#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/bootmem.h>
#include <linux/bit_spinlock.h>
#include <linux/page_cgroup.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/memory.h>
#include <linux/vmalloc.h>
#include <linux/cgroup.h>
#include <linux/swapops.h>
#include <linux/kmemleak.h>

static void __meminit init_page_cgroup(struct page_cgroup *pc, unsigned long id)
{
        pc->flags = 0;
        set_page_cgroup_array_id(pc, id);
        pc->mem_cgroup = NULL;
        INIT_LIST_HEAD(&pc->lru);
}
static unsigned long total_usage;

#if !defined(CONFIG_SPARSEMEM)


void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
{
        pgdat->node_page_cgroup = NULL;
}

struct page_cgroup *lookup_page_cgroup(struct page *page)
{
        unsigned long pfn = page_to_pfn(page);
        unsigned long offset;
        struct page_cgroup *base;

        base = NODE_DATA(page_to_nid(page))->node_page_cgroup;
        if (unlikely(!base))
                return NULL;

        offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
        return base + offset;
}

struct page *lookup_cgroup_page(struct page_cgroup *pc)
{
        unsigned long pfn;
        struct page *page;
        pg_data_t *pgdat;

        pgdat = NODE_DATA(page_cgroup_array_id(pc));
        pfn = pc - pgdat->node_page_cgroup + pgdat->node_start_pfn;
        page = pfn_to_page(pfn);
        VM_BUG_ON(pc != lookup_page_cgroup(page));
        return page;
}

static int __init alloc_node_page_cgroup(int nid)
{
        struct page_cgroup *base, *pc;
        unsigned long table_size;
        unsigned long start_pfn, nr_pages, index;

        start_pfn = NODE_DATA(nid)->node_start_pfn;
        nr_pages = NODE_DATA(nid)->node_spanned_pages;

        if (!nr_pages)
                return 0;

        table_size = sizeof(struct page_cgroup) * nr_pages;

        base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
                        table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
        if (!base)
                return -ENOMEM;
        for (index = 0; index < nr_pages; index++) {
                pc = base + index;
                init_page_cgroup(pc, nid);
        }
        NODE_DATA(nid)->node_page_cgroup = base;
        total_usage += table_size;
        return 0;
}

void __init page_cgroup_init_flatmem(void)
{

        int nid, fail;

        if (mem_cgroup_disabled())
                return;

        for_each_online_node(nid)  {
                fail = alloc_node_page_cgroup(nid);
                if (fail)
                        goto fail;
        }
        printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
        printk(KERN_INFO "please try 'cgroup_disable=memory' option if you"
        " don't want memory cgroups\n");
        return;
fail:
        printk(KERN_CRIT "allocation of page_cgroup failed.\n");
        printk(KERN_CRIT "please try 'cgroup_disable=memory' boot option\n");
        panic("Out of memory");
}

#else /* CONFIG_FLAT_NODE_MEM_MAP */

struct page_cgroup *lookup_page_cgroup(struct page *page)
{
        unsigned long pfn = page_to_pfn(page);
        struct mem_section *section = __pfn_to_section(pfn);

        if (!section->page_cgroup)
                return NULL;
        return section->page_cgroup + pfn;
}

struct page *lookup_cgroup_page(struct page_cgroup *pc)
{
        struct mem_section *section;
        struct page *page;
        unsigned long nr;

        nr = page_cgroup_array_id(pc);
        section = __nr_to_section(nr);
        page = pfn_to_page(pc - section->page_cgroup);
        VM_BUG_ON(pc != lookup_page_cgroup(page));
        return page;
}

static void *__init_refok alloc_page_cgroup(size_t size, int nid)
{
        void *addr = NULL;

        addr = alloc_pages_exact_nid(nid, size, GFP_KERNEL | __GFP_NOWARN);
        if (addr)
                return addr;

        if (node_state(nid, N_HIGH_MEMORY))
                addr = vmalloc_node(size, nid);
        else
                addr = vmalloc(size);

        return addr;
}

#ifdef CONFIG_MEMORY_HOTPLUG
static void free_page_cgroup(void *addr)
{
        if (is_vmalloc_addr(addr)) {
                vfree(addr);
        } else {
                struct page *page = virt_to_page(addr);
                size_t table_size =
                        sizeof(struct page_cgroup) * PAGES_PER_SECTION;

                BUG_ON(PageReserved(page));
                free_pages_exact(addr, table_size);
        }
}
#endif

static int __init_refok init_section_page_cgroup(unsigned long pfn)
{
        struct page_cgroup *base, *pc;
        struct mem_section *section;
        unsigned long table_size;
        unsigned long nr;
        int nid, index;

        nr = pfn_to_section_nr(pfn);
        section = __nr_to_section(nr);

        if (section->page_cgroup)
                return 0;

        nid = page_to_nid(pfn_to_page(pfn));
        table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
        base = alloc_page_cgroup(table_size, nid);

