/*
* 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 > sbi->max_victim_search)
p->max_search = sbi->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);
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)
{
struct f2fs_io_info fio = {
.type = DATA,
.rw = WRITE_SYNC,
};
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);
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, &fio);
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, 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);
}
