Re: s6-rc - odd warn logging and a best practices question

From: Laurent Bercot <ska-skaware_at_skarnet.org>
Date: Fri, 21 Aug 2015 11:11:14 +0200

On 21/08/2015 07:01, Colin Booth wrote:
> Not a bug in s6-rc or s6 but in some Debian script somewhere. Some
> single-user script appears to re-mount all mount points, which has the
> net result of causing all file handles into tmpfs mounts to go stale.

  Wow. Is it a "mount -o remount", or a umount followed by a mount ?
  If a -o remount has this effect on file handles, then it's probably
worth reporting to the kernel guys, because it's insane.

  Even if the script does something nonsensical such as remounting
everything read-only, which hardly makes any sense for a tmpfs,
this is not normal behaviour: when I remount a partition in read-only
mode, and there are still open descriptors for writing, the mount()
call fails with EBUSY; it does not silently invalidate all the writing
descriptors!


> I am learning way more about the complexities of the distro boot cycle
> than I'd ever expected to this week.

  Last time I looked at a mainstream distro's boot cycle, i.e. almost
10 years ago, it was already unnecessarily complex and convoluted; and
Debian was far from the worst. I doubt it has become simpler since.

  systemd will probably make scripting simpler, by moving a lot of the
complexity into the C code. Which is obviously the worst possible
solution.

-- 
  Laurent
Received on Fri Aug 21 2015 - 09:11:14 UTC

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