null_blk: add usage hints for NVM
authorYasuaki Ishimatsu <yasu.isimatu@gmail.com>
Wed, 16 Nov 2016 15:26:11 +0000 (08:26 -0700)
committerJens Axboe <axboe@fb.com>
Wed, 16 Nov 2016 15:26:11 +0000 (08:26 -0700)
commit92153d30c7c8863022cad684926d71ffaed6a56d
treef1ebf00c6fa2521dec6234ca2b76ebb6c23a49d2
parent0a6219a95f0b0690fb7094acb26002e7a4791197
null_blk: add usage hints for NVM

If CONFIG_NVM is disabled, loading null_block module with use_lightnvm=1
fails. But there are no messages and documents related to the failure.

Add the appropriate error message.

Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Massaged the text a bit.

Signed-off-by: Jens Axboe <axboe@fb.com>
Documentation/block/null_blk.txt
drivers/block/null_blk.c