fs/f2fs/gc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * fs/f2fs/gc.c
   4  *
   5  * Copyright (c) 2012 Samsung Electronics Co., Ltd.
   6  *             http://www.samsung.com/
   7  */
   8 #include <linux/fs.h>
   9 #include <linux/module.h>
  10 #include <linux/backing-dev.h>
  11 #include <linux/init.h>
  12 #include <linux/f2fs_fs.h>
  13 #include <linux/kthread.h>
  14 #include <linux/delay.h>
  15 #include <linux/freezer.h>
  16
  17 #include "f2fs.h"
  18 #include "node.h"
  19 #include "segment.h"
  20 #include "gc.h"
  21 #include <trace/events/f2fs.h>
  22
  23 static int gc_thread_func(void *data)
  24 {
  25         struct f2fs_sb_info *sbi = data;
  26         struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
  27         wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
  28         unsigned int wait_ms;
  29
  30         wait_ms = gc_th->min_sleep_time;
  31
  32         set_freezable();
  33         do {
  34                 wait_event_interruptible_timeout(*wq,
  35                                 kthread_should_stop() || freezing(current) ||
  36                                 gc_th->gc_wake,
  37                                 msecs_to_jiffies(wait_ms));
  38
  39                 /* give it a try one time */
  40                 if (gc_th->gc_wake)
  41                         gc_th->gc_wake = 0;
  42
  43                 if (try_to_freeze()) {
  44                         stat_other_skip_bggc_count(sbi);
  45                         continue;
  46                 }
  47                 if (kthread_should_stop())
  48                         break;
  49
  50                 if (sbi->sb->s_writers.frozen >= SB_FREEZE_WRITE) {
  51                         increase_sleep_time(gc_th, &wait_ms);
  52                         stat_other_skip_bggc_count(sbi);
  53                         continue;
  54                 }
  55
  56                 if (time_to_inject(sbi, FAULT_CHECKPOINT)) {
  57                         f2fs_show_injection_info(FAULT_CHECKPOINT);
  58                         f2fs_stop_checkpoint(sbi, false);
  59                 }
  60
  61                 if (!sb_start_write_trylock(sbi->sb)) {
  62                         stat_other_skip_bggc_count(sbi);
  63                         continue;
  64                 }
  65
  66                 /*
  67                  * [GC triggering condition]
  68                  * 0. GC is not conducted currently.
  69                  * 1. There are enough dirty segments.
  70                  * 2. IO subsystem is idle by checking the # of writeback pages.
  71                  * 3. IO subsystem is idle by checking the # of requests in
  72                  *    bdev's request list.
  73                  *
  74                  * Note) We have to avoid triggering GCs frequently.
  75                  * Because it is possible that some segments can be
  76                  * invalidated soon after by user update or deletion.
  77                  * So, I'd like to wait some time to collect dirty segments.
  78                  */
  79                 if (sbi->gc_mode == GC_URGENT) {
  80                         wait_ms = gc_th->urgent_sleep_time;
  81                         mutex_lock(&sbi->gc_mutex);
  82                         goto do_gc;
  83                 }
  84
  85                 if (!mutex_trylock(&sbi->gc_mutex)) {
  86                         stat_other_skip_bggc_count(sbi);
  87                         goto next;
  88                 }
  89
  90                 if (!is_idle(sbi, GC_TIME)) {
  91                         increase_sleep_time(gc_th, &wait_ms);
  92                         mutex_unlock(&sbi->gc_mutex);
  93                         stat_io_skip_bggc_count(sbi);
  94                         goto next;
  95                 }
  96
  97                 if (has_enough_invalid_blocks(sbi))
  98                         decrease_sleep_time(gc_th, &wait_ms);
  99                 else
 100                         increase_sleep_time(gc_th, &wait_ms);
 101 do_gc:
 102                 stat_inc_bggc_count(sbi);
 103
 104                 /* if return value is not zero, no victim was selected */
 105                 if (f2fs_gc(sbi, test_opt(sbi, FORCE_FG_GC), true, NULL_SEGNO))
 106                         wait_ms = gc_th->no_gc_sleep_time;
 107
 108                 trace_f2fs_background_gc(sbi->sb, wait_ms,
 109                                 prefree_segments(sbi), free_segments(sbi));
 110
 111                 /* balancing f2fs's metadata periodically */
 112                 f2fs_balance_fs_bg(sbi);
 113 next:
 114                 sb_end_write(sbi->sb);
 115
 116         } while (!kthread_should_stop());
 117         return 0;
 118 }
 119
 120 int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
 121 {
 122         struct f2fs_gc_kthread *gc_th;
 123         dev_t dev = sbi->sb->s_bdev->bd_dev;
 124         int err = 0;
 125
 126         gc_th = f2fs_kmalloc(sbi, sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
 127         if (!gc_th) {
 128                 err = -ENOMEM;
 129                 goto out;
 130         }
 131
 132         gc_th->urgent_sleep_time = DEF_GC_THREAD_URGENT_SLEEP_TIME;
 133         gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME;
 134         gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
 135         gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
 136
 137         gc_th->gc_wake= 0;
 138
 139         sbi->gc_thread = gc_th;
 140         init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
 141         sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
 142                         "f2fs_gc-%u:%u", MAJOR(dev), MINOR(dev));
 143         if (IS_ERR(gc_th->f2fs_gc_task)) {
 144                 err = PTR_ERR(gc_th->f2fs_gc_task);
 145                 kvfree(gc_th);
 146                 sbi->gc_thread = NULL;
 147         }
 148 out:
 149         return err;
 150 }
 151
 152 void f2fs_stop_gc_thread(struct f2fs_sb_info *sbi)
 153 {
 154         struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
 155         if (!gc_th)
 156                 return;
 157         kthread_stop(gc_th->f2fs_gc_task);
 158         kvfree(gc_th);
 159         sbi->gc_thread = NULL;
 160 }
 161
 162 static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
 163 {
 164         int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
 165
 166         switch (sbi->gc_mode) {
 167         case GC_IDLE_CB:
 168                 gc_mode = GC_CB;
 169                 break;
 170         case GC_IDLE_GREEDY:
 171         case GC_URGENT:
 172                 gc_mode = GC_GREEDY;
 173                 break;
 174         }
 175         return gc_mode;
 176 }
 177
 178 static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
 179                         int type, struct victim_sel_policy *p)
 180 {
 181         struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 182
 183         if (p->alloc_mode == SSR) {
 184                 p->gc_mode = GC_GREEDY;
 185                 p->dirty_segmap = dirty_i->dirty_segmap[type];
 186                 p->max_search = dirty_i->nr_dirty[type];
 187                 p->ofs_unit = 1;
 188         } else {
 189                 p->gc_mode = select_gc_type(sbi, gc_type);
 190                 p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
 191                 p->max_search = dirty_i->nr_dirty[DIRTY];
 192                 p->ofs_unit = sbi->segs_per_sec;
 193         }
 194
 195         /* we need to check every dirty segments in the FG_GC case */
 196         if (gc_type != FG_GC &&
 197                         (sbi->gc_mode != GC_URGENT) &&
 198                         p->max_search > sbi->max_victim_search)
 199                 p->max_search = sbi->max_victim_search;
 200
 201         /* let's select beginning hot/small space first in no_heap mode*/
 202         if (test_opt(sbi, NOHEAP) &&
 203                 (type == CURSEG_HOT_DATA || IS_NODESEG(type)))
 204                 p->offset = 0;
 205         else
 206                 p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
 207 }
 208
 209 static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
 210                                 struct victim_sel_policy *p)
 211 {
 212         /* SSR allocates in a segment unit */
 213         if (p->alloc_mode == SSR)
 214                 return sbi->blocks_per_seg;
 215         if (p->gc_mode == GC_GREEDY)
 216                 return 2 * sbi->blocks_per_seg * p->ofs_unit;
 217         else if (p->gc_mode == GC_CB)
 218                 return UINT_MAX;
 219         else /* No other gc_mode */
 220                 return 0;
 221 }
 222
 223 static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
 224 {
 225         struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 226         unsigned int secno;
 227
 228         /*
 229          * If the gc_type is FG_GC, we can select victim segments
 230          * selected by background GC before.
