:resize action on physical volume doesn't work on unallocated pvs

[klarna-marcus-nilsson]

Reproduce:

lvm_physical_volume "/dev/sdb" do
action [:create, :resize]
end

pe_count becomes 0, because the PE Size is zero until it is allocated.

[rolffujino]

This is what is breaking the code:
pe_size = pv_size / pv[0].pe_count

On a completely new/clean physical volume, the pe_count is equal to '0'.

[root@default-centos-74 ~]# pvs /dev/sdb -o pv_all
  Fmt  PV UUID                                DevSize PV         Maj Min PMdaFree  PMdaSize  PExtVsn 1st PE  PSize PFree Used Attr Allocatable Exported   Missing    PE  Alloc PV Tags #PMda #PMdaUse BA Start BA Size PInUse Duplicate
  lvm2 zKdkF1-BEug-fikS-ucbM-5pUh-4E10-QfpYyO   2.00g /dev/sdb   8   16         0   1020.00k       2   1.00m 2.00g 2.00g   0  ---                                      0     0             1        1       0       0                  

[root@default-centos-74 ~]# pvdisplay /dev/sdb
  "/dev/sdb" is a new physical volume of "2.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb
  VG Name               
  PV Size               2.00 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               zKdkF1-BEug-fikS-ucbM-5pUh-4E10-QfpYyO

I would submit a fix but I am not 100% sure what this block of code is trying to achieve:

    # get the size the OS says the block device is
    block_device_raw_size = pv[0].dev_size.to_i
    # get the size LVM thinks the PV is
    pv_size = pv[0].size.to_i
    pe_size = pv_size / pv[0].pe_count

    # get the amount of space that cannot be allocated
    non_allocatable_space = block_device_raw_size % pe_size
    # if it's an exact amount LVM appears to just take 1 full extent
    non_allocatable_space = pe_size if non_allocatable_space == 0

    block_device_allocatable_size = block_device_raw_size - non_allocatable_space

    # only resize if they are not same
    if pv_size != block_device_allocatable_size

I might be missing something, but couldn't this entire section be replaced by:

    dev_size = pv[0].dev_size.to_i
    pv_size = pv[0].size.to_i

    if pv_size != dev_size

[rolffujino]

For those curious this is my workaround:

lvm_physical_volume '/dev/sdb' do
  if `pvs /dev/sdb -o pv_pe_count --noheadings | sed 's/ //g\` != 0
    action :resize
  else
    action :create
  end
end

[rolffujino]

With the version 13+ of the chef-client you should make sure to use full paths in my workaround, otherwise it won't work because it can't find the commands.

lvm_physical_volume '/dev/sdb' do
  if `/usr/sbin/pvs /dev/sdb -o pv_pe_count --noheadings | sed 's/ //g\` != 0
    action :resize
  else
    action :create
  end
end

Please see this issue for more details:
#167