// SPDX-License-Identifier: GPL-2.0
/*
 * 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>
 *
 * block_age-based extent cache added by:
 * Copyright (c) 2022 xiaomi Co., Ltd.
 *             http://www.xiaomi.com/
 */

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

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

bool sanity_check_extent_cache(struct inode *inode, struct folio *ifolio)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct f2fs_extent *i_ext = &F2FS_INODE(ifolio)->i_ext;
        struct extent_info ei;
        int devi;

        get_read_extent_info(&ei, i_ext);

        if (!ei.len)
                return true;

        if (!f2fs_is_valid_blkaddr(sbi, ei.blk, DATA_GENERIC_ENHANCE) ||
            !f2fs_is_valid_blkaddr(sbi, ei.blk + ei.len - 1,
                                        DATA_GENERIC_ENHANCE)) {
                f2fs_warn(sbi, "%s: inode (ino=%lx) extent info [%u, %u, %u] is incorrect, run fsck to fix",
                          __func__, inode->i_ino,
                          ei.blk, ei.fofs, ei.len);
                return false;
        }

        if (!IS_DEVICE_ALIASING(inode))
                return true;

        for (devi = 0; devi < sbi->s_ndevs; devi++) {
                if (FDEV(devi).start_blk != ei.blk ||
                                FDEV(devi).end_blk != ei.blk + ei.len - 1)
                        continue;

                if (devi == 0) {
                        f2fs_warn(sbi,
                            "%s: inode (ino=%lx) is an alias of meta device",
                            __func__, inode->i_ino);
                        return false;
                }

                if (bdev_is_zoned(FDEV(devi).bdev)) {
                        f2fs_warn(sbi,
                            "%s: device alias inode (ino=%lx)'s extent info "
                            "[%u, %u, %u] maps to zoned block device",
                            __func__, inode->i_ino, ei.blk, ei.fofs, ei.len);
                        return false;
                }
                return true;
        }

        f2fs_warn(sbi, "%s: device alias inode (ino=%lx)'s extent info "
                        "[%u, %u, %u] is inconsistent w/ any devices",
                        __func__, inode->i_ino, ei.blk, ei.fofs, ei.len);
        return false;
}

static void __set_extent_info(struct extent_info *ei,
                                unsigned int fofs, unsigned int len,
                                block_t blk, bool keep_clen,
                                unsigned long age, unsigned long last_blocks,
                                enum extent_type type)
{
        ei->fofs = fofs;
        ei->len = len;

        if (type == EX_READ) {
                ei->blk = blk;
                if (keep_clen)
                        return;
#ifdef CONFIG_F2FS_FS_COMPRESSION
                ei->c_len = 0;
#endif
        } else if (type == EX_BLOCK_AGE) {
                ei->age = age;
                ei->last_blocks = last_blocks;
        }
}

static bool __init_may_extent_tree(struct inode *inode, enum extent_type type)
{
        if (type == EX_READ)
                return test_opt(F2FS_I_SB(inode), READ_EXTENT_CACHE) &&
                        S_ISREG(inode->i_mode);
        if (type == EX_BLOCK_AGE)
                return test_opt(F2FS_I_SB(inode), AGE_EXTENT_CACHE) &&
                        (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode));
        return false;
}

static bool __may_extent_tree(struct inode *inode, enum extent_type type)
{
        if (IS_DEVICE_ALIASING(inode) && type == EX_READ)
                return true;

        /*
         * for recovered files during mount do not create extents
         * if shrinker is not registered.
         */
        if (list_empty(&F2FS_I_SB(inode)->s_list))
                return false;

        if (!__init_may_extent_tree(inode, type))
                return false;

        if (type == EX_READ) {
                if (is_inode_flag_set(inode, FI_NO_EXTENT))
                        return false;
                if (is_inode_flag_set(inode, FI_COMPRESSED_FILE) &&
                                 !f2fs_sb_has_readonly(F2FS_I_SB(inode)))
                        return false;
        } else if (type == EX_BLOCK_AGE) {
                if (is_inode_flag_set(inode, FI_COMPRESSED_FILE))
                        return false;
                if (file_is_cold(inode))
                        return false;
        }
        return true;
}

static void __try_update_largest_extent(struct extent_tree *et,
                                                struct extent_node *en)
{
        if (et->type != EX_READ)
                return;
        if (en->ei.len <= et->largest.len)
                return;

