/* * This file is part of UBIFS. * * Copyright (C) 2006-2008 Nokia Corporation. * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published by * the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. * * You should have received a copy of the GNU General Public License along with * this program; if not, write to the Free Software Foundation, Inc., 51 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA * * Authors: Adrian Hunter * Artem Bityutskiy (Битюцкий Артём) */ /* * This file implements garbage collection. The procedure for garbage collection * is different depending on whether a LEB as an index LEB (contains index * nodes) or not. For non-index LEBs, garbage collection finds a LEB which * contains a lot of dirty space (obsolete nodes), and copies the non-obsolete * nodes to the journal, at which point the garbage-collected LEB is free to be * reused. For index LEBs, garbage collection marks the non-obsolete index nodes * dirty in the TNC, and after the next commit, the garbage-collected LEB is * to be reused. Garbage collection will cause the number of dirty index nodes * to grow, however sufficient space is reserved for the index to ensure the * commit will never run out of space. * * Notes about dead watermark. At current UBIFS implementation we assume that * LEBs which have less than @c->dead_wm bytes of free + dirty space are full * and not worth garbage-collecting. The dead watermark is one min. I/O unit * size, or min. UBIFS node size, depending on what is greater. Indeed, UBIFS * Garbage Collector has to synchronize the GC head's write buffer before * returning, so this is about wasting one min. I/O unit. However, UBIFS GC can * actually reclaim even very small pieces of dirty space by garbage collecting * enough dirty LEBs, but we do not bother doing this at this implementation. * * Notes about dark watermark. The results of GC work depends on how big are * the UBIFS nodes GC deals with. Large nodes make GC waste more space. Indeed, * if GC move data from LEB A to LEB B and nodes in LEB A are large, GC would * have to waste large pieces of free space at the end of LEB B, because nodes * from LEB A would not fit. And the worst situation is when all nodes are of * maximum size. So dark watermark is the amount of free + dirty space in LEB * which are guaranteed to be reclaimable. If LEB has less space, the GC might * be unable to reclaim it. So, LEBs with free + dirty greater than dark * watermark are "good" LEBs from GC's point of few. The other LEBs are not so * good, and GC takes extra care when moving them. */ #include <linux/pagemap.h> #include "ubifs.h" /* * GC may need to move more than one LEB to make progress. The below constants * define "soft" and "hard" limits on the number of LEBs the garbage collector * may move. */ #define SOFT_LEBS_LIMIT 4 #define HARD_LEBS_LIMIT 32 /** * switch_gc_head - switch the garbage collection journal head. * @c: UBIFS file-system description object * @buf: buffer to write * @len: length of the buffer to write * @lnum: LEB number written is returned here * @offs: offset written is returned here * * This function switch the GC head to the next LEB which is reserved in * @c->gc_lnum. Returns %0 in case of success, %-EAGAIN if commit is required, * and other negative error code in case of failures. */ static int switch_gc_head(struct ubifs_info *c) { int err, gc_lnum = c->gc_lnum; struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; ubifs_assert(gc_lnum != -1); dbg_gc("switch GC head from LEB %d:%d to LEB %d (waste %d bytes)", wbuf->lnum, wbuf->offs + wbuf->used, gc_lnum, c->leb_size - wbuf->offs - wbuf->used); err = ubifs_wbuf_sync_nolock(wbuf); if (err) return err; /* * The GC write-buffer was synchronized, we may safely unmap * 'c->gc_lnum'. */ err = ubifs_leb_unmap(c, gc_lnum); if (err) return err; err = ubifs_add_bud_to_log(c, GCHD, gc_lnum, 0); if (err) return err; c->gc_lnum = -1; err = ubifs_wbuf_seek_nolock(wbuf, gc_lnum, 0, UBI_LONGTERM); return err; } /** * list_sort - sort a list. * @priv: private data, passed to @cmp * @head: the list to sort * @cmp: the elements comparison function * * This function has been implemented by Mark J Roberts <mjr@znex.org>. It * implements "merge sort" which has O(nlog(n)) complexity. The list is sorted * in ascending order. * * The comparison function @cmp is supposed to return a negative value if @a is * than @b, and a positive value if @a is greater than @b. If @a and @b are * equivalent, then it does not matter what this function returns. */ static void list_sort(void *priv, struct list_head *head, int (*cmp)(void *priv, struct list_head *a, struct list_head *b)) { struct list_head *p, *q, *e, *list, *tail, *oldhead; int insize, nmerges, psize, qsize, i; if (list_empty(head)) return; list = head->next; list_del(head); insize = 1; for (;;) { p = oldhead = list; list = tail = NULL; nmerges = 0; while (p) { nmerges++; q = p; psize = 0; for (i = 0; i < insize; i++) { psize++; q = q->next == oldhead ? NULL : q->next; if (!q) break; } qsize = insize; while (psize > 0 || (qsize > 0 && q)) { if (!psize) { e = q; q = q->next; qsize--; if (q == oldhead) q = NULL; } else if (!qsize || !q) { e = p; p = p->next; psize--; if (p == oldhead) p = NULL; } else if (cmp(priv, p, q) <= 0) { e = p; p = p->next; psize--; if (p == oldhead) p = NULL; } else { e = q; q = q->next; qsize--; if (q == oldhead) q = NULL; } if (tail) tail->next = e; else list = e; e->prev = tail; tail = e; } p = q; } tail->next = list; list->prev = tail; if (nmerges <= 1) break; insize *= 2; } head->next = list; head->prev = list->prev; list->prev->next = head; list->prev = head; } /** * data_nodes_cmp - compare 2 data nodes. * @priv: UBIFS file-system description object * @a: first data node * @a: second data node * * This function compares data nodes @a and @b. Returns %1 if @a has greater * inode or block number, and %-1 otherwise. */ int data_nodes_cmp(void *priv, struct list_head *a, struct list_head *b) { ino_t inuma, inumb; struct ubifs_info *c = priv; struct ubifs_scan_node *sa, *sb; cond_resched(); sa = list_entry(a, struct ubifs_scan_node, list); sb = list_entry(b, struct ubifs_scan_node, list); ubifs_assert(key_type(c, &sa->key) == UBIFS_DATA_KEY); ubifs_assert(key_type(c, &sb->key) == UBIFS_DATA_KEY); inuma = key_inum(c, &sa->key); inumb = key_inum(c, &sb->key); if (inuma == inumb) { unsigned int blka = key_block(c, &sa->key); unsigned int blkb = key_block(c, &sb->key); if (blka <= blkb) return -1; } else if (inuma <= inumb) return -1; return 1; } /* * nondata_nodes_cmp - compare 2 non-data nodes. * @priv: UBIFS file-system description object * @a: first node * @a: second node * * This function compares nodes @a and @b. It makes sure that inode nodes go * first and sorted by length in descending order. Directory entry nodes go * after inode nodes and are sorted in ascending hash valuer order. */ int nondata_nodes_cmp(void *priv, struct list_head *a, struct list_head *b) { int typea, typeb; ino_t inuma, inumb; struct ubifs_info *c = priv; struct ubifs_scan_node *sa, *sb; cond_resched(); sa = list_entry(a, struct ubifs_scan_node, list); sb = list_entry(b, struct ubifs_scan_node, list); typea = key_type(c, &sa->key); typeb = key_type(c, &sb->key); ubifs_assert(typea != UBIFS_DATA_KEY && typeb != UBIFS_DATA_KEY); /* Inodes go before directory entries */ if (typea == UBIFS_INO_KEY) { if (typeb == UBIFS_INO_KEY) return sb->len - sa->len; return -1; } if (typeb == UBIFS_INO_KEY) return 1; ubifs_assert(typea == UBIFS_DENT_KEY && typeb == UBIFS_DENT_KEY); inuma = key_inum(c, &sa->key); inumb = key_inum(c, &sb->key); if (inuma == inumb) { uint32_t hasha = key_hash(c, &sa->key); uint32_t hashb = key_hash(c, &sb->key); if (hasha <= hashb) return -1; } else if (inuma <= inumb) return -1; return 1; } /** * sort_nodes - sort nodes for GC. * @c: UBIFS file-system description object * @sleb: describes nodes to sort and contains the result on exit * @nondata: contains non-data nodes on exit * @min: minimum node size is returned here * * This function sorts the list of inodes to garbage collect. First of all, it * kills obsolete nodes and separates data and non-data nodes to the * @sleb->nodes and @nondata lists correspondingly. * * Data nodes are then sorted in block number order - this is important for * bulk-read; data nodes with lower inode number go before data nodes with * higher inode number, and data nodes with lower block number go before data * nodes with higher block number; * * Non-data nodes are sorted as follows. * o First go inode nodes - they are sorted in descending length order. * o Then go directory entry nodes - they are sorted in hash order, which * should supposedly optimize 'readdir()'. Direntry nodes with lower parent * inode number go before direntry nodes with higher parent inode number, * and direntry nodes with lower name hash values go before direntry nodes * with higher name hash values. * * This function returns zero in case of success and a negative error code in * case of failure. */ static int sort_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb, struct list_head *nondata, int *min) { struct ubifs_scan_node *snod, *tmp; *min = INT_MAX; /* Separate data nodes and non-data nodes */ list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) { int err; ubifs_assert(snod->type != UBIFS_IDX_NODE); ubifs_assert(snod->type != UBIFS_REF_NODE); ubifs_assert(snod->type != UBIFS_CS_NODE); err = ubifs_tnc_has_node(c, &snod->key, 0, sleb->lnum, snod->offs, 0); if (err < 0) return err; if (!err) { /* The node is obsolete, remove it from the list */ list_del(&snod->list); kfree(snod); continue; } if (snod->len < *min) *min = snod->len; if (key_type(c, &snod->key) != UBIFS_DATA_KEY) list_move_tail(&snod->list, nondata); } /* Sort data and non-data nodes */ list_sort(c, &sleb->nodes, &data_nodes_cmp); list_sort(c, nondata, &nondata_nodes_cmp); return 0; } /** * move_node - move a node. * @c: UBIFS file-system description object * @sleb: describes the LEB to move nodes from * @snod: the mode to move * @wbuf: write-buffer to move node to * * This function moves node @snod to @wbuf, changes TNC correspondingly, and * destroys @snod. Returns zero in case of success and a negative error code in * case of failure. */ static int move_node(struct ubifs_info *c, struct ubifs_scan_leb *sleb, struct ubifs_scan_node *snod, struct ubifs_wbuf *wbuf) { int err, new_lnum = wbuf->lnum, new_offs = wbuf->offs + wbuf->used; cond_resched(); err = ubifs_wbuf_write_nolock(wbuf, snod->node, snod->len); if (err) return err; err = ubifs_tnc_replace(c, &snod->key, sleb->lnum, snod->offs, new_lnum, new_offs, snod->len); list_del(&snod->list); kfree(snod); return err; } /** * move_nodes - move nodes. * @c: UBIFS file-system description object * @sleb: describes the LEB to move nodes from * * This function moves valid nodes from data LEB described by @sleb to the GC * journal head. This function returns zero in case of success, %-EAGAIN if * commit is required, and other negative error codes in case of other * failures. */ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb) { int err, min; LIST_HEAD(nondata); struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; if (wbuf->lnum == -1) { /* * The GC journal head is not set, because it is the first GC * invocation since mount. */ err = switch_gc_head(c); if (err) return err; } err = sort_nodes(c, sleb, &nondata, &min); if (err) goto out; /* Write nodes to their new location. Use the first-fit strategy */ while (1) { int avail; struct ubifs_scan_node *snod, *tmp; /* Move data nodes */ list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) { avail = c->leb_size - wbuf->offs - wbuf->used; if (snod->len > avail) /* * Do not skip data nodes in order to optimize * bulk-read. */ break; err = move_node(c, sleb, snod, wbuf); if (err) goto out; } /* Move non-data nodes */ list_for_each_entry_safe(snod, tmp, &nondata, list) { avail = c->leb_size - wbuf->offs - wbuf->used; if (avail < min) break; if (snod->len > avail) { /* * Keep going only if this is an inode with * some data. Otherwise stop and switch the GC * head. IOW, we assume that data-less inode * nodes and direntry nodes are roughly of the * same size. */ if (key_type(c, &snod->key) == UBIFS_DENT_KEY || snod->len == UBIFS_INO_NODE_SZ) break; continue; } err = move_node(c, sleb, snod, wbuf); if (err) goto out; } if (list_empty(&sleb->nodes) && list_empty(&nondata)) break; /* * Waste the rest of the space in the LEB and switch to the * next LEB. */ err = switch_gc_head(c); if (err) goto out; } return 0; out: list_splice_tail(&nondata, &sleb->nodes); return err; } /** * gc_sync_wbufs - sync write-buffers for GC. * @c: UBIFS file-system description object * * We must guarantee that obsoleting nodes are on flash. Unfortunately they may * be in a write-buffer instead. That is, a node could be written to a * write-buffer, obsoleting another node in a LEB that is GC'd. If that LEB is * erased before the write-buffer is sync'd and then there is an unclean * unmount, then an existing node is lost. To avoid this, we sync all * write-buffers. * * This function returns %0 on success or a negative error code on failure. */ static int gc_sync_wbufs(struct ubifs_info *c) { int err, i; for (i = 0; i < c->jhead_cnt; i++) { if (i == GCHD) continue; err = ubifs_wbuf_sync(&c->jheads[i].wbuf); if (err) return err; } return 0; } /** * ubifs_garbage_collect_leb - garbage-collect a logical eraseblock. * @c: UBIFS file-system description object * @lp: describes the LEB to garbage collect * * This function garbage-collects an LEB and returns one of the @LEB_FREED, * @LEB_RETAINED, etc positive codes in case of success, %-EAGAIN if commit is * required, and other negative error codes in case of failures. */ int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp) { struct ubifs_scan_leb *sleb; struct ubifs_scan_node *snod; struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; int err = 0, lnum = lp->lnum; ubifs_assert(c->gc_lnum != -1 || wbuf->offs + wbuf->used == 0 || c->need_recovery); ubifs_assert(c->gc_lnum != lnum); ubifs_assert(wbuf->lnum != lnum); /* * We scan the entire LEB even though we only really need to scan up to * (c->leb_size - lp->free). */ sleb = ubifs_scan(c, lnum, 0, c->sbuf, 0); if (IS_ERR(sleb)) return PTR_ERR(sleb); ubifs_assert(!list_empty(&sleb->nodes)); snod = list_entry(sleb->nodes.next, struct ubifs_scan_node, list); if (snod->type == UBIFS_IDX_NODE) { struct ubifs_gced_idx_leb *idx_gc; dbg_gc("indexing LEB %d (free %d, dirty %d)", lnum, lp->free, lp->dirty); list_for_each_entry(snod, &sleb->nodes, list) { struct ubifs_idx_node *idx = snod->node; int level = le16_to_cpu(idx->level); ubifs_assert(snod->type == UBIFS_IDX_NODE); key_read(c, ubifs_idx_key(c, idx), &snod->key); err = ubifs_dirty_idx_node(c, &snod->key, level, lnum, snod->offs); if (err) goto out; } idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS); if (!idx_gc) { err = -ENOMEM; goto out; } idx_gc->lnum = lnum; idx_gc->unmap = 0; list_add(&idx_gc->list, &c->idx_gc); /* * Don't release the LEB until after the next commit, because * it may contain data which is needed for recovery. So * although we freed this LEB, it will become usable only after * the commit. */ err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, LPROPS_INDEX, 1); if (err) goto out; err = LEB_FREED_IDX; } else { dbg_gc("data LEB %d (free %d, dirty %d)", lnum, lp->free, lp->dirty); err = move_nodes(c, sleb); if (err) goto out_inc_seq; err = gc_sync_wbufs(c); if (err) goto out_inc_seq; err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, 0, 0); if (err) goto out_inc_seq; /* Allow for races with TNC */ c->gced_lnum = lnum; smp_wmb(); c->gc_seq += 1; smp_wmb(); if (c->gc_lnum == -1) { c->gc_lnum = lnum; err = LEB_RETAINED; } else { err = ubifs_wbuf_sync_nolock(wbuf); if (err) goto out; err = ubifs_leb_unmap(c, lnum); if (err) goto out; err = LEB_FREED; } } out: ubifs_scan_destroy(sleb); return err; out_inc_seq: /* We may have moved at least some nodes so allow for races with TNC */ c->gced_lnum = lnum; smp_wmb(); c->gc_seq += 1; smp_wmb(); goto out; } /** * ubifs_garbage_collect - UBIFS garbage collector. * @c: UBIFS file-system description object * @anyway: do GC even if there are free LEBs * * This function does out-of-place garbage collection. The return codes are: * o positive LEB number if the LEB has been freed and may be used; * o %-EAGAIN if the caller has to run commit; * o %-ENOSPC if GC failed to make any progress; * o other negative error codes in case of other errors. * * Garbage collector writes data to the journal when GC'ing data LEBs, and just * marking indexing nodes dirty when GC'ing indexing LEBs. Thus, at some point * commit may be required. But commit cannot be run from inside GC, because the * caller might be holding the commit lock, so %-EAGAIN is returned instead; * And this error code means that the caller has to run commit, and re-run GC * if there is still no free space. * * There are many reasons why this function may return %-EAGAIN: * o the log is full and there is no space to write an LEB reference for * @c->gc_lnum; * o the journal is too large and exceeds size limitations; * o GC moved indexing LEBs, but they can be used only after the commit; * o the shrinker fails to find clean znodes to free and requests the commit; * o etc. * * Note, if the file-system is close to be full, this function may return * %-EAGAIN infinitely, so the caller has to limit amount of re-invocations of * the function. E.g., this happens if the limits on the journal size are too * tough and GC writes too much to the journal before an LEB is freed. This * might also mean that the journal is too large, and the TNC becomes to big, * so that the shrinker is constantly called, finds not clean znodes to free, * and requests commit. Well, this may also happen if the journal is all right, * but another kernel process consumes too much memory. Anyway, infinite * %-EAGAIN may happen, but in some extreme/misconfiguration cases. */ int ubifs_garbage_collect(struct ubifs_info *c, int anyway) { int i, err, ret, min_space = c->dead_wm; struct ubifs_lprops lp; struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; ubifs_assert_cmt_locked(c); if (ubifs_gc_should_commit(c)) return -EAGAIN; mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead); if (c->ro_media) { ret = -EROFS; goto out_unlock; } /* We expect the write-buffer to be empty on entry */ ubifs_assert(!wbuf->used); for (i = 0; ; i++) { int space_before = c->leb_size - wbuf->offs - wbuf->used; int space_after; cond_resched(); /* Give the commit an opportunity to run */ if (ubifs_gc_should_commit(c)) { ret = -EAGAIN; break; } if (i > SOFT_LEBS_LIMIT && !list_empty(&c->idx_gc)) { /* * We've done enough iterations. Indexing LEBs were * moved and will be available after the commit. */ dbg_gc("soft limit, some index LEBs GC'ed, -EAGAIN"); ubifs_commit_required(c); ret = -EAGAIN; break; } if (i > HARD_LEBS_LIMIT) { /* * We've moved too many LEBs and have not made * progress, give up. */ dbg_gc("hard limit, -ENOSPC"); ret = -ENOSPC; break; } /* * Empty and freeable LEBs can turn up while we waited for * the wbuf lock, or while we have been running GC. In that * case, we should just return one of those instead of * continuing to GC dirty LEBs. Hence we request * 'ubifs_find_dirty_leb()' to return an empty LEB if it can. */ ret = ubifs_find_dirty_leb(c, &lp, min_space, anyway ? 