4 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
5 * http://www.samsung.com/
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
12 #include <linux/module.h>
13 #include <linux/backing-dev.h>
14 #include <linux/proc_fs.h>
15 #include <linux/init.h>
16 #include <linux/f2fs_fs.h>
17 #include <linux/kthread.h>
18 #include <linux/delay.h>
19 #include <linux/freezer.h>
20 #include <linux/blkdev.h>
26 #include <trace/events/f2fs.h>
28 static struct kmem_cache *winode_slab;
30 static int gc_thread_func(void *data)
32 struct f2fs_sb_info *sbi = data;
33 wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
36 wait_ms = GC_THREAD_MIN_SLEEP_TIME;
42 wait_event_interruptible_timeout(*wq,
43 kthread_should_stop(),
44 msecs_to_jiffies(wait_ms));
45 if (kthread_should_stop())
48 if (sbi->sb->s_writers.frozen >= SB_FREEZE_WRITE) {
49 wait_ms = GC_THREAD_MAX_SLEEP_TIME;
54 * [GC triggering condition]
55 * 0. GC is not conducted currently.
56 * 1. There are enough dirty segments.
57 * 2. IO subsystem is idle by checking the # of writeback pages.
58 * 3. IO subsystem is idle by checking the # of requests in
59 * bdev's request list.
61 * Note) We have to avoid triggering GCs too much frequently.
62 * Because it is possible that some segments can be
63 * invalidated soon after by user update or deletion.
64 * So, I'd like to wait some time to collect dirty segments.
66 if (!mutex_trylock(&sbi->gc_mutex))
70 wait_ms = increase_sleep_time(wait_ms);
71 mutex_unlock(&sbi->gc_mutex);
75 if (has_enough_invalid_blocks(sbi))
76 wait_ms = decrease_sleep_time(wait_ms);
78 wait_ms = increase_sleep_time(wait_ms);
82 /* if return value is not zero, no victim was selected */
84 wait_ms = GC_THREAD_NOGC_SLEEP_TIME;
85 } while (!kthread_should_stop());
89 int start_gc_thread(struct f2fs_sb_info *sbi)
91 struct f2fs_gc_kthread *gc_th;
92 dev_t dev = sbi->sb->s_bdev->bd_dev;
94 if (!test_opt(sbi, BG_GC))
96 gc_th = kmalloc(sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
100 sbi->gc_thread = gc_th;
101 init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
102 sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
103 "f2fs_gc-%u:%u", MAJOR(dev), MINOR(dev));
104 if (IS_ERR(gc_th->f2fs_gc_task)) {
106 sbi->gc_thread = NULL;
112 void stop_gc_thread(struct f2fs_sb_info *sbi)
114 struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
117 kthread_stop(gc_th->f2fs_gc_task);
119 sbi->gc_thread = NULL;
122 static int select_gc_type(int gc_type)
124 return (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
127 static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
128 int type, struct victim_sel_policy *p)
130 struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
132 if (p->alloc_mode == SSR) {
133 p->gc_mode = GC_GREEDY;
134 p->dirty_segmap = dirty_i->dirty_segmap[type];
137 p->gc_mode = select_gc_type(gc_type);
138 p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
139 p->ofs_unit = sbi->segs_per_sec;
141 p->offset = sbi->last_victim[p->gc_mode];
144 static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
145 struct victim_sel_policy *p)
147 /* SSR allocates in a segment unit */
148 if (p->alloc_mode == SSR)
149 return 1 << sbi->log_blocks_per_seg;
150 if (p->gc_mode == GC_GREEDY)
151 return (1 << sbi->log_blocks_per_seg) * p->ofs_unit;
152 else if (p->gc_mode == GC_CB)
154 else /* No other gc_mode */
158 static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
160 struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
161 unsigned int hint = 0;
165 * If the gc_type is FG_GC, we can select victim segments
166 * selected by background GC before.
167 * Those segments guarantee they have small valid blocks.
