/*
 * f2fs extent cache support
 *
 * Copyright (c) 2015 Motorola Mobility
 * Copyright (c) 2015 Samsung Electronics
 * Authors: Jaegeuk Kim <jaegeuk@kernel.org>
 *          Chao Yu <chao2.yu@samsung.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/fs.h>
#include <linux/f2fs_fs.h>

#include "f2fs.h"
#include "node.h"
#include <trace/events/f2fs.h>

static struct kmem_cache *extent_tree_slab;
static struct kmem_cache *extent_node_slab;

static struct extent_node *__attach_extent_node(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_info *ei,
                                struct rb_node *parent, struct rb_node **p)
{
        struct extent_node *en;

        en = kmem_cache_alloc(extent_node_slab, GFP_ATOMIC);
        if (!en)
                return NULL;

        en->ei = *ei;
        INIT_LIST_HEAD(&en->list);

        rb_link_node(&en->rb_node, parent, p);
        rb_insert_color(&en->rb_node, &et->root);
        et->count++;
        atomic_inc(&sbi->total_ext_node);
        return en;
}

static void __detach_extent_node(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_node *en)
{
        rb_erase(&en->rb_node, &et->root);
        et->count--;
        atomic_dec(&sbi->total_ext_node);

        if (et->cached_en == en)
                et->cached_en = NULL;
}

static struct extent_tree *__grab_extent_tree(struct inode *inode)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et;
        nid_t ino = inode->i_ino;

        down_write(&sbi->extent_tree_lock);
        et = radix_tree_lookup(&sbi->extent_tree_root, ino);
        if (!et) {
                et = f2fs_kmem_cache_alloc(extent_tree_slab, GFP_NOFS);
                f2fs_radix_tree_insert(&sbi->extent_tree_root, ino, et);
                memset(et, 0, sizeof(struct extent_tree));
                et->ino = ino;
                et->root = RB_ROOT;
                et->cached_en = NULL;
                rwlock_init(&et->lock);
                atomic_set(&et->refcount, 0);
                et->count = 0;
                sbi->total_ext_tree++;
        }
        atomic_inc(&et->refcount);
        up_write(&sbi->extent_tree_lock);

        /* never died until evict_inode */
        F2FS_I(inode)->extent_tree = et;

        return et;
}

static struct extent_node *__lookup_extent_tree(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, unsigned int fofs)
{
        struct rb_node *node = et->root.rb_node;
        struct extent_node *en = et->cached_en;

        if (en) {
                struct extent_info *cei = &en->ei;

                if (cei->fofs <= fofs && cei->fofs + cei->len > fofs) {
                        stat_inc_cached_node_hit(sbi);
                        return en;
                }
        }

        while (node) {
                en = rb_entry(node, struct extent_node, rb_node);

                if (fofs < en->ei.fofs) {
                        node = node->rb_left;
                } else if (fofs >= en->ei.fofs + en->ei.len) {
                        node = node->rb_right;
                } else {
                        stat_inc_rbtree_node_hit(sbi);
                        return en;
                }
        }
        return NULL;
}

static struct extent_node *__init_extent_tree(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_info *ei)
{
        struct rb_node **p = &et->root.rb_node;
        struct extent_node *en;

        en = __attach_extent_node(sbi, et, ei, NULL, p);
        if (!en)
                return NULL;

        et->largest = en->ei;
        et->cached_en = en;
        return en;
}

static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
                                        struct extent_tree *et, bool free_all)
{
        struct rb_node *node, *next;
        struct extent_node *en;
        unsigned int count = et->count;

        node = rb_first(&et->root);
        while (node) {
                next = rb_next(node);
                en = rb_entry(node, struct extent_node, rb_node);

                if (free_all) {
                        spin_lock(&sbi->extent_lock);
                        if (!list_empty(&en->list))
                                list_del_init(&en->list);
                        spin_unlock(&sbi->extent_lock);
                }

                if (free_all || list_empty(&en->list)) {
                        __detach_extent_node(sbi, et, en);
                        kmem_cache_free(extent_node_slab, en);
                }
                node = next;
        }

        return count - et->count;
}

static void __drop_largest_extent(struct inode *inode,
                                        pgoff_t fofs, unsigned int len)
{
        struct extent_info *largest = &F2FS_I(inode)->extent_tree->largest;

        if (fofs < largest->fofs + largest->len && fofs + len > largest->fofs)
                largest->len = 0;
}

void f2fs_drop_largest_extent(struct inode *inode, pgoff_t fofs)
{
        if (!f2fs_may_extent_tree(inode))
                return;

