fs/f2fs/gc.c

   1 /*
   2  * fs/f2fs/gc.c
   3  *
   4  * Copyright (c) 2012 Samsung Electronics Co., Ltd.
   5  *             http://www.samsung.com/
   6  *
   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.
  10  */
  11 #include <linux/fs.h>
  12 #include <linux/module.h>
  13 #include <linux/backing-dev.h>
  14 #include <linux/init.h>
  15 #include <linux/f2fs_fs.h>
  16 #include <linux/kthread.h>
  17 #include <linux/delay.h>
  18 #include <linux/freezer.h>
  19 #include <linux/blkdev.h>
  20
  21 #include "f2fs.h"
  22 #include "node.h"
  23 #include "segment.h"
  24 #include "gc.h"
  25 #include <trace/events/f2fs.h>
  26
  27 static struct kmem_cache *winode_slab;
  28
  29 static int gc_thread_func(void *data)
  30 {
  31         struct f2fs_sb_info *sbi = data;
  32         struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
  33         wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
  34         long wait_ms;
  35
  36         wait_ms = gc_th->min_sleep_time;
  37
  38         do {
  39                 if (try_to_freeze())
  40                         continue;
  41                 else
  42                         wait_event_interruptible_timeout(*wq,
  43                                                 kthread_should_stop(),
  44                                                 msecs_to_jiffies(wait_ms));
  45                 if (kthread_should_stop())
  46                         break;
  47
  48                 if (sbi->sb->s_writers.frozen >= SB_FREEZE_WRITE) {
  49                         wait_ms = increase_sleep_time(gc_th, wait_ms);
  50                         continue;
  51                 }
  52
  53                 /*
  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.
  60                  *
  61                  * Note) We have to avoid triggering GCs 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.
  65                  */
  66                 if (!mutex_trylock(&sbi->gc_mutex))
  67                         continue;
  68
  69                 if (!is_idle(sbi)) {
  70                         wait_ms = increase_sleep_time(gc_th, wait_ms);
  71                         mutex_unlock(&sbi->gc_mutex);
  72                         continue;
  73                 }
  74
  75                 if (has_enough_invalid_blocks(sbi))
  76                         wait_ms = decrease_sleep_time(gc_th, wait_ms);
  77                 else
  78                         wait_ms = increase_sleep_time(gc_th, wait_ms);
  79
  80                 stat_inc_bggc_count(sbi);
  81
  82                 /* if return value is not zero, no victim was selected */
  83                 if (f2fs_gc(sbi))
  84                         wait_ms = gc_th->no_gc_sleep_time;
  85
  86                 /* balancing f2fs's metadata periodically */
  87                 f2fs_balance_fs_bg(sbi);
  88
  89         } while (!kthread_should_stop());
  90         return 0;
  91 }
  92
  93 int start_gc_thread(struct f2fs_sb_info *sbi)
  94 {
  95         struct f2fs_gc_kthread *gc_th;
  96         dev_t dev = sbi->sb->s_bdev->bd_dev;
  97         int err = 0;
  98
  99         if (!test_opt(sbi, BG_GC))
 100                 goto out;
 101         gc_th = kmalloc(sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
 102         if (!gc_th) {
 103                 err = -ENOMEM;
 104                 goto out;
 105         }
 106
 107         gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME;
 108         gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
 109         gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
 110
 111         gc_th->gc_idle = 0;
 112
 113         sbi->gc_thread = gc_th;
 114         init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
 115         sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
 116                         "f2fs_gc-%u:%u", MAJOR(dev), MINOR(dev));
 117         if (IS_ERR(gc_th->f2fs_gc_task)) {
 118                 err = PTR_ERR(gc_th->f2fs_gc_task);
 119                 kfree(gc_th);
 120                 sbi->gc_thread = NULL;
 121         }
 122 out:
 123         return err;
 124 }
 125
 126 void stop_gc_thread(struct f2fs_sb_info *sbi)
 127 {
 128         struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
 129         if (!gc_th)
 130                 return;
 131         kthread_stop(gc_th->f2fs_gc_task);
 132         kfree(gc_th);
 133         sbi->gc_thread = NULL;
 134 }
 135
 136 static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type)
 137 {
 138         int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
 139
 140         if (gc_th && gc_th->gc_idle) {
