Re: kern/56232: Unstable system with tar on /dev

[Martin Husemann <martin%duskware.de@localhost>]

The following reply was made to PR kern/56232; it has been noted by GNATS.

From: Martin Husemann <martin%duskware.de@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/56232: Unstable system with tar on /dev
Date: Fri, 4 Jun 2021 10:24:00 +0200

 We had this discussion before, I think there even is an open PR against tar.
 Folks are in eiteher of two camps:
 
  - tar needs to open the file and extract ACLs from the filedescriptor,
    otherwise there would be races.
 
     -> solution: the kernel should never do state changes (like rewind tapes
        or similar) on plain "open" of a device node
 
  - tar should avoid all this dance when there are no ACLs anyway on the
    file system it is traversing. State changes on device open may be a hack,
    but they are a very ancient unix hack and quite common.
 
 There is an option to tar (I forgot which) to not backup ACLs - and then 
 everything should be fine.
 
 IMHO this option should be on by default.
 
 Martin