Since we unconditionally running blkdiscard on disks, we may get ioctl error message on some disks which does not support TRIM. This can be ignore but it's bad UX, so let's skip running blkdiscard when TRIM is not supported on the disk. Fixes #2774 Signed-off-by: Takuya ASADA <syuu@scylladb.com> Message-Id: <1517992904-13838-1-git-send-email-syuu@scylladb.com>