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Diffstat (limited to 'ubifs-utils/libubifs/gc.c')
| -rw-r--r-- | ubifs-utils/libubifs/gc.c | 1017 |
1 files changed, 1017 insertions, 0 deletions
diff --git a/ubifs-utils/libubifs/gc.c b/ubifs-utils/libubifs/gc.c new file mode 100644 index 0000000..3134d07 --- /dev/null +++ b/ubifs-utils/libubifs/gc.c @@ -0,0 +1,1017 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * This file is part of UBIFS. + * + * Copyright (C) 2006-2008 Nokia Corporation. + * + * 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 view. The other LEBs are not so + * good, and GC takes extra care when moving them. + */ + +#include <linux/slab.h> +#include <linux/pagemap.h> +#include <linux/list_sort.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 + * + * 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(c, 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); + return err; +} + +/** + * data_nodes_cmp - compare 2 data nodes. + * @priv: UBIFS file-system description object + * @a: first data node + * @b: second data node + * + * This function compares data nodes @a and @b. Returns %1 if @a has greater + * inode or block number, and %-1 otherwise. + */ +static int data_nodes_cmp(void *priv, const struct list_head *a, + const struct list_head *b) +{ + ino_t inuma, inumb; + struct ubifs_info *c = priv; + struct ubifs_scan_node *sa, *sb; + + cond_resched(); + if (a == b) + return 0; + + sa = list_entry(a, struct ubifs_scan_node, list); + sb = list_entry(b, struct ubifs_scan_node, list); + + ubifs_assert(c, key_type(c, &sa->key) == UBIFS_DATA_KEY); + ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DATA_KEY); + ubifs_assert(c, sa->type == UBIFS_DATA_NODE); + ubifs_assert(c, sb->type == UBIFS_DATA_NODE); + + 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. + */ +static int nondata_nodes_cmp(void *priv, const struct list_head *a, + const struct list_head *b) +{ + ino_t inuma, inumb; + struct ubifs_info *c = priv; + struct ubifs_scan_node *sa, *sb; + + cond_resched(); + if (a == b) + return 0; + + sa = list_entry(a, struct ubifs_scan_node, list); + sb = list_entry(b, struct ubifs_scan_node, list); + + ubifs_assert(c, key_type(c, &sa->key) != UBIFS_DATA_KEY && + key_type(c, &sb->key) != UBIFS_DATA_KEY); + ubifs_assert(c, sa->type != UBIFS_DATA_NODE && + sb->type != UBIFS_DATA_NODE); + + /* Inodes go before directory entries */ + if (sa->type == UBIFS_INO_NODE) { + if (sb->type == UBIFS_INO_NODE) + return sb->len - sa->len; + return -1; + } + if (sb->type == UBIFS_INO_NODE) + return 1; + + ubifs_assert(c, key_type(c, &sa->key) == UBIFS_DENT_KEY || + key_type(c, &sa->key) == UBIFS_XENT_KEY); + ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DENT_KEY || + key_type(c, &sb->key) == UBIFS_XENT_KEY); + ubifs_assert(c, sa->type == UBIFS_DENT_NODE || + sa->type == UBIFS_XENT_NODE); + ubifs_assert(c, sb->type == UBIFS_DENT_NODE || + sb->type == UBIFS_XENT_NODE); + + 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) +{ + int err; + 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) { + ubifs_assert(c, snod->type == UBIFS_INO_NODE || + snod->type == UBIFS_DATA_NODE || + snod->type == UBIFS_DENT_NODE || + snod->type == UBIFS_XENT_NODE || + snod->type == UBIFS_TRUN_NODE || + snod->type == UBIFS_AUTH_NODE); + + if (snod->type != UBIFS_INO_NODE && + snod->type != UBIFS_DATA_NODE && + snod->type != UBIFS_DENT_NODE && + snod->type != UBIFS_XENT_NODE) { + /* Probably truncation node, zap it */ + list_del(&snod->list); + kfree(snod); + continue; + } + + ubifs_assert(c, key_type(c, &snod->key) == UBIFS_DATA_KEY || + key_type(c, &snod->key) == UBIFS_INO_KEY || + key_type(c, &snod->key) == UBIFS_DENT_KEY || + key_type(c, &snod->key) == UBIFS_XENT_KEY); + + 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); + + err = dbg_check_data_nodes_order(c, &sleb->nodes); + if (err) + return err; + err = dbg_check_nondata_nodes_order(c, nondata); + if (err) + return err; + 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, moved = 0; + 