Comment # 7 on bug 1174939 from Arvin Schnell

I cannot say how the system got into the broken state. AFAIS snapper
itself does not disable btrfs quota on the file system level at all.

snapper does the modifications like enabling quota on the /.snapshots
directory (which is always read-write).

Also notice that the read-only flag on btrfs is something different than
the read-only flag of the mount command. So a 'mount -o remount,rw /'
does not have the desired result.

You have to use 'btrfs property get /' to get the read-only flag of
the file system.

Closing as WORKSFORME. Please reopen if it is known how quotas got
disabled. Maybe check kernel messages for errors.