[mirror_ubuntu-bionic-kernel.git] / fs / f2fs / gc.c

/*
 * fs/f2fs/gc.c
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.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/module.h>
#include <linux/backing-dev.h>
#include <linux/init.h>
#include <linux/f2fs_fs.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/blkdev.h>

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

static struct kmem_cache *winode_slab;

static int gc_thread_func(void *data)
{
        struct f2fs_sb_info *sbi = data;
        struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
        wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
        long wait_ms;

        wait_ms = gc_th->min_sleep_time;

        do {
                if (try_to_freeze())
                        continue;
                else
                        wait_event_interruptible_timeout(*wq,
                                                kthread_should_stop(),
                                                msecs_to_jiffies(wait_ms));
                if (kthread_should_stop())
                        break;

                if (sbi->sb->s_writers.frozen >= SB_FREEZE_WRITE) {
                        wait_ms = increase_sleep_time(gc_th, wait_ms);
                        continue;
                }

                /*
                 * [GC triggering condition]
                 * 0. GC is not conducted currently.
                 * 1. There are enough dirty segments.
                 * 2. IO subsystem is idle by checking the # of writeback pages.
                 * 3. IO subsystem is idle by checking the # of requests in
                 *    bdev's request list.
                 *
                 * Note) We have to avoid triggering GCs too much frequently.
                 * Because it is possible that some segments can be
                 * invalidated soon after by user update or deletion.
                 * So, I'd like to wait some time to collect dirty segments.
                 */
                if (!mutex_trylock(&sbi->gc_mutex))
                        continue;

                if (!is_idle(sbi)) {
                        wait_ms = increase_sleep_time(gc_th, wait_ms);
                        mutex_unlock(&sbi->gc_mutex);
                        continue;
                }

                if (has_enough_invalid_blocks(sbi))
                        wait_ms = decrease_sleep_time(gc_th, wait_ms);
                else
                        wait_ms = increase_sleep_time(gc_th, wait_ms);

                stat_inc_bggc_count(sbi);

                /* if return value is not zero, no victim was selected */
                if (f2fs_gc(sbi))
                        wait_ms = gc_th->no_gc_sleep_time;

                /* balancing f2fs's metadata periodically */
                f2fs_balance_fs_bg(sbi);

        } while (!kthread_should_stop());
        return 0;
}

int start_gc_thread(struct f2fs_sb_info *sbi)
{
        struct f2fs_gc_kthread *gc_th;
        dev_t dev = sbi->sb->s_bdev->bd_dev;
        int err = 0;

        if (!test_opt(sbi, BG_GC))
                goto out;
        gc_th = kmalloc(sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
        if (!gc_th) {
                err = -ENOMEM;
                goto out;
        }

        gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME;
        gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
        gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;

        gc_th->gc_idle = 0;

        sbi->gc_thread = gc_th;
        init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
        sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
                        "f2fs_gc-%u:%u", MAJOR(dev), MINOR(dev));
        if (IS_ERR(gc_th->f2fs_gc_task)) {
                err = PTR_ERR(gc_th->f2fs_gc_task);
                kfree(gc_th);
                sbi->gc_thread = NULL;
        }
out:
        return err;
}

void stop_gc_thread(struct f2fs_sb_info *sbi)
{
        struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
        if (!gc_th)
                return;
        kthread_stop(gc_th->f2fs_gc_task);
        kfree(gc_th);
        sbi->gc_thread = NULL;
}

static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type)
{
        int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;

        if (gc_th && gc_th->gc_idle) {
                if (gc_th->gc_idle == 1)
                        gc_mode = GC_CB;
                else if (gc_th->gc_idle == 2)
                        gc_mode = GC_GREEDY;
        }
        return gc_mode;
}

static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
                        int type, struct victim_sel_policy *p)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);

        if (p->alloc_mode == SSR) {
                p->gc_mode = GC_GREEDY;
                p->dirty_segmap = dirty_i->dirty_segmap[type];
                p->max_search = dirty_i->nr_dirty[type];
                p->ofs_unit = 1;
        } else {
                p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
                p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
                p->max_search = dirty_i->nr_dirty[DIRTY];
                p->ofs_unit = sbi->segs_per_sec;
        }