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 - + ubifs_auth_node_sz(c); + if (snod->len > avail) + /* + * Do not skip data nodes in order to optimize + * bulk-read. + */ + break; + + err = ubifs_shash_update(c, c->jheads[GCHD].log_hash, + snod->node, snod->len); + if (err) + goto out; + + err = move_node(c, sleb, snod, wbuf); + if (err) + goto out; + moved = 1; + } + + /* Move non-data nodes */ + list_for_each_entry_safe(snod, tmp, &nondata, list) { + avail = c->leb_size - wbuf->offs - wbuf->used - + ubifs_auth_node_sz(c); + 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 = ubifs_shash_update(c, c->jheads[GCHD].log_hash, + snod->node, snod->len); + if (err) + goto out; + + err = move_node(c, sleb, snod, wbuf); + if (err) + goto out; + moved = 1; + } + + if (ubifs_authenticated(c) && moved) { + struct ubifs_auth_node *auth; + + auth = kmalloc(ubifs_auth_node_sz(c), GFP_NOFS); + if (!auth) { + err = -ENOMEM; + goto out; + } + + err = ubifs_prepare_auth_node(c, auth, + c->jheads[GCHD].log_hash); + if (err) { + kfree(auth); + goto out; + } + + err = ubifs_wbuf_write_nolock(wbuf, auth, + ubifs_auth_node_sz(c)); + if (err) { + kfree(auth); + goto out; + } + + ubifs_add_dirt(c, wbuf->lnum, ubifs_auth_node_sz(c)); + } + + 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, c->gc_lnum != -1 || wbuf->offs + wbuf->used == 0 || + c->need_recovery); + ubifs_assert(c, c->gc_lnum != lnum); + ubifs_assert(c, wbuf->lnum != lnum); + + if (lp->free + lp->dirty == c->leb_size) { + /* Special case - a free LEB */ + dbg_gc("LEB %d is free, return it", lp->lnum); + ubifs_assert(c, !(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->lnum'. + */ + err = gc_sync_wbufs(c); + if (err) + return err; + err = ubifs_change_one_lp(c, lp->lnum, c->leb_size, + 0, 0, 0, 0); + if (err) + return err; + } + err = ubifs_leb_unmap(c, lp->lnum); + if (err) + return err; + + if (c->gc_lnum == -1) { + c->gc_lnum = lnum; + return LEB_RETAINED; + } + + return LEB_FREED; + } + + /* + * 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(c, !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(c, 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); + ubifs_assert(c, !c->ro_media && !c->ro_mount); + + if (ubifs_gc_should_commit(c)) + return -EAGAIN; + + mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead); + + if (c->ro_error) { + ret = -EROFS; + goto out_unlock; + } + + /* We expect the write-buffer to be empty on entry */ + ubifs_assert(c, !wbuf->used); + + for (i = 0; ; i++) { + int space_before, space_after; + + /* Maybe continue after find and break before find */ + lp.lnum = -1; + + 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); + + 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) { + /* + * This is not error, so we have to return the + * LEB to lprops. But if 'ubifs_return_leb()' + * fails, its failure code is propagated to the + * caller instead of the original '-EAGAIN'. + */ + err = ubifs_return_leb(c, lp.lnum); + if (err) { + ret = err; + /* + * An LEB may always be "taken", + * so setting ubifs to read-only, + * and then executing sync wbuf will + * return -EROFS and enter the "out" + * error branch. + */ + ubifs_ro_mode(c, ret); + } + /* Maybe double return LEB if goto out */ + lp.lnum = -1; + 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(c, 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(c, ret < 0); + ubifs_assert(c, ret != -ENOSPC && ret != -EAGAIN); + ubifs_wbuf_sync_nolock(wbuf); + ubifs_ro_mode(c, ret); + mutex_unlock(&wbuf->io_mutex); + if (lp.lnum != -1) + 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 (!lp) + break; + ubifs_assert(c, !(lp->flags & LPROPS_TAKEN)); + ubifs_assert(c, !(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(c, !(lp->flags & LPROPS_TAKEN)); + ubifs_assert(c, !(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(c, !(lp->flags & LPROPS_TAKEN)); + ubifs_assert(c, 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(c, lp->flags & LPROPS_TAKEN); + ubifs_assert(c, !(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; +} |