 231          * Those segments guarantee they have small valid blocks.
 232          */
 233         for_each_set_bit(secno, dirty_i->victim_secmap, MAIN_SECS(sbi)) {
 234                 if (sec_usage_check(sbi, secno))
 235                         continue;
 236                 clear_bit(secno, dirty_i->victim_secmap);
 237                 return GET_SEG_FROM_SEC(sbi, secno);
 238         }
 239         return NULL_SEGNO;
 240 }
 241
 242 static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned int segno)
 243 {
 244         struct sit_info *sit_i = SIT_I(sbi);
 245         unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
 246         unsigned int start = GET_SEG_FROM_SEC(sbi, secno);
 247         unsigned long long mtime = 0;
 248         unsigned int vblocks;
 249         unsigned char age = 0;
 250         unsigned char u;
 251         unsigned int i;
 252
 253         for (i = 0; i < sbi->segs_per_sec; i++)
 254                 mtime += get_seg_entry(sbi, start + i)->mtime;
 255         vblocks = get_valid_blocks(sbi, segno, true);
 256
 257         mtime = div_u64(mtime, sbi->segs_per_sec);
 258         vblocks = div_u64(vblocks, sbi->segs_per_sec);
 259
 260         u = (vblocks * 100) >> sbi->log_blocks_per_seg;
 261
 262         /* Handle if the system time has changed by the user */
 263         if (mtime < sit_i->min_mtime)
 264                 sit_i->min_mtime = mtime;
 265         if (mtime > sit_i->max_mtime)
 266                 sit_i->max_mtime = mtime;
 267         if (sit_i->max_mtime != sit_i->min_mtime)
 268                 age = 100 - div64_u64(100 * (mtime - sit_i->min_mtime),
 269                                 sit_i->max_mtime - sit_i->min_mtime);
 270
 271         return UINT_MAX - ((100 * (100 - u) * age) / (100 + u));
 272 }
 273
 274 static inline unsigned int get_gc_cost(struct f2fs_sb_info *sbi,
 275                         unsigned int segno, struct victim_sel_policy *p)
 276 {
 277         if (p->alloc_mode == SSR)
 278                 return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
 279
 280         /* alloc_mode == LFS */
 281         if (p->gc_mode == GC_GREEDY)
 282                 return get_valid_blocks(sbi, segno, true);
 283         else
 284                 return get_cb_cost(sbi, segno);
 285 }
 286
 287 static unsigned int count_bits(const unsigned long *addr,
 288                                 unsigned int offset, unsigned int len)
 289 {
 290         unsigned int end = offset + len, sum = 0;
 291
 292         while (offset < end) {
 293                 if (test_bit(offset++, addr))
 294                         ++sum;
 295         }
 296         return sum;
 297 }
 298
 299 /*
 300  * This function is called from two paths.
 301  * One is garbage collection and the other is SSR segment selection.
 302  * When it is called during GC, it just gets a victim segment
 303  * and it does not remove it from dirty seglist.
 304  * When it is called from SSR segment selection, it finds a segment
 305  * which has minimum valid blocks and removes it from dirty seglist.
