/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 */

#define DEBUG_SUBSYSTEM S_LNET

#include <libcfs/libcfs.h>


struct kmem_cache *cfs_page_t_slab;
struct kmem_cache *cfs_page_p_slab;

struct page *virt_to_page(void *addr)
{
	struct page *pg;
	pg = kmem_cache_alloc(cfs_page_t_slab, 0);

	if (NULL == pg) {
		cfs_enter_debugger();
		return NULL;
	}

	memset(pg, 0, sizeof(struct page));
	pg->addr = (void *)((__u64)addr & (~((__u64)PAGE_SIZE-1)));
	pg->mapping = addr;
	atomic_set(&pg->count, 1);
	set_bit(PG_virt, &(pg->flags));
	cfs_enter_debugger();
	return pg;
}

/*
 * alloc_page
 *   To allocate the struct page and also 1 page of memory
 *
 * Arguments:
 *   flags:  the allocation options
 *
 * Return Value:
 *   pointer to the struct page strcture in success or
 *   NULL in failure case
 *
 * Notes: 
 *   N/A
 */

atomic_t libcfs_total_pages;

struct page *alloc_page(int flags)
{
	struct page *pg;
	pg = kmem_cache_alloc(cfs_page_t_slab, 0);

	if (NULL == pg) {
	cfs_enter_debugger();
	return NULL;
	}

	memset(pg, 0, sizeof(struct page));
	pg->addr = kmem_cache_alloc(cfs_page_p_slab, 0);
	atomic_set(&pg->count, 1);

	if (pg->addr) {
		if (cfs_is_flag_set(flags, __GFP_ZERO))
			memset(pg->addr, 0, PAGE_CACHE_SIZE);
		atomic_inc(&libcfs_total_pages);
	} else {
		cfs_enter_debugger();
		kmem_cache_free(cfs_page_t_slab, pg);
		pg = NULL;
	}

	return pg;
}

/*
 * __free_page
 *   To free the struct page including the page
 *
 * Arguments:
 *   pg:  pointer to the struct page strcture
 *
 * Return Value:
 *   N/A
 *
 * Notes: 
 *   N/A
 */
void __free_page(struct page *pg)
{
	ASSERT(pg != NULL);
	ASSERT(pg->addr  != NULL);
	ASSERT(atomic_read(&pg->count) <= 1);

	if (!test_bit(PG_virt, &pg->flags)) {
		kmem_cache_free(cfs_page_p_slab, pg->addr);
		atomic_dec(&libcfs_total_pages);
	} else {
		cfs_enter_debugger();
	}
	kmem_cache_free(cfs_page_t_slab, pg);
}

int kmem_is_in_cache(const void *addr, const struct kmem_cache *kmem)
{
	KdPrint(("kmem_is_in_cache: not implemented. (should maintain a"
		 "chain to keep all allocations traced.)\n"));
	return 1;
}

/*
 * kmalloc
 *   To allocate memory from system pool
 *
 * Arguments:
 *   nr_bytes:  length in bytes of the requested buffer
 *   flags:     flags indiction
 *
 * Return Value:
 *   NULL: if there's no enough memory space in system
 *   the address of the allocated memory in success.
 *
 * Notes: 
 *   This operation can be treated as atomic.
 */

void *
kmalloc(size_t nr_bytes, u_int32_t flags)
{
	void *ptr;

	/* Ignore the flags: always allcoate from NonPagedPool */
	ptr = ExAllocatePoolWithTag(NonPagedPool, nr_bytes, 'Lufs');
	if (ptr != NULL && (flags & __GFP_ZERO))
		memset(ptr, 0, nr_bytes);

	if (!ptr)
		cfs_enter_debugger();

	return ptr;
}

/*
 * kfree
 *   To free the sepcified memory to system pool
 *
 * Arguments:
 *   addr:   pointer to the buffer to be freed
 *
 * Return Value:
 *   N/A
 *
 * Notes: 
 *    This operation can be treated as atomic.
 */

void
kfree(void *addr)
{
	ExFreePool(addr);
}

/*
 * vmalloc
 *   To allocate large block of memory from system pool
 *
 * Arguments:
 *   nr_bytes:  length in bytes of the requested buffer
 *
 * Return Value:
 *   NULL: if there's no enough memory space in system
 *   the address of the allocated memory in success.
 *
 * Notes: 
 *   N/A
 */

void *
vmalloc(size_t nr_bytes)
{
	return kmalloc(nr_bytes, 0);
}

/*
 * vfree
 *   To free the sepcified memory to system pool
 *
 * Arguments:
 *   addr:   pointer to the buffer to be freed
 *
 * Return Value:
 *   N/A
 *
 * Notes: 
 *   N/A
 */

void vfree(void *addr)
{
	kfree(addr);
}


/*
 * kmem_cache_create
 *   To create a SLAB cache
 *
 * Arguments:
 *   name:   name string of the SLAB cache to be created
 *   size:   size in bytes of SLAB entry buffer
 *   offset: offset in the page
 *   flags:  SLAB creation flags
*
 * Return Value:
 *   The poitner of cfs_memory_cache structure in success.
 *   NULL pointer in failure case.
 *
 * Notes: 
 *   1, offset won't be used here.
 *   2, it could be better to induce a lock to protect the access of the
 *       SLAB structure on SMP if there's not outside lock protection.
 *   3, parameters C/D are removed.
 */

struct kmem_cache *kmem_cache_create(const char *name, size_t size,
				     size_t offset, unsigned long flags,
				     void *ctor)
{
	struct kmem_cache *kmc = NULL;

