include/linux/page_frag_cache.h

   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