 306  */
 307 static int get_victim_by_default(struct f2fs_sb_info *sbi,
 308                 unsigned int *result, int gc_type, int type, char alloc_mode)
 309 {
 310         struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 311         struct sit_info *sm = SIT_I(sbi);
 312         struct victim_sel_policy p;
 313         unsigned int secno, last_victim;
 314         unsigned int last_segment = MAIN_SEGS(sbi);
 315         unsigned int nsearched = 0;
 316
 317         mutex_lock(&dirty_i->seglist_lock);
 318
 319         p.alloc_mode = alloc_mode;
 320         select_policy(sbi, gc_type, type, &p);
 321
 322         p.min_segno = NULL_SEGNO;
 323         p.min_cost = get_max_cost(sbi, &p);
 324
 325         if (*result != NULL_SEGNO) {
 326                 if (get_valid_blocks(sbi, *result, false) &&
 327                         !sec_usage_check(sbi, GET_SEC_FROM_SEG(sbi, *result)))
 328                         p.min_segno = *result;
 329                 goto out;
 330         }
 331
 332         if (p.max_search == 0)
 333                 goto out;
 334
 335         if (__is_large_section(sbi) && p.alloc_mode == LFS) {
 336                 if (sbi->next_victim_seg[BG_GC] != NULL_SEGNO) {
 337                         p.min_segno = sbi->next_victim_seg[BG_GC];
 338                         *result = p.min_segno;
 339                         sbi->next_victim_seg[BG_GC] = NULL_SEGNO;
 340                         goto got_result;
 341                 }
 342                 if (gc_type == FG_GC &&
 343                                 sbi->next_victim_seg[FG_GC] != NULL_SEGNO) {
 344                         p.min_segno = sbi->next_victim_seg[FG_GC];
 345                         *result = p.min_segno;
 346                         sbi->next_victim_seg[FG_GC] = NULL_SEGNO;
 347                         goto got_result;
 348                 }
 349         }
 350
 351         last_victim = sm->last_victim[p.gc_mode];
 352         if (p.alloc_mode == LFS && gc_type == FG_GC) {
 353                 p.min_segno = check_bg_victims(sbi);
 354                 if (p.min_segno != NULL_SEGNO)
 355                         goto got_it;
 356         }
 357
 358         while (1) {
 359                 unsigned long cost;
 360                 unsigned int segno;
 361
 362                 segno = find_next_bit(p.dirty_segmap, last_segment, p.offset);
 363                 if (segno >= last_segment) {
 364                         if (sm->last_victim[p.gc_mode]) {
 365                                 last_segment =
 366                                         sm->last_victim[p.gc_mode];
 367                                 sm->last_victim[p.gc_mode] = 0;
 368                                 p.offset = 0;
 369                                 continue;
 370                         }
 371                         break;
 372                 }
 373
 374                 p.offset = segno + p.ofs_unit;
 375                 if (p.ofs_unit > 1) {
 376                         p.offset -= segno % p.ofs_unit;
 377                         nsearched += count_bits(p.dirty_segmap,
 378                                                 p.offset - p.ofs_unit,
 379                                                 p.ofs_unit);
 380                 } else {
 381                         nsearched++;
 382                 }
 383
 384                 secno = GET_SEC_FROM_SEG(sbi, segno);
 385
 386                 if (sec_usage_check(sbi, secno))
 387                         goto next;
 388                 /* Don't touch checkpointed data */
 389                 if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
 390                                         get_ckpt_valid_blocks(sbi, segno)))
 391                         goto next;
 392                 if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
 393                         goto next;
 394
 395                 cost = get_gc_cost(sbi, segno, &p);
 396
 397                 if (p.min_cost > cost) {
 398                         p.min_segno = segno;
 399                         p.min_cost = cost;
 400                 }
 401 next:
 402                 if (nsearched >= p.max_search) {
 403                         if (!sm->last_victim[p.gc_mode] && segno <= last_victim)
 404                                 sm->last_victim[p.gc_mode] = last_victim + 1;
 405                         else
 406                                 sm->last_victim[p.gc_mode] = segno + 1;
 407                         sm->last_victim[p.gc_mode] %= MAIN_SEGS(sbi);
 408                         break;
 409                 }
 410         }
 411         if (p.min_segno != NULL_SEGNO) {
 412 got_it:
 413                 *result = (p.min_segno / p.ofs_unit) * p.ofs_unit;
 414 got_result:
 415                 if (p.alloc_mode == LFS) {
 416                         secno = GET_SEC_FROM_SEG(sbi, p.min_segno);
 417                         if (gc_type == FG_GC)
 418                                 sbi->cur_victim_sec = secno;
 419                         else
 420                                 set_bit(secno, dirty_i->victim_secmap);
 421                 }
 422
 423         }
 424 out:
 425         if (p.min_segno != NULL_SEGNO)
 426                 trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
 427                                 sbi->cur_victim_sec,
 428                                 prefree_segments(sbi), free_segments(sbi));
 429         mutex_unlock(&dirty_i->seglist_lock);
 430
 431         return (p.min_segno == NULL_SEGNO) ? 0 : 1;
 432 }
 433
 434 static const struct victim_selection default_v_ops = {
 435         .get_victim = get_victim_by_default,
 436 };
 437
 438 static struct inode *find_gc_inode(struct gc_inode_list *gc_list, nid_t ino)
 439 {
 440         struct inode_entry *ie;
 441
 442         ie = radix_tree_lookup(&gc_list->iroot, ino);
 443         if (ie)
 444                 return ie->inode;
 445         return NULL;
 446 }
 447
 448 static void add_gc_inode(struct gc_inode_list *gc_list, struct inode *inode)
 449 {
 450         struct inode_entry *new_ie;
 451
 452         if (inode == find_gc_inode(gc_list, inode->i_ino)) {
 453                 iput(inode);
 454                 return;
 455         }
 456         new_ie = f2fs_kmem_cache_alloc(f2fs_inode_entry_slab, GFP_NOFS);
 457         new_ie->inode = inode;
 458
 459         f2fs_radix_tree_insert(&gc_list->iroot, inode->i_ino, new_ie);
 460         list_add_tail(&new_ie->list, &gc_list->ilist);
 461 }
 462
 463 static void put_gc_inode(struct gc_inode_list *gc_list)
 464 {
 465         struct inode_entry *ie, *next_ie;
 466         list_for_each_entry_safe(ie, next_ie, &gc_list->ilist, list) {
 467                 radix_tree_delete(&gc_list->iroot, ie->inode->i_ino);
 468                 iput(ie->inode);
 469                 list_del(&ie->list);
 470                 kmem_cache_free(f2fs_inode_entry_slab, ie);
 471         }
 472 }
 473
 474 static int check_valid_map(struct f2fs_sb_info *sbi,
 475                                 unsigned int segno, int offset)
 476 {
 477         struct sit_info *sit_i = SIT_I(sbi);
 478         struct seg_entry *sentry;
 479         int ret;
 480
 481         down_read(&sit_i->sentry_lock);
 482         sentry = get_seg_entry(sbi, segno);
 483         ret = f2fs_test_bit(offset, sentry->cur_valid_map);
 484         up_read(&sit_i->sentry_lock);
 485         return ret;
 486 }
 487
 488 /*
 489  * This function compares node address got in summary with that in NAT.
 490  * On validity, copy that node with cold status, otherwise (invalid node)
 491  * ignore that.
