loop: do not print warn message if partition scan is successful

mainline inclusion
from mainline-5.1-rc1
commit 40853d6fc619a6fd3d3177c3973a2eac9b598a80
category: bugfix
bugzilla: 12073
CVE: NA
---------------------------

Do not print warn message when the partition scan returns 0.

Fixes: d57f3374ba48 ("loop: Move special partition reread handling in loop_clr_fd()")
Signed-off-by: NDongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NYufen Yu <yuyufen@huawei.com>
Reviewed-by: Nzhengbin <zhengbin13@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/block/loop.c

@@ -1116,8 +1116,9 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
 			err = __blkdev_reread_part(bdev);
 		else
 			err = blkdev_reread_part(bdev);
-		pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
-			__func__, lo_number, err);
+		if (err)
+			pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
+				__func__, lo_number, err);
 		/* Device is gone, no point in returning error */
 		err = 0;
 	}