	/*  The name of the SLAB could not exceed 20 chars */

	if (name && strlen(name) >= 20)
		goto errorout;

	/* Allocate and initialize the SLAB strcture */

	kmc = kmalloc(sizeof(struct kmem_cache), 0);

	if (NULL == kmc)
		goto errorout;

	memset(kmc, 0, sizeof(struct kmem_cache));
	kmc->flags = flags;

    if (name) {
        strcpy(&kmc->name[0], name);
    }

    /* Initialize the corresponding LookAside list */

    ExInitializeNPagedLookasideList(
            &(kmc->npll),
            NULL,
            NULL,
            0,
            size,
            'pnmk',
            0);
 
errorout:

    return kmc;
}

/*
 *kmem_cache_destroy
 *   To destroy the unused SLAB cache
 *
 * Arguments:
 *   kmc: the SLAB cache to be destroied.
 *
 * Return Value:
 *   0: in success case.
 *   1: in failure case.
 *
 * Notes: 
 *   N/A
 */

kmem_cache_destroy(struct kmem_cache *kmc)
{
	ASSERT(kmc != NULL);

	ExDeleteNPagedLookasideList(&(kmc->npll));

	kfree(kmc);

	return 0;
}

/*
 * kmem_cache_alloc
 *   To allocate an object (LookAside entry) from the SLAB
 *
 * Arguments:
 *   kmc:   the SLAB cache to be allocated from.
 *   flags: flags for allocation options
 *
 * Return Value:
 *   object buffer address: in success case.
 *   NULL: in failure case.
 *
 * Notes: 
 *   N/A
 */

void *kmem_cache_alloc(struct kmem_cache *kmc, int flags)
{
	void *buf = NULL;

	buf = ExAllocateFromNPagedLookasideList(&(kmc->npll));

	return buf;
}

/*
 * kmem_cache_free
 *   To free an object (LookAside entry) to the SLAB cache
 *
 * Arguments:
 *   kmc: the SLAB cache to be freed to.
 *   buf: the pointer to the object to be freed.
 *
 * Return Value:
 *   N/A
 *
 * Notes: 
 *   N/A
 */

void kmem_cache_free(struct kmem_cache *kmc, void *buf)
{
    ExFreeToNPagedLookasideList(&(kmc->npll), buf);
}

spinlock_t  shrinker_guard = {0};
struct list_head shrinker_hdr = LIST_HEAD_INIT(shrinker_hdr);
struct timer_list shrinker_timer = {0};

struct shrinker *set_shrinker(int seeks, shrink_callback cb)
{
	struct shrinker *s = (struct shrinker *)
	kmalloc(sizeof(struct shrinker), __GFP_ZERO);
	if (s) {
		s->cb = cb;
		s->seeks = seeks;
		s->nr = 2;
		spin_lock(&shrinker_guard);
		list_add(&s->list, &shrinker_hdr);
		spin_unlock(&shrinker_guard);
	}

	return s;
}

void remove_shrinker(struct shrinker *s)
{
	struct shrinker *tmp;
	spin_lock(&shrinker_guard);
#if TRUE
	list_for_each_entry(tmp, &shrinker_hdr, list) {
		if (tmp == s) {
			list_del(&tmp->list);
			break;
		}
	}
#else
	list_del(&s->list);
#endif
	spin_unlock(&shrinker_guard);
	kfree(s);
}

/* time ut test proc */
void shrinker_timer_proc(ulong_ptr_t arg)
{
	struct shrinker *s;
	spin_lock(&shrinker_guard);

	list_for_each_entry(s, &shrinker_hdr, list) {
		s->cb(s->nr, __GFP_FS);
	}
	spin_unlock(&shrinker_guard);
	cfs_timer_arm(&shrinker_timer, 300);
}

int start_shrinker_timer()
{
    /* initialize shriner timer */
    cfs_timer_init(&shrinker_timer, shrinker_timer_proc, NULL);

    /* start the timer to trigger in 5 minutes */
    cfs_timer_arm(&shrinker_timer, 300);

    return 0;
}

void stop_shrinker_timer()
{
    /* cancel the timer */
    cfs_timer_disarm(&shrinker_timer);
    cfs_timer_done(&shrinker_timer);
}