170 secno = find_next_bit(dirty_i->victim_secmap, TOTAL_SECS(sbi), hint++);
171 if (secno < TOTAL_SECS(sbi)) {
172 if (sec_usage_check(sbi, secno))
174 clear_bit(secno, dirty_i->victim_secmap);
175 return secno * sbi->segs_per_sec;
180 static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned int segno)
182 struct sit_info *sit_i = SIT_I(sbi);
183 unsigned int secno = GET_SECNO(sbi, segno);
184 unsigned int start = secno * sbi->segs_per_sec;
185 unsigned long long mtime = 0;
186 unsigned int vblocks;
187 unsigned char age = 0;
191 for (i = 0; i < sbi->segs_per_sec; i++)
192 mtime += get_seg_entry(sbi, start + i)->mtime;
193 vblocks = get_valid_blocks(sbi, segno, sbi->segs_per_sec);
195 mtime = div_u64(mtime, sbi->segs_per_sec);
196 vblocks = div_u64(vblocks, sbi->segs_per_sec);
198 u = (vblocks * 100) >> sbi->log_blocks_per_seg;
200 /* Handle if the system time is changed by user */
201 if (mtime < sit_i->min_mtime)
202 sit_i->min_mtime = mtime;
203 if (mtime > sit_i->max_mtime)
204 sit_i->max_mtime = mtime;
205 if (sit_i->max_mtime != sit_i->min_mtime)
206 age = 100 - div64_u64(100 * (mtime - sit_i->min_mtime),
207 sit_i->max_mtime - sit_i->min_mtime);
209 return UINT_MAX - ((100 * (100 - u) * age) / (100 + u));
212 static unsigned int get_gc_cost(struct f2fs_sb_info *sbi, unsigned int segno,
213 struct victim_sel_policy *p)
215 if (p->alloc_mode == SSR)
216 return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
218 /* alloc_mode == LFS */
219 if (p->gc_mode == GC_GREEDY)
220 return get_valid_blocks(sbi, segno, sbi->segs_per_sec);
222 return get_cb_cost(sbi, segno);
226 * This function is called from two paths.
227 * One is garbage collection and the other is SSR segment selection.
228 * When it is called during GC, it just gets a victim segment
229 * and it does not remove it from dirty seglist.
230 * When it is called from SSR segment selection, it finds a segment
231 * which has minimum valid blocks and removes it from dirty seglist.
233 static int get_victim_by_default(struct f2fs_sb_info *sbi,
234 unsigned int *result, int gc_type, int type, char alloc_mode)
236 struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
237 struct victim_sel_policy p;
241 p.alloc_mode = alloc_mode;
242 select_policy(sbi, gc_type, type, &p);
244 p.min_segno = NULL_SEGNO;
245 p.min_cost = get_max_cost(sbi, &p);
247 mutex_lock(&dirty_i->seglist_lock);
249 if (p.alloc_mode == LFS && gc_type == FG_GC) {
250 p.min_segno = check_bg_victims(sbi);
251 if (p.min_segno != NULL_SEGNO)
259 segno = find_next_bit(p.dirty_segmap,
260 TOTAL_SEGS(sbi), p.offset);
261 if (segno >= TOTAL_SEGS(sbi)) {
262 if (sbi->last_victim[p.gc_mode]) {
263 sbi->last_victim[p.gc_mode] = 0;
269 p.offset = ((segno / p.ofs_unit) * p.ofs_unit) + p.ofs_unit;
270 secno = GET_SECNO(sbi, segno);
272 if (sec_usage_check(sbi, secno))
274 if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
277 cost = get_gc_cost(sbi, segno, &p);
279 if (p.min_cost > cost) {
284 if (cost == get_max_cost(sbi, &p))
287 if (nsearched++ >= MAX_VICTIM_SEARCH) {
288 sbi->last_victim[p.gc_mode] = segno;
293 if (p.min_segno != NULL_SEGNO) {
294 if (p.alloc_mode == LFS) {
295 secno = GET_SECNO(sbi, p.min_segno);
296 if (gc_type == FG_GC)
297 sbi->cur_victim_sec = secno;
299 set_bit(secno, dirty_i->victim_secmap);
301 *result = (p.min_segno / p.ofs_unit) * p.ofs_unit;
303 trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
305 prefree_segments(sbi), free_segments(sbi));
307 mutex_unlock(&dirty_i->seglist_lock);
309 return (p.min_segno == NULL_SEGNO) ? 0 : 1;
312 static const struct victim_selection default_v_ops = {
313 .get_victim = get_victim_by_default,
316 static struct inode *find_gc_inode(nid_t ino, struct list_head *ilist)
318 struct list_head *this;
319 struct inode_entry *ie;
321 list_for_each(this, ilist) {
322 ie = list_entry(this, struct inode_entry, list);
323 if (ie->inode->i_ino == ino)
329 static void add_gc_inode(struct inode *inode, struct list_head *ilist)
331 struct list_head *this;
332 struct inode_entry *new_ie, *ie;
334 list_for_each(this, ilist) {
335 ie = list_entry(this, struct inode_entry, list);
336 if (ie->inode == inode) {
342 new_ie = kmem_cache_alloc(winode_slab, GFP_NOFS);
347 new_ie->inode = inode;
348 list_add_tail(&new_ie->list, ilist);
351 static void put_gc_inode(struct list_head *ilist)
353 struct inode_entry *ie, *next_ie;
354 list_for_each_entry_safe(ie, next_ie, ilist, list) {
357 kmem_cache_free(winode_slab, ie);
361 static int check_valid_map(struct f2fs_sb_info *sbi,
362 unsigned int segno, int offset)
364 struct sit_info *sit_i = SIT_I(sbi);
365 struct seg_entry *sentry;
368 mutex_lock(&sit_i->sentry_lock);
369 sentry = get_seg_entry(sbi, segno);
370 ret = f2fs_test_bit(offset, sentry->cur_valid_map);
371 mutex_unlock(&sit_i->sentry_lock);
376 * This function compares node address got in summary with that in NAT.