 492  */
 493 static int gc_node_segment(struct f2fs_sb_info *sbi,
 494                 struct f2fs_summary *sum, unsigned int segno, int gc_type)
 495 {
 496         struct f2fs_summary *entry;
 497         block_t start_addr;
 498         int off;
 499         int phase = 0;
 500         bool fggc = (gc_type == FG_GC);
 501         int submitted = 0;
 502
 503         start_addr = START_BLOCK(sbi, segno);
 504
 505 next_step:
 506         entry = sum;
 507
 508         if (fggc && phase == 2)
 509                 atomic_inc(&sbi->wb_sync_req[NODE]);
 510
 511         for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
 512                 nid_t nid = le32_to_cpu(entry->nid);
 513                 struct page *node_page;
 514                 struct node_info ni;
 515                 int err;
 516
 517                 /* stop BG_GC if there is not enough free sections. */
 518                 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0))
 519                         return submitted;
 520
 521                 if (check_valid_map(sbi, segno, off) == 0)
 522                         continue;
 523
 524                 if (phase == 0) {
 525                         f2fs_ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nid), 1,
 526                                                         META_NAT, true);
 527                         continue;
 528                 }
 529
 530                 if (phase == 1) {
 531                         f2fs_ra_node_page(sbi, nid);
 532                         continue;
 533                 }
 534
 535                 /* phase == 2 */
 536                 node_page = f2fs_get_node_page(sbi, nid);
 537                 if (IS_ERR(node_page))
 538                         continue;
 539
 540                 /* block may become invalid during f2fs_get_node_page */
 541                 if (check_valid_map(sbi, segno, off) == 0) {
 542                         f2fs_put_page(node_page, 1);
 543                         continue;
 544                 }
 545
 546                 if (f2fs_get_node_info(sbi, nid, &ni)) {
 547                         f2fs_put_page(node_page, 1);
 548                         continue;
 549                 }
 550
 551                 if (ni.blk_addr != start_addr + off) {
 552                         f2fs_put_page(node_page, 1);
 553                         continue;
 554                 }
 555
 556                 err = f2fs_move_node_page(node_page, gc_type);
 557                 if (!err && gc_type == FG_GC)
 558                         submitted++;
 559                 stat_inc_node_blk_count(sbi, 1, gc_type);
 560         }
 561
 562         if (++phase < 3)
 563                 goto next_step;
 564
 565         if (fggc)
 566                 atomic_dec(&sbi->wb_sync_req[NODE]);
 567         return submitted;
 568 }
 569
 570 /*
 571  * Calculate start block index indicating the given node offset.
 572  * Be careful, caller should give this node offset only indicating direct node
 573  * blocks. If any node offsets, which point the other types of node blocks such
 574  * as indirect or double indirect node blocks, are given, it must be a caller's
 575  * bug.
 576  */
 577 block_t f2fs_start_bidx_of_node(unsigned int node_ofs, struct inode *inode)
 578 {
 579         unsigned int indirect_blks = 2 * NIDS_PER_BLOCK + 4;
 580         unsigned int bidx;
 581
 582         if (node_ofs == 0)
 583                 return 0;
 584
 585         if (node_ofs <= 2) {
 586                 bidx = node_ofs - 1;
 587         } else if (node_ofs <= indirect_blks) {
 588                 int dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1);
 589                 bidx = node_ofs - 2 - dec;
 590         } else {
 591                 int dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1);
 592                 bidx = node_ofs - 5 - dec;
 593         }
 594         return bidx * ADDRS_PER_BLOCK + ADDRS_PER_INODE(inode);
 595 }
 596
 597 static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 598                 struct node_info *dni, block_t blkaddr, unsigned int *nofs)
 599 {
 600         struct page *node_page;
 601         nid_t nid;
 602         unsigned int ofs_in_node;
 603         block_t source_blkaddr;
 604
 605         nid = le32_to_cpu(sum->nid);
 606         ofs_in_node = le16_to_cpu(sum->ofs_in_node);
 607
 608         node_page = f2fs_get_node_page(sbi, nid);
 609         if (IS_ERR(node_page))
 610                 return false;
 611
 612         if (f2fs_get_node_info(sbi, nid, dni)) {
 613                 f2fs_put_page(node_page, 1);
 614                 return false;
 615         }
 616
 617         if (sum->version != dni->version) {
 618                 f2fs_msg(sbi->sb, KERN_WARNING,
 619                                 "%s: valid data with mismatched node version.",
 620                                 __func__);
 621                 set_sbi_flag(sbi, SBI_NEED_FSCK);
 622         }
 623
 624         *nofs = ofs_of_node(node_page);
 625         source_blkaddr = datablock_addr(NULL, node_page, ofs_in_node);
 626         f2fs_put_page(node_page, 1);
 627
 628         if (source_blkaddr != blkaddr)
 629                 return false;
 630         return true;
 631 }
 632
 633 static int ra_data_block(struct inode *inode, pgoff_t index)
 634 {
 635         struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 636         struct address_space *mapping = inode->i_mapping;
 637         struct dnode_of_data dn;
 638         struct page *page;
 639         struct extent_info ei = {0, 0, 0};
 640         struct f2fs_io_info fio = {
 641                 .sbi = sbi,
 642                 .ino = inode->i_ino,
 643                 .type = DATA,
 644                 .temp = COLD,
 645                 .op = REQ_OP_READ,
 646                 .op_flags = 0,
 647                 .encrypted_page = NULL,
 648                 .in_list = false,
 649                 .retry = false,
 650         };
 651         int err;
 652
 653         page = f2fs_grab_cache_page(mapping, index, true);
 654         if (!page)
 655                 return -ENOMEM;
 656
 657         if (f2fs_lookup_extent_cache(inode, index, &ei)) {
 658                 dn.data_blkaddr = ei.blk + index - ei.fofs;
 659                 goto got_it;
 660         }
 661
 662         set_new_dnode(&dn, inode, NULL, NULL, 0);
 663         err = f2fs_get_dnode_of_data(&dn, index, LOOKUP_NODE);
 664         if (err)
 665                 goto put_page;
 666         f2fs_put_dnode(&dn);
 667
 668         if (unlikely(!f2fs_is_valid_blkaddr(sbi, dn.data_blkaddr,
 669                                                 DATA_GENERIC))) {
 670                 err = -EFAULT;
 671                 goto put_page;
 672         }
 673 got_it:
 674         /* read page */
 675         fio.page = page;
 676         fio.new_blkaddr = fio.old_blkaddr = dn.data_blkaddr;
 677
 678         /*
 679          * don't cache encrypted data into meta inode until previous dirty
 680          * data were writebacked to avoid racing between GC and flush.