        et->largest = en->ei;
        et->largest_updated = true;
}

static bool __is_extent_mergeable(struct extent_info *back,
                struct extent_info *front, enum extent_type type)
{
        if (type == EX_READ) {
#ifdef CONFIG_F2FS_FS_COMPRESSION
                if (back->c_len && back->len != back->c_len)
                        return false;
                if (front->c_len && front->len != front->c_len)
                        return false;
#endif
                return (back->fofs + back->len == front->fofs &&
                                back->blk + back->len == front->blk);
        } else if (type == EX_BLOCK_AGE) {
                return (back->fofs + back->len == front->fofs &&
                        abs(back->age - front->age) <= SAME_AGE_REGION &&
                        abs(back->last_blocks - front->last_blocks) <=
                                                        SAME_AGE_REGION);
        }
        return false;
}

static bool __is_back_mergeable(struct extent_info *cur,
                struct extent_info *back, enum extent_type type)
{
        return __is_extent_mergeable(back, cur, type);
}

static bool __is_front_mergeable(struct extent_info *cur,
                struct extent_info *front, enum extent_type type)
{
        return __is_extent_mergeable(cur, front, type);
}

static struct extent_node *__lookup_extent_node(struct rb_root_cached *root,
                        struct extent_node *cached_en, unsigned int fofs)
{
        struct rb_node *node = root->rb_root.rb_node;
        struct extent_node *en;

        /* check a cached entry */
        if (cached_en && cached_en->ei.fofs <= fofs &&
                        cached_en->ei.fofs + cached_en->ei.len > fofs)
                return cached_en;

        /* check rb_tree */
        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
                        return en;
        }
        return NULL;
}

/*
 * lookup rb entry in position of @fofs in rb-tree,
 * if hit, return the entry, otherwise, return NULL
 * @prev_ex: extent before fofs
 * @next_ex: extent after fofs
 * @insert_p: insert point for new extent at fofs
 * in order to simplify the insertion after.
 * tree must stay unchanged between lookup and insertion.
 */
static struct extent_node *__lookup_extent_node_ret(struct rb_root_cached *root,
                                struct extent_node *cached_en,
                                unsigned int fofs,
                                struct extent_node **prev_entry,
                                struct extent_node **next_entry,
                                struct rb_node ***insert_p,
                                struct rb_node **insert_parent,
                                bool *leftmost)
{
        struct rb_node **pnode = &root->rb_root.rb_node;
        struct rb_node *parent = NULL, *tmp_node;
        struct extent_node *en = cached_en;

        *insert_p = NULL;
        *insert_parent = NULL;
        *prev_entry = NULL;
        *next_entry = NULL;

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

        if (en && en->ei.fofs <= fofs && en->ei.fofs + en->ei.len > fofs)
                goto lookup_neighbors;

        *leftmost = true;

        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;
                        *leftmost = false;
                } 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_entry = rb_entry_safe(tmp_node, struct extent_node, rb_node);

        tmp_node = parent;
        if (parent && fofs < en->ei.fofs)
                tmp_node = rb_prev(parent);
        *prev_entry = rb_entry_safe(tmp_node, struct extent_node, rb_node);
        return NULL;

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

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,
                                bool leftmost)
{
        struct extent_tree_info *eti = &sbi->extent_tree[et->type];
        struct extent_node *en;

        en = f2fs_kmem_cache_alloc(extent_node_slab, GFP_ATOMIC, false, sbi);
        if (!en)
                return NULL;

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

        rb_link_node(&en->rb_node, parent, p);
        rb_insert_color_cached(&en->rb_node, &et->root, leftmost);
        atomic_inc(&et->node_cnt);
        atomic_inc(&eti->total_ext_node);
        return en;
}

static void __detach_extent_node(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_node *en)
{
        struct extent_tree_info *eti = &sbi->extent_tree[et->type];

        rb_erase_cached(&en->rb_node, &et->root);
        atomic_dec(&et->node_cnt);
        atomic_dec(&eti->total_ext_node);

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

/*
 * Flow to release an extent_node:
 * 1. list_del_init
 * 2. __detach_extent_node
 * 3. kmem_cache_free.
 */
static void __release_extent_node(struct f2fs_sb_info *sbi,
                        struct extent_tree *et, struct extent_node *en)
{
        struct extent_tree_info *eti = &sbi->extent_tree[et->type];

        spin_lock(&eti->extent_lock);
        f2fs_bug_on(sbi, list_empty(&en->list));
        list_del_init(&en->list);
        spin_unlock(&eti->extent_lock);

