exfat: fix incorrect update of stream entry in __exfat_truncate()

At truncate, there is a problem of incorrect updating in the file entry
pointer instead of stream entry. This will cause the problem of
overwriting the time field of the file entry to new_size. Fix it to
update stream entry.

Fixes: 98d9170 ("exfat: add file operations")
Cc: stable@vger.kernel.org # v5.7
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>

fs/exfat/file.c

@@ -171,11 +171,11 @@ int __exfat_truncate(struct inode *inode, loff_t new_size)
 
 		/* File size should be zero if there is no cluster allocated */
 		if (ei->start_clu == EXFAT_EOF_CLUSTER) {
-			ep->dentry.stream.valid_size = 0;
-			ep->dentry.stream.size = 0;
+			ep2->dentry.stream.valid_size = 0;
+			ep2->dentry.stream.size = 0;
 		} else {
-			ep->dentry.stream.valid_size = cpu_to_le64(new_size);
-			ep->dentry.stream.size = ep->dentry.stream.valid_size;
+			ep2->dentry.stream.valid_size = cpu_to_le64(new_size);
+			ep2->dentry.stream.size = ep->dentry.stream.valid_size;
 		}
 
 		if (new_size == 0) {