[RFC v2 01/11] file: add callback for pre-mapping dmabuf

[Christoph Hellwig]

On Thu, Dec 04, 2025 at 12:09:46PM +0100, Christian König wrote:
> > I find the naming pretty confusing a well.  But what this does is to
> > tell the file system/driver that it should expect a future
> > read_iter/write_iter operation that takes data from / puts data into
> > the dmabuf passed to this operation.
> 
> That explanation makes much more sense.
> 
> The remaining question is why does the underlying file system / driver
> needs to know that it will get addresses from a DMA-buf?

This eventually ends up calling dma_buf_dynamic_attach and provides
a way to find the dma_buf_attachment later in the I/O path.