        __detach_extent_node(sbi, et, en);
}

static struct extent_tree *__grab_extent_tree(struct inode *inode,
                                                enum extent_type type)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree_info *eti = &sbi->extent_tree[type];
        struct extent_tree *et;
        nid_t ino = inode->i_ino;

        mutex_lock(&eti->extent_tree_lock);
        et = radix_tree_lookup(&eti->extent_tree_root, ino);
        if (!et) {
                et = f2fs_kmem_cache_alloc(extent_tree_slab,
                                        GFP_NOFS, true, NULL);
                f2fs_radix_tree_insert(&eti->extent_tree_root, ino, et);
                memset(et, 0, sizeof(struct extent_tree));
                et->ino = ino;
                et->type = type;
                et->root = RB_ROOT_CACHED;
                et->cached_en = NULL;
                rwlock_init(&et->lock);
                INIT_LIST_HEAD(&et->list);
                atomic_set(&et->node_cnt, 0);
                atomic_inc(&eti->total_ext_tree);
        } else {
                atomic_dec(&eti->total_zombie_tree);
                list_del_init(&et->list);
        }
        mutex_unlock(&eti->extent_tree_lock);

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

        return et;
}

static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, unsigned int nr_shrink)
{
        struct rb_node *node, *next;
        struct extent_node *en;
        unsigned int count;

        node = rb_first_cached(&et->root);

        for (count = 0; node && count < nr_shrink; count++) {
                next = rb_next(node);
                en = rb_entry(node, struct extent_node, rb_node);
                __release_extent_node(sbi, et, en);
                node = next;
        }

        return count;
}

static void __drop_largest_extent(struct extent_tree *et,
                                        pgoff_t fofs, unsigned int len)
{
        if (fofs < (pgoff_t)et->largest.fofs + et->largest.len &&
                        fofs + len > et->largest.fofs) {
                et->largest.len = 0;
                et->largest_updated = true;
        }
}

void f2fs_init_read_extent_tree(struct inode *inode, struct folio *ifolio)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree_info *eti = &sbi->extent_tree[EX_READ];
        struct f2fs_extent *i_ext = &F2FS_INODE(ifolio)->i_ext;
        struct extent_tree *et;
        struct extent_node *en;
        struct extent_info ei = {0};

        if (!__may_extent_tree(inode, EX_READ)) {
                /* drop largest read extent */
                if (i_ext->len) {
                        f2fs_folio_wait_writeback(ifolio, NODE, true, true);
                        i_ext->len = 0;
                        folio_mark_dirty(ifolio);
                }
                set_inode_flag(inode, FI_NO_EXTENT);
                return;
        }

        et = __grab_extent_tree(inode, EX_READ);

        get_read_extent_info(&ei, i_ext);

        write_lock(&et->lock);
        if (atomic_read(&et->node_cnt) || !ei.len)
                goto skip;

        if (IS_DEVICE_ALIASING(inode)) {
                et->largest = ei;
                goto skip;
        }

        en = __attach_extent_node(sbi, et, &ei, NULL,
                                &et->root.rb_root.rb_node, true);
        if (en) {
                et->largest = en->ei;
                et->cached_en = en;

                spin_lock(&eti->extent_lock);
                list_add_tail(&en->list, &eti->extent_list);
                spin_unlock(&eti->extent_lock);
        }
skip:
        /* Let's drop, if checkpoint got corrupted. */
        if (f2fs_cp_error(sbi)) {
                et->largest.len = 0;
                et->largest_updated = true;
        }
        write_unlock(&et->lock);
}

void f2fs_init_age_extent_tree(struct inode *inode)
{
        if (!__init_may_extent_tree(inode, EX_BLOCK_AGE))
                return;
        __grab_extent_tree(inode, EX_BLOCK_AGE);
}

void f2fs_init_extent_tree(struct inode *inode)
{
        /* initialize read cache */
        if (__init_may_extent_tree(inode, EX_READ))
                __grab_extent_tree(inode, EX_READ);

