tree 6bbd8a28bd9513188b29f1dec567841726053bc6
parent 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa
author Shaohua Li <shli@fb.com> 1502748294 -0700
committer Jens Axboe <axboe@kernel.dk> 1503500043 -0600

nullb: add interface to power on disk

The device created in nullb configfs interface isn't power on by
default. After user configures the device, user can do 'echo 1 >
xxx/nullb/device_name/power' to power on the device, which will create a
disk. the xxx/nullb/device_name/index is the disk index, so if the index
is 2, the new created disk should be named as /dev/nullb2. Note, the
'index' is only valid after disk is power on.

'echo 0 > xxx/nullb/device_name/power' will remove the disk. Note, this
doesn't remove the device. To remove the device, user should do 'rmdir
xxx/nullb/device_name'. Removing the device will remove the disk too.

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>