Call blkdiscard iff it exists

Since dm-writeboost works correctly without calling blkdiscard,
call it iff it exist for suppressing the unnecessary error message.

Signed-off-by: Satoru Takeuchi <satoru.takeuchi@gmail.com>
Check if whether some scripts run under root privilege or not

Since some scripts requires root privilege, check if it before
running them and display proper warning message if needed.

Signed-off-by: Satoru Takeuchi <satoru.takeuchi@gmail.com>
Unify kernel module loading routine

Signed-off-by: Satoru Takeuchi <satoru.takeuchi@gmail.com>
cleanup-cache.sh: Add parameter check

Signed-off-by: Satoru Takeuchi <satoru.takeuchi@gmail.com>
Merge pull request #48 from satoru-takeuchi/sat-add-error-check-v2

Sat add error check v2