        __drop_largest_extent(inode, fofs, 1);
}

void f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et;
        struct extent_node *en;
        struct extent_info ei;

        if (!f2fs_may_extent_tree(inode))
                return;

        et = __grab_extent_tree(inode);

        if (!i_ext || le32_to_cpu(i_ext->len) < F2FS_MIN_EXTENT_LEN)
                return;

        set_extent_info(&ei, le32_to_cpu(i_ext->fofs),
                le32_to_cpu(i_ext->blk), le32_to_cpu(i_ext->len));

        write_lock(&et->lock);
        if (et->count)
                goto out;

        en = __init_extent_tree(sbi, et, &ei);
        if (en) {
                spin_lock(&sbi->extent_lock);
                list_add_tail(&en->list, &sbi->extent_list);
                spin_unlock(&sbi->extent_lock);
        }
out:
        write_unlock(&et->lock);
}

static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
                                                        struct extent_info *ei)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et = F2FS_I(inode)->extent_tree;
        struct extent_node *en;
        bool ret = false;

        f2fs_bug_on(sbi, !et);

        trace_f2fs_lookup_extent_tree_start(inode, pgofs);

        read_lock(&et->lock);

        if (et->largest.fofs <= pgofs &&
                        et->largest.fofs + et->largest.len > pgofs) {
                *ei = et->largest;
                ret = true;
                stat_inc_largest_node_hit(sbi);
                goto out;
        }

        en = __lookup_extent_tree(sbi, et, pgofs);
        if (en) {
                *ei = en->ei;
                spin_lock(&sbi->extent_lock);
                if (!list_empty(&en->list))
                        list_move_tail(&en->list, &sbi->extent_list);
                et->cached_en = en;
                spin_unlock(&sbi->extent_lock);
                ret = true;
        }
out:
        stat_inc_total_hit(sbi);
        read_unlock(&et->lock);

        trace_f2fs_lookup_extent_tree_end(inode, pgofs, ei);
        return ret;
}


/*
 * lookup extent at @fofs, if hit, return the extent
 * if not, return NULL and
 * @prev_ex: extent before fofs
 * @next_ex: extent after fofs
 * @insert_p: insert point for new extent at fofs
 * in order to simpfy the insertion after.
 * tree must stay unchanged between lookup and insertion.
 */
static struct extent_node *__lookup_extent_tree_ret(struct extent_tree *et,
                                unsigned int fofs,
                                struct extent_node **prev_ex,
                                struct extent_node **next_ex,
                                struct rb_node ***insert_p,
                                struct rb_node **insert_parent)
{
        struct rb_node **pnode = &et->root.rb_node;
        struct rb_node *parent = NULL, *tmp_node;
        struct extent_node *en = et->cached_en;

        *insert_p = NULL;
        *insert_parent = NULL;
        *prev_ex = NULL;
        *next_ex = NULL;

        if (RB_EMPTY_ROOT(&et->root))
                return NULL;

        if (en) {
                struct extent_info *cei = &en->ei;

                if (cei->fofs <= fofs && cei->fofs + cei->len > fofs)
                        goto lookup_neighbors;
        }

        while (*pnode) {
                parent = *pnode;
                en = rb_entry(*pnode, struct extent_node, rb_node);

                if (fofs < en->ei.fofs)
                        pnode = &(*pnode)->rb_left;
                else if (fofs >= en->ei.fofs + en->ei.len)
                        pnode = &(*pnode)->rb_right;
                else
                        goto lookup_neighbors;
        }

        *insert_p = pnode;
        *insert_parent = parent;

        en = rb_entry(parent, struct extent_node, rb_node);
        tmp_node = parent;
        if (parent && fofs > en->ei.fofs)
                tmp_node = rb_next(parent);
        *next_ex = tmp_node ?
                rb_entry(tmp_node, struct extent_node, rb_node) : NULL;

        tmp_node = parent;
        if (parent && fofs < en->ei.fofs)
                tmp_node = rb_prev(parent);
        *prev_ex = tmp_node ?
                rb_entry(tmp_node, struct extent_node, rb_node) : NULL;
        return NULL;

