[RFC 01/12] file: add callback returning dev for dma operations

[Pavel Begunkov <asml.silence@gmail.com>]

Add a file callback returning a device that can be used for
dma pre-mapping buffers. There should be only one device per file, and
a file should never return different deivecs during its lifetime.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 include/linux/fs.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 96c7925a6551..9ab5aa413c62 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -82,6 +82,7 @@ struct fs_context;
 struct fs_parameter_spec;
 struct fileattr;
 struct iomap_ops;
+struct device;
 
 extern void __init inode_init(void);
 extern void __init inode_init_early(void);
@@ -2190,6 +2191,7 @@ struct file_operations {
 	int (*uring_cmd_iopoll)(struct io_uring_cmd *, struct io_comp_batch *,
 				unsigned int poll_flags);
 	int (*mmap_prepare)(struct vm_area_desc *);
+	struct device *(*get_dma_device)(struct file *);
 } __randomize_layout;
 
 /* Supports async buffered reads */
-- 
2.49.0