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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * This file is part of UBIFS.4 *5 * Copyright (C) 2006-2008 Nokia Corporation.6 *7 * Authors: Adrian Hunter8 * Artem Bityutskiy (Битюцкий Артём)9 */10 11/*12 * This file implements garbage collection. The procedure for garbage collection13 * is different depending on whether a LEB as an index LEB (contains index14 * nodes) or not. For non-index LEBs, garbage collection finds a LEB which15 * contains a lot of dirty space (obsolete nodes), and copies the non-obsolete16 * nodes to the journal, at which point the garbage-collected LEB is free to be17 * reused. For index LEBs, garbage collection marks the non-obsolete index nodes18 * dirty in the TNC, and after the next commit, the garbage-collected LEB is19 * to be reused. Garbage collection will cause the number of dirty index nodes20 * to grow, however sufficient space is reserved for the index to ensure the21 * commit will never run out of space.22 *23 * Notes about dead watermark. At current UBIFS implementation we assume that24 * LEBs which have less than @c->dead_wm bytes of free + dirty space are full25 * and not worth garbage-collecting. The dead watermark is one min. I/O unit26 * size, or min. UBIFS node size, depending on what is greater. Indeed, UBIFS27 * Garbage Collector has to synchronize the GC head's write buffer before28 * returning, so this is about wasting one min. I/O unit. However, UBIFS GC can29 * actually reclaim even very small pieces of dirty space by garbage collecting30 * enough dirty LEBs, but we do not bother doing this at this implementation.31 *32 * Notes about dark watermark. The results of GC work depends on how big are33 * the UBIFS nodes GC deals with. Large nodes make GC waste more space. Indeed,34 * if GC move data from LEB A to LEB B and nodes in LEB A are large, GC would35 * have to waste large pieces of free space at the end of LEB B, because nodes36 * from LEB A would not fit. And the worst situation is when all nodes are of37 * maximum size. So dark watermark is the amount of free + dirty space in LEB38 * which are guaranteed to be reclaimable. If LEB has less space, the GC might39 * be unable to reclaim it. So, LEBs with free + dirty greater than dark40 * watermark are "good" LEBs from GC's point of view. The other LEBs are not so41 * good, and GC takes extra care when moving them.42 */43 44#include <linux/slab.h>45#include <linux/pagemap.h>46#include <linux/list_sort.h>47#include "ubifs.h"48 49/*50 * GC may need to move more than one LEB to make progress. The below constants51 * define "soft" and "hard" limits on the number of LEBs the garbage collector52 * may move.53 */54#define SOFT_LEBS_LIMIT 455#define HARD_LEBS_LIMIT 3256 57/**58 * switch_gc_head - switch the garbage collection journal head.59 * @c: UBIFS file-system description object60 *61 * This function switch the GC head to the next LEB which is reserved in62 * @c->gc_lnum. Returns %0 in case of success, %-EAGAIN if commit is required,63 * and other negative error code in case of failures.64 */65static int switch_gc_head(struct ubifs_info *c)66{67 int err, gc_lnum = c->gc_lnum;68 struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;69 70 ubifs_assert(c, gc_lnum != -1);71 dbg_gc("switch GC head from LEB %d:%d to LEB %d (waste %d bytes)",72 wbuf->lnum, wbuf->offs + wbuf->used, gc_lnum,73 c->leb_size - wbuf->offs - wbuf->used);74 75 err = ubifs_wbuf_sync_nolock(wbuf);76 if (err)77 return err;78 79 /*80 * The GC write-buffer was synchronized, we may safely unmap81 * 'c->gc_lnum'.82 */83 err = ubifs_leb_unmap(c, gc_lnum);84 if (err)85 return err;86 87 err = ubifs_add_bud_to_log(c, GCHD, gc_lnum, 0);88 if (err)89 return err;90 91 c->gc_lnum = -1;92 err = ubifs_wbuf_seek_nolock(wbuf, gc_lnum, 0);93 return err;94}95 96/**97 * data_nodes_cmp - compare 2 data nodes.98 * @priv: UBIFS file-system description object99 * @a: first data node100 * @b: second data node101 *102 * This function compares data nodes @a and @b. Returns %1 if @a has greater103 * inode or block number, and %-1 otherwise.104 */105static int data_nodes_cmp(void *priv, const struct list_head *a,106 const struct list_head *b)107{108 ino_t inuma, inumb;109 struct ubifs_info *c = priv;110 struct ubifs_scan_node *sa, *sb;111 112 cond_resched();113 if (a == b)114 return 0;115 116 sa = list_entry(a, struct ubifs_scan_node, list);117 sb = list_entry(b, struct ubifs_scan_node, list);118 119 ubifs_assert(c, key_type(c, &sa->key) == UBIFS_DATA_KEY);120 ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DATA_KEY);121 ubifs_assert(c, sa->type == UBIFS_DATA_NODE);122 ubifs_assert(c, sb->type == UBIFS_DATA_NODE);123 124 inuma = key_inum(c, &sa->key);125 inumb = key_inum(c, &sb->key);126 127 if (inuma == inumb) {128 unsigned int blka = key_block(c, &sa->key);129 unsigned int blkb = key_block(c, &sb->key);130 131 if (blka <= blkb)132 return -1;133 } else if (inuma <= inumb)134 return -1;135 136 return 1;137}138 139/*140 * nondata_nodes_cmp - compare 2 non-data nodes.141 * @priv: UBIFS file-system description object142 * @a: first node143 * @a: second node144 *145 * This function compares nodes @a and @b. It makes sure that inode nodes go146 * first and sorted by length in descending order. Directory entry nodes go147 * after inode nodes and are sorted in ascending hash valuer order.148 */149static int nondata_nodes_cmp(void *priv, const struct list_head *a,150 const struct list_head *b)151{152 ino_t inuma, inumb;153 struct ubifs_info *c = priv;154 struct ubifs_scan_node *sa, *sb;155 156 cond_resched();157 if (a == b)158 return 0;159 160 sa = list_entry(a, struct ubifs_scan_node, list);161 sb = list_entry(b, struct ubifs_scan_node, list);162 163 ubifs_assert(c, key_type(c, &sa->key) != UBIFS_DATA_KEY &&164 key_type(c, &sb->key) != UBIFS_DATA_KEY);165 ubifs_assert(c, sa->type != UBIFS_DATA_NODE &&166 sb->type != UBIFS_DATA_NODE);167 168 /* Inodes go before directory entries */169 if (sa->type == UBIFS_INO_NODE) {170 if (sb->type == UBIFS_INO_NODE)171 return sb->len - sa->len;172 return -1;173 }174 if (sb->type == UBIFS_INO_NODE)175 return 1;176 177 ubifs_assert(c, key_type(c, &sa->key) == UBIFS_DENT_KEY ||178 key_type(c, &sa->key) == UBIFS_XENT_KEY);179 ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DENT_KEY ||180 key_type(c, &sb->key) == UBIFS_XENT_KEY);181 ubifs_assert(c, sa->type == UBIFS_DENT_NODE ||182 sa->type == UBIFS_XENT_NODE);183 ubifs_assert(c, sb->type == UBIFS_DENT_NODE ||184 sb->type == UBIFS_XENT_NODE);185 186 inuma = key_inum(c, &sa->key);187 inumb = key_inum(c, &sb->key);188 189 if (inuma == inumb) {190 uint32_t hasha = key_hash(c, &sa->key);191 uint32_t hashb = key_hash(c, &sb->key);192 193 if (hasha <= hashb)194 return -1;195 } else if (inuma <= inumb)196 return -1;197 198 return 1;199}200 201/**202 * sort_nodes - sort nodes for GC.203 * @c: UBIFS file-system description object204 * @sleb: describes nodes to sort and contains the result on exit205 * @nondata: contains non-data nodes on exit206 * @min: minimum node size is returned here207 *208 * This function sorts the list of inodes to garbage collect. First of all, it209 * kills obsolete nodes and separates data and non-data nodes to the210 * @sleb->nodes and @nondata lists correspondingly.211 *212 * Data nodes are then sorted in block number order - this is important for213 * bulk-read; data nodes with lower inode number go before data nodes with214 * higher inode number, and data nodes with lower block number go before data215 * nodes with higher block number;216 *217 * Non-data nodes are sorted as follows.218 * o First go inode nodes - they are sorted in descending length order.219 * o Then go directory entry nodes - they are sorted in hash order, which220 * should supposedly optimize 'readdir()'. Direntry nodes with lower parent221 * inode number go before direntry nodes with higher parent inode number,222 * and direntry nodes with lower name hash values go before direntry nodes223 * with higher name hash values.224 *225 * This function returns zero in case of success and a negative error code in226 * case of failure.227 */228static int sort_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb,229 struct list_head *nondata, int *min)230{231 int err;232 struct ubifs_scan_node *snod, *tmp;233 234 *min = INT_MAX;235 236 /* Separate data nodes and non-data nodes */237 list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {238 ubifs_assert(c, snod->type == UBIFS_INO_NODE ||239 snod->type == UBIFS_DATA_NODE ||240 snod->type == UBIFS_DENT_NODE ||241 snod->type == UBIFS_XENT_NODE ||242 snod->type == UBIFS_TRUN_NODE ||243 snod->type == UBIFS_AUTH_NODE);244 245 if (snod->type != UBIFS_INO_NODE &&246 snod->type != UBIFS_DATA_NODE &&247 snod->type != UBIFS_DENT_NODE &&248 snod->type != UBIFS_XENT_NODE) {249 /* Probably truncation node, zap it */250 list_del(&snod->list);251 kfree(snod);252 continue;253 }254 255 ubifs_assert(c, key_type(c, &snod->key) == UBIFS_DATA_KEY ||256 key_type(c, &snod->key) == UBIFS_INO_KEY ||257 key_type(c, &snod->key) == UBIFS_DENT_KEY ||258 key_type(c, &snod->key) == UBIFS_XENT_KEY);259 260 err = ubifs_tnc_has_node(c, &snod->key, 0, sleb->lnum,261 snod->offs, 0);262 if (err < 0)263 return err;264 265 if (!err) {266 /* The node is obsolete, remove it from the list */267 list_del(&snod->list);268 kfree(snod);269 continue;270 }271 272 if (snod->len < *min)273 *min = snod->len;274 275 if (key_type(c, &snod->key) != UBIFS_DATA_KEY)276 list_move_tail(&snod->list, nondata);277 }278 279 /* Sort data and non-data nodes */280 list_sort(c, &sleb->nodes, &data_nodes_cmp);281 list_sort(c, nondata, &nondata_nodes_cmp);282 283 err = dbg_check_data_nodes_order(c, &sleb->nodes);284 if (err)285 return err;286 err = dbg_check_nondata_nodes_order(c, nondata);287 if (err)288 return err;289 return 0;290}291 292/**293 * move_node - move a node.294 * @c: UBIFS file-system description object295 * @sleb: describes the LEB to move nodes from296 * @snod: the mode to move297 * @wbuf: write-buffer to move node to298 *299 * This function moves node @snod to @wbuf, changes TNC correspondingly, and300 * destroys @snod. Returns zero in case of success and a negative error code in301 * case of failure.302 */303static int move_node(struct ubifs_info *c, struct ubifs_scan_leb *sleb,304 struct ubifs_scan_node *snod, struct ubifs_wbuf *wbuf)305{306 int err, new_lnum = wbuf->lnum, new_offs = wbuf->offs + wbuf->used;307 308 cond_resched();309 err = ubifs_wbuf_write_nolock(wbuf, snod->node, snod->len);310 if (err)311 return err;312 313 err = ubifs_tnc_replace(c, &snod->key, sleb->lnum,314 snod->offs, new_lnum, new_offs,315 snod->len);316 list_del(&snod->list);317 kfree(snod);318 return err;319}320 321/**322 * move_nodes - move nodes.323 * @c: UBIFS file-system description object324 * @sleb: describes the LEB to move nodes from325 *326 * This function moves valid nodes from data LEB described by @sleb to the GC327 * journal head. This function returns zero in case of success, %-EAGAIN if328 * commit is required, and other negative error codes in case of other329 * failures.330 */331static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)332{333 int err, min;334 LIST_HEAD(nondata);335 struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;336 337 if (wbuf->lnum == -1) {338 /*339 * The GC journal head is not set, because it is the first GC340 * invocation since mount.341 */342 err = switch_gc_head(c);343 if (err)344 return err;345 }346 347 err = sort_nodes(c, sleb, &nondata, &min);348 if (err)349 goto out;350 351 /* Write nodes to their new location. Use the first-fit strategy */352 while (1) {353 int avail, moved = 0;354 struct ubifs_scan_node *snod, *tmp;355 356 /* Move data nodes */357 list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {358 avail = c->leb_size - wbuf->offs - wbuf->used -359 ubifs_auth_node_sz(c);360 if (snod->len > avail)361 /*362 * Do not skip data nodes in order to optimize363 * bulk-read.364 */365 break;366 367 err = ubifs_shash_update(c, c->jheads[GCHD].log_hash,368 snod->node, snod->len);369 if (err)370 goto out;371 372 err = move_node(c, sleb, snod, wbuf);373 if (err)374 goto out;375 moved = 1;376 }377 378 /* Move non-data nodes */379 list_for_each_entry_safe(snod, tmp, &nondata, list) {380 avail = c->leb_size - wbuf->offs - wbuf->used -381 ubifs_auth_node_sz(c);382 if (avail < min)383 break;384 385 if (snod->len > avail) {386 /*387 * Keep going only if this is an inode with388 * some data. Otherwise stop and switch the GC389 * head. IOW, we assume that data-less inode390 * nodes and direntry nodes are roughly of the391 * same size.392 */393 if (key_type(c, &snod->key) == UBIFS_DENT_KEY ||394 snod->len == UBIFS_INO_NODE_SZ)395 break;396 continue;397 }398 399 err = ubifs_shash_update(c, c->jheads[GCHD].log_hash,400 snod->node, snod->len);401 if (err)402 goto out;403 404 err = move_node(c, sleb, snod, wbuf);405 if (err)406 goto out;407 moved = 1;408 }409 410 if (ubifs_authenticated(c) && moved) {411 struct ubifs_auth_node *auth;412 413 auth = kmalloc(ubifs_auth_node_sz(c), GFP_NOFS);414 if (!auth) {415 err = -ENOMEM;416 goto out;417 }418 419 err = ubifs_prepare_auth_node(c, auth,420 c->jheads[GCHD].log_hash);421 if (err) {422 kfree(auth);423 goto out;424 }425 426 err = ubifs_wbuf_write_nolock(wbuf, auth,427 ubifs_auth_node_sz(c));428 if (err) {429 kfree(auth);430 goto out;431 }432 433 ubifs_add_dirt(c, wbuf->lnum, ubifs_auth_node_sz(c));434 }435 436 if (list_empty(&sleb->nodes) && list_empty(&nondata))437 break;438 439 /*440 * Waste the rest of the space in the LEB and switch to the441 * next LEB.442 */443 err = switch_gc_head(c);444 if (err)445 goto out;446 }447 448 return 0;449 450out:451 list_splice_tail(&nondata, &sleb->nodes);452 return err;453}454 455/**456 * gc_sync_wbufs - sync write-buffers for GC.457 * @c: UBIFS file-system description object458 *459 * We must guarantee that obsoleting nodes are on flash. Unfortunately they may460 * be in a write-buffer instead. That is, a node could be written to a461 * write-buffer, obsoleting another node in a LEB that is GC'd. If that LEB is462 * erased before the write-buffer is sync'd and then there is an unclean463 * unmount, then an existing node is lost. To avoid this, we sync all464 * write-buffers.465 *466 * This function returns %0 on success or a negative error code on failure.467 */468static int gc_sync_wbufs(struct ubifs_info *c)469{470 int err, i;471 472 for (i = 0; i < c->jhead_cnt; i++) {473 if (i == GCHD)474 continue;475 err = ubifs_wbuf_sync(&c->jheads[i].wbuf);476 if (err)477 return err;478 }479 return 0;480}481 482/**483 * ubifs_garbage_collect_leb - garbage-collect a logical eraseblock.484 * @c: UBIFS file-system description object485 * @lp: describes the LEB to garbage collect486 *487 * This function garbage-collects an LEB and returns one of the @LEB_FREED,488 * @LEB_RETAINED, etc positive codes in case of success, %-EAGAIN if commit is489 * required, and other negative error codes in case of failures.490 */491int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp)492{493 struct ubifs_scan_leb *sleb;494 struct ubifs_scan_node *snod;495 struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;496 int err = 0, lnum = lp->lnum;497 498 ubifs_assert(c, c->gc_lnum != -1 || wbuf->offs + wbuf->used == 0 ||499 c->need_recovery);500 ubifs_assert(c, c->gc_lnum != lnum);501 ubifs_assert(c, wbuf->lnum != lnum);502 503 if (lp->free + lp->dirty == c->leb_size) {504 /* Special case - a free LEB */505 dbg_gc("LEB %d is free, return it", lp->lnum);506 ubifs_assert(c, !(lp->flags & LPROPS_INDEX));507 508 if (lp->free != c->leb_size) {509 /*510 * Write buffers must be sync'd before unmapping511 * freeable LEBs, because one of them may contain data512 * which obsoletes something in 'lp->lnum'.513 */514 err = gc_sync_wbufs(c);515 if (err)516 return err;517 err = ubifs_change_one_lp(c, lp->lnum, c->leb_size,518 0, 0, 0, 0);519 if (err)520 return err;521 }522 err = ubifs_leb_unmap(c, lp->lnum);523 if (err)524 return err;525 526 if (c->gc_lnum == -1) {527 c->gc_lnum = lnum;528 return LEB_RETAINED;529 }530 531 return LEB_FREED;532 }533 534 /*535 * We scan the entire LEB even though we only really need to scan up to536 * (c->leb_size - lp->free).537 */538 sleb = ubifs_scan(c, lnum, 0, c->sbuf, 0);539 if (IS_ERR(sleb))540 return PTR_ERR(sleb);541 542 ubifs_assert(c, !list_empty(&sleb->nodes));543 snod = list_entry(sleb->nodes.next, struct ubifs_scan_node, list);544 545 if (snod->type == UBIFS_IDX_NODE) {546 struct ubifs_gced_idx_leb *idx_gc;547 548 dbg_gc("indexing LEB %d (free %d, dirty %d)",549 lnum, lp->free, lp->dirty);550 list_for_each_entry(snod, &sleb->nodes, list) {551 struct ubifs_idx_node *idx = snod->node;552 int level = le16_to_cpu(idx->level);553 554 ubifs_assert(c, snod->type == UBIFS_IDX_NODE);555 key_read(c, ubifs_idx_key(c, idx), &snod->key);556 err = ubifs_dirty_idx_node(c, &snod->key, level, lnum,557 snod->offs);558 if (err)559 goto out;560 }561 562 idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS);563 if (!idx_gc) {564 err = -ENOMEM;565 goto out;566 }567 568 idx_gc->lnum = lnum;569 idx_gc->unmap = 0;570 list_add(&idx_gc->list, &c->idx_gc);571 572 /*573 * Don't release the LEB until after the next commit, because574 * it may contain data which is needed for recovery. So575 * although we freed this LEB, it will become usable only after576 * the commit.577 */578 err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0,579 LPROPS_INDEX, 1);580 if (err)581 goto out;582 err = LEB_FREED_IDX;583 } else {584 dbg_gc("data LEB %d (free %d, dirty %d)",585 lnum, lp->free, lp->dirty);586 587 err = move_nodes(c, sleb);588 if (err)589 goto out_inc_seq;590 591 err = gc_sync_wbufs(c);592 if (err)593 goto out_inc_seq;594 595 err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, 0, 0);596 if (err)597 goto out_inc_seq;598 599 /* Allow for races with TNC */600 c->gced_lnum = lnum;601 smp_wmb();602 c->gc_seq += 1;603 smp_wmb();604 605 if (c->gc_lnum == -1) {606 c->gc_lnum = lnum;607 err = LEB_RETAINED;608 } else {609 err = ubifs_wbuf_sync_nolock(wbuf);610 if (err)611 goto out;612 613 err = ubifs_leb_unmap(c, lnum);614 if (err)615 goto out;616 617 err = LEB_FREED;618 }619 }620 621out:622 ubifs_scan_destroy(sleb);623 return err;624 625out_inc_seq:626 /* We may have moved at least some nodes so allow for races with TNC */627 c->gced_lnum = lnum;628 smp_wmb();629 c->gc_seq += 1;630 smp_wmb();631 goto out;632}633 634/**635 * ubifs_garbage_collect - UBIFS garbage collector.636 * @c: UBIFS file-system description object637 * @anyway: do GC even if there are free LEBs638 *639 * This function does out-of-place garbage collection. The return codes are:640 * o positive LEB number if the LEB has been freed