isofs: check the return value of sb_min_blocksize() in isofs_fill_super

sb_min_blocksize() may return 0. Check its return value to avoid
opt->blocksize and sb->s_blocksize is 0.

Cc: stable@vger.kernel.org # v6.15
Fixes: 1b17a46 ("isofs: convert isofs to use the new mount API")
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Yongpeng Yang <yangyongpeng@xiaomi.com>
Link: https://patch.msgid.link/20251104125009.2111925-4-yangyongpeng.storage@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: Yongpeng Yang

fs/isofs/inode.c

@@ -610,6 +610,11 @@ static int isofs_fill_super(struct super_block *s, struct fs_context *fc)
 		goto out_freesbi;
 	}
 	opt->blocksize = sb_min_blocksize(s, opt->blocksize);
+	if (!opt->blocksize) {
+		printk(KERN_ERR
+		       "ISOFS: unable to set blocksize\n");
+		goto out_freesbi;
+	}
 
 	sbi->s_high_sierra = 0; /* default is iso9660 */
 	sbi->s_session = opt->session;