Subject: Re: bug#19570: bug: df and bind mounts

From: Bernhard Voelker <[email-masked]>
Date: Mon, 12 Jan 2015 22:27:13 +0100

On 01/12/2015 02:31 AM, Pádraig Brady wrote:
> On 11/01/15 23:36, Vladimir A. Pavlov wrote:
>> run /run tmpfs rw,noatime,nodiratime,nodev,noexec,mode=0755,size=1m 0 0
>> /run/cgs/httpd /usr/cgs/httpd/run none rw,bind 0 0

> Thanks for the analysis and patch,
> Current tests pass at least with it.
> I'll analyse a little more, add tests and probably push.

hmm, tmpfs is problematic anyway, as one can specify anything
as the dummy backing source device:

  $ mount -t tmpfs hello:/world /mnt
  $ mount -t tmpfs something /mnt
  $ mount -t tmpfs / /mnt
  $ findmnt /mnt
  TARGET SOURCE       FSTYPE OPTIONS
  /mnt   hello:/world tmpfs  rw,relatime
  /mnt   something    tmpfs  rw,relatime
  /mnt   /            tmpfs  rw,relatime

  $ df -a --out=source,target | grep /mnt
  hello:/world   /mnt
  something      /mnt
  /              /mnt

I'd almost tend to recommend to classify tmpfs as dummy
file system like procfs etc.

Have a nice day,
Berny