 681          */
 682         f2fs_wait_on_page_writeback(page, DATA, true, true);
 683
 684         f2fs_wait_on_block_writeback(inode, dn.data_blkaddr);
 685
 686         fio.encrypted_page = f2fs_pagecache_get_page(META_MAPPING(sbi),
 687                                         dn.data_blkaddr,
 688                                         FGP_LOCK | FGP_CREAT, GFP_NOFS);
 689         if (!fio.encrypted_page) {
 690                 err = -ENOMEM;
 691                 goto put_page;
 692         }
 693
 694         err = f2fs_submit_page_bio(&fio);
 695         if (err)
 696                 goto put_encrypted_page;
 697         f2fs_put_page(fio.encrypted_page, 0);
 698         f2fs_put_page(page, 1);
 699         return 0;
 700 put_encrypted_page:
 701         f2fs_put_page(fio.encrypted_page, 1);
 702 put_page:
 703         f2fs_put_page(page, 1);
 704         return err;
 705 }
 706
 707 /*
 708  * Move data block via META_MAPPING while keeping locked data page.
 709  * This can be used to move blocks, aka LBAs, directly on disk.
 710  */
 711 static int move_data_block(struct inode *inode, block_t bidx,
 712                                 int gc_type, unsigned int segno, int off)
 713 {
 714         struct f2fs_io_info fio = {
 715                 .sbi = F2FS_I_SB(inode),
 716                 .ino = inode->i_ino,
 717                 .type = DATA,
 718                 .temp = COLD,
 719                 .op = REQ_OP_READ,
 720                 .op_flags = 0,
 721                 .encrypted_page = NULL,
 722                 .in_list = false,
 723                 .retry = false,
 724         };
 725         struct dnode_of_data dn;
 726         struct f2fs_summary sum;
 727         struct node_info ni;
 728         struct page *page, *mpage;
 729         block_t newaddr;
 730         int err = 0;
 731         bool lfs_mode = test_opt(fio.sbi, LFS);
 732
 733         /* do not read out */
 734         page = f2fs_grab_cache_page(inode->i_mapping, bidx, false);
 735         if (!page)
 736                 return -ENOMEM;
 737
 738         if (!check_valid_map(F2FS_I_SB(inode), segno, off)) {
 739                 err = -ENOENT;
 740                 goto out;
 741         }
 742
 743         if (f2fs_is_atomic_file(inode)) {
 744                 F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC]++;
 745                 F2FS_I_SB(inode)->skipped_atomic_files[gc_type]++;
 746                 err = -EAGAIN;
 747                 goto out;
 748         }
 749
 750         if (f2fs_is_pinned_file(inode)) {
 751                 f2fs_pin_file_control(inode, true);
 752                 err = -EAGAIN;
 753                 goto out;
 754         }
 755
 756         set_new_dnode(&dn, inode, NULL, NULL, 0);
 757         err = f2fs_get_dnode_of_data(&dn, bidx, LOOKUP_NODE);
 758         if (err)
 759                 goto out;
 760
 761         if (unlikely(dn.data_blkaddr == NULL_ADDR)) {
 762                 ClearPageUptodate(page);
 763                 err = -ENOENT;
 764                 goto put_out;
 765         }
 766
 767         /*
 768          * don't cache encrypted data into meta inode until previous dirty
 769          * data were writebacked to avoid racing between GC and flush.
 770          */
 771         f2fs_wait_on_page_writeback(page, DATA, true, true);
 772
 773         f2fs_wait_on_block_writeback(inode, dn.data_blkaddr);
 774
 775         err = f2fs_get_node_info(fio.sbi, dn.nid, &ni);
 776         if (err)
 777                 goto put_out;
 778
 779         set_summary(&sum, dn.nid, dn.ofs_in_node, ni.version);
 780
 781         /* read page */
 782         fio.page = page;
 783         fio.new_blkaddr = fio.old_blkaddr = dn.data_blkaddr;
 784
 785         if (lfs_mode)
 786                 down_write(&fio.sbi->io_order_lock);
 787
 788         f2fs_allocate_data_block(fio.sbi, NULL, fio.old_blkaddr, &newaddr,
 789                                         &sum, CURSEG_COLD_DATA, NULL, false);
 790
 791         fio.encrypted_page = f2fs_pagecache_get_page(META_MAPPING(fio.sbi),
 792                                 newaddr, FGP_LOCK | FGP_CREAT, GFP_NOFS);
 793         if (!fio.encrypted_page) {
 794                 err = -ENOMEM;
 795                 goto recover_block;
 796         }
 797
 798         mpage = f2fs_pagecache_get_page(META_MAPPING(fio.sbi),
 799                                         fio.old_blkaddr, FGP_LOCK, GFP_NOFS);
 800         if (mpage) {
 801                 bool updated = false;
 802
 803                 if (PageUptodate(mpage)) {
 804                         memcpy(page_address(fio.encrypted_page),
 805                                         page_address(mpage), PAGE_SIZE);
 806                         updated = true;
 807                 }
 808                 f2fs_put_page(mpage, 1);
 809                 invalidate_mapping_pages(META_MAPPING(fio.sbi),
 810                                         fio.old_blkaddr, fio.old_blkaddr);
 811                 if (updated)
 812                         goto write_page;
 813         }
 814
 815         err = f2fs_submit_page_bio(&fio);
 816         if (err)
 817                 goto put_page_out;
 818
 819         /* write page */
 820         lock_page(fio.encrypted_page);
 821
 822         if (unlikely(fio.encrypted_page->mapping != META_MAPPING(fio.sbi))) {
 823                 err = -EIO;
 824                 goto put_page_out;
 825         }
 826         if (unlikely(!PageUptodate(fio.encrypted_page))) {
 827                 err = -EIO;
 828                 goto put_page_out;
 829         }
 830
 831 write_page:
 832         f2fs_wait_on_page_writeback(fio.encrypted_page, DATA, true, true);
 833         set_page_dirty(fio.encrypted_page);
 834         if (clear_page_dirty_for_io(fio.encrypted_page))
 835                 dec_page_count(fio.sbi, F2FS_DIRTY_META);
 836
 837         set_page_writeback(fio.encrypted_page);
 838         ClearPageError(page);
 839
 840         /* allocate block address */
 841         f2fs_wait_on_page_writeback(dn.node_page, NODE, true, true);
 842
 843         fio.op = REQ_OP_WRITE;
 844         fio.op_flags = REQ_SYNC;
 845         fio.new_blkaddr = newaddr;
 846         f2fs_submit_page_write(&fio);
 847         if (fio.retry) {
 848                 err = -EAGAIN;
 849                 if (PageWriteback(fio.encrypted_page))
 850                         end_page_writeback(fio.encrypted_page);
 851                 goto put_page_out;
 852         }
 853
 854         f2fs_update_iostat(fio.sbi, FS_GC_DATA_IO, F2FS_BLKSIZE);
 855
 856         f2fs_update_data_blkaddr(&dn, newaddr);
 857         set_inode_flag(inode, FI_APPEND_WRITE);
 858         if (page->index == 0)
 859                 set_inode_flag(inode, FI_FIRST_BLOCK_WRITTEN);
 860 put_page_out:
 861         f2fs_put_page(fio.encrypted_page, 1);
 862 recover_block:
 863         if (lfs_mode)
 864                 up_write(&fio.sbi->io_order_lock);
 865         if (err)
