Hello, I'm trying to add a test to fsperf and it requires the use of nullblk. I'm trying to use the configfs thing, and it's doing some odd things. My basic reproducer is modprobe null_blk mkdir /sys/kernel/config/nullb/nullb0 echo some shit into the config echo 1 > /sys/kernel/config/nullb/nullb0/power Now null_blk apparently defaults to nr_devices == 1, so it creates nullb0 on modprobe. But this doesn't show up in the configfs directory. There's no way to find this out until when I try to mkfs my nullb0 and it doesn't work. The above steps gets my device created at /dev/nullb1, but there's no actual way to figure out that's what happened. If I do something like /sys/kernel/config/nullb/nullbfsperf I still just get nullb<number>, I don't get my fancy name. I don't really care what the solution looks like, I either need to be able to create a random name and have a symlink automatically created so I can get to the right device node (which I don't think can be done without udev, so I'm not fan of this) or I need a way to figure out from configfs which device my thing actually got created as. It would also be nice if /sys/kernel/config/nullb/nullb0 was populated at modinfo time so I know it's there already, then I could do something silly like get the next number and use that as my device. Thanks, Josef
