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, TOTAL_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,
 285                                                 TOTAL_SEGS(sbi), p.offset);
 286                 if (segno >= TOTAL_SEGS(sbi)) {
 287                         if (sbi->last_victim[p.gc_mode]) {
 288                                 sbi->last_victim[p.gc_mode] = 0;
 289                                 p.offset = 0;
 290                                 continue;
 291                         }
 292                         break;
 293                 }
 294
 295                 p.offset = segno + p.ofs_unit;
 296                 if (p.ofs_unit > 1)
 297                         p.offset -= segno % p.ofs_unit;
 298
 299                 secno = GET_SECNO(sbi, segno);
 300
 301                 if (sec_usage_check(sbi, secno))
 302                         continue;
 303                 if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
 304                         continue;
 305
 306                 cost = get_gc_cost(sbi, segno, &p);
 307
 308                 if (p.min_cost > cost) {
 309                         p.min_segno = segno;
 310                         p.min_cost = cost;
 311                 } else if (unlikely(cost == max_cost)) {
 312                         continue;
 313                 }
 314
 315                 if (nsearched++ >= p.max_search) {
 316                         sbi->last_victim[p.gc_mode] = segno;
 317                         break;
 318                 }
 319         }
 320         if (p.min_segno != NULL_SEGNO) {
 321 got_it:
 322                 if (p.alloc_mode == LFS) {
 323                         secno = GET_SECNO(sbi, p.min_segno);
 324                         if (gc_type == FG_GC)
 325                                 sbi->cur_victim_sec = secno;
 326                         else
 327                                 set_bit(secno, dirty_i->victim_secmap);
 328                 }
 329                 *result = (p.min_segno / p.ofs_unit) * p.ofs_unit;
 330
 331                 trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
 332                                 sbi->cur_victim_sec,
 333                                 prefree_segments(sbi), free_segments(sbi));
 334         }
 335         mutex_unlock(&dirty_i->seglist_lock);
 336
 337         return (p.min_segno == NULL_SEGNO) ? 0 : 1;
 338 }
 339
 340 static const struct victim_selection default_v_ops = {
 341         .get_victim = get_victim_by_default,
 342 };
 343
 344 static struct inode *find_gc_inode(nid_t ino, struct list_head *ilist)
 345 {
 346         struct inode_entry *ie;
 347
 348         list_for_each_entry(ie, ilist, list)
 349                 if (ie->inode->i_ino == ino)
 350                         return ie->inode;
 351         return NULL;
 352 }
 353
 354 static void add_gc_inode(struct inode *inode, struct list_head *ilist)
 355 {
 356         struct inode_entry *new_ie;
 357
 358         if (inode == find_gc_inode(inode->i_ino, ilist)) {
 359                 iput(inode);
 360                 return;
 361         }
 362
 363         new_ie = f2fs_kmem_cache_alloc(winode_slab, GFP_NOFS);
 364         new_ie->inode = inode;
 365         list_add_tail(&new_ie->list, ilist);
 366 }
 367
 368 static void put_gc_inode(struct list_head *ilist)
 369 {
 370         struct inode_entry *ie, *next_ie;
 371         list_for_each_entry_safe(ie, next_ie, ilist, list) {
 372                 iput(ie->inode);
 373                 list_del(&ie->list);
 374                 kmem_cache_free(winode_slab, ie);
 375         }
 376 }
 377
 378 static int check_valid_map(struct f2fs_sb_info *sbi,
 379                                 unsigned int segno, int offset)
 380 {
 381         struct sit_info *sit_i = SIT_I(sbi);
 382         struct seg_entry *sentry;
 383         int ret;
 384
 385         mutex_lock(&sit_i->sentry_lock);
 386         sentry = get_seg_entry(sbi, segno);
 387         ret = f2fs_test_bit(offset, sentry->cur_valid_map);
 388         mutex_unlock(&sit_i->sentry_lock);
 389         return ret;
 390 }
 391
 392 /*
 393  * This function compares node address got in summary with that in NAT.
 394  * On validity, copy that node with cold status, otherwise (invalid node)
 395  * ignore that.