        if (p->max_search > MAX_VICTIM_SEARCH)
                p->max_search = MAX_VICTIM_SEARCH;

        p->offset = sbi->last_victim[p->gc_mode];
}

static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
                                struct victim_sel_policy *p)
{
        /* SSR allocates in a segment unit */
        if (p->alloc_mode == SSR)
                return 1 << sbi->log_blocks_per_seg;
        if (p->gc_mode == GC_GREEDY)
                return (1 << sbi->log_blocks_per_seg) * p->ofs_unit;
        else if (p->gc_mode == GC_CB)
                return UINT_MAX;
        else /* No other gc_mode */
                return 0;
}

static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        unsigned int hint = 0;
        unsigned int secno;

        /*
         * If the gc_type is FG_GC, we can select victim segments
         * selected by background GC before.
         * Those segments guarantee they have small valid blocks.
         */
next:
        secno = find_next_bit(dirty_i->victim_secmap, TOTAL_SECS(sbi), hint++);
        if (secno < TOTAL_SECS(sbi)) {
                if (sec_usage_check(sbi, secno))
                        goto next;
                clear_bit(secno, dirty_i->victim_secmap);
                return secno * sbi->segs_per_sec;
        }
        return NULL_SEGNO;
}

static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned int segno)
{
        struct sit_info *sit_i = SIT_I(sbi);
        unsigned int secno = GET_SECNO(sbi, segno);
        unsigned int start = secno * sbi->segs_per_sec;
        unsigned long long mtime = 0;
        unsigned int vblocks;
        unsigned char age = 0;
        unsigned char u;
        unsigned int i;

        for (i = 0; i < sbi->segs_per_sec; i++)
                mtime += get_seg_entry(sbi, start + i)->mtime;
        vblocks = get_valid_blocks(sbi, segno, sbi->segs_per_sec);

        mtime = div_u64(mtime, sbi->segs_per_sec);
        vblocks = div_u64(vblocks, sbi->segs_per_sec);

        u = (vblocks * 100) >> sbi->log_blocks_per_seg;

        /* Handle if the system time is changed by user */
        if (mtime < sit_i->min_mtime)
                sit_i->min_mtime = mtime;
        if (mtime > sit_i->max_mtime)
                sit_i->max_mtime = mtime;
        if (sit_i->max_mtime != sit_i->min_mtime)
                age = 100 - div64_u64(100 * (mtime - sit_i->min_mtime),
                                sit_i->max_mtime - sit_i->min_mtime);

        return UINT_MAX - ((100 * (100 - u) * age) / (100 + u));
}

static inline unsigned int get_gc_cost(struct f2fs_sb_info *sbi,
                        unsigned int segno, struct victim_sel_policy *p)
{
        if (p->alloc_mode == SSR)
                return get_seg_entry(sbi, segno)->ckpt_valid_blocks;

        /* alloc_mode == LFS */
        if (p->gc_mode == GC_GREEDY)
                return get_valid_blocks(sbi, segno, sbi->segs_per_sec);
        else
                return get_cb_cost(sbi, segno);
}

/*
 * This function is called from two paths.
 * One is garbage collection and the other is SSR segment selection.
 * When it is called during GC, it just gets a victim segment
 * and it does not remove it from dirty seglist.
 * When it is called from SSR segment selection, it finds a segment
 * which has minimum valid blocks and removes it from dirty seglist.
 */
static int get_victim_by_default(struct f2fs_sb_info *sbi,
                unsigned int *result, int gc_type, int type, char alloc_mode)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        struct victim_sel_policy p;
        unsigned int secno, max_cost;
        int nsearched = 0;

        p.alloc_mode = alloc_mode;
        select_policy(sbi, gc_type, type, &p);

        p.min_segno = NULL_SEGNO;
        p.min_cost = max_cost = get_max_cost(sbi, &p);

        mutex_lock(&dirty_i->seglist_lock);

        if (p.alloc_mode == LFS && gc_type == FG_GC) {
                p.min_segno = check_bg_victims(sbi);
                if (p.min_segno != NULL_SEGNO)
                        goto got_it;
        }

        while (1) {
                unsigned long cost;
                unsigned int segno;