        /* initialize block age cache */
        if (__init_may_extent_tree(inode, EX_BLOCK_AGE))
                __grab_extent_tree(inode, EX_BLOCK_AGE);
}

static bool __lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
                        struct extent_info *ei, enum extent_type type)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree_info *eti = &sbi->extent_tree[type];
        struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
        struct extent_node *en;
        bool ret = false;

        if (!et)
                return false;

        trace_f2fs_lookup_extent_tree_start(inode, pgofs, type);

        read_lock(&et->lock);

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

        if (IS_DEVICE_ALIASING(inode)) {
                ret = false;
                goto out;
        }

        en = __lookup_extent_node(&et->root, et->cached_en, pgofs);
        if (!en)
                goto out;

        if (en == et->cached_en)
                stat_inc_cached_node_hit(sbi, type);
        else
                stat_inc_rbtree_node_hit(sbi, type);

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

        if (type == EX_READ)
                trace_f2fs_lookup_read_extent_tree_end(inode, pgofs, ei);
        else if (type == EX_BLOCK_AGE)
                trace_f2fs_lookup_age_extent_tree_end(inode, pgofs, ei);
        return ret;
}

static struct extent_node *__try_merge_extent_node(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_info *ei,
                                struct extent_node *prev_ex,
                                struct extent_node *next_ex)
{
        struct extent_tree_info *eti = &sbi->extent_tree[et->type];
        struct extent_node *en = NULL;

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

        if (next_ex && __is_front_mergeable(ei, &next_ex->ei, et->type)) {
                next_ex->ei.fofs = ei->fofs;
                next_ex->ei.len += ei->len;
                if (et->type == EX_READ)
                        next_ex->ei.blk = ei->blk;
                if (en)
                        __release_extent_node(sbi, et, prev_ex);

                en = next_ex;
        }

        if (!en)
                return NULL;

        __try_update_largest_extent(et, en);

        spin_lock(&eti->extent_lock);
        if (!list_empty(&en->list)) {
                list_move_tail(&en->list, &eti->extent_list);
                et->cached_en = en;
        }
        spin_unlock(&eti->extent_lock);
        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,
                                bool leftmost)
{
        struct extent_tree_info *eti = &sbi->extent_tree[et->type];
        struct rb_node **p = &et->root.rb_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;
        }

        leftmost = true;

        /* look up extent_node in the rb tree */
        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;
                        leftmost = false;
                } else {
                        f2fs_err_ratelimited(sbi, "%s: corrupted extent, type: %d, "
                                "extent node in rb tree [%u, %u, %u], age [%llu, %llu], "
                                "extent node to insert [%u, %u, %u], age [%llu, %llu]",
                                __func__, et->type, en->ei.fofs, en->ei.blk, en->ei.len, en->ei.age,
                                en->ei.last_blocks, ei->fofs, ei->blk, ei->len, ei->age, ei->last_blocks);
                        f2fs_bug_on(sbi, 1);
                        return NULL;
                }
        }

do_insert:
        en = __attach_extent_node(sbi, et, ei, parent, p, leftmost);
        if (!en)
                return NULL;

        __try_update_largest_extent(et, en);

        /* update in global extent list */
        spin_lock(&eti->extent_lock);
        list_add_tail(&en->list, &eti->extent_list);
        et->cached_en = en;
        spin_unlock(&eti->extent_lock);
        return en;
}

static unsigned int __destroy_extent_node(struct inode *inode,
                                        enum extent_type type)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
        unsigned int nr_shrink = type == EX_READ ?
                                READ_EXTENT_CACHE_SHRINK_NUMBER :
                                AGE_EXTENT_CACHE_SHRINK_NUMBER;
        unsigned int node_cnt = 0;

        if (!et || !atomic_read(&et->node_cnt))
                return 0;

        while (atomic_read(&et->node_cnt)) {
                write_lock(&et->lock);
                node_cnt += __free_extent_tree(sbi, et, nr_shrink);
                write_unlock(&et->lock);
        }

        f2fs_bug_on(sbi, atomic_read(&et->node_cnt));

        return node_cnt;
}

static void __update_extent_tree_range(struct inode *inode,
                        struct extent_info *tei, enum extent_type type)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
        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 fofs = tei->fofs, len = tei->len;
        unsigned int end = fofs + len;
        bool updated = false;
        bool leftmost = false;

        if (!et)
                return;

