/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PAGE_COUNTER_H
#define _LINUX_PAGE_COUNTER_H

#include <linux/atomic.h>
#include <linux/cache.h>
#include <linux/limits.h>
#include <asm/page.h>

struct page_counter {
        /*
         * Make sure 'usage' does not share cacheline with any other field in
         * v2. The memcg->memory.usage is a hot member of struct mem_cgroup.
         */
        atomic_long_t usage;
        unsigned long failcnt; /* v1-only field */

        CACHELINE_PADDING(_pad1_);

        /* effective memory.min and memory.min usage tracking */
        unsigned long emin;
        atomic_long_t min_usage;
        atomic_long_t children_min_usage;

        /* effective memory.low and memory.low usage tracking */
        unsigned long elow;
        atomic_long_t low_usage;
        atomic_long_t children_low_usage;

        unsigned long watermark;
        /* Latest cg2 reset watermark */
        unsigned long local_watermark;

        /* Keep all the read most fields in a separete cacheline. */
        CACHELINE_PADDING(_pad2_);

        bool protection_support;
        bool track_failcnt;
        unsigned long min;
        unsigned long low;
        unsigned long high;
        unsigned long max;
        struct page_counter *parent;
} ____cacheline_internodealigned_in_smp;

#if BITS_PER_LONG == 32
#define PAGE_COUNTER_MAX LONG_MAX
#else
#define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
#endif

/*
 * Protection is supported only for the first counter (with id 0).
 */
static inline void page_counter_init(struct page_counter *counter,
                                     struct page_counter *parent,
                                     bool protection_support)
{
        counter->usage = (atomic_long_t)ATOMIC_LONG_INIT(0);
        counter->max = PAGE_COUNTER_MAX;
        counter->parent = parent;
        counter->protection_support = protection_support;
        counter->track_failcnt = false;
}

static inline unsigned long page_counter_read(struct page_counter *counter)
{
        return atomic_long_read(&counter->usage);
}

void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
bool page_counter_try_charge(struct page_counter *counter,
                             unsigned long nr_pages,
                             struct page_counter **fail);
void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);

static inline void page_counter_set_high(struct page_counter *counter,
                                         unsigned long nr_pages)
{
        WRITE_ONCE(counter->high, nr_pages);
}

int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
int page_counter_memparse(const char *buf, const char *max,
                          unsigned long *nr_pages);

static inline void page_counter_reset_watermark(struct page_counter *counter)
{
        unsigned long usage = page_counter_read(counter);

        /*
         * Update local_watermark first, so it's always <= watermark
         * (modulo CPU/compiler re-ordering)
         */
        counter->local_watermark = usage;
        counter->watermark = usage;
}

#if IS_ENABLED(CONFIG_MEMCG) || IS_ENABLED(CONFIG_CGROUP_DMEM)
void page_counter_calculate_protection(struct page_counter *root,
                                       struct page_counter *counter,
                                       bool recursive_protection);
#else
static inline void page_counter_calculate_protection(struct page_counter *root,
                                                     struct page_counter *counter,
                                                     bool recursive_protection) {}
#endif

#endif /* _LINUX_PAGE_COUNTER_H */