 396  */
 397 static void gc_node_segment(struct f2fs_sb_info *sbi,
 398                 struct f2fs_summary *sum, unsigned int segno, int gc_type)
 399 {
 400         bool initial = true;
 401         struct f2fs_summary *entry;
 402         int off;
 403
 404 next_step:
 405         entry = sum;
 406
 407         for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
 408                 nid_t nid = le32_to_cpu(entry->nid);
 409                 struct page *node_page;
 410
 411                 /* stop BG_GC if there is not enough free sections. */
 412                 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
 413                         return;
 414
 415                 if (check_valid_map(sbi, segno, off) == 0)
 416                         continue;
 417
 418                 if (initial) {
 419                         ra_node_page(sbi, nid);
 420                         continue;
 421                 }
 422                 node_page = get_node_page(sbi, nid);
 423                 if (IS_ERR(node_page))
 424                         continue;
 425
 426                 /* block may become invalid during get_node_page */
 427                 if (check_valid_map(sbi, segno, off) == 0) {
 428                         f2fs_put_page(node_page, 1);
 429                         continue;
 430                 }
 431
 432                 /* set page dirty and write it */
 433                 if (gc_type == FG_GC) {
 434                         f2fs_wait_on_page_writeback(node_page, NODE);
 435                         set_page_dirty(node_page);
 436                 } else {
 437                         if (!PageWriteback(node_page))
 438                                 set_page_dirty(node_page);
 439                 }
 440                 f2fs_put_page(node_page, 1);
 441                 stat_inc_node_blk_count(sbi, 1);
 442         }
 443
 444         if (initial) {
 445                 initial = false;
 446                 goto next_step;
 447         }
 448
 449         if (gc_type == FG_GC) {
 450                 struct writeback_control wbc = {
 451                         .sync_mode = WB_SYNC_ALL,
 452                         .nr_to_write = LONG_MAX,
 453                         .for_reclaim = 0,
 454                 };
 455                 sync_node_pages(sbi, 0, &wbc);
 456
 457                 /*
 458                  * In the case of FG_GC, it'd be better to reclaim this victim
 459                  * completely.
 460                  */
 461                 if (get_valid_blocks(sbi, segno, 1) != 0)
 462                         goto next_step;
 463         }
 464 }
 465
 466 /*
 467  * Calculate start block index indicating the given node offset.
 468  * Be careful, caller should give this node offset only indicating direct node
 469  * blocks. If any node offsets, which point the other types of node blocks such
 470  * as indirect or double indirect node blocks, are given, it must be a caller's
 471  * bug.
 472  */
 473 block_t start_bidx_of_node(unsigned int node_ofs, struct f2fs_inode_info *fi)
 474 {
 475         unsigned int indirect_blks = 2 * NIDS_PER_BLOCK + 4;
 476         unsigned int bidx;
 477
 478         if (node_ofs == 0)
 479                 return 0;
 480
 481         if (node_ofs <= 2) {
 482                 bidx = node_ofs - 1;
 483         } else if (node_ofs <= indirect_blks) {
 484                 int dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1);
 485                 bidx = node_ofs - 2 - dec;
 486         } else {
 487                 int dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1);
 488                 bidx = node_ofs - 5 - dec;
 489         }
 490         return bidx * ADDRS_PER_BLOCK + ADDRS_PER_INODE(fi);
 491 }
 492
 493 static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 494                 struct node_info *dni, block_t blkaddr, unsigned int *nofs)
 495 {
 496         struct page *node_page;
 497         nid_t nid;
 498         unsigned int ofs_in_node;
 499         block_t source_blkaddr;
 500
 501         nid = le32_to_cpu(sum->nid);
 502         ofs_in_node = le16_to_cpu(sum->ofs_in_node);
 503
 504         node_page = get_node_page(sbi, nid);
 505         if (IS_ERR(node_page))
 506                 return 0;
 507
 508         get_node_info(sbi, nid, dni);
 509
 510         if (sum->version != dni->version) {
 511                 f2fs_put_page(node_page, 1);
 512                 return 0;
 513         }
 514
 515         *nofs = ofs_of_node(node_page);
 516         source_blkaddr = datablock_addr(node_page, ofs_in_node);
 517         f2fs_put_page(node_page, 1);
 518
 519         if (source_blkaddr != blkaddr)
 520                 return 0;
 521         return 1;
 522 }
 523
 524 static void move_data_page(struct inode *inode, struct page *page, int gc_type)
 525 {
 526         struct f2fs_io_info fio = {
 527                 .type = DATA,
 528                 .rw = WRITE_SYNC,
 529         };
 530
 531         if (gc_type == BG_GC) {
 532                 if (PageWriteback(page))
 533                         goto out;
 534                 set_page_dirty(page);
 535                 set_cold_data(page);
 536         } else {
 537                 f2fs_wait_on_page_writeback(page, DATA);
 538
 539                 if (clear_page_dirty_for_io(page))
 540                         inode_dec_dirty_pages(inode);
 541                 set_cold_data(page);
 542                 do_write_data_page(page, &fio);
 543                 clear_cold_data(page);
 544         }
 545 out:
 546         f2fs_put_page(page, 1);
 547 }
 548
 549 /*
 550  * This function tries to get parent node of victim data block, and identifies
 551  * data block validity. If the block is valid, copy that with cold status and
 552  * modify parent node.
