On Tue, Jan 31, 2017 at 01:54:28PM +0100, Jan Kara wrote:

Instead of storing backing_dev_info inside struct request_queue,
allocate it dynamically, reference count it, and free it when the last
reference is dropped. Currently only request_queue holds the reference
but in the following patch we add other users referencing
backing_dev_info.

Do we really need the separate slab cache?  Otherwise this looks
fine to me.