        if (unlikely(len == 0)) {
                f2fs_err_ratelimited(sbi, "%s: extent len is zero, type: %d, "
                        "extent [%u, %u, %u], age [%llu, %llu]",
                        __func__, type, tei->fofs, tei->blk, tei->len,
                        tei->age, tei->last_blocks);
                f2fs_bug_on(sbi, 1);
                return;
        }

        if (type == EX_READ)
                trace_f2fs_update_read_extent_tree_range(inode, fofs, len,
                                                tei->blk, 0);
        else if (type == EX_BLOCK_AGE)
                trace_f2fs_update_age_extent_tree_range(inode, fofs, len,
                                                tei->age, tei->last_blocks);

        write_lock(&et->lock);

        if (type == EX_READ) {
                if (is_inode_flag_set(inode, FI_NO_EXTENT)) {
                        write_unlock(&et->lock);
                        return;
                }

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

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

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

        /* 2. invalidate 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, fofs >= org_end);

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

                if (end < org_end && (type != EX_READ ||
                        (org_end - end >= F2FS_MIN_EXTENT_LEN &&
                        atomic_read(&et->node_cnt) <
                                        sbi->max_read_extent_count))) {
                        if (parts) {
                                __set_extent_info(&ei,
                                        end, org_end - end,
                                        end - dei.fofs + dei.blk, false,
                                        dei.age, dei.last_blocks,
                                        type);
                                en1 = __insert_extent_tree(sbi, et, &ei,
                                                        NULL, NULL, true);
                                next_en = en1;
                        } else {
                                __set_extent_info(&en->ei,
                                        end, en->ei.len - (end - dei.fofs),
                                        en->ei.blk + (end - dei.fofs), true,
                                        dei.age, dei.last_blocks,
                                        type);
                                next_en = en;
                        }
                        parts++;
                }

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

                        next_en = rb_entry_safe(node, struct extent_node,
                                                rb_node);
                }

                if (parts)
                        __try_update_largest_extent(et, en);
                else
                        __release_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;
                }
                en = next_en;
        }

        if (type == EX_BLOCK_AGE)
                goto update_age_extent_cache;

        /* 3. update extent in read extent cache */
        BUG_ON(type != EX_READ);

        if (tei->blk) {
                __set_extent_info(&ei, fofs, len, tei->blk, false,
                                  0, 0, EX_READ);
                if (!__try_merge_extent_node(sbi, et, &ei, prev_en, next_en))
                        __insert_extent_tree(sbi, et, &ei,
                                        insert_p, insert_parent, leftmost);

                /* 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;
                        et->largest_updated = true;
                        set_inode_flag(inode, FI_NO_EXTENT);
                }
        }

        if (et->largest_updated) {
                et->largest_updated = false;
                updated = true;
        }
        goto out_read_extent_cache;
update_age_extent_cache:
        if (tei->last_blocks == F2FS_EXTENT_AGE_INVALID)
                goto out_read_extent_cache;

        __set_extent_info(&ei, fofs, len, 0, false,
                        tei->age, tei->last_blocks, EX_BLOCK_AGE);
        if (!__try_merge_extent_node(sbi, et, &ei, prev_en, next_en))
                __insert_extent_tree(sbi, et, &ei,
                                        insert_p, insert_parent, leftmost);
out_read_extent_cache:
        write_unlock(&et->lock);

        if (is_inode_flag_set(inode, FI_NO_EXTENT))
                __destroy_extent_node(inode, EX_READ);

        if (updated)
                f2fs_mark_inode_dirty_sync(inode, true);
}

#ifdef CONFIG_F2FS_FS_COMPRESSION
void f2fs_update_read_extent_tree_range_compressed(struct inode *inode,
                                pgoff_t fofs, block_t blkaddr, unsigned int llen,
                                unsigned int c_len)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et = F2FS_I(inode)->extent_tree[EX_READ];
        struct extent_node *en = NULL;
        struct extent_node *prev_en = NULL, *next_en = NULL;
        struct extent_info ei;
        struct rb_node **insert_p = NULL, *insert_parent = NULL;
        bool leftmost = false;

        trace_f2fs_update_read_extent_tree_range(inode, fofs, llen,
                                                blkaddr, c_len);