 141                 if (gc_th->gc_idle == 1)
 142                         gc_mode = GC_CB;
 143                 else if (gc_th->gc_idle == 2)
 144                         gc_mode = GC_GREEDY;
 145         }
 146         return gc_mode;
 147 }
 148
 149 static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
 150                         int type, struct victim_sel_policy *p)
 151 {
 152         struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 153
 154         if (p->alloc_mode == SSR) {
 155                 p->gc_mode = GC_GREEDY;
 156                 p->dirty_segmap = dirty_i->dirty_segmap[type];
 157                 p->max_search = dirty_i->nr_dirty[type];
 158                 p->ofs_unit = 1;
 159         } else {
 160                 p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
 161                 p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
 162                 p->max_search = dirty_i->nr_dirty[DIRTY];
 163                 p->ofs_unit = sbi->segs_per_sec;
 164         }
 165
 166         if (p->max_search > sbi->max_victim_search)
 167                 p->max_search = sbi->max_victim_search;
 168
 169         p->offset = sbi->last_victim[p->gc_mode];
 170 }
 171
 172 static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
 173                                 struct victim_sel_policy *p)
 174 {
 175         /* SSR allocates in a segment unit */
 176         if (p->alloc_mode == SSR)
 177                 return 1 << sbi->log_blocks_per_seg;
 178         if (p->gc_mode == GC_GREEDY)
 179                 return (1 << sbi->log_blocks_per_seg) * p->ofs_unit;
 180         else if (p->gc_mode == GC_CB)
 181                 return UINT_MAX;
 182         else /* No other gc_mode */
 183                 return 0;
 184 }
 185
 186 static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
 187 {
 188         struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 189         unsigned int secno;
 190
 191         /*
 192          * If the gc_type is FG_GC, we can select victim segments
 193          * selected by background GC before.
 194          * Those segments guarantee they have small valid blocks.
 195          */
 196         for_each_set_bit(secno, dirty_i->victim_secmap, MAIN_SECS(sbi)) {
 197                 if (sec_usage_check(sbi, secno))
 198                         continue;
 199                 clear_bit(secno, dirty_i->victim_secmap);
 200                 return secno * sbi->segs_per_sec;
 201         }
 202         return NULL_SEGNO;
 203 }
 204
 205 static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned int segno)
 206 {
 207         struct sit_info *sit_i = SIT_I(sbi);
 208         unsigned int secno = GET_SECNO(sbi, segno);
 209         unsigned int start = secno * sbi->segs_per_sec;
 210         unsigned long long mtime = 0;
 211         unsigned int vblocks;
 212         unsigned char age = 0;
 213         unsigned char u;
 214         unsigned int i;
 215
 216         for (i = 0; i < sbi->segs_per_sec; i++)
 217                 mtime += get_seg_entry(sbi, start + i)->mtime;
 218         vblocks = get_valid_blocks(sbi, segno, sbi->segs_per_sec);
 219
 220         mtime = div_u64(mtime, sbi->segs_per_sec);
 221         vblocks = div_u64(vblocks, sbi->segs_per_sec);
 222
 223         u = (vblocks * 100) >> sbi->log_blocks_per_seg;
 224
 225         /* Handle if the system time has changed by the user */
 226         if (mtime < sit_i->min_mtime)
 227                 sit_i->min_mtime = mtime;
 228         if (mtime > sit_i->max_mtime)
 229                 sit_i->max_mtime = mtime;
 230         if (sit_i->max_mtime != sit_i->min_mtime)
 231                 age = 100 - div64_u64(100 * (mtime - sit_i->min_mtime),
 232                                 sit_i->max_mtime - sit_i->min_mtime);
 233
 234         return UINT_MAX - ((100 * (100 - u) * age) / (100 + u));
 235 }
 236
 237 static inline unsigned int get_gc_cost(struct f2fs_sb_info *sbi,
 238                         unsigned int segno, struct victim_sel_policy *p)
 239 {
 240         if (p->alloc_mode == SSR)
 241                 return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
 242
 243         /* alloc_mode == LFS */
 244         if (p->gc_mode == GC_GREEDY)
 245                 return get_valid_blocks(sbi, segno, sbi->segs_per_sec);
 246         else
 247                 return get_cb_cost(sbi, segno);
 248 }
 249
 250 /*
 251  * This function is called from two paths.
 252  * One is garbage collection and the other is SSR segment selection.
 253  * When it is called during GC, it just gets a victim segment
 254  * and it does not remove it from dirty seglist.
