How do I detect a block device is being used as swap inside its request queue handler?

Dear Linus Torvalds et al,

I am having some trouble with an out of tree module for a virtual block device driver. I need to disable the direct reclaim path when the device is used as swap. I cannot see a way to detect that the device is being used as swap, so I am currently disabling it unconditionally.

Is there a clean way to detect that the block device is being used as swap? I am not subscribed to the list, so please CC replies to me.

Yours truly,
Richard Yao

Please disregard my previous email. I just discovered a deadlock that can occur if this were done.