Description of problem:


Version-Release number of selected component (if applicable):
targetcli-2.0rc1.fb19-1.el7.noarch
kernel-3.7.0-0.30.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. create a mdadm raid0 based on 2 devices with the chunk size 4MB
#cat /proc/mdstat 
Personalities : [raid0] 
md0 : active raid0 vdc[1] vdb[0]
      2088960 blocks super 1.2 4096k chunks

2. create the PV on the /dev/md0
#pvs -o+pe_start /dev/md0
  PV         VG   Fmt  Attr PSize PFree 1st PE 
  /dev/md0   vg   lvm2 a--  1.98g 1.91g   8.00m

3. create the vg based on the PV with PE size 8MB ( it's equal to the stripe width of the md0 )
#vgs -o+vg_extent_size
  VG     #PV #LV #SN Attr   VSize  VFree Ext   
  vg       1   1   0 wz--n-  1.98g 1.91g  8.00m

4. create a LV based on the vg then check the LV io_minimal_size and io_opt_size
#blockdev --getiomin --getioopt /dev/vg/lv01 
4194304
8388608

5. create a block store based on the LV then export it via the loop device then check the exported device's io_minimal_size and io_opt_size.
#cat /sys/block/sdc/device/vendor 
LIO-ORG 

#blockdev --getiomin --getioopt /dev/sdc
512
4194304
  
Actual results:
#blockdev --getioopt /dev/sdc /dev/vg/lv01 
4194304
8388608
#blockdev --getiomin /dev/sdc /dev/vg/lv01 
512
4194304


Expected results:
the exported device should has the same io_minimal_size and io_opt_size as the LV's

Additional info: