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/proc_fs.h>
  15 #include <linux/init.h>
  16 #include <linux/f2fs_fs.h>
  17 #include <linux/kthread.h>
  18 #include <linux/delay.h>
  19 #include <linux/freezer.h>
  20 #include <linux/blkdev.h>
  21
  22 #include "f2fs.h"
  23 #include "node.h"
  24 #include "segment.h"
  25 #include "gc.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         wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
  33         long wait_ms;
  34
  35         wait_ms = GC_THREAD_MIN_SLEEP_TIME;
  36
  37         do {
  38                 if (try_to_freeze())
  39                         continue;
  40                 else
  41                         wait_event_interruptible_timeout(*wq,
  42                                                 kthread_should_stop(),
  43                                                 msecs_to_jiffies(wait_ms));
  44                 if (kthread_should_stop())
  45                         break;
  46
  47                 f2fs_balance_fs(sbi);
  48
  49                 if (!test_opt(sbi, BG_GC))
  50                         continue;
  51
  52                 /*
  53                  * [GC triggering condition]
  54                  * 0. GC is not conducted currently.
  55                  * 1. There are enough dirty segments.
  56                  * 2. IO subsystem is idle by checking the # of writeback pages.
  57                  * 3. IO subsystem is idle by checking the # of requests in
  58                  *    bdev's request list.
  59                  *
  60                  * Note) We have to avoid triggering GCs too much frequently.
  61                  * Because it is possible that some segments can be
  62                  * invalidated soon after by user update or deletion.
  63                  * So, I'd like to wait some time to collect dirty segments.
  64                  */
  65                 if (!mutex_trylock(&sbi->gc_mutex))
  66                         continue;
  67
  68                 if (!is_idle(sbi)) {
  69                         wait_ms = increase_sleep_time(wait_ms);
  70                         mutex_unlock(&sbi->gc_mutex);
  71                         continue;
  72                 }
  73
  74                 if (has_enough_invalid_blocks(sbi))
  75                         wait_ms = decrease_sleep_time(wait_ms);
  76                 else
  77                         wait_ms = increase_sleep_time(wait_ms);
  78
  79                 sbi->bg_gc++;
  80
  81                 if (f2fs_gc(sbi, 1) == GC_NONE)
  82                         wait_ms = GC_THREAD_NOGC_SLEEP_TIME;
  83                 else if (wait_ms == GC_THREAD_NOGC_SLEEP_TIME)
  84                         wait_ms = GC_THREAD_MAX_SLEEP_TIME;
  85
  86         } while (!kthread_should_stop());
  87         return 0;
  88 }
  89
  90 int start_gc_thread(struct f2fs_sb_info *sbi)
  91 {
  92         struct f2fs_gc_kthread *gc_th;
  93
  94         gc_th = kmalloc(sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
  95         if (!gc_th)
  96                 return -ENOMEM;
  97
  98         sbi->gc_thread = gc_th;
  99         init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
 100         sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
 101                                 GC_THREAD_NAME);
 102         if (IS_ERR(gc_th->f2fs_gc_task)) {
 103                 kfree(gc_th);
 104                 return -ENOMEM;
 105         }
 106         return 0;
 107 }
 108
 109 void stop_gc_thread(struct f2fs_sb_info *sbi)
 110 {
 111         struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
 112         if (!gc_th)
 113                 return;
 114         kthread_stop(gc_th->f2fs_gc_task);
 115         kfree(gc_th);
 116         sbi->gc_thread = NULL;
 117 }
 118
 119 static int select_gc_type(int gc_type)
 120 {
 121         return (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
 122 }
 123
 124 static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
 125                         int type, struct victim_sel_policy *p)
 126 {
 127         struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 128
 129         if (p->alloc_mode) {
 130                 p->gc_mode = GC_GREEDY;
 131                 p->dirty_segmap = dirty_i->dirty_segmap[type];
 132                 p->ofs_unit = 1;
 133         } else {
 134                 p->gc_mode = select_gc_type(gc_type);
 135                 p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
 136                 p->ofs_unit = sbi->segs_per_sec;
 137         }
 138         p->offset = sbi->last_victim[p->gc_mode];
 139 }
 140
 141 static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
 142                                 struct victim_sel_policy *p)
 143 {
 144         if (p->gc_mode == GC_GREEDY)
 145                 return (1 << sbi->log_blocks_per_seg) * p->ofs_unit;
 146         else if (p->gc_mode == GC_CB)
 147                 return UINT_MAX;
 148         else /* No other gc_mode */
 149                 return 0;
 150 }
 151
 152 static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
 153 {
 154         struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 155         unsigned int segno;
 156
 157         /*
 158          * If the gc_type is FG_GC, we can select victim segments
 159          * selected by background GC before.
 160          * Those segments guarantee they have small valid blocks.
 161          */
 162         segno = find_next_bit(dirty_i->victim_segmap[BG_GC],
 163                                                 TOTAL_SEGS(sbi), 0);
 164         if (segno < TOTAL_SEGS(sbi)) {
 165                 clear_bit(segno, dirty_i->victim_segmap[BG_GC]);
 166                 return segno;
 167         }
 168         return NULL_SEGNO;
 169 }
 170
 171 static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned int segno)
 172 {
 173         struct sit_info *sit_i = SIT_I(sbi);
 174         unsigned int secno = GET_SECNO(sbi, segno);
 175         unsigned int start = secno * sbi->segs_per_sec;
 176         unsigned long long mtime = 0;
 177         unsigned int vblocks;
 178         unsigned char age = 0;
 179         unsigned char u;
 180         unsigned int i;
 181
 182         for (i = 0; i < sbi->segs_per_sec; i++)
 183                 mtime += get_seg_entry(sbi, start + i)->mtime;
 184         vblocks = get_valid_blocks(sbi, segno, sbi->segs_per_sec);
 185
 186         mtime = div_u64(mtime, sbi->segs_per_sec);
 187         vblocks = div_u64(vblocks, sbi->segs_per_sec);
 188
 189         u = (vblocks * 100) >> sbi->log_blocks_per_seg;
 190
 191         /* Handle if the system time is changed by user */
 192         if (mtime < sit_i->min_mtime)
 193                 sit_i->min_mtime = mtime;
 194         if (mtime > sit_i->max_mtime)
 195                 sit_i->max_mtime = mtime;
 196         if (sit_i->max_mtime != sit_i->min_mtime)
 197                 age = 100 - div64_u64(100 * (mtime - sit_i->min_mtime),
 198                                 sit_i->max_mtime - sit_i->min_mtime);
 199
 200         return UINT_MAX - ((100 * (100 - u) * age) / (100 + u));
 201 }
 202
 203 static unsigned int get_gc_cost(struct f2fs_sb_info *sbi, unsigned int segno,
 204                                         struct victim_sel_policy *p)
 205 {
 206         if (p->alloc_mode == SSR)
 207                 return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
 208
 209         /* alloc_mode == LFS */
 210         if (p->gc_mode == GC_GREEDY)
 211                 return get_valid_blocks(sbi, segno, sbi->segs_per_sec);
 212         else
 213                 return get_cb_cost(sbi, segno);
 214 }
 215
 216 /*
 217  * This function is called from two pathes.
 218  * One is garbage collection and the other is SSR segment selection.
 219  * When it is called during GC, it just gets a victim segment
 220  * and it does not remove it from dirty seglist.
 221  * When it is called from SSR segment selection, it finds a segment
 222  * which has minimum valid blocks and removes it from dirty seglist.
 223  */
 224 static int get_victim_by_default(struct f2fs_sb_info *sbi,
 225                 unsigned int *result, int gc_type, int type, char alloc_mode)
 226 {
 227         struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 228         struct victim_sel_policy p;
 229         unsigned int segno;
 230         int nsearched = 0;
 231
 232         p.alloc_mode = alloc_mode;
 233         select_policy(sbi, gc_type, type, &p);
 234
 235         p.min_segno = NULL_SEGNO;
 236         p.min_cost = get_max_cost(sbi, &p);
 237
 238         mutex_lock(&dirty_i->seglist_lock);
 239
 240         if (p.alloc_mode == LFS && gc_type == FG_GC) {
 241                 p.min_segno = check_bg_victims(sbi);
 242                 if (p.min_segno != NULL_SEGNO)
 243                         goto got_it;
 244         }
 245
 246         while (1) {
 247                 unsigned long cost;
 248
 249                 segno = find_next_bit(p.dirty_segmap,
 250                                                 TOTAL_SEGS(sbi), p.offset);
 251                 if (segno >= TOTAL_SEGS(sbi)) {
 252                         if (sbi->last_victim[p.gc_mode]) {
 253                                 sbi->last_victim[p.gc_mode] = 0;
 254                                 p.offset = 0;
 255                                 continue;
 256                         }
 257                         break;
 258                 }
 259                 p.offset = ((segno / p.ofs_unit) * p.ofs_unit) + p.ofs_unit;
 260
 261                 if (test_bit(segno, dirty_i->victim_segmap[FG_GC]))
 262                         continue;
 263                 if (gc_type == BG_GC &&
 264                                 test_bit(segno, dirty_i->victim_segmap[BG_GC]))
 265                         continue;
 266                 if (IS_CURSEC(sbi, GET_SECNO(sbi, segno)))
 267                         continue;
 268
 269                 cost = get_gc_cost(sbi, segno, &p);
 270
 271                 if (p.min_cost > cost) {
 272                         p.min_segno = segno;
 273                         p.min_cost = cost;
 274                 }
 275
 276                 if (cost == get_max_cost(sbi, &p))
 277                         continue;
 278
 279                 if (nsearched++ >= MAX_VICTIM_SEARCH) {
 280                         sbi->last_victim[p.gc_mode] = segno;
 281                         break;
 282                 }
 283         }
 284 got_it:
 285         if (p.min_segno != NULL_SEGNO) {
 286                 *result = (p.min_segno / p.ofs_unit) * p.ofs_unit;
 287                 if (p.alloc_mode == LFS) {
 288                         int i;
 289                         for (i = 0; i < p.ofs_unit; i++)
 290                                 set_bit(*result + i,
 291                                         dirty_i->victim_segmap[gc_type]);
 292                 }
 293         }
 294         mutex_unlock(&dirty_i->seglist_lock);
 295
 296         return (p.min_segno == NULL_SEGNO) ? 0 : 1;
 297 }
 298
 299 static const struct victim_selection default_v_ops = {
 300         .get_victim = get_victim_by_default,
 301 };
 302
 303 static struct inode *find_gc_inode(nid_t ino, struct list_head *ilist)
 304 {
 305         struct list_head *this;
 306         struct inode_entry *ie;
 307
 308         list_for_each(this, ilist) {
 309                 ie = list_entry(this, struct inode_entry, list);
 310                 if (ie->inode->i_ino == ino)
 311                         return ie->inode;
 312         }
 313         return NULL;
 314 }
 315
 316 static void add_gc_inode(struct inode *inode, struct list_head *ilist)
 317 {
 318         struct list_head *this;
 319         struct inode_entry *new_ie, *ie;
 320
 321         list_for_each(this, ilist) {
 322                 ie = list_entry(this, struct inode_entry, list);
 323                 if (ie->inode == inode) {
 324                         iput(inode);
 325                         return;
 326                 }
 327         }
 328 repeat:
 329         new_ie = kmem_cache_alloc(winode_slab, GFP_NOFS);
 330         if (!new_ie) {
 331                 cond_resched();
 332                 goto repeat;
 333         }
 334         new_ie->inode = inode;
 335         list_add_tail(&new_ie->list, ilist);
 336 }
 337
 338 static void put_gc_inode(struct list_head *ilist)
 339 {
 340         struct inode_entry *ie, *next_ie;
 341         list_for_each_entry_safe(ie, next_ie, ilist, list) {
 342                 iput(ie->inode);
 343                 list_del(&ie->list);
 344                 kmem_cache_free(winode_slab, ie);
 345         }
 346 }
 347
 348 static int check_valid_map(struct f2fs_sb_info *sbi,
 349                                 unsigned int segno, int offset)
 350 {
 351         struct sit_info *sit_i = SIT_I(sbi);
 352         struct seg_entry *sentry;
 353         int ret;
 354
 355         mutex_lock(&sit_i->sentry_lock);
 356         sentry = get_seg_entry(sbi, segno);
 357         ret = f2fs_test_bit(offset, sentry->cur_valid_map);
 358         mutex_unlock(&sit_i->sentry_lock);
 359         return ret ? GC_OK : GC_NEXT;
 360 }
 361
 362 /*
 363  * This function compares node address got in summary with that in NAT.
 364  * On validity, copy that node with cold status, otherwise (invalid node)
 365  * ignore that.
 366  */
 367 static int gc_node_segment(struct f2fs_sb_info *sbi,
 368                 struct f2fs_summary *sum, unsigned int segno, int gc_type)
 369 {
 370         bool initial = true;
 371         struct f2fs_summary *entry;
 372         int off;
 373
 374 next_step:
 375         entry = sum;
 376         for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
 377                 nid_t nid = le32_to_cpu(entry->nid);
 378                 struct page *node_page;
 379                 int err;
 380
 381                 /*
 382                  * It makes sure that free segments are able to write
 383                  * all the dirty node pages before CP after this CP.
 384                  * So let's check the space of dirty node pages.
 385                  */
 386                 if (should_do_checkpoint(sbi)) {
 387                         mutex_lock(&sbi->cp_mutex);
 388                         block_operations(sbi);
 389                         return GC_BLOCKED;
 390                 }
 391
 392                 err = check_valid_map(sbi, segno, off);
 393                 if (err == GC_NEXT)
 394                         continue;
 395
 396                 if (initial) {
 397                         ra_node_page(sbi, nid);
 398                         continue;
 399                 }
 400                 node_page = get_node_page(sbi, nid);
 401                 if (IS_ERR(node_page))
 402                         continue;
 403
 404                 /* set page dirty and write it */
 405                 if (!PageWriteback(node_page))
 406                         set_page_dirty(node_page);
 407                 f2fs_put_page(node_page, 1);
 408                 stat_inc_node_blk_count(sbi, 1);
 409         }
 410         if (initial) {
 411                 initial = false;
 412                 goto next_step;
 413         }
 414
 415         if (gc_type == FG_GC) {
 416                 struct writeback_control wbc = {
 417                         .sync_mode = WB_SYNC_ALL,
 418                         .nr_to_write = LONG_MAX,
 419                         .for_reclaim = 0,
 420                 };
 421                 sync_node_pages(sbi, 0, &wbc);
 422         }
 423         return GC_DONE;
 424 }
 425
 426 /*
 427  * Calculate start block index that this node page contains
 428  */
 429 block_t start_bidx_of_node(unsigned int node_ofs)
 430 {
 431         unsigned int indirect_blks = 2 * NIDS_PER_BLOCK + 4;
 432         unsigned int bidx;
 433
 434         if (node_ofs == 0)
 435                 return 0;
 436
 437         if (node_ofs <= 2) {
 438                 bidx = node_ofs - 1;
 439         } else if (node_ofs <= indirect_blks) {
 440                 int dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1);
 441                 bidx = node_ofs - 2 - dec;
 442         } else {
 443                 int dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1);
 444                 bidx = node_ofs - 5 - dec;
 445         }
 446         return bidx * ADDRS_PER_BLOCK + ADDRS_PER_INODE;
 447 }
 448
 449 static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 450                 struct node_info *dni, block_t blkaddr, unsigned int *nofs)
 451 {
 452         struct page *node_page;
 453         nid_t nid;
 454         unsigned int ofs_in_node;
 455         block_t source_blkaddr;
 456
 457         nid = le32_to_cpu(sum->nid);
 458         ofs_in_node = le16_to_cpu(sum->ofs_in_node);
 459
 460         node_page = get_node_page(sbi, nid);
 461         if (IS_ERR(node_page))
 462                 return GC_NEXT;
 463
 464         get_node_info(sbi, nid, dni);
 465
 466         if (sum->version != dni->version) {
 467                 f2fs_put_page(node_page, 1);
 468                 return GC_NEXT;
 469         }
 470
 471         *nofs = ofs_of_node(node_page);
 472         source_blkaddr = datablock_addr(node_page, ofs_in_node);
 473         f2fs_put_page(node_page, 1);
 474
 475         if (source_blkaddr != blkaddr)
 476                 return GC_NEXT;
 477         return GC_OK;
 478 }
 479
 480 static void move_data_page(struct inode *inode, struct page *page, int gc_type)
 481 {
 482         if (page->mapping != inode->i_mapping)
 483                 goto out;
 484
 485         if (inode != page->mapping->host)
 486                 goto out;
 487
 488         if (PageWriteback(page))
 489                 goto out;
 490
 491         if (gc_type == BG_GC) {
 492                 set_page_dirty(page);
 493                 set_cold_data(page);
 494         } else {
 495                 struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 496                 mutex_lock_op(sbi, DATA_WRITE);
 497                 if (clear_page_dirty_for_io(page) &&
 498                         S_ISDIR(inode->i_mode)) {
 499                         dec_page_count(sbi, F2FS_DIRTY_DENTS);
 500                         inode_dec_dirty_dents(inode);
 501                 }
 502                 set_cold_data(page);
 503                 do_write_data_page(page);
 504                 mutex_unlock_op(sbi, DATA_WRITE);
 505                 clear_cold_data(page);
 506         }
 507 out:
 508         f2fs_put_page(page, 1);
 509 }
 510
 511 /*
 512  * This function tries to get parent node of victim data block, and identifies
 513  * data block validity. If the block is valid, copy that with cold status and
 514  * modify parent node.