        /*
         * The value stored in section->page_cgroup is (base - pfn)
         * and it does not point to the memory block allocated above,
         * causing kmemleak false positives.
         */
        kmemleak_not_leak(base);

        if (!base) {
                printk(KERN_ERR "page cgroup allocation failure\n");
                return -ENOMEM;
        }

        for (index = 0; index < PAGES_PER_SECTION; index++) {
                pc = base + index;
                init_page_cgroup(pc, nr);
        }

        section->page_cgroup = base - pfn;
        total_usage += table_size;
        return 0;
}
#ifdef CONFIG_MEMORY_HOTPLUG
void __free_page_cgroup(unsigned long pfn)
{
        struct mem_section *ms;
        struct page_cgroup *base;

        ms = __pfn_to_section(pfn);
        if (!ms || !ms->page_cgroup)
                return;
        base = ms->page_cgroup + pfn;
        free_page_cgroup(base);
        ms->page_cgroup = NULL;
}

int __meminit online_page_cgroup(unsigned long start_pfn,
                        unsigned long nr_pages,
                        int nid)
{
        unsigned long start, end, pfn;
        int fail = 0;

        start = start_pfn & ~(PAGES_PER_SECTION - 1);
        end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);

        for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
                if (!pfn_present(pfn))
                        continue;
                fail = init_section_page_cgroup(pfn);
        }
        if (!fail)
                return 0;

        /* rollback */
        for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
                __free_page_cgroup(pfn);

        return -ENOMEM;
}

int __meminit offline_page_cgroup(unsigned long start_pfn,
                unsigned long nr_pages, int nid)
{
        unsigned long start, end, pfn;

        start = start_pfn & ~(PAGES_PER_SECTION - 1);
        end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);

        for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
                __free_page_cgroup(pfn);
        return 0;

}

static int __meminit page_cgroup_callback(struct notifier_block *self,
                               unsigned long action, void *arg)
{
        struct memory_notify *mn = arg;
        int ret = 0;
        switch (action) {
        case MEM_GOING_ONLINE:
                ret = online_page_cgroup(mn->start_pfn,
                                   mn->nr_pages, mn->status_change_nid);
                break;
        case MEM_OFFLINE:
                offline_page_cgroup(mn->start_pfn,
                                mn->nr_pages, mn->status_change_nid);
                break;
        case MEM_CANCEL_ONLINE:
        case MEM_GOING_OFFLINE:
                break;
        case MEM_ONLINE:
        case MEM_CANCEL_OFFLINE:
                break;
        }

        return notifier_from_errno(ret);
}

#endif

void __init page_cgroup_init(void)
{
        unsigned long pfn;
        int fail = 0;

        if (mem_cgroup_disabled())
                return;

        for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
                if (!pfn_present(pfn))
                        continue;
                fail = init_section_page_cgroup(pfn);
        }
        if (fail) {
                printk(KERN_CRIT "try 'cgroup_disable=memory' boot option\n");
                panic("Out of memory");
        } else {
                hotplug_memory_notifier(page_cgroup_callback, 0);
        }
        printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
        printk(KERN_INFO "please try 'cgroup_disable=memory' option if you don't"
        " want memory cgroups\n");
}

void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
{
        return;
}

#endif


#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP

static DEFINE_MUTEX(swap_cgroup_mutex);
struct swap_cgroup_ctrl {
        struct page **map;
        unsigned long length;
        spinlock_t      lock;
};

struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];

struct swap_cgroup {
        unsigned short          id;
};
#define SC_PER_PAGE     (PAGE_SIZE/sizeof(struct swap_cgroup))
#define SC_POS_MASK     (SC_PER_PAGE - 1)

/*
 * SwapCgroup implements "lookup" and "exchange" operations.
 * In typical usage, this swap_cgroup is accessed via memcg's charge/uncharge
 * against SwapCache. At swap_free(), this is accessed directly from swap.
 *
 * This means,
 *  - we have no race in "exchange" when we're accessed via SwapCache because
 *    SwapCache(and its swp_entry) is under lock.
 *  - When called via swap_free(), there is no user of this entry and no race.
 * Then, we don't need lock around "exchange".
 *
 * TODO: we can push these buffers out to HIGHMEM.
 */

