include/linux/page_counter.h

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