Installing and configuring Cinder: commands for creating volume group are not sudo(ed)

Cinder installation here: http://docs.openstack.org/trunk/openstack-compute/install/apt/content/osfolubuntu-cinder.html

The commands aimed to create the volume group that cinder uses for hosting the logical volumes must be sudo-ed.

In details:

1) ------------------

dd if=/dev/zero of=cinder-volumes bs=1 count=0 seek=2G

must be changed to

sudo dd if=/dev/zero of=/var/lib/cinder/cinder-backing-file bs=1 count=0 seek=2G

2) ------------------
losetup /dev/loop2 cinder-volumes

must be changed to

sudo losetup /dev/loop2 /var/lib/cinder/cinder-backing-file

3) ------------------

pvcreate /dev/loop2

must be changed to

sudo pvcreate /dev/loop2

4) ------------------

vgcreate cinder-volumes /dev/loop2

must be changed to

sudo vgcreate cinder-volumes /dev/loop2

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NOTE 1: I changed the name of the backing file created at step 1). This is not necessary but it's a better solution than the one proposed by the manual because the backing file (the file that is used for storing the volume group and the logical volumes) is placed in a directory related to cinder (it's /var/lib/cinder/) rather than whatever directory happens to be used by the installer when s/he submits the command.
It's cleaner.

NOTE 2: After the sequence of commands, it would be nice to verify that the volume group is really created as expected.
In order to do that, it's sufficient to submit the following command:
 $ sudo vgscan
  Reading all physical volumes. This may take a while...
  Found volume group "cinder-volumes" using metadata type lvm2