Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

[Pierre Ynard]

> > I don't understand this. Merely having a libary installed should
> > not imply any userspace actions. If some packages need device
> > mapper functionality, they need to depend on dmsetup, not just
> > libdevmapper.
> 
> Yes, it does. The sole purpose of libdevmapper is to configure the
> device mapper part of the kernel. To do this it needs a working udev.

I run LVM on a non-dynamic system without udev installed. The udev rules
are a no-op on my system. libdevmapper still does its job just fine. So
it seems that no, it doesn't "need" a working udev.

If it "needed" a working udev to apply the dmsetup udev rules, then it
should have a dependency not just on the udev rules, but on udev itself.
But we've gone over that issue already before:

> lvm2 (2.02.64-1) unstable; urgency=low
> 
>   * Enable udev sync, remove explicit udev dependency, bump dmsetup
> dependency to get it working. (closes: #543163)
> 
>  -- Bastian Blank   Wed, 19 May 2010 13:33:09 +

So, from this point of view, it doesn't make sense to say that
libdevmapper needs a hard dependency relationship with something that
may or may not be a no-op, depending on the status of other packages
that have however no dependency with it.

Beyond the circular dependency, there is the problem of respecting the
policy and avoiding package and daemon bloat through unwarranted hard
dependencies. All I want and need on my system is the LVM init service,
the LVM utilities, and the device mapper dynamic libraries they use;
which is main and significant functionality in itself. However with the
current lvm2 package I have no choice but getting way more than that.

Do you think it could be beneficial to create a meta-package, under
whose umbrella the dependencies on anything needed for a "fully working
LVM experience" could be simply moved? Between plugins and udev, there
seem to be different degrees of what a dependency is, so that could be a
nice approach to it.

Best regards,

-- 
Pierre Ynard
"Une âme dans un corps, c'est comme un dessin sur une feuille de papier."

Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

[Martin Pitt]

Hello,

Bastian Blank [2010-06-19 15:35 +0200]:
> On Sat, Jun 19, 2010 at 03:30:00PM +0200, Bill Allombert wrote:
> > On Sat, Jun 19, 2010 at 03:08:53PM +0200, Bastian Blank wrote:
> > > You are free to send a patch to acomplish this.
> > Well, move the udev rules to devmapper-udev-rules and set up the 
> > dependencies
> > as follow:
> > dmsetup -> libdevmapper1.02.1 -> devmapper-udev-rules
> 
> Please try again. The library needs the rules to work properly and the
> udev rules calls dmsetup.

I don't understand this. Merely having a libary installed should not
imply any userspace actions. If some packages need device mapper
functionality, they need to depend on dmsetup, not just libdevmapper.

We've seen quite a lot of upgrade failures due to this circular
dependency, so it's clearly a problem:

| Unpacking dmsetup (2:1.02.90-2ubuntu1) over (2:1.02.77-6ubuntu2) ...
| Preparing to unpack .../libdevmapper1.02.1_2%3a1.02.90-2ubuntu1_amd64.deb ...
| Unpacking libdevmapper1.02.1:amd64 (2:1.02.90-2ubuntu1) over 
(2:1.02.77-6ubuntu2) ...
| Preparing to unpack .../libudev1_219-7ubuntu6_amd64.deb ...
| Unpacking libudev1:amd64 (219-7ubuntu6) over (204-5ubuntu20.15) ...
| Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
| Setting up libudev1:amd64 (219-7ubuntu6) ...
| dpkg: dependency problems prevent configuration of libdevmapper1.02.1:amd64:
|  libdevmapper1.02.1:amd64 depends on dmsetup (>= 2:1.02.90-2ubuntu1); however:
|   Package dmsetup is not configured yet.
| 
| dpkg: error processing package libdevmapper1.02.1:amd64 (--configure):
|  dependency problems - leaving unconfigured

This then causes a trail of followup errors, like failing to configure
libcryptsetup4, systemd-sysv, and init.

IMHO the cleanest solution is to drop libdevmapper1.02.1's dependency
to dmsetup entirely. For fixing the upgrade bug it should be
sufficient to downgrade it to Recommends, though, to hint apt into
ordering it correctly.

Thanks,

Martin

-- 
Martin Pitt| http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)


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Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

[Martin Pitt]

Hello Bastian,

Bastian Blank [2015-12-16 14:04 +]:
> Please report failures with Ubuntu to the Ubuntu bug tracker, not the
> Debian one.

It is (https://launchpad.net/bugs/1032823), but the circular dep is
exactly the same way in Debian, thus why would Debian upgrades not be
be affected? We just don't automatically report them in Debian.

dmsetup is already required, so lowering libdevmapper's depends:
dmsetup to recommends should not have any practical consequences other
than fixing this circular dependency and upgrade bug.

Anyway, if you are not interested in this I'll shut up.

