Scrub filter for `Data,single`

[opk12]

I'd like to do less I/O than a full scrub, but auto-repair important things. What about a filter to skip file contents or single block groups?

I have a USB 2 drive, attached to my desktop, with Data,single (70 GB) and Metadata,DUP (3 GB). I keep backups.

I've been told that, in case of a bad block, the userspace will always see I/O error and never see corrupted data. So if I understand correctly, I should not scrub to protect sensitive data, but to trade I/O for the estimated time spent in restoring from backups.

• I'd like to scrub and auto-repair metadata, to prevent that a directory corruption breaks part of the filesystem and interrupts my work.
• I'd not scrub the file contents, 70 GB over USB 2 (that's slow). The disk is new (no bad blocks). A random broken file every now and then will probably go unnoticed, but I can quickly restore it. Data is single and unrepairable.
• I do not read the scrub log. Regardless of how often bad blocks will be reported, the disk is for desktop usage at home, so I'll replace it at 10-15 years of age, before the day that I turn on the PC and the disk does not spin up.