 553  * If the parent node is not valid or the data block address is different,
 554  * the victim data block is ignored.
 555  */
 556 static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 557                 struct list_head *ilist, unsigned int segno, int gc_type)
 558 {
 559         struct super_block *sb = sbi->sb;
 560         struct f2fs_summary *entry;
 561         block_t start_addr;
 562         int off;
 563         int phase = 0;
 564
 565         start_addr = START_BLOCK(sbi, segno);
 566
 567 next_step:
 568         entry = sum;
 569
 570         for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
 571                 struct page *data_page;
 572                 struct inode *inode;
 573                 struct node_info dni; /* dnode info for the data */
 574                 unsigned int ofs_in_node, nofs;
 575                 block_t start_bidx;
 576
 577                 /* stop BG_GC if there is not enough free sections. */
 578                 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
 579                         return;
 580
 581                 if (check_valid_map(sbi, segno, off) == 0)
 582                         continue;
 583
 584                 if (phase == 0) {
 585                         ra_node_page(sbi, le32_to_cpu(entry->nid));
 586                         continue;
 587                 }
 588
 589                 /* Get an inode by ino with checking validity */
 590                 if (check_dnode(sbi, entry, &dni, start_addr + off, &nofs) == 0)
 591                         continue;
 592
 593                 if (phase == 1) {
 594                         ra_node_page(sbi, dni.ino);
 595                         continue;
 596                 }
 597
 598                 ofs_in_node = le16_to_cpu(entry->ofs_in_node);
 599
 600                 if (phase == 2) {
 601                         inode = f2fs_iget(sb, dni.ino);
 602                         if (IS_ERR(inode) || is_bad_inode(inode))
 603                                 continue;
 604
 605                         start_bidx = start_bidx_of_node(nofs, F2FS_I(inode));
 606
 607                         data_page = find_data_page(inode,
 608                                         start_bidx + ofs_in_node, false);
 609                         if (IS_ERR(data_page))
 610                                 goto next_iput;
 611
 612                         f2fs_put_page(data_page, 0);
 613                         add_gc_inode(inode, ilist);
 614                 } else {
 615                         inode = find_gc_inode(dni.ino, ilist);
 616                         if (inode) {
 617                                 start_bidx = start_bidx_of_node(nofs,
 618                                                                 F2FS_I(inode));
 619                                 data_page = get_lock_data_page(inode,
 620                                                 start_bidx + ofs_in_node);
 621                                 if (IS_ERR(data_page))
 622                                         continue;
 623                                 move_data_page(inode, data_page, gc_type);
 624                                 stat_inc_data_blk_count(sbi, 1);
 625                         }
 626                 }
 627                 continue;
 628 next_iput:
 629                 iput(inode);
 630         }
 631
 632         if (++phase < 4)
 633                 goto next_step;
 634
 635         if (gc_type == FG_GC) {
 636                 f2fs_submit_merged_bio(sbi, DATA, WRITE);
 637
 638                 /*
 639                  * In the case of FG_GC, it'd be better to reclaim this victim
 640                  * completely.
