[already sent 2 days ago, but did not appear on the list]

On Mon, Dec 02, 2013 at 11:36:47PM +0100, Thierry De Leeuw wrote:

Hi,

Running Linux 3.12.1. I have disk /dev/sda2 with LVM that has, amongst
other, lvHome as a bcache device, and the cache resides on /dev/sdb1

My PC hung and I had to do a forced shutdown.

Now the /dev/bcache0 (and so on) do not appear anymore.

Perhaps you need to re-register / re-attach the backing device to the
caching device, something like 

   echo /dev/dm-xx > /sys/fs/bcache/register
   echo yyyyyyy > /sys/devices/virtual/block/dm-xx/bcache/attach   

If that does not help, you can try to force starting the bcache backing
device without the caching device (might give you serious fs damage with
writeback):

  echo "1" > /sys/devices/virtual/block/dm-xx/bcache/running

But since you are using LVM, you might want to create a snapshot of the
backing device LV before doing this, just in case.

Regards
Matthias