                segno = find_next_bit(p.dirty_segmap,
                                                TOTAL_SEGS(sbi), p.offset);
                if (segno >= TOTAL_SEGS(sbi)) {
                        if (sbi->last_victim[p.gc_mode]) {
                                sbi->last_victim[p.gc_mode] = 0;
                                p.offset = 0;
                                continue;
                        }
                        break;
                }

                p.offset = segno + p.ofs_unit;
                if (p.ofs_unit > 1)
                        p.offset -= segno % p.ofs_unit;

                secno = GET_SECNO(sbi, segno);

                if (sec_usage_check(sbi, secno))
                        continue;
                if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
                        continue;

                cost = get_gc_cost(sbi, segno, &p);

                if (p.min_cost > cost) {
                        p.min_segno = segno;
                        p.min_cost = cost;
                } else if (unlikely(cost == max_cost)) {
                        continue;
                }

                if (nsearched++ >= p.max_search) {
                        sbi->last_victim[p.gc_mode] = segno;
                        break;
                }
        }
        if (p.min_segno != NULL_SEGNO) {
got_it:
                if (p.alloc_mode == LFS) {
                        secno = GET_SECNO(sbi, p.min_segno);
                        if (gc_type == FG_GC)
                                sbi->cur_victim_sec = secno;
                        else
                                set_bit(secno, dirty_i->victim_secmap);
                }
                *result = (p.min_segno / p.ofs_unit) * p.ofs_unit;

                trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
                                sbi->cur_victim_sec,
                                prefree_segments(sbi), free_segments(sbi));
        }
        mutex_unlock(&dirty_i->seglist_lock);

        return (p.min_segno == NULL_SEGNO) ? 0 : 1;
}

static const struct victim_selection default_v_ops = {
        .get_victim = get_victim_by_default,
};

static struct inode *find_gc_inode(nid_t ino, struct list_head *ilist)
{
        struct inode_entry *ie;

        list_for_each_entry(ie, ilist, list)
                if (ie->inode->i_ino == ino)
                        return ie->inode;
        return NULL;
}

static void add_gc_inode(struct inode *inode, struct list_head *ilist)
{
        struct inode_entry *new_ie;

        if (inode == find_gc_inode(inode->i_ino, ilist)) {
                iput(inode);
                return;
        }

        new_ie = f2fs_kmem_cache_alloc(winode_slab, GFP_NOFS);
        new_ie->inode = inode;
        list_add_tail(&new_ie->list, ilist);
}

static void put_gc_inode(struct list_head *ilist)
{
        struct inode_entry *ie, *next_ie;
        list_for_each_entry_safe(ie, next_ie, ilist, list) {
                iput(ie->inode);
                list_del(&ie->list);
                kmem_cache_free(winode_slab, ie);
        }
}

static int check_valid_map(struct f2fs_sb_info *sbi,
                                unsigned int segno, int offset)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct seg_entry *sentry;
        int ret;

        mutex_lock(&sit_i->sentry_lock);
        sentry = get_seg_entry(sbi, segno);
        ret = f2fs_test_bit(offset, sentry->cur_valid_map);
        mutex_unlock(&sit_i->sentry_lock);
        return ret;
}

/*
 * This function compares node address got in summary with that in NAT.
 * On validity, copy that node with cold status, otherwise (invalid node)
 * ignore that.
 */
static void gc_node_segment(struct f2fs_sb_info *sbi,
                struct f2fs_summary *sum, unsigned int segno, int gc_type)
{
        bool initial = true;
        struct f2fs_summary *entry;
        int off;

next_step:
        entry = sum;

        for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
                nid_t nid = le32_to_cpu(entry->nid);
                struct page *node_page;

                /* stop BG_GC if there is not enough free sections. */
                if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
                        return;

                if (check_valid_map(sbi, segno, off) == 0)
                        continue;

                if (initial) {
                        ra_node_page(sbi, nid);
                        continue;
                }
                node_page = get_node_page(sbi, nid);
                if (IS_ERR(node_page))
                        continue;