377 * On validity, copy that node with cold status, otherwise (invalid node)
380 static void gc_node_segment(struct f2fs_sb_info *sbi,
381 struct f2fs_summary *sum, unsigned int segno, int gc_type)
384 struct f2fs_summary *entry;
390 for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
391 nid_t nid = le32_to_cpu(entry->nid);
392 struct page *node_page;
394 /* stop BG_GC if there is not enough free sections. */
395 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
398 if (check_valid_map(sbi, segno, off) == 0)
402 ra_node_page(sbi, nid);
405 node_page = get_node_page(sbi, nid);
406 if (IS_ERR(node_page))
409 /* set page dirty and write it */
410 if (gc_type == FG_GC) {
411 f2fs_submit_bio(sbi, NODE, true);
412 wait_on_page_writeback(node_page);
413 set_page_dirty(node_page);
415 if (!PageWriteback(node_page))
416 set_page_dirty(node_page);
418 f2fs_put_page(node_page, 1);
419 stat_inc_node_blk_count(sbi, 1);
427 if (gc_type == FG_GC) {
428 struct writeback_control wbc = {
429 .sync_mode = WB_SYNC_ALL,
430 .nr_to_write = LONG_MAX,
433 sync_node_pages(sbi, 0, &wbc);
436 * In the case of FG_GC, it'd be better to reclaim this victim
439 if (get_valid_blocks(sbi, segno, 1) != 0)
445 * Calculate start block index indicating the given node offset.
446 * Be careful, caller should give this node offset only indicating direct node
447 * blocks. If any node offsets, which point the other types of node blocks such
448 * as indirect or double indirect node blocks, are given, it must be a caller's
451 block_t start_bidx_of_node(unsigned int node_ofs)
453 unsigned int indirect_blks = 2 * NIDS_PER_BLOCK + 4;
461 } else if (node_ofs <= indirect_blks) {
462 int dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1);
463 bidx = node_ofs - 2 - dec;
465 int dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1);
466 bidx = node_ofs - 5 - dec;
468 return bidx * ADDRS_PER_BLOCK + ADDRS_PER_INODE;
471 static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
472 struct node_info *dni, block_t blkaddr, unsigned int *nofs)
474 struct page *node_page;
476 unsigned int ofs_in_node;
477 block_t source_blkaddr;
479 nid = le32_to_cpu(sum->nid);
480 ofs_in_node = le16_to_cpu(sum->ofs_in_node);
482 node_page = get_node_page(sbi, nid);
483 if (IS_ERR(node_page))
486 get_node_info(sbi, nid, dni);
488 if (sum->version != dni->version) {
489 f2fs_put_page(node_page, 1);
493 *nofs = ofs_of_node(node_page);
494 source_blkaddr = datablock_addr(node_page, ofs_in_node);
495 f2fs_put_page(node_page, 1);
497 if (source_blkaddr != blkaddr)
502 static void move_data_page(struct inode *inode, struct page *page, int gc_type)
504 if (gc_type == BG_GC) {
505 if (PageWriteback(page))
507 set_page_dirty(page);
510 struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
512 if (PageWriteback(page)) {
513 f2fs_submit_bio(sbi, DATA, true);
514 wait_on_page_writeback(page);
517 if (clear_page_dirty_for_io(page) &&
518 S_ISDIR(inode->i_mode)) {
519 dec_page_count(sbi, F2FS_DIRTY_DENTS);
520 inode_dec_dirty_dents(inode);
523 do_write_data_page(page);
524 clear_cold_data(page);
527 f2fs_put_page(page, 1);
531 * This function tries to get parent node of victim data block, and identifies
532 * data block validity. If the block is valid, copy that with cold status and
533 * modify parent node.
