include/linux/page_counter.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_PAGE_COUNTER_H
   3 #define _LINUX_PAGE_COUNTER_H
   4
   5 #include <linux/atomic.h>
   6 #include <linux/kernel.h>
   7 #include <asm/page.h>
   8
   9 struct page_counter {
  10         atomic_long_t count;
  11         unsigned long limit;
  12         struct page_counter *parent;
  13
  14         /* legacy */
  15         unsigned long watermark;
  16         unsigned long failcnt;
  17 };
  18
  19 #if BITS_PER_LONG == 32
  20 #define PAGE_COUNTER_MAX LONG_MAX
  21 #else
  22 #define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
  23 #endif
  24
  25 static inline void page_counter_init(struct page_counter *counter,
  26                                      struct page_counter *parent)
  27 {
  28         atomic_long_set(&counter->count, 0);
  29         counter->limit = PAGE_COUNTER_MAX;
  30         counter->parent = parent;
  31 }
  32
  33 static inline unsigned long page_counter_read(struct page_counter *counter)
  34 {
  35         return atomic_long_read(&counter->count);
  36 }
  37
  38 void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
  39 void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
  40 bool page_counter_try_charge(struct page_counter *counter,
  41                              unsigned long nr_pages,
  42                              struct page_counter **fail);
  43 void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
  44 int page_counter_limit(struct page_counter *counter, unsigned long limit);
  45 int page_counter_memparse(const char *buf, const char *max,
  46                           unsigned long *nr_pages);
  47
  48 static inline void page_counter_reset_watermark(struct page_counter *counter)
  49 {
  50         counter->watermark = page_counter_read(counter);
  51 }
  52
  53 #endif /* _LINUX_PAGE_COUNTER_H */