I just did mkfs on my file system, so why do I get permission denied mounting it?
You probably miss-typed the cluster name on mkfs. Use the ‘dmesg’ command to see what gfs is complaining about. If that’s the problem, you can use gfs_tool or another mkfs to fix it. Even if this is not your problem, if you have a problem mounting, always use dmesg to view complaints from the kernel.