--- /dev/null
+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2006-2008 Nokia Corporation.
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ *
+ * 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.
+ */
+#ifndef __UBOOT__
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/list_sort.h>
+#endif
+#include "ubifs.h"
+
+#ifndef __UBOOT__
+/*
+ * 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_wbuf_sync_nolock(wbuf);
+ 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
+ * @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.
+ */
+static 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();
+ 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(key_type(c, &sa->key) == UBIFS_DATA_KEY);
+ ubifs_assert(key_type(c, &sb->key) == UBIFS_DATA_KEY);
+ ubifs_assert(sa->type == UBIFS_DATA_NODE);
+ ubifs_assert(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, 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();
+ 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(key_type(c, &sa->key) != UBIFS_DATA_KEY &&
+ key_type(c, &sb->key) != UBIFS_DATA_KEY);
+ ubifs_assert(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(key_type(c, &sa->key) == UBIFS_DENT_KEY ||
+ key_type(c, &sa->key) == UBIFS_XENT_KEY);
+ ubifs_assert(key_type(c, &sb->key) == UBIFS_DENT_KEY ||
+ key_type(c, &sb->key) == UBIFS_XENT_KEY);
+ ubifs_assert(sa->type == UBIFS_DENT_NODE ||
+ sa->type == UBIFS_XENT_NODE);
+ ubifs_assert(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(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);
+
+ 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(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;
+ 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);
+
+ 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(!(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'.
+ */
+ 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(!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);
+ ubifs_assert(!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(!wbuf->used);
+
+ for (i = 0; ; i++) {
+ int space_before, 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);
+
+ 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;
+ 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_wbuf_sync_nolock(wbuf);
+ ubifs_ro_mode(c, ret);
+ 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;
+}
+#endif
+/**
+ * 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);
+ }
+}
+#ifndef __UBOOT__
+/**
+ * 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;
+}
+#endif
projects / oweals / u-boot.git / commitdiff