[dm-devel] [PATCH] dm: fix blk-mq request-based DM queue initialization

[Christoph Hellwig]

On Tue, Apr 28, 2015 at 08:59:13PM -0400, Mike Snitzer wrote:
> Commit bfebd1cdb4 ("dm: add full blk-mq support to request-based DM")
> didn't properly account for the need to short-circuit re-initializing
> DM's blk-mq request_queue if it was already initialized.
> 
> Fix dm_init_request_based_blk_mq_queue() to return early if the
> mapped_device's tag_set already has its driver_data set to the
> mapped_device pointer.

I'm not quite up to speed with this area of code, but shouldn't
we always tear the queue fully down before trying to reinitialize it?