 866                 f2fs_do_replace_block(fio.sbi, &sum, newaddr, fio.old_blkaddr,
 867                                                                 true, true);
 868 put_out:
 869         f2fs_put_dnode(&dn);
 870 out:
 871         f2fs_put_page(page, 1);
 872         return err;
 873 }
 874
 875 static int move_data_page(struct inode *inode, block_t bidx, int gc_type,
 876                                                         unsigned int segno, int off)
 877 {
 878         struct page *page;
 879         int err = 0;
 880
 881         page = f2fs_get_lock_data_page(inode, bidx, true);
 882         if (IS_ERR(page))
 883                 return PTR_ERR(page);
 884
 885         if (!check_valid_map(F2FS_I_SB(inode), segno, off)) {
 886                 err = -ENOENT;
 887                 goto out;
 888         }
 889
 890         if (f2fs_is_atomic_file(inode)) {
 891                 F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC]++;
 892                 F2FS_I_SB(inode)->skipped_atomic_files[gc_type]++;
 893                 err = -EAGAIN;
 894                 goto out;
 895         }
 896         if (f2fs_is_pinned_file(inode)) {
 897                 if (gc_type == FG_GC)
 898                         f2fs_pin_file_control(inode, true);
 899                 err = -EAGAIN;
 900                 goto out;
 901         }
 902
 903         if (gc_type == BG_GC) {
 904                 if (PageWriteback(page)) {
 905                         err = -EAGAIN;
 906                         goto out;
 907                 }
 908                 set_page_dirty(page);
 909                 set_cold_data(page);
 910         } else {
 911                 struct f2fs_io_info fio = {
 912                         .sbi = F2FS_I_SB(inode),
 913                         .ino = inode->i_ino,
 914                         .type = DATA,
 915                         .temp = COLD,
 916                         .op = REQ_OP_WRITE,
 917                         .op_flags = REQ_SYNC,
 918                         .old_blkaddr = NULL_ADDR,
 919                         .page = page,
 920                         .encrypted_page = NULL,
 921                         .need_lock = LOCK_REQ,
 922                         .io_type = FS_GC_DATA_IO,
 923                 };
 924                 bool is_dirty = PageDirty(page);
 925
 926 retry:
 927                 f2fs_wait_on_page_writeback(page, DATA, true, true);
 928
 929                 set_page_dirty(page);
 930                 if (clear_page_dirty_for_io(page)) {
 931                         inode_dec_dirty_pages(inode);
 932                         f2fs_remove_dirty_inode(inode);
 933                 }
 934
 935                 set_cold_data(page);
 936
 937                 err = f2fs_do_write_data_page(&fio);
 938                 if (err) {
 939                         clear_cold_data(page);
 940                         if (err == -ENOMEM) {
 941                                 congestion_wait(BLK_RW_ASYNC, HZ/50);
 942                                 goto retry;
 943                         }
 944                         if (is_dirty)
 945                                 set_page_dirty(page);
 946                 }
 947         }
 948 out:
 949         f2fs_put_page(page, 1);
 950         return err;
 951 }
 952
 953 /*
 954  * This function tries to get parent node of victim data block, and identifies
 955  * data block validity. If the block is valid, copy that with cold status and
 956  * modify parent node.
 957  * If the parent node is not valid or the data block address is different,
 958  * the victim data block is ignored.
 959  */
 960 static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 961                 struct gc_inode_list *gc_list, unsigned int segno, int gc_type)
 962 {
 963         struct super_block *sb = sbi->sb;
 964         struct f2fs_summary *entry;
 965         block_t start_addr;
 966         int off;
 967         int phase = 0;
 968         int submitted = 0;
 969
 970         start_addr = START_BLOCK(sbi, segno);
 971
 972 next_step:
 973         entry = sum;
 974
 975         for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
 976                 struct page *data_page;
 977                 struct inode *inode;
 978                 struct node_info dni; /* dnode info for the data */
 979                 unsigned int ofs_in_node, nofs;
 980                 block_t start_bidx;
 981                 nid_t nid = le32_to_cpu(entry->nid);
 982
 983                 /* stop BG_GC if there is not enough free sections. */
 984                 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0))
 985                         return submitted;
 986
 987                 if (check_valid_map(sbi, segno, off) == 0)
 988                         continue;
 989
 990                 if (phase == 0) {
 991                         f2fs_ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nid), 1,
 992                                                         META_NAT, true);
 993                         continue;
 994                 }
 995
 996                 if (phase == 1) {
 997                         f2fs_ra_node_page(sbi, nid);
 998                         continue;
 999                 }
1000
1001                 /* Get an inode by ino with checking validity */
1002                 if (!is_alive(sbi, entry, &dni, start_addr + off, &nofs))
1003                         continue;
1004
1005                 if (phase == 2) {
1006                         f2fs_ra_node_page(sbi, dni.ino);
1007                         continue;
1008                 }
1009
1010                 ofs_in_node = le16_to_cpu(entry->ofs_in_node);
1011
1012                 if (phase == 3) {
1013                         inode = f2fs_iget(sb, dni.ino);
1014                         if (IS_ERR(inode) || is_bad_inode(inode))
1015                                 continue;
1016
1017                         if (!down_write_trylock(
1018                                 &F2FS_I(inode)->i_gc_rwsem[WRITE])) {
1019                                 iput(inode);
1020                                 sbi->skipped_gc_rwsem++;
1021                                 continue;
1022                         }
1023
1024                         start_bidx = f2fs_start_bidx_of_node(nofs, inode) +
1025                                                                 ofs_in_node;
1026
1027                         if (f2fs_post_read_required(inode)) {
1028                                 int err = ra_data_block(inode, start_bidx);
1029
1030                                 up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
1031                                 if (err) {
1032                                         iput(inode);
1033                                         continue;
1034                                 }
1035                                 add_gc_inode(gc_list, inode);
1036                                 continue;
1037                         }
1038