 255  * When it is called from SSR segment selection, it finds a segment
 256  * which has minimum valid blocks and removes it from dirty seglist.
 257  */
 258 static int get_victim_by_default(struct f2fs_sb_info *sbi,
 259                 unsigned int *result, int gc_type, int type, char alloc_mode)
 260 {
 261         struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 262         struct victim_sel_policy p;
 263         unsigned int secno, max_cost;
 264         int nsearched = 0;
 265
 266         mutex_lock(&dirty_i->seglist_lock);
 267
 268         p.alloc_mode = alloc_mode;
 269         select_policy(sbi, gc_type, type, &p);
 270
 271         p.min_segno = NULL_SEGNO;
 272         p.min_cost = max_cost = get_max_cost(sbi, &p);
 273
 274         if (p.alloc_mode == LFS && gc_type == FG_GC) {
 275                 p.min_segno = check_bg_victims(sbi);
 276                 if (p.min_segno != NULL_SEGNO)
 277                         goto got_it;
 278         }
 279
 280         while (1) {
 281                 unsigned long cost;
 282                 unsigned int segno;
 283
 284                 segno = find_next_bit(p.dirty_segmap, MAIN_SEGS(sbi), p.offset);
 285                 if (segno >= MAIN_SEGS(sbi)) {
 286                         if (sbi->last_victim[p.gc_mode]) {
 287                                 sbi->last_victim[p.gc_mode] = 0;
 288                                 p.offset = 0;
 289                                 continue;
 290                         }
 291                         break;
 292                 }
 293
 294                 p.offset = segno + p.ofs_unit;
 295                 if (p.ofs_unit > 1)
 296                         p.offset -= segno % p.ofs_unit;
 297
 298                 secno = GET_SECNO(sbi, segno);
 299
 300                 if (sec_usage_check(sbi, secno))
 301                         continue;
 302                 if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
 303                         continue;
 304
 305                 cost = get_gc_cost(sbi, segno, &p);
 306
 307                 if (p.min_cost > cost) {
 308                         p.min_segno = segno;
 309                         p.min_cost = cost;
 310                 } else if (unlikely(cost == max_cost)) {
 311                         continue;
 312                 }
 313
 314                 if (nsearched++ >= p.max_search) {
 315                         sbi->last_victim[p.gc_mode] = segno;
 316                         break;
 317                 }
 318         }
 319         if (p.min_segno != NULL_SEGNO) {
 320 got_it:
 321                 if (p.alloc_mode == LFS) {
 322                         secno = GET_SECNO(sbi, p.min_segno);
 323                         if (gc_type == FG_GC)
 324                                 sbi->cur_victim_sec = secno;
 325                         else
 326                                 set_bit(secno, dirty_i->victim_secmap);
 327                 }
 328                 *result = (p.min_segno / p.ofs_unit) * p.ofs_unit;
 329
 330                 trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
 331                                 sbi->cur_victim_sec,
 332                                 prefree_segments(sbi), free_segments(sbi));
 333         }
 334         mutex_unlock(&dirty_i->seglist_lock);
 335
 336         return (p.min_segno == NULL_SEGNO) ? 0 : 1;
 337 }
 338
 339 static const struct victim_selection default_v_ops = {
 340         .get_victim = get_victim_by_default,
 341 };
 342
 343 static struct inode *find_gc_inode(nid_t ino, struct list_head *ilist)
 344 {
 345         struct inode_entry *ie;
 346
 347         list_for_each_entry(ie, ilist, list)
 348                 if (ie->inode->i_ino == ino)
 349                         return ie->inode;
 350         return NULL;
 351 }
 352
 353 static void add_gc_inode(struct inode *inode, struct list_head *ilist)
 354 {
 355         struct inode_entry *new_ie;
 356
 357         if (inode == find_gc_inode(inode->i_ino, ilist)) {
 358                 iput(inode);
 359                 return;
 360         }
 361
 362         new_ie = f2fs_kmem_cache_alloc(winode_slab, GFP_NOFS);
 363         new_ie->inode = inode;
 364         list_add_tail(&new_ie->list, ilist);
 365 }
 366
 367 static void put_gc_inode(struct list_head *ilist)
 368 {
 369         struct inode_entry *ie, *next_ie;
 370         list_for_each_entry_safe(ie, next_ie, ilist, list) {
 371                 iput(ie->inode);
 372                 list_del(&ie->list);
 373                 kmem_cache_free(winode_slab, ie);
 374         }
 375 }
 376
 377 static int check_valid_map(struct f2fs_sb_info *sbi,
 378                                 unsigned int segno, int offset)
 379 {
 380         struct sit_info *sit_i = SIT_I(sbi);
 381         struct seg_entry *sentry;
 382         int ret;
 383
 384         mutex_lock(&sit_i->sentry_lock);
 385         sentry = get_seg_entry(sbi, segno);
 386         ret = f2fs_test_bit(offset, sentry->cur_valid_map);
 387         mutex_unlock(&sit_i->sentry_lock);
 388         return ret;
 389 }
 390
 391 /*
 392  * This function compares node address got in summary with that in NAT.
