Re: [PATCH for-6.10-rc1] block: fix blk_validate_limits() to properly handle stacked devices

On Thu, May 23, 2024 at 11:38:21AM -0400, Mike Snitzer wrote:

Sure, we could elevate it to blk_validate_limits (and callers) but
adding a 'stacking' parameter is more intrusive on an API level.

Best to just update blk_set_stacking_limits() to set a new 'stacking'
flag in struct queue_limits, and update blk_stack_limits() to stack
that flag up.

I've verified this commit to work and have staged it in linux-next via
linux-dm.git's 'for-next', see:

https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-next&id=cedc03d697ff255dd5b600146521434e2e921815

Jens (and obviously: Christoph, Ming and others), I'm happy to send
this to Linus tomorrow morning if you could please provide your
Reviewed-by or Acked-by.  I'd prefer to keep the intermediate DM fix
just to "show the work and testing".

A stacking flag in the limits is fundamentally wrong, please don't
do this.