/lib/udev/rules.d/60-zvol.rules is in zfsutils-linux 0.6.5.6-0ubuntu8.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | KERNEL=="zd*" SUBSYSTEM=="block" ACTION=="add|change" PROGRAM="/lib/udev/zvol_id $tempnode" SYMLINK+="zvol/%c"
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