 515  * If the parent node is not valid or the data block address is different,
 516  * the victim data block is ignored.
 517  */
 518 static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 519                 struct list_head *ilist, unsigned int segno, int gc_type)
 520 {
 521         struct super_block *sb = sbi->sb;
 522         struct f2fs_summary *entry;
 523         block_t start_addr;
 524         int err, off;
 525         int phase = 0;
 526
 527         start_addr = START_BLOCK(sbi, segno);
 528
 529 next_step:
 530         entry = sum;
 531         for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
 532                 struct page *data_page;
 533                 struct inode *inode;
 534                 struct node_info dni; /* dnode info for the data */
 535                 unsigned int ofs_in_node, nofs;
 536                 block_t start_bidx;
 537
 538                 /*
 539                  * It makes sure that free segments are able to write
 540                  * all the dirty node pages before CP after this CP.
 541                  * So let's check the space of dirty node pages.
 542                  */
 543                 if (should_do_checkpoint(sbi)) {
 544                         mutex_lock(&sbi->cp_mutex);
 545                         block_operations(sbi);
 546                         err = GC_BLOCKED;
 547                         goto stop;
 548                 }
 549
 550                 err = check_valid_map(sbi, segno, off);
 551                 if (err == GC_NEXT)
 552                         continue;
 553
 554                 if (phase == 0) {
 555                         ra_node_page(sbi, le32_to_cpu(entry->nid));
 556                         continue;
 557                 }
 558
 559                 /* Get an inode by ino with checking validity */
 560                 err = check_dnode(sbi, entry, &dni, start_addr + off, &nofs);
 561                 if (err == GC_NEXT)
 562                         continue;
 563
 564                 if (phase == 1) {
 565                         ra_node_page(sbi, dni.ino);
 566                         continue;
 567                 }
 568
 569                 start_bidx = start_bidx_of_node(nofs);
 570                 ofs_in_node = le16_to_cpu(entry->ofs_in_node);
 571
 572                 if (phase == 2) {
 573                         inode = f2fs_iget_nowait(sb, dni.ino);
 574                         if (IS_ERR(inode))
 575                                 continue;
 576
 577                         data_page = find_data_page(inode,
 578                                         start_bidx + ofs_in_node);
 579                         if (IS_ERR(data_page))
 580                                 goto next_iput;
 581
 582                         f2fs_put_page(data_page, 0);
 583                         add_gc_inode(inode, ilist);
 584                 } else {
 585                         inode = find_gc_inode(dni.ino, ilist);
 586                         if (inode) {
 587                                 data_page = get_lock_data_page(inode,
 588                                                 start_bidx + ofs_in_node);
 589                                 if (IS_ERR(data_page))
 590                                         continue;
 591                                 move_data_page(inode, data_page, gc_type);
 592                                 stat_inc_data_blk_count(sbi, 1);
 593                         }
 594                 }
 595                 continue;
 596 next_iput:
 597                 iput(inode);
 598         }
 599         if (++phase < 4)
 600                 goto next_step;
 601         err = GC_DONE;
 602 stop:
 603         if (gc_type == FG_GC)
 604                 f2fs_submit_bio(sbi, DATA, true);
 605         return err;
 606 }
 607
 608 static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
 609                                                 int gc_type, int type)
 610 {
 611         struct sit_info *sit_i = SIT_I(sbi);
 612         int ret;
 613         mutex_lock(&sit_i->sentry_lock);
 614         ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type, type, LFS);
 615         mutex_unlock(&sit_i->sentry_lock);
 616         return ret;
 617 }
 618
 619 static int do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
 620                                 struct list_head *ilist, int gc_type)
 621 {
 622         struct page *sum_page;
 623         struct f2fs_summary_block *sum;
 624         int ret = GC_DONE;
 625
 626         /* read segment summary of victim */
 627         sum_page = get_sum_page(sbi, segno);
 628         if (IS_ERR(sum_page))
 629                 return GC_ERROR;
 630
 631         /*
 632          * CP needs to lock sum_page. In this time, we don't need
 633          * to lock this page, because this summary page is not gone anywhere.
 634          * Also, this page is not gonna be updated before GC is done.
 635          */
 636         unlock_page(sum_page);
 637         sum = page_address(sum_page);
 638
 639         switch (GET_SUM_TYPE((&sum->footer))) {
 640         case SUM_TYPE_NODE:
 641                 ret = gc_node_segment(sbi, sum->entries, segno, gc_type);
 642                 break;
 643         case SUM_TYPE_DATA:
 644                 ret = gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);
 645                 break;
 646         }
 647         stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
 648         stat_inc_call_count(sbi->stat_info);
 649
 650         f2fs_put_page(sum_page, 0);
 651         return ret;
 652 }
 653
 654 int f2fs_gc(struct f2fs_sb_info *sbi, int nGC)
 655 {
 656         unsigned int segno;
 657         int old_free_secs, cur_free_secs;
 658         int gc_status, nfree;
 659         struct list_head ilist;
 660         int gc_type = BG_GC;
 661
 662         INIT_LIST_HEAD(&ilist);
 663 gc_more:
 664         nfree = 0;
 665         gc_status = GC_NONE;
 666
 667         if (has_not_enough_free_secs(sbi))
 668                 old_free_secs = reserved_sections(sbi);
 669         else
 670                 old_free_secs = free_sections(sbi);
 671
 672         while (sbi->sb->s_flags & MS_ACTIVE) {
 673                 int i;
 674                 if (has_not_enough_free_secs(sbi))
 675                         gc_type = FG_GC;
 676
 677                 cur_free_secs = free_sections(sbi) + nfree;
 678
 679                 /* We got free space successfully. */
 680                 if (nGC < cur_free_secs - old_free_secs)
 681                         break;
 682
 683                 if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
 684                         break;
 685
 686                 for (i = 0; i < sbi->segs_per_sec; i++) {
 687                         /*
 688                          * do_garbage_collect will give us three gc_status:
 689                          * GC_ERROR, GC_DONE, and GC_BLOCKED.
 690                          * If GC is finished uncleanly, we have to return
 691                          * the victim to dirty segment list.
 692                          */
 693                         gc_status = do_garbage_collect(sbi, segno + i,
 694                                         &ilist, gc_type);
 695                         if (gc_status != GC_DONE)
 696                                 goto stop;
 697                         nfree++;
 698                 }
 699         }
 700 stop:
 701         if (has_not_enough_free_secs(sbi) || gc_status == GC_BLOCKED) {
 702                 write_checkpoint(sbi, (gc_status == GC_BLOCKED), false);
 703                 if (nfree)
 704                         goto gc_more;
 705         }
 706         mutex_unlock(&sbi->gc_mutex);
 707
 708         put_gc_inode(&ilist);
 709         BUG_ON(!list_empty(&ilist));
 710         return gc_status;
 711 }
 712
 713 void build_gc_manager(struct f2fs_sb_info *sbi)
 714 {
 715         DIRTY_I(sbi)->v_ops = &default_v_ops;
 716 }
 717
 718 int create_gc_caches(void)
 719 {
 720         winode_slab = f2fs_kmem_cache_create("f2fs_gc_inodes",
 721                         sizeof(struct inode_entry), NULL);
 722         if (!winode_slab)
 723                 return -ENOMEM;
 724         return 0;
 725 }
 726
 727 void destroy_gc_caches(void)
 728 {
 729         kmem_cache_destroy(winode_slab);
 730 }