        /* it is safe here to check FI_NO_EXTENT w/o et->lock in ro image */
        if (is_inode_flag_set(inode, FI_NO_EXTENT))
                return;

        write_lock(&et->lock);

        en = __lookup_extent_node_ret(&et->root,
                                        et->cached_en, fofs,
                                        &prev_en, &next_en,
                                        &insert_p, &insert_parent,
                                        &leftmost);
        if (en)
                goto unlock_out;

        __set_extent_info(&ei, fofs, llen, blkaddr, true, 0, 0, EX_READ);
        ei.c_len = c_len;

        if (!__try_merge_extent_node(sbi, et, &ei, prev_en, next_en))
                __insert_extent_tree(sbi, et, &ei,
                                insert_p, insert_parent, leftmost);
unlock_out:
        write_unlock(&et->lock);
}
#endif

static unsigned long long __calculate_block_age(struct f2fs_sb_info *sbi,
                                                unsigned long long new,
                                                unsigned long long old)
{
        unsigned int rem_old, rem_new;
        unsigned long long res;
        unsigned int weight = sbi->last_age_weight;

        res = div_u64_rem(new, 100, &rem_new) * (100 - weight)
                + div_u64_rem(old, 100, &rem_old) * weight;

        if (rem_new)
                res += rem_new * (100 - weight) / 100;
        if (rem_old)
                res += rem_old * weight / 100;

        return res;
}

/* This returns a new age and allocated blocks in ei */
static int __get_new_block_age(struct inode *inode, struct extent_info *ei,
                                                block_t blkaddr)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        loff_t f_size = i_size_read(inode);
        unsigned long long cur_blocks =
                                atomic64_read(&sbi->allocated_data_blocks);
        struct extent_info tei = *ei;   /* only fofs and len are valid */

        /*
         * When I/O is not aligned to a PAGE_SIZE, update will happen to the last
         * file block even in seq write. So don't record age for newly last file
         * block here.
         */
        if ((f_size >> PAGE_SHIFT) == ei->fofs && f_size & (PAGE_SIZE - 1) &&
                        blkaddr == NEW_ADDR)
                return -EINVAL;

        if (__lookup_extent_tree(inode, ei->fofs, &tei, EX_BLOCK_AGE)) {
                unsigned long long cur_age;

                if (cur_blocks >= tei.last_blocks)
                        cur_age = cur_blocks - tei.last_blocks;
                else
                        /* allocated_data_blocks overflow */
                        cur_age = (ULLONG_MAX - 1) - tei.last_blocks + cur_blocks;

                if (tei.age)
                        ei->age = __calculate_block_age(sbi, cur_age, tei.age);
                else
                        ei->age = cur_age;
                ei->last_blocks = cur_blocks;
                WARN_ON(ei->age > cur_blocks);
                return 0;
        }

        f2fs_bug_on(sbi, blkaddr == NULL_ADDR);

        /* the data block was allocated for the first time */
        if (blkaddr == NEW_ADDR)
                goto out;

        if (__is_valid_data_blkaddr(blkaddr) &&
            !f2fs_is_valid_blkaddr(sbi, blkaddr, DATA_GENERIC_ENHANCE))
                return -EINVAL;
out:
        /*
         * init block age with zero, this can happen when the block age extent
         * was reclaimed due to memory constraint or system reboot
         */
        ei->age = 0;
        ei->last_blocks = cur_blocks;
        return 0;
}

static void __update_extent_cache(struct dnode_of_data *dn, enum extent_type type)
{
        struct extent_info ei = {};

        if (!__may_extent_tree(dn->inode, type))
                return;

        ei.fofs = f2fs_start_bidx_of_node(ofs_of_node(dn->node_folio), dn->inode) +
                                                                dn->ofs_in_node;
        ei.len = 1;

        if (type == EX_READ) {
                if (dn->data_blkaddr == NEW_ADDR)
                        ei.blk = NULL_ADDR;
                else
                        ei.blk = dn->data_blkaddr;
        } else if (type == EX_BLOCK_AGE) {
                if (__get_new_block_age(dn->inode, &ei, dn->data_blkaddr))
                        return;
        }
        __update_extent_tree_range(dn->inode, &ei, type);
}

static unsigned int __shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink,
                                        enum extent_type type)
{
        struct extent_tree_info *eti = &sbi->extent_tree[type];
        struct extent_tree *et, *next;
        struct extent_node *en;
        unsigned int node_cnt = 0, tree_cnt = 0;
        int remained;

        if (!atomic_read(&eti->total_zombie_tree))
                goto free_node;

        if (!mutex_trylock(&eti->extent_tree_lock))
                goto out;