                /* set page dirty and write it */
                if (gc_type == FG_GC) {
                        f2fs_wait_on_page_writeback(node_page, NODE, true);
                        set_page_dirty(node_page);
                } else {
                        if (!PageWriteback(node_page))
                                set_page_dirty(node_page);
                }
                f2fs_put_page(node_page, 1);
                stat_inc_node_blk_count(sbi, 1);
        }

        if (initial) {
                initial = false;
                goto next_step;
        }

        if (gc_type == FG_GC) {
                struct writeback_control wbc = {
                        .sync_mode = WB_SYNC_ALL,
                        .nr_to_write = LONG_MAX,
                        .for_reclaim = 0,
                };
                sync_node_pages(sbi, 0, &wbc);

                /*
                 * In the case of FG_GC, it'd be better to reclaim this victim
                 * completely.
                 */
                if (get_valid_blocks(sbi, segno, 1) != 0)
                        goto next_step;
        }
}

/*
 * Calculate start block index indicating the given node offset.
 * Be careful, caller should give this node offset only indicating direct node
 * blocks. If any node offsets, which point the other types of node blocks such
 * as indirect or double indirect node blocks, are given, it must be a caller's
 * bug.
 */
block_t start_bidx_of_node(unsigned int node_ofs, struct f2fs_inode_info *fi)
{
        unsigned int indirect_blks = 2 * NIDS_PER_BLOCK + 4;
        unsigned int bidx;

        if (node_ofs == 0)
                return 0;

        if (node_ofs <= 2) {
                bidx = node_ofs - 1;
        } else if (node_ofs <= indirect_blks) {
                int dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1);
                bidx = node_ofs - 2 - dec;
        } else {
                int dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1);
                bidx = node_ofs - 5 - dec;
        }
        return bidx * ADDRS_PER_BLOCK + ADDRS_PER_INODE(fi);
}

static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
                struct node_info *dni, block_t blkaddr, unsigned int *nofs)
{
        struct page *node_page;
        nid_t nid;
        unsigned int ofs_in_node;
        block_t source_blkaddr;

        nid = le32_to_cpu(sum->nid);
        ofs_in_node = le16_to_cpu(sum->ofs_in_node);

        node_page = get_node_page(sbi, nid);
        if (IS_ERR(node_page))
                return 0;

        get_node_info(sbi, nid, dni);

        if (sum->version != dni->version) {
                f2fs_put_page(node_page, 1);
                return 0;
        }

        *nofs = ofs_of_node(node_page);
        source_blkaddr = datablock_addr(node_page, ofs_in_node);
        f2fs_put_page(node_page, 1);

        if (source_blkaddr != blkaddr)
                return 0;
        return 1;
}

static void move_data_page(struct inode *inode, struct page *page, int gc_type)
{
        if (gc_type == BG_GC) {
                if (PageWriteback(page))
                        goto out;
                set_page_dirty(page);
                set_cold_data(page);
        } else {
                struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);

                f2fs_wait_on_page_writeback(page, DATA, true);

                if (clear_page_dirty_for_io(page) &&
                        S_ISDIR(inode->i_mode)) {
                        dec_page_count(sbi, F2FS_DIRTY_DENTS);
                        inode_dec_dirty_dents(inode);
                }
                set_cold_data(page);
                do_write_data_page(page);
                clear_cold_data(page);
        }
out:
        f2fs_put_page(page, 1);
}

/*
 * This function tries to get parent node of victim data block, and identifies
 * data block validity. If the block is valid, copy that with cold status and
 * modify parent node.
 * If the parent node is not valid or the data block address is different,
 * the victim data block is ignored.
 */
static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
                struct list_head *ilist, unsigned int segno, int gc_type)
{
        struct super_block *sb = sbi->sb;
        struct f2fs_summary *entry;
        block_t start_addr;
        int off;
        int phase = 0;

        start_addr = START_BLOCK(sbi, segno);

next_step:
        entry = sum;

        for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
                struct page *data_page;
                struct inode *inode;
                struct node_info dni; /* dnode info for the data */
                unsigned int ofs_in_node, nofs;
                block_t start_bidx;

                /* stop BG_GC if there is not enough free sections. */
                if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
                        return;

                if (check_valid_map(sbi, segno, off) == 0)
                        continue;

                if (phase == 0) {
                        ra_node_page(sbi, le32_to_cpu(entry->nid));
                        continue;
                }

