[dm-devel] reinstate dm target local ioctl support

[Christoph Hellwig]

On Thu, Jan 28, 2016 at 01:50:19PM +0000, Andy Whitcroft wrote:
> However this also removed the possibility of a dm target having target
> specific ioctls.  Currently this is not used by any in-tree targets but
> was utilised by the flashcache out-of-tree module.
> 
> How would we feel about carrying something like the patch below in
> mainline to allow for such target local ioctls.

Bad.  Because a) targets shouldn't have their own ioctls and b) your out
of tree modules are your problem, don't burden us wіth upstream
workarounds for it.