1 /* SPDX-License-Identifier: MIT */
2 /*
3  * Copyright © 2024 Intel Corporation
4  */
5 
6 #ifndef _TTM_BACKUP_H_
7 #define _TTM_BACKUP_H_
8 
9 #include <linux/mm_types.h>
10 #include <linux/shmem_fs.h>
11 
12 /**
13  * ttm_backup_handle_to_page_ptr() - Convert handle to struct page pointer
14  * @handle: The handle to convert.
15  *
16  * Converts an opaque handle received from the
17  * ttm_backup_backup_page() function to an (invalid)
18  * struct page pointer suitable for a struct page array.
19  *
20  * Return: An (invalid) struct page pointer.
21  */
22 static inline struct page *
23 ttm_backup_handle_to_page_ptr(unsigned long handle)
24 {
25 	return (struct page *)(handle << 1 | 1);
26 }
27 
28 /**
29  * ttm_backup_page_ptr_is_handle() - Whether a struct page pointer is a handle
30  * @page: The struct page pointer to check.
31  *
32  * Return: true if the struct page pointer is a handld returned from
33  * ttm_backup_handle_to_page_ptr(). False otherwise.
34  */
35 static inline bool ttm_backup_page_ptr_is_handle(const struct page *page)
36 {
37 	return (unsigned long)page & 1;
38 }
39 
40 /**
41  * ttm_backup_page_ptr_to_handle() - Convert a struct page pointer to a handle
42  * @page: The struct page pointer to convert
43  *
44  * Return: The handle that was previously used in
45  * ttm_backup_handle_to_page_ptr() to obtain a struct page pointer, suitable
46  * for use as argument in the struct ttm_backup_drop() or
47  * ttm_backup_copy_page() functions.
48  */
49 static inline unsigned long
50 ttm_backup_page_ptr_to_handle(const struct page *page)
51 {
52 	WARN_ON(!ttm_backup_page_ptr_is_handle(page));
53 	return (unsigned long)page >> 1;
54 }
55 
56 void ttm_backup_drop(struct file *backup, pgoff_t handle);
57 
58 int ttm_backup_copy_page(struct file *backup, struct page *dst,
59 			 pgoff_t handle, bool intr);
60 
61 s64
62 ttm_backup_backup_page(struct file *backup, struct page *page,
63 		       bool writeback, pgoff_t idx, gfp_t page_gfp,
64 		       gfp_t alloc_gfp);
65 
66 void ttm_backup_fini(struct file *backup);
67 
68 u64 ttm_backup_bytes_avail(void);
69 
70 struct file *ttm_backup_shmem_create(loff_t size);
71 
72 #endif
73