exfat: fix range validation error in alloc and free cluster

There is check error in range condition that can never be entered
even with invalid input.
Replace incorrent checking code with already existing valid checker.
Signed-off-by: hyeongseok.kim <hyeongseok@gmail.com>
Acked-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>

fs/exfat/fatent.c

@@ -169,7 +169,7 @@ int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
 		return 0;
 
 	/* check cluster validation */
-	if (p_chain->dir < 2 && p_chain->dir >= sbi->num_clusters) {
+	if (!is_valid_cluster(sbi, p_chain->dir)) {
 		exfat_err(sb, "invalid start cluster (%u)", p_chain->dir);
 		return -EIO;
 	}
@@ -346,7 +346,7 @@ int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
 	}
 
 	/* check cluster validation */
-	if (hint_clu < EXFAT_FIRST_CLUSTER && hint_clu >= sbi->num_clusters) {
+	if (!is_valid_cluster(sbi, hint_clu)) {
 		exfat_err(sb, "hint_cluster is invalid (%u)",
 			hint_clu);
 		hint_clu = EXFAT_FIRST_CLUSTER;