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>
diff --git a/Documentation/block/null_blk.txt b/Documentation/block/null_blk.txt
index d8880ca..3140dbd 100644
--- a/Documentation/block/null_blk.txt
+++ b/Documentation/block/null_blk.txt
@@ -72,4 +72,4 @@
queue for each CPU node in the system.
use_lightnvm=[0/1]: Default: 0
- Register device with LightNVM. Requires blk-mq to be used.
+ Register device with LightNVM. Requires blk-mq and CONFIG_NVM to be enabled.
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index ba6f4a2e..4943ee2 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -577,6 +577,7 @@ static void null_nvm_unregister(struct nullb *nullb)
#else
static int null_nvm_register(struct nullb *nullb)
{
+ pr_err("null_blk: CONFIG_NVM needs to be enabled for LightNVM\n");
return -EINVAL;
}
static void null_nvm_unregister(struct nullb *nullb) {}