1039                         data_page = f2fs_get_read_data_page(inode,
1040                                                 start_bidx, REQ_RAHEAD, true);
1041                         up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
1042                         if (IS_ERR(data_page)) {
1043                                 iput(inode);
1044                                 continue;
1045                         }
1046
1047                         f2fs_put_page(data_page, 0);
1048                         add_gc_inode(gc_list, inode);
1049                         continue;
1050                 }
1051
1052                 /* phase 4 */
1053                 inode = find_gc_inode(gc_list, dni.ino);
1054                 if (inode) {
1055                         struct f2fs_inode_info *fi = F2FS_I(inode);
1056                         bool locked = false;
1057                         int err;
1058
1059                         if (S_ISREG(inode->i_mode)) {
1060                                 if (!down_write_trylock(&fi->i_gc_rwsem[READ]))
1061                                         continue;
1062                                 if (!down_write_trylock(
1063                                                 &fi->i_gc_rwsem[WRITE])) {
1064                                         sbi->skipped_gc_rwsem++;
1065                                         up_write(&fi->i_gc_rwsem[READ]);
1066                                         continue;
1067                                 }
1068                                 locked = true;
1069
1070                                 /* wait for all inflight aio data */
1071                                 inode_dio_wait(inode);
1072                         }
1073
1074                         start_bidx = f2fs_start_bidx_of_node(nofs, inode)
1075                                                                 + ofs_in_node;
1076                         if (f2fs_post_read_required(inode))
1077                                 err = move_data_block(inode, start_bidx,
1078                                                         gc_type, segno, off);
1079                         else
1080                                 err = move_data_page(inode, start_bidx, gc_type,
1081                                                                 segno, off);
1082
1083                         if (!err && (gc_type == FG_GC ||
1084                                         f2fs_post_read_required(inode)))
1085                                 submitted++;
1086
1087                         if (locked) {
1088                                 up_write(&fi->i_gc_rwsem[WRITE]);
1089                                 up_write(&fi->i_gc_rwsem[READ]);
1090                         }
1091
1092                         stat_inc_data_blk_count(sbi, 1, gc_type);
1093                 }
1094         }
1095
1096         if (++phase < 5)
1097                 goto next_step;
1098
1099         return submitted;
1100 }
1101
1102 static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
1103                         int gc_type)
1104 {
1105         struct sit_info *sit_i = SIT_I(sbi);
1106         int ret;
1107
1108         down_write(&sit_i->sentry_lock);
1109         ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type,
1110                                               NO_CHECK_TYPE, LFS);
1111         up_write(&sit_i->sentry_lock);
1112         return ret;
1113 }
1114
1115 static int do_garbage_collect(struct f2fs_sb_info *sbi,
1116                                 unsigned int start_segno,
1117                                 struct gc_inode_list *gc_list, int gc_type)
1118 {
1119         struct page *sum_page;
1120         struct f2fs_summary_block *sum;
1121         struct blk_plug plug;
1122         unsigned int segno = start_segno;
1123         unsigned int end_segno = start_segno + sbi->segs_per_sec;
1124         int seg_freed = 0, migrated = 0;
1125         unsigned char type = IS_DATASEG(get_seg_entry(sbi, segno)->type) ?
1126                                                 SUM_TYPE_DATA : SUM_TYPE_NODE;
1127         int submitted = 0;
1128
1129         if (__is_large_section(sbi))
1130                 end_segno = rounddown(end_segno, sbi->segs_per_sec);
1131
1132         /* readahead multi ssa blocks those have contiguous address */
1133         if (__is_large_section(sbi))
1134                 f2fs_ra_meta_pages(sbi, GET_SUM_BLOCK(sbi, segno),
1135                                         end_segno - segno, META_SSA, true);
1136
1137         /* reference all summary page */
1138         while (segno < end_segno) {
1139                 sum_page = f2fs_get_sum_page(sbi, segno++);
1140                 if (IS_ERR(sum_page)) {
1141                         int err = PTR_ERR(sum_page);
1142
1143                         end_segno = segno - 1;
1144                         for (segno = start_segno; segno < end_segno; segno++) {
1145                                 sum_page = find_get_page(META_MAPPING(sbi),
1146                                                 GET_SUM_BLOCK(sbi, segno));
1147                                 f2fs_put_page(sum_page, 0);
1148                                 f2fs_put_page(sum_page, 0);
1149                         }
1150                         return err;
1151                 }
1152                 unlock_page(sum_page);
1153         }
1154
1155         blk_start_plug(&plug);
1156
1157         for (segno = start_segno; segno < end_segno; segno++) {
1158
1159                 /* find segment summary of victim */
1160                 sum_page = find_get_page(META_MAPPING(sbi),
1161                                         GET_SUM_BLOCK(sbi, segno));
1162                 f2fs_put_page(sum_page, 0);
1163
1164                 if (get_valid_blocks(sbi, segno, false) == 0)
1165                         goto freed;
1166                 if (__is_large_section(sbi) &&
1167                                 migrated >= sbi->migration_granularity)
1168                         goto skip;
1169                 if (!PageUptodate(sum_page) || unlikely(f2fs_cp_error(sbi)))
1170                         goto skip;
1171
1172                 sum = page_address(sum_page);
1173                 if (type != GET_SUM_TYPE((&sum->footer))) {
1174                         f2fs_msg(sbi->sb, KERN_ERR, "Inconsistent segment (%u) "
1175                                 "type [%d, %d] in SSA and SIT",
1176                                 segno, type, GET_SUM_TYPE((&sum->footer)));
1177                         set_sbi_flag(sbi, SBI_NEED_FSCK);
1178                         goto skip;
1179                 }
1180
1181                 /*
1182                  * this is to avoid deadlock:
1183                  * - lock_page(sum_page)         - f2fs_replace_block
1184                  *  - check_valid_map()            - down_write(sentry_lock)
1185                  *   - down_read(sentry_lock)     - change_curseg()
1186                  *                                  - lock_page(sum_page)
1187                  */
