Incase of RDR with restricted access the
ceph user will not have access to all the objects
or all the pools where mapping exists

This commits add a check to continue to get
the volume if there is a permission error

Signed-off-by: Madhu Rajanna <[email protected]>

The go-ceph rbd.GroupCreate() now returns ErrExist in case the group
that is created, already exists. The previous check only ever matched
the string comparison, which is prone to errors in case the contents is
modified by go-ceph.

Signed-off-by: Niels de Vos <[email protected]>

The main change that is useful, is the new rbd.ErrExist error.

Signed-off-by: Niels de Vos <[email protected]>

`ensureImageCleanup()` can cause a panic when an image was deleted, but
the journal still contained a reference. By opening the IOContext before
using, an error may be returned instead of a panic when using a `nil` or
freed IOContext.

Signed-off-by: Niels de Vos <[email protected]>