Thanks,

Martin
-- 
Martin Pitt| http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)

Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

[Bastian Blank]

On Wed, Dec 16, 2015 at 02:58:48PM +0100, Martin Pitt wrote:
> Bastian Blank [2010-06-19 15:35 +0200]:
> > Please try again. The library needs the rules to work properly and the
> > udev rules calls dmsetup.
> I don't understand this. Merely having a libary installed should not
> imply any userspace actions. If some packages need device mapper
> functionality, they need to depend on dmsetup, not just libdevmapper.

Yes, it does.  The sole purpose of libdevmapper is to configure the
device mapper part of the kernel.  To do this it needs a working udev.

> We've seen quite a lot of upgrade failures due to this circular
> dependency, so it's clearly a problem:

Please report failures with Ubuntu to the Ubuntu bug tracker, not the
Debian one.

Regards,
Bastian

-- 
Military secrets are the most fleeting of all.
-- Spock, "The Enterprise Incident", stardate 5027.4

Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

[Bastian Blank]

Hi Martin

On Wed, Dec 16, 2015 at 03:54:10PM +0100, Martin Pitt wrote:
> Bastian Blank [2015-12-16 14:04 +]:
> > Please report failures with Ubuntu to the Ubuntu bug tracker, not the
> > Debian one.
> It is (https://launchpad.net/bugs/1032823), but the circular dep is
> exactly the same way in Debian, thus why would Debian upgrades not be
> be affected? We just don't automatically report them in Debian.

It is your task to show that Debian is affected.  I have never seen
this problem at all and I would assume a lot more bug reports if this
would be show up more often.

> dmsetup is already required, so lowering libdevmapper's depends:
> dmsetup to recommends should not have any practical consequences other
> than fixing this circular dependency and upgrade bug.

No, dmsetup is _not_ required, it never was:

| Package: dmsetup
| Source: lvm2 (2.02.111-2.2)
| Section: admin
| Priority: optional

You mean dmsetup is required in Ubuntu?  Then you may have found your
problem.  apt have some special handling of required and/or essential
packages.

Regards,
Bastian

-- 
Sometimes a feeling is all we humans have to go on.
-- Kirk, "A Taste of Armageddon", stardate 3193.9

Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

[Bill Allombert]

Package: dmsetup
Version: 2:1.02.48-2
Severity: important

Hello Debian LVM Team,

There is a circular dependency between dmsetup and libdevmapper1.02.1:

dmsetup :Depends: libdevmapper1.02.1 (= 2:1.02.47)
libdevmapper1.02.1  :Depends: dmsetup (= 2:1.02.48-2)

Circular dependencies involving shared libraries are known to cause problems
during upgrade between stable releases, so we should try to get rid of them.

Cheers,
-- 
Bill. ballo...@debian.org

Imagine a large red swirl here. 



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Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

[Bastian Blank]

severity 586424 normal
thanks

On Sat, Jun 19, 2010 at 02:49:20PM +0200, Bill Allombert wrote:
 There is a circular dependency between dmsetup and libdevmapper1.02.1:
 dmsetup   :Depends: libdevmapper1.02.1 (= 2:1.02.47)
 libdevmapper1.02.1:Depends: dmsetup (= 2:1.02.48-2)

Known and documented.

 Circular dependencies involving shared libraries are known to cause problems
 during upgrade between stable releases, so we should try to get rid of them.

You are free to send a patch to acomplish this.

Bastian

-- 
I object to intellect without discipline;  I object to power without
constructive purpose.
-- Spock, The Squire of Gothos, stardate 2124.5



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Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

[Bill Allombert]

On Sat, Jun 19, 2010 at 03:08:53PM +0200, Bastian Blank wrote:
 severity 586424 normal
 thanks
 
 On Sat, Jun 19, 2010 at 02:49:20PM +0200, Bill Allombert wrote:
  There is a circular dependency between dmsetup and libdevmapper1.02.1:
  dmsetup :Depends: libdevmapper1.02.1 (= 2:1.02.47)
  libdevmapper1.02.1  :Depends: dmsetup (= 2:1.02.48-2)
 
 Known and documented.
 
  Circular dependencies involving shared libraries are known to cause problems
  during upgrade between stable releases, so we should try to get rid of them.
 
 You are free to send a patch to acomplish this.

Well, move the udev rules to devmapper-udev-rules and set up the dependencies
as follow:

dmsetup - libdevmapper1.02.1 - devmapper-udev-rules

Cheers,
-- 
Bill. ballo...@debian.org

Imagine a large red swirl here. 



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Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

[Bastian Blank]

On Sat, Jun 19, 2010 at 03:30:00PM +0200, Bill Allombert wrote:
 On Sat, Jun 19, 2010 at 03:08:53PM +0200, Bastian Blank wrote:
  You are free to send a patch to acomplish this.
 Well, move the udev rules to devmapper-udev-rules and set up the dependencies
 as follow:
 dmsetup - libdevmapper1.02.1 - devmapper-udev-rules

Please try again. The library needs the rules to work properly and the
udev rules calls dmsetup.

Bastian

-- 
A little suffering is good for the soul.
-- Kirk, The Corbomite Maneuver, stardate 1514.0



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