f2fs: hanlde error case in f2fs_ioc_shutdown

This patch makes f2fs_ioc_shutdown handling error case correctly.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -1839,14 +1839,20 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
 	switch (in) {
 	case F2FS_GOING_DOWN_FULLSYNC:
 		sb = freeze_bdev(sb->s_bdev);
-		if (sb && !IS_ERR(sb)) {
+		if (IS_ERR(sb)) {
+			ret = PTR_ERR(sb);
+			goto out;
+		}
+		if (sb) {
 			f2fs_stop_checkpoint(sbi, false);
 			thaw_bdev(sb->s_bdev, sb);
 		}
 		break;
 	case F2FS_GOING_DOWN_METASYNC:
 		/* do checkpoint only */
-		f2fs_sync_fs(sb, 1);
+		ret = f2fs_sync_fs(sb, 1);
+		if (ret)
+			goto out;
 		f2fs_stop_checkpoint(sbi, false);
 		break;
 	case F2FS_GOING_DOWN_NOSYNC: