[Pkg-sysvinit-devel] Bug#653073: Switching /etc/mtab to /proc/mounts and removing /lib/init/rw

[Michael Tokarev]

On 19.01.2012 19:09, Michael Tokarev wrote:
> On 18.01.2012 18:18, Roger Leigh wrote:
>> clone 653073 -1
>> retitle -1 df: [patch] Please ignore rootfs in df output
>> reassign -1 coreutils
>> thanks
>>
>> On Wed, Jan 18, 2012 at 03:05:58PM +0100, Goswin von Brederlow wrote:
>>> jidanni at jidanni.org writes:
>>>
>>>> Forty years of pleasant df(1) and mount(1) reading shattered in one day,
>>>> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=653073
>>>
>>> Any update on why the root filesystem is listed by UUID? Is that a
>>> problem of busybox mount reporting the long device name to the kernel
>>> why real mount uses the short one?
>>
>> This needs to be investigated by Dan, as I requested in the report.
>> It's just a matter of looking at what is really happening in the
>> initramfs with e.g. break=init-bottom.
> 
> It is due to busybox mount, which does not perform any canonicalizing
> of the device argument but passes it as-is to the kernel.  On the
> contrary, mount from util-linux resolves the symlink if given as
> the device name.
> 
> And initramfs does this:
> 
> init:		UUID=*)
> init:			ROOT="/dev/disk/by-uuid/${ROOT#UUID=}"
> 
> whichis later passed to busybox's mount, which happily passes
> this /dev/disk/... stuff to kernel, which in turn happily
> shows it in /proc/mounts.
> 
> It looks like mount from klibc does not do any canonicalisation
> too, only util-linux mount does.
[]
> And yes it is kinda trivial to add a call to realpath(3) to
> busybox (or equivalent).

Or add readlink into initramfs-tools, for that matter.

But it is still not clear if it is a bug or not :)

/mjt