Created attachment 801361 [details]
screenlog (transcript of terminal session under "screen" running "zypper dup".
I should have mentioned that I do not use "btrfs" on my system.
The "screenlog.0" is just a transcript with "screen -L" of the session where I
ran "zypper". Search for "btrfsmaint" to find the relevant lines.
Repeat runs of "zypper dup" are in the same screenlog.0 file, including the
repeat after a reboot.