On Wed, Jan 07, 2026 at 05:01:51PM +0100, Christoph Hellwig wrote: > On Wed, Jan 07, 2026 at 04:56:05PM +0100, Christian König wrote: > > > But I am wondering why not make it as one subsystem interface, such as > > > nvme > > > ioctl, then the whole implementation can be simplified a lot. It is > > > reasonable > > > because subsystem is exactly the side for consuming/importing the dma-buf. > > > > Yeah that it might be better if it's more nvme specific came to me as well. > > The feature is in no way nvme specific. nvme is just the initial > underlying driver. It makes total sense to support this for any high > performance block device, and to pass it through file systems.
But why does FS care the dma buffer attachment? Since high performance host controller is exactly the dma buffer attachment point. If the callback is added in `struct file_operations` for wiring dma buffer and the importer(host contrller), you will see it is hard to let it cross device mapper/raid or other stackable block devices. Thanks, Ming