0 : 1); if (ret) { if (ret == -ENOSPC) dbg_gc("no more dirty LEBs"); break; } dbg_gc("found LEB %d: free %d, dirty %d, sum %d " "(min. space %d)", lp.lnum, lp.free, lp.dirty, lp.free + lp.dirty, min_space); if (lp.free + lp.dirty == c->leb_size) { /* An empty LEB was returned */ dbg_gc("LEB %d is free, return it", lp.lnum); /* * ubifs_find_dirty_leb() doesn't return freeable index * LEBs. */ ubifs_assert(!(lp.flags & LPROPS_INDEX)); if (lp.free != c->leb_size) { /* * Write buffers must be sync'd before * unmapping freeable LEBs, because one of them * may contain data which obsoletes something * in 'lp.pnum'. */ ret = gc_sync_wbufs(c); if (ret) goto out; ret = ubifs_change_one_lp(c, lp.lnum, c->leb_size, 0, 0, 0, 0); if (ret) goto out; } ret = ubifs_leb_unmap(c, lp.lnum); if (ret) goto out; ret = lp.lnum; break; } space_before = c->leb_size - wbuf->offs - wbuf->used; if (wbuf->lnum == -1) space_before = 0; ret = ubifs_garbage_collect_leb(c, &lp); if (ret < 0) { if (ret == -EAGAIN || ret == -ENOSPC) { /* * These codes are not errors, so we have to * return the LEB to lprops. But if the * 'ubifs_return_leb()' function fails, its * failure code is propagated to the caller * instead of the original '-EAGAIN' or * '-ENOSPC'. */ err = ubifs_return_leb(c, lp.lnum); if (err) ret = err; break; } goto out; } if (ret == LEB_FREED) { /* An LEB has been freed and is ready for use */ dbg_gc("LEB %d freed, return", lp.lnum); ret = lp.lnum; break; } if (ret == LEB_FREED_IDX) { /* * This was an indexing LEB and it cannot be * immediately used. And instead of requesting the * commit straight away, we try to garbage collect some * more. */ dbg_gc("indexing LEB %d freed, continue", lp.lnum); continue; } ubifs_assert(ret == LEB_RETAINED); space_after = c->leb_size - wbuf->offs - wbuf->used; dbg_gc("LEB %d retained, freed %d bytes", lp.lnum, space_after - space_before); if (space_after > space_before) { /* GC makes progress, keep working */ min_space >>= 1; if (min_space < c->dead_wm) min_space = c->dead_wm; continue; } dbg_gc("did not make progress"); /* * GC moved an LEB bud have not done any progress. This means * that the previous GC head LEB contained too few free space * and the LEB which was GC'ed contained only large nodes which * did not fit that space. * * We can do 2 things: * 1. pick another LEB in a hope it'll contain a small node * which will fit the space we have at the end of current GC * head LEB, but there is no guarantee, so we try this out * unless we have already been working for too long; * 2. request an LEB with more dirty space, which will force * 'ubifs_find_dirty_leb()' to start scanning the lprops * table, instead of just picking one from the heap * (previously it already picked the dirtiest LEB). */ if (i < SOFT_LEBS_LIMIT) { dbg_gc("try again"); continue; } min_space <<= 1; if (min_space > c->dark_wm) min_space = c->dark_wm; dbg_gc("set min. space to %d", min_space); } if (ret == -ENOSPC && !list_empty(&c->idx_gc)) { dbg_gc("no space, some index LEBs GC'ed, -EAGAIN"); ubifs_commit_required(c); ret = -EAGAIN; } err = ubifs_wbuf_sync_nolock(wbuf); if (!err) err = ubifs_leb_unmap(c, c->gc_lnum); if (err) { ret = err; goto out; } out_unlock: mutex_unlock(&wbuf->io_mutex); return ret; out: ubifs_assert(ret < 0); ubifs_assert(ret != -ENOSPC && ret != -EAGAIN); ubifs_ro_mode(c, ret); ubifs_wbuf_sync_nolock(wbuf); mutex_unlock(&wbuf->io_mutex); ubifs_return_leb(c, lp.lnum); return ret; } /** * ubifs_gc_start_commit - garbage collection at start of commit. * @c: UBIFS file-system description object * * If