lookup_neighbors:
        if (fofs == en->ei.fofs) {
                /* lookup prev node for merging backward later */
                tmp_node = rb_prev(&en->rb_node);
                *prev_ex = tmp_node ?
                        rb_entry(tmp_node, struct extent_node, rb_node) : NULL;
        }
        if (fofs == en->ei.fofs + en->ei.len - 1) {
                /* lookup next node for merging frontward later */
                tmp_node = rb_next(&en->rb_node);
                *next_ex = tmp_node ?
                        rb_entry(tmp_node, struct extent_node, rb_node) : NULL;
        }
        return en;
}

static struct extent_node *__try_merge_extent_node(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_info *ei,
                                struct extent_node **den,
                                struct extent_node *prev_ex,
                                struct extent_node *next_ex)
{
        struct extent_node *en = NULL;

        if (prev_ex && __is_back_mergeable(ei, &prev_ex->ei)) {
                prev_ex->ei.len += ei->len;
                ei = &prev_ex->ei;
                en = prev_ex;
        }

        if (next_ex && __is_front_mergeable(ei, &next_ex->ei)) {
                if (en) {
                        __detach_extent_node(sbi, et, prev_ex);
                        *den = prev_ex;
                }
                next_ex->ei.fofs = ei->fofs;
                next_ex->ei.blk = ei->blk;
                next_ex->ei.len += ei->len;
                en = next_ex;
        }

        if (en) {
                __try_update_largest_extent(et, en);
                et->cached_en = en;
        }
        return en;
}

static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_info *ei,
                                struct rb_node **insert_p,
                                struct rb_node *insert_parent)
{
        struct rb_node **p = &et->root.rb_node;
        struct rb_node *parent = NULL;
        struct extent_node *en = NULL;

        if (insert_p && insert_parent) {
                parent = insert_parent;
                p = insert_p;
                goto do_insert;
        }

        while (*p) {
                parent = *p;
                en = rb_entry(parent, struct extent_node, rb_node);

                if (ei->fofs < en->ei.fofs)
                        p = &(*p)->rb_left;
                else if (ei->fofs >= en->ei.fofs + en->ei.len)
                        p = &(*p)->rb_right;
                else
                        f2fs_bug_on(sbi, 1);
        }
do_insert:
        en = __attach_extent_node(sbi, et, ei, parent, p);
        if (!en)
                return NULL;

        __try_update_largest_extent(et, en);
        et->cached_en = en;
        return en;
}

static unsigned int f2fs_update_extent_tree_range(struct inode *inode,
                                pgoff_t fofs, block_t blkaddr, unsigned int len)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et = F2FS_I(inode)->extent_tree;
        struct extent_node *en = NULL, *en1 = NULL;
        struct extent_node *prev_en = NULL, *next_en = NULL;
        struct extent_info ei, dei, prev;
        struct rb_node **insert_p = NULL, *insert_parent = NULL;
        unsigned int end = fofs + len;
        unsigned int pos = (unsigned int)fofs;

        if (!et)
                return false;

        trace_f2fs_update_extent_tree_range(inode, fofs, blkaddr, len);

        write_lock(&et->lock);

        if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT)) {
                write_unlock(&et->lock);
                return false;
        }

        prev = et->largest;
        dei.len = 0;

        /*
         * drop largest extent before lookup, in case it's already
         * been shrunk from extent tree
         */
        __drop_largest_extent(inode, fofs, len);

        /* 1. lookup first extent node in range [fofs, fofs + len - 1] */
        en = __lookup_extent_tree_ret(et, fofs, &prev_en, &next_en,
                                        &insert_p, &insert_parent);
        if (!en)
                en = next_en;

        /* 2. invlidate all extent nodes in range [fofs, fofs + len - 1] */
        while (en && en->ei.fofs < end) {
                unsigned int org_end;
                int parts = 0;  /* # of parts current extent split into */

                next_en = en1 = NULL;

                dei = en->ei;
                org_end = dei.fofs + dei.len;
                f2fs_bug_on(sbi, pos >= org_end);

                if (pos > dei.fofs &&   pos - dei.fofs >= F2FS_MIN_EXTENT_LEN) {
                        en->ei.len = pos - en->ei.fofs;
                        prev_en = en;
                        parts = 1;
                }

                if (end < org_end && org_end - end >= F2FS_MIN_EXTENT_LEN) {
                        if (parts) {
                                set_extent_info(&ei, end,
                                                end - dei.fofs + dei.blk,
                                                org_end - end);
                                en1 = __insert_extent_tree(sbi, et, &ei,
                                                        NULL, NULL);
                                next_en = en1;
                        } else {
                                en->ei.fofs = end;
                                en->ei.blk += end - dei.fofs;
                                en->ei.len -= end - dei.fofs;
                                next_en = en;
                        }
                        parts++;
                }

                if (!next_en) {
                        struct rb_node *node = rb_next(&en->rb_node);

