block: warn when putting the final reference on a registered disk

Warn when the last reference on a live disk is put without calling
del_gendisk first.  There are some BDI related bug reports that look
like a case of this, so make sure we have the proper instrumentation
to catch it.

Signed-off-by: Christoph Hellwig <>
Signed-off-by: Jens Axboe <>
1 file changed