: Andy Wu <[email protected]>
Reviewed-by: Aoyama Wataru <[email protected]>
Acked-by: Sungjong Seo <[email protected]>
Signed-off-by: Namjae Jeon <[email protected]>

Author: YuezhangMo

fatent.c

@@ -278,8 +278,7 @@ int exfat_zeroed_cluster(struct inode *dir, unsigned int clu)
 	struct super_block *sb = dir->i_sb;
 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
 	struct buffer_head *bh;
-	sector_t blknr, last_blknr;
-	int i;
+	sector_t blknr, last_blknr, i;
 
 	blknr = exfat_cluster_to_sector(sbi, clu);
 	last_blknr = blknr + sbi->sect_per_clus;