/*
 * allocate buffer for swap_cgroup.
 */
static int swap_cgroup_prepare(int type)
{
        struct page *page;
        struct swap_cgroup_ctrl *ctrl;
        unsigned long idx, max;

        ctrl = &swap_cgroup_ctrl[type];

        for (idx = 0; idx < ctrl->length; idx++) {
                page = alloc_page(GFP_KERNEL | __GFP_ZERO);
                if (!page)
                        goto not_enough_page;
                ctrl->map[idx] = page;
        }
        return 0;
not_enough_page:
        max = idx;
        for (idx = 0; idx < max; idx++)
                __free_page(ctrl->map[idx]);

        return -ENOMEM;
}

/**
 * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry.
 * @end: swap entry to be cmpxchged
 * @old: old id
 * @new: new id
 *
 * Returns old id at success, 0 at failure.
 * (There is no mem_cgroup using 0 as its id)
 */
unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
                                        unsigned short old, unsigned short new)
{
        int type = swp_type(ent);
        unsigned long offset = swp_offset(ent);
        unsigned long idx = offset / SC_PER_PAGE;
        unsigned long pos = offset & SC_POS_MASK;
        struct swap_cgroup_ctrl *ctrl;
        struct page *mappage;
        struct swap_cgroup *sc;
        unsigned long flags;
        unsigned short retval;

        ctrl = &swap_cgroup_ctrl[type];

        mappage = ctrl->map[idx];
        sc = page_address(mappage);
        sc += pos;
        spin_lock_irqsave(&ctrl->lock, flags);
        retval = sc->id;
        if (retval == old)
                sc->id = new;
        else
                retval = 0;
        spin_unlock_irqrestore(&ctrl->lock, flags);
        return retval;
}

/**
 * swap_cgroup_record - record mem_cgroup for this swp_entry.
 * @ent: swap entry to be recorded into
 * @mem: mem_cgroup to be recorded
 *
 * Returns old value at success, 0 at failure.
 * (Of course, old value can be 0.)
 */
unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
{
        int type = swp_type(ent);
        unsigned long offset = swp_offset(ent);
        unsigned long idx = offset / SC_PER_PAGE;
        unsigned long pos = offset & SC_POS_MASK;
        struct swap_cgroup_ctrl *ctrl;
        struct page *mappage;
        struct swap_cgroup *sc;
        unsigned short old;
        unsigned long flags;

        ctrl = &swap_cgroup_ctrl[type];

        mappage = ctrl->map[idx];
        sc = page_address(mappage);
        sc += pos;
        spin_lock_irqsave(&ctrl->lock, flags);
        old = sc->id;
        sc->id = id;
        spin_unlock_irqrestore(&ctrl->lock, flags);

        return old;
}

/**
 * lookup_swap_cgroup - lookup mem_cgroup tied to swap entry
 * @ent: swap entry to be looked up.
 *
 * Returns CSS ID of mem_cgroup at success. 0 at failure. (0 is invalid ID)
 */
unsigned short lookup_swap_cgroup(swp_entry_t ent)
{
        int type = swp_type(ent);
        unsigned long offset = swp_offset(ent);
        unsigned long idx = offset / SC_PER_PAGE;
        unsigned long pos = offset & SC_POS_MASK;
        struct swap_cgroup_ctrl *ctrl;
        struct page *mappage;
        struct swap_cgroup *sc;
        unsigned short ret;

        ctrl = &swap_cgroup_ctrl[type];
        mappage = ctrl->map[idx];
        sc = page_address(mappage);
        sc += pos;
        ret = sc->id;
        return ret;
}

int swap_cgroup_swapon(int type, unsigned long max_pages)
{
        void *array;
        unsigned long array_size;
        unsigned long length;
        struct swap_cgroup_ctrl *ctrl;

        if (!do_swap_account)
                return 0;

        length = ((max_pages/SC_PER_PAGE) + 1);
        array_size = length * sizeof(void *);

        array = vmalloc(array_size);
        if (!array)
                goto nomem;

        memset(array, 0, array_size);
        ctrl = &swap_cgroup_ctrl[type];
        mutex_lock(&swap_cgroup_mutex);
        ctrl->length = length;
        ctrl->map = array;
        spin_lock_init(&ctrl->lock);
        if (swap_cgroup_prepare(type)) {
                /* memory shortage */
                ctrl->map = NULL;
                ctrl->length = 0;
                vfree(array);
                mutex_unlock(&swap_cgroup_mutex);
                goto nomem;
        }
        mutex_unlock(&swap_cgroup_mutex);

        return 0;
nomem:
        printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.\n");
        printk(KERN_INFO
                "swap_cgroup can be disabled by noswapaccount boot option\n");
        return -ENOMEM;
}

void swap_cgroup_swapoff(int type)
{
        int i;
        struct swap_cgroup_ctrl *ctrl;

        if (!do_swap_account)
                return;

        mutex_lock(&swap_cgroup_mutex);
        ctrl = &swap_cgroup_ctrl[type];
        if (ctrl->map) {
                for (i = 0; i < ctrl->length; i++) {
                        struct page *page = ctrl->map[i];
                        if (page)
                                __free_page(page);
                }
                vfree(ctrl->map);
                ctrl->map = NULL;
                ctrl->length = 0;
        }
        mutex_unlock(&swap_cgroup_mutex);
}

#endif