                        next_en = node ?
                                rb_entry(node, struct extent_node, rb_node)
                                : NULL;
                }

                if (parts)
                        __try_update_largest_extent(et, en);
                else
                        __detach_extent_node(sbi, et, en);

                /*
                 * if original extent is split into zero or two parts, extent
                 * tree has been altered by deletion or insertion, therefore
                 * invalidate pointers regard to tree.
                 */
                if (parts != 1) {
                        insert_p = NULL;
                        insert_parent = NULL;
                }

                /* update in global extent list */
                spin_lock(&sbi->extent_lock);
                if (!parts && !list_empty(&en->list))
                        list_del(&en->list);
                if (en1)
                        list_add_tail(&en1->list, &sbi->extent_list);
                spin_unlock(&sbi->extent_lock);

                /* release extent node */
                if (!parts)
                        kmem_cache_free(extent_node_slab, en);

                en = next_en;
        }

        /* 3. update extent in extent cache */
        if (blkaddr) {
                struct extent_node *den = NULL;

                set_extent_info(&ei, fofs, blkaddr, len);
                en1 = __try_merge_extent_node(sbi, et, &ei, &den,
                                                        prev_en, next_en);
                if (!en1)
                        en1 = __insert_extent_tree(sbi, et, &ei,
                                                insert_p, insert_parent);

                /* give up extent_cache, if split and small updates happen */
                if (dei.len >= 1 &&
                                prev.len < F2FS_MIN_EXTENT_LEN &&
                                et->largest.len < F2FS_MIN_EXTENT_LEN) {
                        et->largest.len = 0;
                        set_inode_flag(F2FS_I(inode), FI_NO_EXTENT);
                }

                spin_lock(&sbi->extent_lock);
                if (en1) {
                        if (list_empty(&en1->list))
                                list_add_tail(&en1->list, &sbi->extent_list);
                        else
                                list_move_tail(&en1->list, &sbi->extent_list);
                }
                if (den && !list_empty(&den->list))
                        list_del(&den->list);
                spin_unlock(&sbi->extent_lock);

                if (den)
                        kmem_cache_free(extent_node_slab, den);
        }

        if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT))
                __free_extent_tree(sbi, et, true);

        write_unlock(&et->lock);

        return !__is_extent_same(&prev, &et->largest);
}

unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
{
        struct extent_tree *treevec[EXT_TREE_VEC_SIZE];
        struct extent_node *en, *tmp;
        unsigned long ino = F2FS_ROOT_INO(sbi);
        struct radix_tree_root *root = &sbi->extent_tree_root;
        unsigned int found;
        unsigned int node_cnt = 0, tree_cnt = 0;
        int remained;

        if (!test_opt(sbi, EXTENT_CACHE))
                return 0;

        if (!down_write_trylock(&sbi->extent_tree_lock))
                goto out;

        /* 1. remove unreferenced extent tree */
        while ((found = radix_tree_gang_lookup(root,
                                (void **)treevec, ino, EXT_TREE_VEC_SIZE))) {
                unsigned i;

                ino = treevec[found - 1]->ino + 1;
                for (i = 0; i < found; i++) {
                        struct extent_tree *et = treevec[i];

                        if (!atomic_read(&et->refcount)) {
                                write_lock(&et->lock);
                                node_cnt += __free_extent_tree(sbi, et, true);
                                write_unlock(&et->lock);

                                radix_tree_delete(root, et->ino);
                                kmem_cache_free(extent_tree_slab, et);
                                sbi->total_ext_tree--;
                                tree_cnt++;

                                if (node_cnt + tree_cnt >= nr_shrink)
                                        goto unlock_out;
                        }
                }
        }
        up_write(&sbi->extent_tree_lock);

        /* 2. remove LRU extent entries */
        if (!down_write_trylock(&sbi->extent_tree_lock))
                goto out;

        remained = nr_shrink - (node_cnt + tree_cnt);

        spin_lock(&sbi->extent_lock);
        list_for_each_entry_safe(en, tmp, &sbi->extent_list, list) {
                if (!remained--)
                        break;
                list_del_init(&en->list);
        }
        spin_unlock(&sbi->extent_lock);