        /* 1. remove unreferenced extent tree */
        list_for_each_entry_safe(et, next, &eti->zombie_list, list) {
                if (atomic_read(&et->node_cnt)) {
                        write_lock(&et->lock);
                        node_cnt += __free_extent_tree(sbi, et,
                                        nr_shrink - node_cnt - tree_cnt);
                        write_unlock(&et->lock);
                }

                if (atomic_read(&et->node_cnt))
                        goto unlock_out;

                list_del_init(&et->list);
                radix_tree_delete(&eti->extent_tree_root, et->ino);
                kmem_cache_free(extent_tree_slab, et);
                atomic_dec(&eti->total_ext_tree);
                atomic_dec(&eti->total_zombie_tree);
                tree_cnt++;

                if (node_cnt + tree_cnt >= nr_shrink)
                        goto unlock_out;
                cond_resched();
        }
        mutex_unlock(&eti->extent_tree_lock);

free_node:
        /* 2. remove LRU extent entries */
        if (!mutex_trylock(&eti->extent_tree_lock))
                goto out;

        remained = nr_shrink - (node_cnt + tree_cnt);

        spin_lock(&eti->extent_lock);
        for (; remained > 0; remained--) {
                if (list_empty(&eti->extent_list))
                        break;
                en = list_first_entry(&eti->extent_list,
                                        struct extent_node, list);
                et = en->et;
                if (!write_trylock(&et->lock)) {
                        /* refresh this extent node's position in extent list */
                        list_move_tail(&en->list, &eti->extent_list);
                        continue;
                }

                list_del_init(&en->list);
                spin_unlock(&eti->extent_lock);

                __detach_extent_node(sbi, et, en);

                write_unlock(&et->lock);
                node_cnt++;
                spin_lock(&eti->extent_lock);
        }
        spin_unlock(&eti->extent_lock);

unlock_out:
        mutex_unlock(&eti->extent_tree_lock);
out:
        trace_f2fs_shrink_extent_tree(sbi, node_cnt, tree_cnt, type);

        return node_cnt + tree_cnt;
}

/* read extent cache operations */
bool f2fs_lookup_read_extent_cache(struct inode *inode, pgoff_t pgofs,
                                struct extent_info *ei)
{
        if (!__may_extent_tree(inode, EX_READ))
                return false;

        return __lookup_extent_tree(inode, pgofs, ei, EX_READ);
}

bool f2fs_lookup_read_extent_cache_block(struct inode *inode, pgoff_t index,
                                block_t *blkaddr)
{
        struct extent_info ei = {};

        if (!f2fs_lookup_read_extent_cache(inode, index, &ei))
                return false;
        *blkaddr = ei.blk + index - ei.fofs;
        return true;
}

void f2fs_update_read_extent_cache(struct dnode_of_data *dn)
{
        return __update_extent_cache(dn, EX_READ);
}

void f2fs_update_read_extent_cache_range(struct dnode_of_data *dn,
                                pgoff_t fofs, block_t blkaddr, unsigned int len)
{
        struct extent_info ei = {
                .fofs = fofs,
                .len = len,
                .blk = blkaddr,
        };

        if (!__may_extent_tree(dn->inode, EX_READ))
                return;

        __update_extent_tree_range(dn->inode, &ei, EX_READ);
}

unsigned int f2fs_shrink_read_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
{
        if (!test_opt(sbi, READ_EXTENT_CACHE))
                return 0;

        return __shrink_extent_tree(sbi, nr_shrink, EX_READ);
}

/* block age extent cache operations */
bool f2fs_lookup_age_extent_cache(struct inode *inode, pgoff_t pgofs,
                                struct extent_info *ei)
{
        if (!__may_extent_tree(inode, EX_BLOCK_AGE))
                return false;

        return __lookup_extent_tree(inode, pgofs, ei, EX_BLOCK_AGE);
}

void f2fs_update_age_extent_cache(struct dnode_of_data *dn)
{
        return __update_extent_cache(dn, EX_BLOCK_AGE);
}

void f2fs_update_age_extent_cache_range(struct dnode_of_data *dn,
                                pgoff_t fofs, unsigned int len)
{
        struct extent_info ei = {
                .fofs = fofs,
                .len = len,
                .last_blocks = F2FS_EXTENT_AGE_INVALID,
        };

        if (!__may_extent_tree(dn->inode, EX_BLOCK_AGE))
                return;