                /* Get an inode by ino with checking validity */
                if (check_dnode(sbi, entry, &dni, start_addr + off, &nofs) == 0)
                        continue;

                if (phase == 1) {
                        ra_node_page(sbi, dni.ino);
                        continue;
                }

                ofs_in_node = le16_to_cpu(entry->ofs_in_node);

                if (phase == 2) {
                        inode = f2fs_iget(sb, dni.ino);
                        if (IS_ERR(inode))
                                continue;

                        start_bidx = start_bidx_of_node(nofs, F2FS_I(inode));

                        data_page = find_data_page(inode,
                                        start_bidx + ofs_in_node, false);
                        if (IS_ERR(data_page))
                                goto next_iput;

                        f2fs_put_page(data_page, 0);
                        add_gc_inode(inode, ilist);
                } else {
                        inode = find_gc_inode(dni.ino, ilist);
                        if (inode) {
                                start_bidx = start_bidx_of_node(nofs,
                                                                F2FS_I(inode));
                                data_page = get_lock_data_page(inode,
                                                start_bidx + ofs_in_node);
                                if (IS_ERR(data_page))
                                        continue;
                                move_data_page(inode, data_page, gc_type);
                                stat_inc_data_blk_count(sbi, 1);
                        }
                }
                continue;
next_iput:
                iput(inode);
        }

        if (++phase < 4)
                goto next_step;

        if (gc_type == FG_GC) {
                f2fs_submit_merged_bio(sbi, DATA, true, WRITE);

                /*
                 * In the case of FG_GC, it'd be better to reclaim this victim
                 * completely.
                 */
                if (get_valid_blocks(sbi, segno, 1) != 0) {
                        phase = 2;
                        goto next_step;
                }
        }
}

static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
                                                int gc_type, int type)
{
        struct sit_info *sit_i = SIT_I(sbi);
        int ret;
        mutex_lock(&sit_i->sentry_lock);
        ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type, type, LFS);
        mutex_unlock(&sit_i->sentry_lock);
        return ret;
}

static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
                                struct list_head *ilist, int gc_type)
{
        struct page *sum_page;
        struct f2fs_summary_block *sum;
        struct blk_plug plug;

        /* read segment summary of victim */
        sum_page = get_sum_page(sbi, segno);

        blk_start_plug(&plug);

        sum = page_address(sum_page);

        switch (GET_SUM_TYPE((&sum->footer))) {
        case SUM_TYPE_NODE:
                gc_node_segment(sbi, sum->entries, segno, gc_type);
                break;
        case SUM_TYPE_DATA:
                gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);
                break;
        }
        blk_finish_plug(&plug);

        stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
        stat_inc_call_count(sbi->stat_info);

        f2fs_put_page(sum_page, 1);
}

int f2fs_gc(struct f2fs_sb_info *sbi)
{
        struct list_head ilist;
        unsigned int segno, i;
        int gc_type = BG_GC;
        int nfree = 0;
        int ret = -1;

        INIT_LIST_HEAD(&ilist);
gc_more:
        if (unlikely(!(sbi->sb->s_flags & MS_ACTIVE)))
                goto stop;

        if (gc_type == BG_GC && has_not_enough_free_secs(sbi, nfree)) {
                gc_type = FG_GC;
                write_checkpoint(sbi, false);
        }

        if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
                goto stop;
        ret = 0;

        for (i = 0; i < sbi->segs_per_sec; i++)
                do_garbage_collect(sbi, segno + i, &ilist, gc_type);

        if (gc_type == FG_GC) {
                sbi->cur_victim_sec = NULL_SEGNO;
                nfree++;
                WARN_ON(get_valid_blocks(sbi, segno, sbi->segs_per_sec));
        }

        if (has_not_enough_free_secs(sbi, nfree))
                goto gc_more;

        if (gc_type == FG_GC)
                write_checkpoint(sbi, false);
stop:
        mutex_unlock(&sbi->gc_mutex);

        put_gc_inode(&ilist);
        return ret;
}

void build_gc_manager(struct f2fs_sb_info *sbi)
{
        DIRTY_I(sbi)->v_ops = &default_v_ops;
}

int __init create_gc_caches(void)
{
        winode_slab = f2fs_kmem_cache_create("f2fs_gc_inodes",
                        sizeof(struct inode_entry), NULL);
        if (!winode_slab)
                return -ENOMEM;
        return 0;
}

void destroy_gc_caches(void)
{
        kmem_cache_destroy(winode_slab);
}