Chris Murphy posted on Sat, 30 Jul 2016 14:02:17 -0600 as excerpted:

Short version: When systemd-logind login.conf KillUserProcesses=yes, and
the user does "sudo btrfs scrub start" in e.g. GNOME Terminal, and then
logs out of the shell, the user space operation is killed, and btrfs
scrub status reports that the scrub was aborted. [1]

What does btrfs scrub resume do?  Resume, or error?

If it resumes, I'd say RESOLVED/NOTABUG as both that systemd option and 
btrfs scrub appear to be working as intended.  If it doesn't, then 
there's definitely a btrfs bug, even if you argue it's only in the 
documentation, because the manpage (tho still 4.6.1, here) says it 
resumes an interrupted scrub but won't start a new one if the scrub 
finished successfully, and an abort is definitely an interruption, not a 
successful finish.

-- 
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"Every nonfree program has a lord, a master --
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