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Date: Sun, 17 Jul 2011 19:38:33 -0700
From: "Linda A. Walsh" <lvm@tlinx.org>
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Subject: [linux-lvm] Inconsistent naming needs to be fixed (was Re:
	Inconsistent naming...?)
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To: LVM general discussion and development <linux-lvm@redhat.com>

Linda A. Walsh wrote:

 > Alasdair G Kergon wrote:
 >> On Sun, Jul 10, 2011 at 06:31:27PM -0700, Linda A. Walsh wrote:
 >>> Notice the device name.   notice how the single dashes are now
 >>> displayed as two dashes?!?! 
 >> Roughly: a dash is the separator we chose, and we double it to escape a
 >> real dash.  But we still need to extend our escaping mechanism to handle
 >> characters that udev states it doesn't support in primary device names
 >> but which the old /dev did used to support (and so we still do).
 >
 >    Roughly, if I give a script the mount point of a logical device, how
 >    can I find out the name of the LV it is on?

   Ok, I think I bass-ackwards way of hacking around this -- but my
   solution is unique to my usage and conventions.

   In my 'application' (meaning 'usage'), I start with a mount-point
of a volume I want to take a snapshot of. I want to map that mount
point back to the original dev.  It's not straightforward when the
device in /proc/mounts, isn't the real device NOR is it the name I
used!   I.e. real dev = /dev/dm-[0-x], name i used /dev/VG/LV.
What /proc/mounts shows:  /mapper/dev/<mangled VG>-<mangled LV>.

   So who's responsible for that mess of code so we can get /proc to
either, show the value I used (when I mount by LABEL I see the 'real'
devices in mounts -- not /dev/disk-by-label/<label>.   It isn't consistent
but it's worse, as it choose a name that's gone through some
'translation'...


   Am I being more clear about why this create problems (besides
being confusing and just looking bad (because my computer has
to come up with it's own name for a dev -- neither the one
I used nor the real name? 

   Now, I can kludge around this, by knowing some different pieces
of information unique to my app/situation, but in the general case,
it would be unpredictable, and that's bad, as I'd like to release these
scripts if I can get them working to my satisfaction.

    Can the situation with /proc/mounts be fixed?