1188                 if (type == SUM_TYPE_NODE)
1189                         submitted += gc_node_segment(sbi, sum->entries, segno,
1190                                                                 gc_type);
1191                 else
1192                         submitted += gc_data_segment(sbi, sum->entries, gc_list,
1193                                                         segno, gc_type);
1194
1195                 stat_inc_seg_count(sbi, type, gc_type);
1196
1197 freed:
1198                 if (gc_type == FG_GC &&
1199                                 get_valid_blocks(sbi, segno, false) == 0)
1200                         seg_freed++;
1201                 migrated++;
1202
1203                 if (__is_large_section(sbi) && segno + 1 < end_segno)
1204                         sbi->next_victim_seg[gc_type] = segno + 1;
1205 skip:
1206                 f2fs_put_page(sum_page, 0);
1207         }
1208
1209         if (submitted)
1210                 f2fs_submit_merged_write(sbi,
1211                                 (type == SUM_TYPE_NODE) ? NODE : DATA);
1212
1213         blk_finish_plug(&plug);
1214
1215         stat_inc_call_count(sbi->stat_info);
1216
1217         return seg_freed;
1218 }
1219
1220 int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
1221                         bool background, unsigned int segno)
1222 {
1223         int gc_type = sync ? FG_GC : BG_GC;
1224         int sec_freed = 0, seg_freed = 0, total_freed = 0;
1225         int ret = 0;
1226         struct cp_control cpc;
1227         unsigned int init_segno = segno;
1228         struct gc_inode_list gc_list = {
1229                 .ilist = LIST_HEAD_INIT(gc_list.ilist),
1230                 .iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS),
1231         };
1232         unsigned long long last_skipped = sbi->skipped_atomic_files[FG_GC];
1233         unsigned long long first_skipped;
1234         unsigned int skipped_round = 0, round = 0;
1235
1236         trace_f2fs_gc_begin(sbi->sb, sync, background,
1237                                 get_pages(sbi, F2FS_DIRTY_NODES),
1238                                 get_pages(sbi, F2FS_DIRTY_DENTS),
1239                                 get_pages(sbi, F2FS_DIRTY_IMETA),
1240                                 free_sections(sbi),
1241                                 free_segments(sbi),
1242                                 reserved_segments(sbi),
1243                                 prefree_segments(sbi));
1244
1245         cpc.reason = __get_cp_reason(sbi);
1246         sbi->skipped_gc_rwsem = 0;
1247         first_skipped = last_skipped;
1248 gc_more:
1249         if (unlikely(!(sbi->sb->s_flags & SB_ACTIVE))) {
1250                 ret = -EINVAL;
1251                 goto stop;
1252         }
1253         if (unlikely(f2fs_cp_error(sbi))) {
1254                 ret = -EIO;
1255                 goto stop;
1256         }
1257
1258         if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0)) {
1259                 /*
1260                  * For example, if there are many prefree_segments below given
1261                  * threshold, we can make them free by checkpoint. Then, we
1262                  * secure free segments which doesn't need fggc any more.
1263                  */
1264                 if (prefree_segments(sbi) &&
1265                                 !is_sbi_flag_set(sbi, SBI_CP_DISABLED)) {
1266                         ret = f2fs_write_checkpoint(sbi, &cpc);
1267                         if (ret)
1268                                 goto stop;
1269                 }
1270                 if (has_not_enough_free_secs(sbi, 0, 0))
1271                         gc_type = FG_GC;
1272         }
1273
1274         /* f2fs_balance_fs doesn't need to do BG_GC in critical path. */
1275         if (gc_type == BG_GC && !background) {
1276                 ret = -EINVAL;
1277                 goto stop;
1278         }
1279         if (!__get_victim(sbi, &segno, gc_type)) {
1280                 ret = -ENODATA;
1281                 goto stop;
1282         }
1283
1284         seg_freed = do_garbage_collect(sbi, segno, &gc_list, gc_type);
1285         if (gc_type == FG_GC && seg_freed == sbi->segs_per_sec)
1286                 sec_freed++;
1287         total_freed += seg_freed;
1288
1289         if (gc_type == FG_GC) {
1290                 if (sbi->skipped_atomic_files[FG_GC] > last_skipped ||
1291                                                 sbi->skipped_gc_rwsem)
1292                         skipped_round++;
1293                 last_skipped = sbi->skipped_atomic_files[FG_GC];
1294                 round++;
1295         }
1296
1297         if (gc_type == FG_GC)
1298                 sbi->cur_victim_sec = NULL_SEGNO;
1299
1300         if (sync)
1301                 goto stop;
1302
1303         if (has_not_enough_free_secs(sbi, sec_freed, 0)) {
1304                 if (skipped_round <= MAX_SKIP_GC_COUNT ||
1305                                         skipped_round * 2 < round) {
1306                         segno = NULL_SEGNO;
1307                         goto gc_more;
1308                 }
1309
1310                 if (first_skipped < last_skipped &&
1311                                 (last_skipped - first_skipped) >
1312                                                 sbi->skipped_gc_rwsem) {
1313                         f2fs_drop_inmem_pages_all(sbi, true);
1314                         segno = NULL_SEGNO;
1315                         goto gc_more;
1316                 }
1317                 if (gc_type == FG_GC && !is_sbi_flag_set(sbi, SBI_CP_DISABLED))
1318                         ret = f2fs_write_checkpoint(sbi, &cpc);
1319         }
1320 stop:
1321         SIT_I(sbi)->last_victim[ALLOC_NEXT] = 0;
1322         SIT_I(sbi)->last_victim[FLUSH_DEVICE] = init_segno;
1323
1324         trace_f2fs_gc_end(sbi->sb, ret, total_freed, sec_freed,
1325                                 get_pages(sbi, F2FS_DIRTY_NODES),
1326                                 get_pages(sbi, F2FS_DIRTY_DENTS),
1327                                 get_pages(sbi, F2FS_DIRTY_IMETA),
1328                                 free_sections(sbi),
1329                                 free_segments(sbi),
1330                                 reserved_segments(sbi),
1331                                 prefree_segments(sbi));
1332
1333         mutex_unlock(&sbi->gc_mutex);
1334
1335         put_gc_inode(&gc_list);
1336
1337         if (sync && !ret)
1338                 ret = sec_freed ? 0 : -EAGAIN;
1339         return ret;
1340 }
1341
1342 void f2fs_build_gc_manager(struct f2fs_sb_info *sbi)
1343 {
1344         DIRTY_I(sbi)->v_ops = &default_v_ops;
1345
1346         sbi->gc_pin_file_threshold = DEF_GC_FAILED_PINNED_FILES;
1347
1348         /* give warm/cold data area from slower device */
1349         if (sbi->s_ndevs && !__is_large_section(sbi))
1350                 SIT_I(sbi)->last_victim[ALLOC_NEXT] =
1351                                 GET_SEGNO(sbi, FDEV(0).end_blk) + 1;
1352 }