 393  * On validity, copy that node with cold status, otherwise (invalid node)
 394  * ignore that.
 395  */
 396 static void gc_node_segment(struct f2fs_sb_info *sbi,
 397                 struct f2fs_summary *sum, unsigned int segno, int gc_type)
 398 {
 399         bool initial = true;
 400         struct f2fs_summary *entry;
 401         int off;
 402
 403 next_step:
 404         entry = sum;
 405
 406         for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
 407                 nid_t nid = le32_to_cpu(entry->nid);
 408                 struct page *node_page;
 409
 410                 /* stop BG_GC if there is not enough free sections. */
 411                 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
 412                         return;
 413
 414                 if (check_valid_map(sbi, segno, off) == 0)
 415                         continue;
 416
 417                 if (initial) {
 418                         ra_node_page(sbi, nid);
 419                         continue;
 420                 }
 421                 node_page = get_node_page(sbi, nid);
 422                 if (IS_ERR(node_page))
 423                         continue;
 424
 425                 /* block may become invalid during get_node_page */
 426                 if (check_valid_map(sbi, segno, off) == 0) {
 427                         f2fs_put_page(node_page, 1);
 428                         continue;
 429                 }
 430
 431                 /* set page dirty and write it */
 432                 if (gc_type == FG_GC) {
 433                         f2fs_wait_on_page_writeback(node_page, NODE);
 434                         set_page_dirty(node_page);
 435                 } else {
 436                         if (!PageWriteback(node_page))
 437                                 set_page_dirty(node_page);
 438                 }
 439                 f2fs_put_page(node_page, 1);
 440                 stat_inc_node_blk_count(sbi, 1);
 441         }
 442
 443         if (initial) {
 444                 initial = false;
 445                 goto next_step;
 446         }
 447
 448         if (gc_type == FG_GC) {
 449                 struct writeback_control wbc = {
 450                         .sync_mode = WB_SYNC_ALL,
 451                         .nr_to_write = LONG_MAX,
 452                         .for_reclaim = 0,
 453                 };
 454                 sync_node_pages(sbi, 0, &wbc);
 455
 456                 /*
 457                  * In the case of FG_GC, it'd be better to reclaim this victim
 458                  * completely.
 459                  */
 460                 if (get_valid_blocks(sbi, segno, 1) != 0)
 461                         goto next_step;
 462         }
 463 }
 464
 465 /*
 466  * Calculate start block index indicating the given node offset.
 467  * Be careful, caller should give this node offset only indicating direct node
 468  * blocks. If any node offsets, which point the other types of node blocks such
 469  * as indirect or double indirect node blocks, are given, it must be a caller's
 470  * bug.