        __update_extent_tree_range(dn->inode, &ei, EX_BLOCK_AGE);
}

unsigned int f2fs_shrink_age_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
{
        if (!test_opt(sbi, AGE_EXTENT_CACHE))
                return 0;

        return __shrink_extent_tree(sbi, nr_shrink, EX_BLOCK_AGE);
}

void f2fs_destroy_extent_node(struct inode *inode)
{
        __destroy_extent_node(inode, EX_READ);
        __destroy_extent_node(inode, EX_BLOCK_AGE);
}

static void __drop_extent_tree(struct inode *inode, enum extent_type type)
{
        struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
        bool updated = false;

        if (!__may_extent_tree(inode, type))
                return;

        write_lock(&et->lock);
        if (type == EX_READ) {
                set_inode_flag(inode, FI_NO_EXTENT);
                if (et->largest.len) {
                        et->largest.len = 0;
                        updated = true;
                }
        }
        write_unlock(&et->lock);

        __destroy_extent_node(inode, type);

        if (updated)
                f2fs_mark_inode_dirty_sync(inode, true);
}

void f2fs_drop_extent_tree(struct inode *inode)
{
        __drop_extent_tree(inode, EX_READ);
        __drop_extent_tree(inode, EX_BLOCK_AGE);
}

static void __destroy_extent_tree(struct inode *inode, enum extent_type type)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree_info *eti = &sbi->extent_tree[type];
        struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
        unsigned int node_cnt = 0;

        if (!et)
                return;

        if (inode->i_nlink && !is_bad_inode(inode) &&
                                        atomic_read(&et->node_cnt)) {
                mutex_lock(&eti->extent_tree_lock);
                list_add_tail(&et->list, &eti->zombie_list);
                atomic_inc(&eti->total_zombie_tree);
                mutex_unlock(&eti->extent_tree_lock);
                return;
        }

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

        /* delete extent tree entry in radix tree */
        mutex_lock(&eti->extent_tree_lock);
        f2fs_bug_on(sbi, atomic_read(&et->node_cnt));
        radix_tree_delete(&eti->extent_tree_root, inode->i_ino);
        kmem_cache_free(extent_tree_slab, et);
        atomic_dec(&eti->total_ext_tree);
        mutex_unlock(&eti->extent_tree_lock);

        F2FS_I(inode)->extent_tree[type] = NULL;

        trace_f2fs_destroy_extent_tree(inode, node_cnt, type);
}

void f2fs_destroy_extent_tree(struct inode *inode)
{
        __destroy_extent_tree(inode, EX_READ);
        __destroy_extent_tree(inode, EX_BLOCK_AGE);
}

static void __init_extent_tree_info(struct extent_tree_info *eti)
{
        INIT_RADIX_TREE(&eti->extent_tree_root, GFP_NOIO);
        mutex_init(&eti->extent_tree_lock);
        INIT_LIST_HEAD(&eti->extent_list);
        spin_lock_init(&eti->extent_lock);
        atomic_set(&eti->total_ext_tree, 0);
        INIT_LIST_HEAD(&eti->zombie_list);
        atomic_set(&eti->total_zombie_tree, 0);
        atomic_set(&eti->total_ext_node, 0);
}

void f2fs_init_extent_cache_info(struct f2fs_sb_info *sbi)
{
        __init_extent_tree_info(&sbi->extent_tree[EX_READ]);
        __init_extent_tree_info(&sbi->extent_tree[EX_BLOCK_AGE]);

        /* initialize for block age extents */
        atomic64_set(&sbi->allocated_data_blocks, 0);
        sbi->hot_data_age_threshold = DEF_HOT_DATA_AGE_THRESHOLD;
        sbi->warm_data_age_threshold = DEF_WARM_DATA_AGE_THRESHOLD;
        sbi->last_age_weight = LAST_AGE_WEIGHT;
        sbi->max_read_extent_count = DEF_MAX_READ_EXTENT_COUNT;
}

int __init f2fs_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 f2fs_destroy_extent_cache(void)
{
        kmem_cache_destroy(extent_node_slab);
        kmem_cache_destroy(extent_tree_slab);
}