UBIFS: add new flash file system

This is a new flash file system. See
http://www.linux-mtd.infradead.org/doc/ubifs.html

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>

1 files changed, 773 insertions, 0 deletions

diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
new file mode 100644
index 000000000000..d0f3dac29081
--- /dev/null
+++ b/fs/ubifs/gc.c
@@ -0,0 +1,773 @@
+/*
+ * 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.
+ */
+
+#include <linux/pagemap.h>
+#include "ubifs.h"
+
+/*
+ * GC tries to optimize the way it fit nodes to available space, and it sorts
+ * nodes a little. The below constants are watermarks which define "large",
+ * "medium", and "small" nodes.
+ */
+#define MEDIUM_NODE_WM (UBIFS_BLOCK_SIZE / 4)
+#define SMALL_NODE_WM  UBIFS_MAX_DENT_NODE_SZ
+
+/*
+ * GC may need to move more then 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;
+}
+
+/**
+ * move_nodes - move nodes.
+ * @c: UBIFS file-system description object
+ * @sleb: describes nodes to move
+ *
+ * This function moves valid nodes from data LEB described by @sleb to the GC
+ * journal head. The obsolete nodes are dropped.
+ *
+ * When moving nodes we have to deal with classical bin-packing problem: the
+ * space in the current GC journal head LEB and in @c->gc_lnum are the "bins",
+ * where the nodes in the @sleb->nodes list are the elements which should be
+ * fit optimally to the bins. This function uses the "first fit decreasing"
+ * strategy, although it does not really sort the nodes but just split them on
+ * 3 classes - large, medium, and small, so they are roughly sorted.
+ *
+ * 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)
+{
+        struct ubifs_scan_node *snod, *tmp;
+        struct list_head large, medium, small;
+        struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
+        int avail, err, min = INT_MAX;
+
+        INIT_LIST_HEAD(&large);
+        INIT_LIST_HEAD(&medium);
+        INIT_LIST_HEAD(&small);
+
+        list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {
+                struct list_head *lst;
+
+                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)
+                        goto out;
+
+                lst = &snod->list;
+                list_del(lst);
+                if (!err) {
+                        /* The node is obsolete, remove it from the list */
+                        kfree(snod);
+                        continue;
+                }
+
+                /*
+                 * Sort the list of nodes so that large nodes go first, and
+                 * small nodes go last.
+                 */
+                if (snod->len > MEDIUM_NODE_WM)
+                        list_add(lst, &large);
+                else if (snod->len > SMALL_NODE_WM)
+                        list_add(lst, &medium);
+                else
+                        list_add(lst, &small);
+
+                /* And find the smallest node */
+                if (snod->len < min)
+                        min = snod->len;
+        }
+
+        /*
+         * Join the tree lists so that we'd have one roughly sorted list
+         * ('large' will be the head of the joined list).
+         */
+        list_splice(&medium, large.prev);
+        list_splice(&small, large.prev);
+
+        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)
+                        goto out;
+        }
+
+        /* Write nodes to their new location. Use the first-fit strategy */
+        while (1) {
+                avail = c->leb_size - wbuf->offs - wbuf->used;
+                list_for_each_entry_safe(snod, tmp, &large, list) {
+                        int new_lnum, new_offs;
+
+                        if (avail < min)
+                                break;
+
+                        if (snod->len > avail)
+                                /* This node does not fit */
+                                continue;
+
+                        cond_resched();
+
+                        new_lnum = wbuf->lnum;
+                        new_offs = wbuf->offs + wbuf->used;
+                        err = ubifs_wbuf_write_nolock(wbuf, snod->node,
+                                                      snod->len);
+                        if (err)
+                                goto out;
+                        err = ubifs_tnc_replace(c, &snod->key, sleb->lnum,
+                                                snod->offs, new_lnum, new_offs,
+                                                snod->len);
+                        if (err)
+                                goto out;
+
+                        avail = c->leb_size - wbuf->offs - wbuf->used;
+                        list_del(&snod->list);
+                        kfree(snod);
+                }
+
+                if (list_empty(&large))
+                        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_for_each_entry_safe(snod, tmp, &large, list) {
+                list_del(&snod->list);
+                kfree(snod);
+        }
+        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);
+        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 date 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;
+
+                err = gc_sync_wbufs(c);
+                if (err)
+                        goto out;
+
+                err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, 0, 0);
+                if (err)
+                        goto out;
+
+                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;
+}
+
+/**
+ * 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 (unlikely(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 (unlikely(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 (unlikely(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 (unlikely(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 idx_gc list. It is called when unmounting or
+ * remounting read-only so locks are not needed.
+ */
+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;
+}