Handle a possible volume attachment visibility wait/race issue

The attached volume does not became necessarily immediately
visible on the guest even if the volume is in the 'in-use' state.
We may need to wait until it appears in the /proc/partitions
before any other action.

This patch also increase log verbosity, you will be able to see
 the actually visible partitions on the guest system.

Change-Id: I2b2d908b791d07066e5357ec0d213b953d5ce204
1 file changed