a LEB has only dirty and free space, then we may safely unmap it and make * it free. Note, we cannot do this with indexing LEBs because dirty space may * correspond index nodes that are required for recovery. In that case, the * LEB cannot be unmapped until after the next commit. * * This function returns %0 upon success and a negative error code upon failure. */ int ubifs_gc_start_commit(struct ubifs_info *c) { struct ubifs_gced_idx_leb *idx_gc; const struct ubifs_lprops *lp; int err = 0, flags; ubifs_get_lprops(c); /* * Unmap (non-index) freeable LEBs. Note that recovery requires that all * wbufs are sync'd before this, which is done in 'do_commit()'. */ while (1) { lp = ubifs_fast_find_freeable(c); if (IS_ERR(lp)) { err = PTR_ERR(lp); goto out; } if (!lp) break; ubifs_assert(!(lp->flags & LPROPS_TAKEN)); ubifs_assert(!(lp->flags & LPROPS_INDEX)); err = ubifs_leb_unmap(c, lp->lnum); if (err) goto out; lp = ubifs_change_lp(c, lp, c->leb_size, 0, lp->flags, 0); if (IS_ERR(lp)) { err = PTR_ERR(lp); goto out; } ubifs_assert(!(lp->flags & LPROPS_TAKEN)); ubifs_assert(!(lp->flags & LPROPS_INDEX)); } /* Mark GC'd index LEBs OK to unmap after this commit finishes */ list_for_each_entry(idx_gc, &c->idx_gc, list) idx_gc->unmap = 1; /* Record index freeable LEBs for unmapping after commit */ while (1) { lp = ubifs_fast_find_frdi_idx(c); if (IS_ERR(lp)) { err = PTR_ERR(lp); goto out; } if (!lp) break; idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS); if (!idx_gc) { err = -ENOMEM; goto out; } ubifs_assert(!(lp->flags & LPROPS_TAKEN)); ubifs_assert(lp->flags & LPROPS_INDEX); /* Don't release the LEB until after the next commit */ flags = (lp->flags | LPROPS_TAKEN) ^ LPROPS_INDEX; lp = ubifs_change_lp(c, lp, c->leb_size, 0, flags, 1); if (IS_ERR(lp)) { err = PTR_ERR(lp); kfree(idx_gc); goto out; } ubifs_assert(lp->flags & LPROPS_TAKEN); ubifs_assert(!(lp->flags & LPROPS_INDEX)); idx_gc->lnum = lp->lnum; idx_gc->unmap = 1; list_add(&idx_gc->list, &c->idx_gc); } out: ubifs_release_lprops(c); return err; } /** * ubifs_gc_end_commit - garbage collection at end of commit. * @c: UBIFS file-system description object * * This function completes out-of-place garbage collection of index LEBs. */ int ubifs_gc_end_commit(struct ubifs_info *c) { struct ubifs_gced_idx_leb *idx_gc, *tmp; struct ubifs_wbuf *wbuf; int err = 0; wbuf = &c->jheads[GCHD].wbuf; mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead); list_for_each_entry_safe(idx_gc, tmp, &c->idx_gc, list) if (idx_gc->unmap) { dbg_gc("LEB %d", idx_gc->lnum); err = ubifs_leb_unmap(c, idx_gc->lnum); if (err) goto out; err = ubifs_change_one_lp(c, idx_gc->lnum, LPROPS_NC, LPROPS_NC, 0, LPROPS_TAKEN, -1); if (err) goto out; list_del(&idx_gc->list); kfree(idx_gc); } out: mutex_unlock(&wbuf->io_mutex); return err; } /** * ubifs_destroy_idx_gc - destroy idx_gc list. * @c: UBIFS file-system description object * * This function destroys the @c->idx_gc list. It is called when unmounting * so locks are not needed. Returns zero in case of success and a negative * error code in case of failure. */ void ubifs_destroy_idx_gc(struct ubifs_info *c) { while (!list_empty(&c->idx_gc)) { struct ubifs_gced_idx_leb *idx_gc; idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, list); c->idx_gc_cnt -= 1; list_del(&idx_gc->list); kfree(idx_gc); } } /** * ubifs_get_idx_gc_leb - get a LEB from GC'd index LEB list. * @c: UBIFS file-system description object * * Called during start commit so locks are not needed. */ int ubifs_get_idx_gc_leb(struct ubifs_info *c) { struct ubifs_gced_idx_leb *idx_gc; int lnum; if (list_empty(&c->idx_gc)) return -ENOSPC; idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, list); lnum = idx_gc->lnum; /* c->idx_gc_cnt is updated by the caller when lprops are updated */ list_del(&idx_gc->list); kfree(idx_gc); return lnum; }