1 /* SPDX-License-Identifier: GPL-2.0 */
2 
3 #ifndef _LINUX_PAGE_FRAG_CACHE_H
4 #define _LINUX_PAGE_FRAG_CACHE_H
5 
6 #include <linux/bits.h>
7 #include <linux/log2.h>
8 #include <linux/mm_types_task.h>
9 #include <linux/types.h>
10 
11 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
12 /* Use a full byte here to enable assembler optimization as the shift
13  * operation is usually expecting a byte.
14  */
15 #define PAGE_FRAG_CACHE_ORDER_MASK		GENMASK(7, 0)
16 #else
17 /* Compiler should be able to figure out we don't read things as any value
18  * ANDed with 0 is 0.
19  */
20 #define PAGE_FRAG_CACHE_ORDER_MASK		0
21 #endif
22 
23 #define PAGE_FRAG_CACHE_PFMEMALLOC_BIT		(PAGE_FRAG_CACHE_ORDER_MASK + 1)
24 
25 static inline bool encoded_page_decode_pfmemalloc(unsigned long encoded_page)
26 {
27 	return !!(encoded_page & PAGE_FRAG_CACHE_PFMEMALLOC_BIT);
28 }
29 
30 static inline void page_frag_cache_init(struct page_frag_cache *nc)
31 {
32 	nc->encoded_page = 0;
33 }
34 
35 static inline bool page_frag_cache_is_pfmemalloc(struct page_frag_cache *nc)
36 {
37 	return encoded_page_decode_pfmemalloc(nc->encoded_page);
38 }
39 
40 void page_frag_cache_drain(struct page_frag_cache *nc);
41 void __page_frag_cache_drain(struct page *page, unsigned int count);
42 void *__page_frag_alloc_align(struct page_frag_cache *nc, unsigned int fragsz,
43 			      gfp_t gfp_mask, unsigned int align_mask);
44 
45 static inline void *page_frag_alloc_align(struct page_frag_cache *nc,
46 					  unsigned int fragsz, gfp_t gfp_mask,
47 					  unsigned int align)
48 {
49 	WARN_ON_ONCE(!is_power_of_2(align));
50 	return __page_frag_alloc_align(nc, fragsz, gfp_mask, -align);
51 }
52 
53 static inline void *page_frag_alloc(struct page_frag_cache *nc,
54 				    unsigned int fragsz, gfp_t gfp_mask)
55 {
56 	return __page_frag_alloc_align(nc, fragsz, gfp_mask, ~0u);
57 }
58 
59 void page_frag_free(void *addr);
60 
61 #endif
62