[RFC v2 05/11] block: add infra to handle dmabuf tokens

[Christoph Hellwig]

On Sun, Nov 23, 2025 at 10:51:25PM +0000, Pavel Begunkov wrote:
> +struct dma_token *blkdev_dma_map(struct file *file,
> +				 struct dma_token_params *params)

Given that this is a direct file operation instance it should be
in block/fops.c.  If we do want a generic helper below it, it
should take a struct block_device instead.  But we can probably
defer that until a user for that shows up.