and may be used;641 * o %-EAGAIN if the caller has to run commit;642 * o %-ENOSPC if GC failed to make any progress;643 * o other negative error codes in case of other errors.644 *645 * Garbage collector writes data to the journal when GC'ing data LEBs, and just646 * marking indexing nodes dirty when GC'ing indexing LEBs. Thus, at some point647 * commit may be required. But commit cannot be run from inside GC, because the648 * caller might be holding the commit lock, so %-EAGAIN is returned instead;649 * And this error code means that the caller has to run commit, and re-run GC650 * if there is still no free space.651 *652 * There are many reasons why this function may return %-EAGAIN:653 * o the log is full and there is no space to write an LEB reference for654 * @c->gc_lnum;655 * o the journal is too large and exceeds size limitations;656 * o GC moved indexing LEBs, but they can be used only after the commit;657 * o the shrinker fails to find clean znodes to free and requests the commit;658 * o etc.659 *660 * Note, if the file-system is close to be full, this function may return661 * %-EAGAIN infinitely, so the caller has to limit amount of re-invocations of662 * the function. E.g., this happens if the limits on the journal size are too663 * tough and GC writes too much to the journal before an LEB is freed. This664 * might also mean that the journal is too large, and the TNC becomes to big,665 * so that the shrinker is constantly called, finds not clean znodes to free,666 * and requests commit. Well, this may also happen if the journal is all right,667 * but another kernel process consumes too much memory. Anyway, infinite668 * %-EAGAIN may happen, but in some extreme/misconfiguration cases.669 */670int ubifs_garbage_collect(struct ubifs_info *c, int anyway)671{672 int i, err, ret, min_space = c->dead_wm;673 struct ubifs_lprops lp;674 struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;675 676 ubifs_assert_cmt_locked(c);677 ubifs_assert(c, !c->ro_media && !c->ro_mount);678 679 if (ubifs_gc_should_commit(c))680 return -EAGAIN;681 682 mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);683 684 if (c->ro_error) {685 ret = -EROFS;686 goto out_unlock;687 }688 689 /* We expect the write-buffer to be empty on entry */690 ubifs_assert(c, !wbuf->used);691 692 for (i = 0; ; i++) {693 int space_before, space_after;694 695 /* Maybe continue after find and break before find */696 lp.lnum = -1;697 698 cond_resched();699 700 /* Give the commit an opportunity to run */701 if (ubifs_gc_should_commit(c)) {702 ret = -EAGAIN;703 break;704 }705 706 if (i > SOFT_LEBS_LIMIT && !list_empty(&c->idx_gc)) {707 /*708 * We've done enough iterations. Indexing LEBs were709 * moved and will be available after the commit.710 */711 dbg_gc("soft limit, some index LEBs GC'ed, -EAGAIN");712 ubifs_commit_required(c);713 ret = -EAGAIN;714 break;715 }716 717 if (i > HARD_LEBS_LIMIT) {718 /*719 * We've moved too many LEBs and have not made720 * progress, give up.721 */722 dbg_gc("hard limit, -ENOSPC");723 ret = -ENOSPC;724 break;725 }726 727 /*728 * Empty and freeable LEBs can turn up while we waited for729 * the wbuf lock, or while we have been running GC. In that730 * case, we should just return one of those instead of731 * continuing to GC dirty LEBs. Hence we request732 * 'ubifs_find_dirty_leb()' to return an empty LEB if it can.733 */734 ret = ubifs_find_dirty_leb(c, &lp, min_space, anyway ? 0 : 1);735 if (ret) {736 if (ret == -ENOSPC)737 dbg_gc("no more dirty LEBs");738 break;739 }740 741 dbg_gc("found LEB %d: free %d, dirty %d, sum %d (min. space %d)",742 lp.lnum, lp.free, lp.dirty, lp.free + lp.dirty,743 min_space);744 745 space_before = c->leb_size - wbuf->offs - wbuf->used;746 if (wbuf->lnum == -1)747 space_before = 0;748 749 ret = ubifs_garbage_collect_leb(c, &lp);750 if (ret < 0) {751 if (ret == -EAGAIN) {752 /*753 * This is not error, so we have to return the754 * LEB to lprops. But if 'ubifs_return_leb()'755 * fails, its failure code is propagated to the756 * caller instead of the original '-EAGAIN'.757 */758 err = ubifs_return_leb(c, lp.lnum);759 if (err) {760 ret = err;761 /*762 * An LEB may always be "taken",763 * so setting ubifs to read-only,764 * and then executing sync wbuf will765 * return -EROFS and enter the "out"766 * error branch.767 */768 ubifs_ro_mode(c, ret);769 }770 /* Maybe double return LEB if goto out */771 lp.lnum = -1;772 break;773 }774 goto out;775 }776 777 if (ret == LEB_FREED) {778 /* An LEB has been freed and is ready for use */779 dbg_gc("LEB %d freed, return", lp.lnum);780 ret = lp.lnum;781 break;782 }783 784 if (ret == LEB_FREED_IDX) {785 /*786 * This was an indexing LEB and it cannot be787 * immediately used. And instead of requesting the788 * commit straight away, we try to garbage collect some789 * more.790 */791 dbg_gc("indexing LEB %d freed, continue", lp.lnum);792 continue;793 }794 795 ubifs_assert(c, ret == LEB_RETAINED);796 space_after = c->leb_size - wbuf->offs - wbuf->used;797 dbg_gc("LEB %d retained, freed %d bytes", lp.lnum,798 space_after - space_before);799 800 if (space_after > space_before) {801 /* GC makes progress, keep working */802 min_space >>= 1;803 if (min_space < c->dead_wm)804 min_space = c->dead_wm;805 continue;806 }807 808 dbg_gc("did not make progress");809 810 /*811 * GC moved an LEB bud have not done any progress. This means812 * that the previous GC head LEB contained too few free space813 * and the LEB which was GC'ed contained only large nodes which814 * did not fit that space.815 *816 * We can do 2 things:817 * 1. pick another LEB in a hope it'll contain a small node818 * which will fit the space we have at the end of current GC819 * head LEB, but there is no guarantee, so we try this out820 * unless we have already been working for too long;821 * 2. request an LEB with more dirty space, which will force822 * 'ubifs_find_dirty_leb()' to start scanning the lprops823 * table, instead of just picking one from the heap824 * (previously it already picked the dirtiest LEB).825 */826 if (i < SOFT_LEBS_LIMIT) {827 dbg_gc("try again");828 continue;829 }830 831 min_space <<= 1;832 if (min_space > c->dark_wm)833 min_space = c->dark_wm;834 dbg_gc("set min. space to %d", min_space);835 }836 837 if (ret == -ENOSPC && !list_empty(&c->idx_gc)) {838 dbg_gc("no space, some index LEBs GC'ed, -EAGAIN");839 ubifs_commit_required(c);840 ret = -EAGAIN;841 }842 843 err = ubifs_wbuf_sync_nolock(wbuf);844 if (!err)845 err = ubifs_leb_unmap(c, c->gc_lnum);846 if (err) {847 ret = err;848 goto out;849 }850out_unlock:851 mutex_unlock(&wbuf->io_mutex);852 return ret;853 854out:855 ubifs_assert(c, ret < 0);856 ubifs_assert(c, ret != -ENOSPC && ret != -EAGAIN);857 ubifs_wbuf_sync_nolock(wbuf);858 ubifs_ro_mode(c, ret);859 mutex_unlock(&wbuf->io_mutex);860 if (lp.lnum != -1)861 ubifs_return_leb(c, lp.lnum);862 return ret;863}864 865/**866 * ubifs_gc_start_commit - garbage collection at start of commit.867 * @c: UBIFS file-system description object868 *869 * If a LEB has only dirty and free space, then we may safely unmap it and make870 * it free. Note, we cannot do this with indexing LEBs because dirty space may871 * correspond index nodes that are required for recovery. In that case, the872 * LEB cannot be unmapped until after the next commit.873 *874 * This function returns %0 upon success and a negative error code upon failure.875 */876int ubifs_gc_start_commit(struct ubifs_info *c)877{878 struct ubifs_gced_idx_leb *idx_gc;879 const struct ubifs_lprops *lp;880 int err = 0, flags;881 882 ubifs_get_lprops(c);883 884 /*885 * Unmap (non-index) freeable LEBs. Note that recovery requires that all886 * wbufs are sync'd before this, which is done in 'do_commit()'.887 */888 while (1) {889 lp = ubifs_fast_find_freeable(c);890 if (!lp)891 break;892 ubifs_assert(c, !(lp->flags & LPROPS_TAKEN));893 ubifs_assert(c, !(lp->flags & LPROPS_INDEX));894 err = ubifs_leb_unmap(c, lp->lnum);895 if (err)896 goto out;897 lp = ubifs_change_lp(c, lp, c->leb_size, 0, lp->flags, 0);898 if (IS_ERR(lp)) {899 err = PTR_ERR(lp);900 goto out;901 }902 ubifs_assert(c, !(lp->flags & LPROPS_TAKEN));903 ubifs_assert(c, !(lp->flags & LPROPS_INDEX));904 }905 906 /* Mark GC'd index LEBs OK to unmap after this commit finishes */907 list_for_each_entry(idx_gc, &c->idx_gc, list)908 idx_gc->unmap = 1;909 910 /* Record index freeable LEBs for unmapping after commit */911 while (1) {912 lp = ubifs_fast_find_frdi_idx(c);913 if (IS_ERR(lp)) {914 err = PTR_ERR(lp);915 goto out;916 }917 if (!lp)918 break;919 idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS);920 if (!idx_gc) {921 err = -ENOMEM;922 goto out;923 }924 ubifs_assert(c, !(lp->flags & LPROPS_TAKEN));925 ubifs_assert(c, lp->flags & LPROPS_INDEX);926 /* Don't release the LEB until after the next commit */927 flags = (lp->flags | LPROPS_TAKEN) ^ LPROPS_INDEX;928 lp = ubifs_change_lp(c, lp, c->leb_size, 0, flags, 1);929 if (IS_ERR(lp)) {930 err = PTR_ERR(lp);931 kfree(idx_gc);932 goto out;933 }934 ubifs_assert(c, lp->flags & LPROPS_TAKEN);935 ubifs_assert(c, !(lp->flags & LPROPS_INDEX));936 idx_gc->lnum = lp->lnum;937 idx_gc->unmap = 1;938 list_add(&idx_gc->list, &c->idx_gc);939 }940out:941 ubifs_release_lprops(c);942 return err;943}944 945/**946 * ubifs_gc_end_commit - garbage collection at end of commit.947 * @c: UBIFS file-system description object948 *949 * This function completes out-of-place garbage collection of index LEBs.950 */951int ubifs_gc_end_commit(struct ubifs_info *c)952{953 struct ubifs_gced_idx_leb *idx_gc, *tmp;954 struct ubifs_wbuf *wbuf;955 int err = 0;956 957 wbuf = &c->jheads[GCHD].wbuf;958 mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);959 list_for_each_entry_safe(idx_gc, tmp, &c->idx_gc, list)960 if (idx_gc->unmap) {961 dbg_gc("LEB %d", idx_gc->lnum);962 err = ubifs_leb_unmap(c, idx_gc->lnum);963 if (err)964 goto out;965 err = ubifs_change_one_lp(c, idx_gc->lnum, LPROPS_NC,966 LPROPS_NC, 0, LPROPS_TAKEN, -1);967 if (err)968 goto out;969 list_del(&idx_gc->list);970 kfree(idx_gc);971 }972out:973 mutex_unlock(&wbuf->io_mutex);974 return err;975}976 977/**978 * ubifs_destroy_idx_gc - destroy idx_gc list.979 * @c: UBIFS file-system description object980 *981 * This function destroys the @c->idx_gc list. It is called when unmounting982 * so locks are not needed. Returns zero in case of success and a negative983 * error code in case of failure.984 */985void ubifs_destroy_idx_gc(struct ubifs_info *c)986{987 while (!list_empty(&c->idx_gc)) {988 struct ubifs_gced_idx_leb *idx_gc;989 990 idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb,991 list);992 c->idx_gc_cnt -= 1;993 list_del(&idx_gc->list);994 kfree(idx_gc);995 }996}997 998/**999 * ubifs_get_idx_gc_leb - get a LEB from GC'd index LEB list.1000 * @c: UBIFS file-system description object1001 *1002 * Called during start commit so locks are not needed.1003 */1004int ubifs_get_idx_gc_leb(struct ubifs_info *c)1005{1006 struct ubifs_gced_idx_leb *idx_gc;1007 int lnum;1008 1009 if (list_empty(&c->idx_gc))1010 return -ENOSPC;1011 idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, list);1012 lnum = idx_gc->lnum;1013 /* c->idx_gc_cnt is updated by the caller when lprops are updated */1014 list_del(&idx_gc->list);1015 kfree(idx_gc);1016 return lnum;1017}1018