 641                  */
 642                 if (get_valid_blocks(sbi, segno, 1) != 0) {
 643                         phase = 2;
 644                         goto next_step;
 645                 }
 646         }
 647 }
 648
 649 static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
 650                                                 int gc_type, int type)
 651 {
 652         struct sit_info *sit_i = SIT_I(sbi);
 653         int ret;
 654         mutex_lock(&sit_i->sentry_lock);
 655         ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type, type, LFS);
 656         mutex_unlock(&sit_i->sentry_lock);
 657         return ret;
 658 }
 659
 660 static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
 661                                 struct list_head *ilist, int gc_type)
 662 {
 663         struct page *sum_page;
 664         struct f2fs_summary_block *sum;
 665         struct blk_plug plug;
 666
 667         /* read segment summary of victim */
 668         sum_page = get_sum_page(sbi, segno);
 669
 670         blk_start_plug(&plug);
 671
 672         sum = page_address(sum_page);
 673
 674         switch (GET_SUM_TYPE((&sum->footer))) {
 675         case SUM_TYPE_NODE:
 676                 gc_node_segment(sbi, sum->entries, segno, gc_type);
 677                 break;
 678         case SUM_TYPE_DATA:
 679                 gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);
 680                 break;
 681         }
 682         blk_finish_plug(&plug);
 683
 684         stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
 685         stat_inc_call_count(sbi->stat_info);
 686
 687         f2fs_put_page(sum_page, 1);
 688 }
 689
 690 int f2fs_gc(struct f2fs_sb_info *sbi)
 691 {
 692         struct list_head ilist;
 693         unsigned int segno, i;
 694         int gc_type = BG_GC;
 695         int nfree = 0;
 696         int ret = -1;
 697         struct cp_control cpc = {
 698                 .reason = CP_SYNC,
 699         };
 700
 701         INIT_LIST_HEAD(&ilist);
 702 gc_more:
 703         if (unlikely(!(sbi->sb->s_flags & MS_ACTIVE)))
 704                 goto stop;
 705         if (unlikely(f2fs_cp_error(sbi)))
 706                 goto stop;
 707
 708         if (gc_type == BG_GC && has_not_enough_free_secs(sbi, nfree)) {
 709                 gc_type = FG_GC;
 710                 write_checkpoint(sbi, &cpc);
 711         }
 712
 713         if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
 714                 goto stop;
 715         ret = 0;
 716
 717         /* readahead multi ssa blocks those have contiguous address */
 718         if (sbi->segs_per_sec > 1)
 719                 ra_meta_pages(sbi, GET_SUM_BLOCK(sbi, segno), sbi->segs_per_sec,
 720                                                                 META_SSA);
 721
 722         for (i = 0; i < sbi->segs_per_sec; i++)
 723                 do_garbage_collect(sbi, segno + i, &ilist, gc_type);
 724
 725         if (gc_type == FG_GC) {
 726                 sbi->cur_victim_sec = NULL_SEGNO;
 727                 nfree++;
 728                 WARN_ON(get_valid_blocks(sbi, segno, sbi->segs_per_sec));
 729         }
 730
 731         if (has_not_enough_free_secs(sbi, nfree))
 732                 goto gc_more;
 733
 734         if (gc_type == FG_GC)
 735                 write_checkpoint(sbi, &cpc);
 736 stop:
 737         mutex_unlock(&sbi->gc_mutex);
 738
 739         put_gc_inode(&ilist);
 740         return ret;
 741 }
 742
 743 void build_gc_manager(struct f2fs_sb_info *sbi)
 744 {
 745         DIRTY_I(sbi)->v_ops = &default_v_ops;
 746 }
 747
 748 int __init create_gc_caches(void)
 749 {
 750         winode_slab = f2fs_kmem_cache_create("f2fs_gc_inodes",
 751                         sizeof(struct inode_entry));
 752         if (!winode_slab)
 753                 return -ENOMEM;
 754         return 0;
 755 }
 756
 757 void destroy_gc_caches(void)
 758 {
 759         kmem_cache_destroy(winode_slab);
 760 }