        /*
         * reset ino for searching victims from beginning of global extent tree.
         */
        ino = F2FS_ROOT_INO(sbi);

        while ((found = radix_tree_gang_lookup(root,
                                (void **)treevec, ino, EXT_TREE_VEC_SIZE))) {
                unsigned i;

                ino = treevec[found - 1]->ino + 1;
                for (i = 0; i < found; i++) {
                        struct extent_tree *et = treevec[i];

                        write_lock(&et->lock);
                        node_cnt += __free_extent_tree(sbi, et, false);
                        write_unlock(&et->lock);

                        if (node_cnt + tree_cnt >= nr_shrink)
                                goto unlock_out;
                }
        }
unlock_out:
        up_write(&sbi->extent_tree_lock);
out:
        trace_f2fs_shrink_extent_tree(sbi, node_cnt, tree_cnt);

        return node_cnt + tree_cnt;
}

unsigned int f2fs_destroy_extent_node(struct inode *inode)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et = F2FS_I(inode)->extent_tree;
        unsigned int node_cnt = 0;

        if (!et)
                return 0;

        write_lock(&et->lock);
        node_cnt = __free_extent_tree(sbi, et, true);
        write_unlock(&et->lock);

        return node_cnt;
}

void f2fs_destroy_extent_tree(struct inode *inode)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et = F2FS_I(inode)->extent_tree;
        unsigned int node_cnt = 0;

        if (!et)
                return;

        if (inode->i_nlink && !is_bad_inode(inode) && et->count) {
                atomic_dec(&et->refcount);
                return;
        }

        /* free all extent info belong to this extent tree */
        node_cnt = f2fs_destroy_extent_node(inode);

        /* delete extent tree entry in radix tree */
        down_write(&sbi->extent_tree_lock);
        atomic_dec(&et->refcount);
        f2fs_bug_on(sbi, atomic_read(&et->refcount) || et->count);
        radix_tree_delete(&sbi->extent_tree_root, inode->i_ino);
        kmem_cache_free(extent_tree_slab, et);
        sbi->total_ext_tree--;
        up_write(&sbi->extent_tree_lock);

        F2FS_I(inode)->extent_tree = NULL;

        trace_f2fs_destroy_extent_tree(inode, node_cnt);
}

bool f2fs_lookup_extent_cache(struct inode *inode, pgoff_t pgofs,
                                        struct extent_info *ei)
{
        if (!f2fs_may_extent_tree(inode))
                return false;

        return f2fs_lookup_extent_tree(inode, pgofs, ei);
}

void f2fs_update_extent_cache(struct dnode_of_data *dn)
{
        struct f2fs_inode_info *fi = F2FS_I(dn->inode);
        pgoff_t fofs;

        if (!f2fs_may_extent_tree(dn->inode))
                return;

        f2fs_bug_on(F2FS_I_SB(dn->inode), dn->data_blkaddr == NEW_ADDR);


        fofs = start_bidx_of_node(ofs_of_node(dn->node_page), fi) +
                                                        dn->ofs_in_node;

        if (f2fs_update_extent_tree_range(dn->inode, fofs, dn->data_blkaddr, 1))
                sync_inode_page(dn);
}

void f2fs_update_extent_cache_range(struct dnode_of_data *dn,
                                pgoff_t fofs, block_t blkaddr, unsigned int len)

{
        if (!f2fs_may_extent_tree(dn->inode))
                return;

        if (f2fs_update_extent_tree_range(dn->inode, fofs, blkaddr, len))
                sync_inode_page(dn);
}

void init_extent_cache_info(struct f2fs_sb_info *sbi)
{
        INIT_RADIX_TREE(&sbi->extent_tree_root, GFP_NOIO);
        init_rwsem(&sbi->extent_tree_lock);
        INIT_LIST_HEAD(&sbi->extent_list);
        spin_lock_init(&sbi->extent_lock);
        sbi->total_ext_tree = 0;
        atomic_set(&sbi->total_ext_node, 0);
}

int __init create_extent_cache(void)
{
        extent_tree_slab = f2fs_kmem_cache_create("f2fs_extent_tree",
                        sizeof(struct extent_tree));
        if (!extent_tree_slab)
                return -ENOMEM;
        extent_node_slab = f2fs_kmem_cache_create("f2fs_extent_node",
                        sizeof(struct extent_node));
        if (!extent_node_slab) {
                kmem_cache_destroy(extent_tree_slab);
                return -ENOMEM;
        }
        return 0;
}

void destroy_extent_cache(void)
{
        kmem_cache_destroy(extent_node_slab);
        kmem_cache_destroy(extent_tree_slab);
}