glfs: add support for resize/reconfig of block backend
glfs: add support for resize/reconfig of block backend

$ targetcli /backstores/user:glfs/ ls
o- user:glfs ........................... [Storage Objects: 1]
  o- test  [sample@192.168.0.105/test (1.0GiB) activated]

$ targetcli /backstores/user:glfs/test get attribute dev_size
dev_size=1073741824

$ truncate -s +1G /mnt/test

$ ls -l /mnt/test
-rw-------. 1 root root 2147483648 Nov  2 15:05 /mnt/test

$ targetcli /backstores/user:glfs/test set attribute dev_size=2147483648
Parameter dev_size is now '2147483648'.

Signed-off-by: Prasanna Kumar Kalever <a78d8f98557446023f5b3ba9944d7be259a978a3@redhat.com>

open-iscsi/tcmu-runner,open-iscsi/tcmu-runner,agrover/tcmu-runner