 471  */
 472 block_t start_bidx_of_node(unsigned int node_ofs, struct f2fs_inode_info *fi)
 473 {
 474         unsigned int indirect_blks = 2 * NIDS_PER_BLOCK + 4;
 475         unsigned int bidx;
 476
 477         if (node_ofs == 0)
 478                 return 0;
 479
 480         if (node_ofs <= 2) {
 481                 bidx = node_ofs - 1;
 482         } else if (node_ofs <= indirect_blks) {
 483                 int dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1);
 484                 bidx = node_ofs - 2 - dec;
 485         } else {
 486                 int dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1);
 487                 bidx = node_ofs - 5 - dec;
 488         }
 489         return bidx * ADDRS_PER_BLOCK + ADDRS_PER_INODE(fi);
 490 }
 491
 492 static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 493                 struct node_info *dni, block_t blkaddr, unsigned int *nofs)
 494 {
 495         struct page *node_page;
 496         nid_t nid;
 497         unsigned int ofs_in_node;
 498         block_t source_blkaddr;
 499
 500         nid = le32_to_cpu(sum->nid);
 501         ofs_in_node = le16_to_cpu(sum->ofs_in_node);
 502
 503         node_page = get_node_page(sbi, nid);
 504         if (IS_ERR(node_page))
 505                 return 0;
 506
 507         get_node_info(sbi, nid, dni);
 508
 509         if (sum->version != dni->version) {
 510                 f2fs_put_page(node_page, 1);
 511                 return 0;
 512         }
 513
 514         *nofs = ofs_of_node(node_page);
 515         source_blkaddr = datablock_addr(node_page, ofs_in_node);
 516         f2fs_put_page(node_page, 1);
 517
 518         if (source_blkaddr != blkaddr)
 519                 return 0;
 520         return 1;
 521 }
 522
 523 static void move_data_page(struct inode *inode, struct page *page, int gc_type)
 524 {
 525         struct f2fs_io_info fio = {
 526                 .type = DATA,
 527                 .rw = WRITE_SYNC,
 528         };
 529
 530         if (gc_type == BG_GC) {
 531                 if (PageWriteback(page))
 532                         goto out;
 533                 set_page_dirty(page);
 534                 set_cold_data(page);
 535         } else {
 536                 f2fs_wait_on_page_writeback(page, DATA);
 537
 538                 if (clear_page_dirty_for_io(page))
 539                         inode_dec_dirty_pages(inode);
 540                 set_cold_data(page);
 541                 do_write_data_page(page, &fio);
 542                 clear_cold_data(page);
 543         }
 544 out:
 545         f2fs_put_page(page, 1);
 546 }
 547
 548 /*
 549  * This function tries to get parent node of victim data block, and identifies
 550  * data block validity. If the block is valid, copy that with cold status and
 551  * modify parent node.
 552  * If the parent node is not valid or the data block address is different,
 553  * the victim data block is ignored.
 554  */
 555 static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 556                 struct list_head *ilist, unsigned int segno, int gc_type)
 557 {
 558         struct super_block *sb = sbi->sb;
 559         struct f2fs_summary *entry;
 560         block_t start_addr;
 561         int off;
 562         int phase = 0;
 563
 564         start_addr = START_BLOCK(sbi, segno);
 565
 566 next_step:
 567         entry = sum;
 568
 569         for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
 570                 struct page *data_page;
 571                 struct inode *inode;
 572                 struct node_info dni; /* dnode info for the data */
 573                 unsigned int ofs_in_node, nofs;
 574                 block_t start_bidx;
 575
 576                 /* stop BG_GC if there is not enough free sections. */
 577                 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
 578                         return;
 579
 580                 if (check_valid_map(sbi, segno, off) == 0)
 581                         continue;
 582
 583                 if (phase == 0) {
 584                         ra_node_page(sbi, le32_to_cpu(entry->nid));
 585                         continue;
 586                 }
 587
 588                 /* Get an inode by ino with checking validity */
 589                 if (check_dnode(sbi, entry, &dni, start_addr + off, &nofs) == 0)
 590                         continue;
 591
 592                 if (phase == 1) {
 593                         ra_node_page(sbi, dni.ino);
 594                         continue;
 595                 }
 596
 597                 ofs_in_node = le16_to_cpu(entry->ofs_in_node);
 598
 599                 if (phase == 2) {
 600                         inode = f2fs_iget(sb, dni.ino);
 601                         if (IS_ERR(inode) || is_bad_inode(inode))
 602                                 continue;
 603
 604                         start_bidx = start_bidx_of_node(nofs, F2FS_I(inode));
 605
 606                         data_page = find_data_page(inode,
 607                                         start_bidx + ofs_in_node, false);
 608                         if (IS_ERR(data_page))
 609                                 goto next_iput;
 610
 611                         f2fs_put_page(data_page, 0);
 612                         add_gc_inode(inode, ilist);
 613                 } else {
 614                         inode = find_gc_inode(dni.ino, ilist);
 615                         if (inode) {
 616                                 start_bidx = start_bidx_of_node(nofs,
 617                                                                 F2FS_I(inode));
 618                                 data_page = get_lock_data_page(inode,
 619                                                 start_bidx + ofs_in_node);
 620                                 if (IS_ERR(data_page))
 621                                         continue;
 622                                 move_data_page(inode, data_page, gc_type);
 623                                 stat_inc_data_blk_count(sbi, 1);
 624                         }
 625                 }
 626                 continue;
 627 next_iput:
 628                 iput(inode);
 629         }
 630
 631         if (++phase < 4)
 632                 goto next_step;
 633
 634         if (gc_type == FG_GC) {
 635                 f2fs_submit_merged_bio(sbi, DATA, WRITE);
 636
 637                 /*
 638                  * In the case of FG_GC, it'd be better to reclaim this victim
 639                  * completely.
