btrfs raid on rootdev is unreliably mounted

[daviessm]

When using a multi-device btrfs root and specifying the root device by UUID on the kernel command line, dracut tests the existence of the device to which the by-uuid symlink points before mounting the root device. However, the other devices may not be ready.

This appears to be because when the btrfs module is included, the rules file 64-btrfs.rules is tested for locally and if it exists, the scripts to wait for the btrfs device(s) to be ready are not added to the ramdisk:

modules.d/90btrfs/module-setup.sh:33

    if ! inst_rules 64-btrfs.rules; then
        inst_rules "$moddir/80-btrfs.rules"
        case "$(btrfs --help)" in
            *device\ ready*)
                inst_script "$moddir/btrfs_device_ready.sh" /sbin/btrfs_finished ;;
            *)
                inst_script "$moddir/btrfs_finished.sh" /sbin/btrfs_finished ;;
        esac
    fi

Is this because dracut assumes the local 64-btrfs.rules file will perform the necessary tasks? Certainly in my case (udev-225) it does not, and I can work around the issue by commenting out the if/fi lines above.

[daviessm]

Additionally, sometimes the "finished" scripts don't get triggered at all. I wasn't able to trace the cause of that and to get the system working ended up making an initrd manually.