534 * If the parent node is not valid or the data block address is different,
535 * the victim data block is ignored.
537 static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
538 struct list_head *ilist, unsigned int segno, int gc_type)
540 struct super_block *sb = sbi->sb;
541 struct f2fs_summary *entry;
546 start_addr = START_BLOCK(sbi, segno);
551 for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
552 struct page *data_page;
554 struct node_info dni; /* dnode info for the data */
555 unsigned int ofs_in_node, nofs;
558 /* stop BG_GC if there is not enough free sections. */
559 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
562 if (check_valid_map(sbi, segno, off) == 0)
566 ra_node_page(sbi, le32_to_cpu(entry->nid));
570 /* Get an inode by ino with checking validity */
571 if (check_dnode(sbi, entry, &dni, start_addr + off, &nofs) == 0)
575 ra_node_page(sbi, dni.ino);
579 start_bidx = start_bidx_of_node(nofs);
580 ofs_in_node = le16_to_cpu(entry->ofs_in_node);
583 inode = f2fs_iget(sb, dni.ino);
587 data_page = find_data_page(inode,
588 start_bidx + ofs_in_node, false);
589 if (IS_ERR(data_page))
592 f2fs_put_page(data_page, 0);
593 add_gc_inode(inode, ilist);
595 inode = find_gc_inode(dni.ino, ilist);
597 data_page = get_lock_data_page(inode,
598 start_bidx + ofs_in_node);
599 if (IS_ERR(data_page))
601 move_data_page(inode, data_page, gc_type);
602 stat_inc_data_blk_count(sbi, 1);
613 if (gc_type == FG_GC) {
614 f2fs_submit_bio(sbi, DATA, true);
617 * In the case of FG_GC, it'd be better to reclaim this victim
620 if (get_valid_blocks(sbi, segno, 1) != 0) {
627 static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
628 int gc_type, int type)
630 struct sit_info *sit_i = SIT_I(sbi);
632 mutex_lock(&sit_i->sentry_lock);
633 ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type, type, LFS);
634 mutex_unlock(&sit_i->sentry_lock);
638 static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
639 struct list_head *ilist, int gc_type)
641 struct page *sum_page;
642 struct f2fs_summary_block *sum;
643 struct blk_plug plug;
645 /* read segment summary of victim */
646 sum_page = get_sum_page(sbi, segno);
647 if (IS_ERR(sum_page))
650 blk_start_plug(&plug);
652 sum = page_address(sum_page);
654 switch (GET_SUM_TYPE((&sum->footer))) {
656 gc_node_segment(sbi, sum->entries, segno, gc_type);
659 gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);
662 blk_finish_plug(&plug);
664 stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
665 stat_inc_call_count(sbi->stat_info);
667 f2fs_put_page(sum_page, 1);
670 int f2fs_gc(struct f2fs_sb_info *sbi)
672 struct list_head ilist;
673 unsigned int segno, i;
678 INIT_LIST_HEAD(&ilist);
680 if (!(sbi->sb->s_flags & MS_ACTIVE))
683 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, nfree)) {
685 write_checkpoint(sbi, false);
688 if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
692 for (i = 0; i < sbi->segs_per_sec; i++)
693 do_garbage_collect(sbi, segno + i, &ilist, gc_type);
695 if (gc_type == FG_GC) {
696 sbi->cur_victim_sec = NULL_SEGNO;
698 WARN_ON(get_valid_blocks(sbi, segno, sbi->segs_per_sec));
701 if (has_not_enough_free_secs(sbi, nfree))
704 if (gc_type == FG_GC)
705 write_checkpoint(sbi, false);
707 mutex_unlock(&sbi->gc_mutex);
709 put_gc_inode(&ilist);
713 void build_gc_manager(struct f2fs_sb_info *sbi)
715 DIRTY_I(sbi)->v_ops = &default_v_ops;
718 int __init create_gc_caches(void)
720 winode_slab = f2fs_kmem_cache_create("f2fs_gc_inodes",
721 sizeof(struct inode_entry), NULL);
727 void destroy_gc_caches(void)
729 kmem_cache_destroy(winode_slab);