 640                  */
 641                 if (get_valid_blocks(sbi, segno, 1) != 0) {
 642                         phase = 2;
 643                         goto next_step;
 644                 }
 645         }
 646 }
 647
 648 static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
 649                                                 int gc_type, int type)
 650 {
 651         struct sit_info *sit_i = SIT_I(sbi);
 652         int ret;
 653         mutex_lock(&sit_i->sentry_lock);
 654         ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type, type, LFS);
 655         mutex_unlock(&sit_i->sentry_lock);
 656         return ret;
 657 }
 658
 659 static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
 660                                 struct list_head *ilist, int gc_type)
 661 {
 662         struct page *sum_page;
 663         struct f2fs_summary_block *sum;
 664         struct blk_plug plug;
 665
 666         /* read segment summary of victim */
 667         sum_page = get_sum_page(sbi, segno);
 668
 669         blk_start_plug(&plug);
 670
 671         sum = page_address(sum_page);
 672
 673         switch (GET_SUM_TYPE((&sum->footer))) {
 674         case SUM_TYPE_NODE:
 675                 gc_node_segment(sbi, sum->entries, segno, gc_type);
 676                 break;
 677         case SUM_TYPE_DATA:
 678                 gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);
 679                 break;
 680         }
 681         blk_finish_plug(&plug);
 682
 683         stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
 684         stat_inc_call_count(sbi->stat_info);
 685
 686         f2fs_put_page(sum_page, 1);
 687 }
 688
 689 int f2fs_gc(struct f2fs_sb_info *sbi)
 690 {
 691         struct list_head ilist;
 692         unsigned int segno, i;
 693         int gc_type = BG_GC;
 694         int nfree = 0;
 695         int ret = -1;
 696         struct cp_control cpc = {
 697                 .reason = CP_SYNC,
 698         };
 699
 700         INIT_LIST_HEAD(&ilist);
 701 gc_more:
 702         if (unlikely(!(sbi->sb->s_flags & MS_ACTIVE)))
 703                 goto stop;
 704         if (unlikely(f2fs_cp_error(sbi)))
 705                 goto stop;
 706
 707         if (gc_type == BG_GC && has_not_enough_free_secs(sbi, nfree)) {
 708                 gc_type = FG_GC;
 709                 write_checkpoint(sbi, &cpc);
 710         }
 711
 712         if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
 713                 goto stop;
 714         ret = 0;
 715
 716         /* readahead multi ssa blocks those have contiguous address */
 717         if (sbi->segs_per_sec > 1)
 718                 ra_meta_pages(sbi, GET_SUM_BLOCK(sbi, segno), sbi->segs_per_sec,
 719                                                                 META_SSA);
 720
 721         for (i = 0; i < sbi->segs_per_sec; i++)
 722                 do_garbage_collect(sbi, segno + i, &ilist, gc_type);
 723
 724         if (gc_type == FG_GC) {
 725                 sbi->cur_victim_sec = NULL_SEGNO;
 726                 nfree++;
 727                 WARN_ON(get_valid_blocks(sbi, segno, sbi->segs_per_sec));
 728         }
 729
 730         if (has_not_enough_free_secs(sbi, nfree))
 731                 goto gc_more;
 732
 733         if (gc_type == FG_GC)
 734                 write_checkpoint(sbi, &cpc);
 735 stop:
 736         mutex_unlock(&sbi->gc_mutex);
 737
 738         put_gc_inode(&ilist);
 739         return ret;
 740 }
 741
 742 void build_gc_manager(struct f2fs_sb_info *sbi)
 743 {
 744         DIRTY_I(sbi)->v_ops = &default_v_ops;
 745 }
 746
 747 int __init create_gc_caches(void)
 748 {
 749         winode_slab = f2fs_kmem_cache_create("f2fs_gc_inodes",
 750                         sizeof(struct inode_entry));
 751         if (!winode_slab)
 752                 return -ENOMEM;
 753         return 0;
 754 }
 755
 756 void destroy_gc_caches(void)
 757 {
 758         kmem_cache_destroy(winode_slab);
 759 }