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, 1103 insertions, 0 deletions

diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c
new file mode 100644
index 000000000000..8117e65ba2e9
--- /dev/null
+++ b/fs/ubifs/tnc_commit.c
@@ -0,0 +1,1103 @@
+/*
+ * 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 TNC functions for committing */
+
+#include "ubifs.h"
+
+/**
+ * make_idx_node - make an index node for fill-the-gaps method of TNC commit.
+ * @c: UBIFS file-system description object
+ * @idx: buffer in which to place new index node
+ * @znode: znode from which to make new index node
+ * @lnum: LEB number where new index node will be written
+ * @offs: offset where new index node will be written
+ * @len: length of new index node
+ */
+static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
+                         struct ubifs_znode *znode, int lnum, int offs, int len)
+{
+        struct ubifs_znode *zp;
+        int i, err;
+
+        /* Make index node */
+        idx->ch.node_type = UBIFS_IDX_NODE;
+        idx->child_cnt = cpu_to_le16(znode->child_cnt);
+        idx->level = cpu_to_le16(znode->level);
+        for (i = 0; i < znode->child_cnt; i++) {
+                struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
+                struct ubifs_zbranch *zbr = &znode->zbranch[i];
+
+                key_write_idx(c, &zbr->key, &br->key);
+                br->lnum = cpu_to_le32(zbr->lnum);
+                br->offs = cpu_to_le32(zbr->offs);
+                br->len = cpu_to_le32(zbr->len);
+                if (!zbr->lnum || !zbr->len) {
+                        ubifs_err("bad ref in znode");
+                        dbg_dump_znode(c, znode);
+                        if (zbr->znode)
+                                dbg_dump_znode(c, zbr->znode);
+                }
+        }
+        ubifs_prepare_node(c, idx, len, 0);
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+        znode->lnum = lnum;
+        znode->offs = offs;
+        znode->len = len;
+#endif
+
+        err = insert_old_idx_znode(c, znode);
+
+        /* Update the parent */
+        zp = znode->parent;
+        if (zp) {
+                struct ubifs_zbranch *zbr;
+
+                zbr = &zp->zbranch[znode->iip];
+                zbr->lnum = lnum;
+                zbr->offs = offs;
+                zbr->len = len;
+        } else {
+                c->zroot.lnum = lnum;
+                c->zroot.offs = offs;
+                c->zroot.len = len;
+        }
+        c->calc_idx_sz += ALIGN(len, 8);
+
+        atomic_long_dec(&c->dirty_zn_cnt);
+
+        ubifs_assert(ubifs_zn_dirty(znode));
+        ubifs_assert(test_bit(COW_ZNODE, &znode->flags));
+
+        __clear_bit(DIRTY_ZNODE, &znode->flags);
+        __clear_bit(COW_ZNODE, &znode->flags);
+
+        return err;
+}
+
+/**
+ * fill_gap - make index nodes in gaps in dirty index LEBs.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number that gap appears in
+ * @gap_start: offset of start of gap
+ * @gap_end: offset of end of gap
+ * @dirt: adds dirty space to this
+ *
+ * This function returns the number of index nodes written into the gap.
+ */
+static int fill_gap(struct ubifs_info *c, int lnum, int gap_start, int gap_end,
+                    int *dirt)
+{
+        int len, gap_remains, gap_pos, written, pad_len;
+
+        ubifs_assert((gap_start & 7) == 0);
+        ubifs_assert((gap_end & 7) == 0);
+        ubifs_assert(gap_end >= gap_start);
+
+        gap_remains = gap_end - gap_start;
+        if (!gap_remains)
+                return 0;
+        gap_pos = gap_start;
+        written = 0;
+        while (c->enext) {
+                len = ubifs_idx_node_sz(c, c->enext->child_cnt);
+                if (len < gap_remains) {
+                        struct ubifs_znode *znode = c->enext;
+                        const int alen = ALIGN(len, 8);
+                        int err;
+
+                        ubifs_assert(alen <= gap_remains);
+                        err = make_idx_node(c, c->ileb_buf + gap_pos, znode,
+                                            lnum, gap_pos, len);
+                        if (err)
+                                return err;
+                        gap_remains -= alen;
+                        gap_pos += alen;
+                        c->enext = znode->cnext;
+                        if (c->enext == c->cnext)
+                                c->enext = NULL;
+                        written += 1;
+                } else
+                        break;
+        }
+        if (gap_end == c->leb_size) {
+                c->ileb_len = ALIGN(gap_pos, c->min_io_size);
+                /* Pad to end of min_io_size */
+                pad_len = c->ileb_len - gap_pos;
+        } else
+                /* Pad to end of gap */
+                pad_len = gap_remains;
+        dbg_gc("LEB %d:%d to %d len %d nodes written %d wasted bytes %d",
+               lnum, gap_start, gap_end, gap_end - gap_start, written, pad_len);
+        ubifs_pad(c, c->ileb_buf + gap_pos, pad_len);
+        *dirt += pad_len;
+        return written;
+}
+
+/**
+ * find_old_idx - find an index node obsoleted since the last commit start.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number of obsoleted index node
+ * @offs: offset of obsoleted index node
+ *
+ * Returns %1 if found and %0 otherwise.
+ */
+static int find_old_idx(struct ubifs_info *c, int lnum, int offs)
+{
+        struct ubifs_old_idx *o;
+        struct rb_node *p;
+
+        p = c->old_idx.rb_node;
+        while (p) {
+                o = rb_entry(p, struct ubifs_old_idx, rb);
+                if (lnum < o->lnum)
+                        p = p->rb_left;
+                else if (lnum > o->lnum)
+                        p = p->rb_right;
+                else if (offs < o->offs)
+                        p = p->rb_left;
+                else if (offs > o->offs)
+                        p = p->rb_right;
+                else
+                        return 1;
+        }
+        return 0;
+}
+
+/**
+ * is_idx_node_in_use - determine if an index node can be overwritten.
+ * @c: UBIFS file-system description object
+ * @key: key of index node
+ * @level: index node level
+ * @lnum: LEB number of index node
+ * @offs: offset of index node
+ *
+ * If @key / @lnum / @offs identify an index node that was not part of the old
+ * index, then this function returns %0 (obsolete).  Else if the index node was
+ * part of the old index but is now dirty %1 is returned, else if it is clean %2
+ * is returned. A negative error code is returned on failure.
+ */
+static int is_idx_node_in_use(struct ubifs_info *c, union ubifs_key *key,
+                              int level, int lnum, int offs)
+{
+        int ret;
+
+        ret = is_idx_node_in_tnc(c, key, level, lnum, offs);
+        if (ret < 0)
+                return ret; /* Error code */
+        if (ret == 0)
+                if (find_old_idx(c, lnum, offs))
+                        return 1;
+        return ret;
+}
+
+/**
+ * layout_leb_in_gaps - layout index nodes using in-the-gaps method.
+ * @c: UBIFS file-system description object
+ * @p: return LEB number here
+ *
+ * This function lays out new index nodes for dirty znodes using in-the-gaps
+ * method of TNC commit.
+ * This function merely puts the next znode into the next gap, making no attempt
+ * to try to maximise the number of znodes that fit.
+ * This function returns the number of index nodes written into the gaps, or a
+ * negative error code on failure.
+ */
+static int layout_leb_in_gaps(struct ubifs_info *c, int *p)
+{
+        struct ubifs_scan_leb *sleb;
+        struct ubifs_scan_node *snod;
+        int lnum, dirt = 0, gap_start, gap_end, err, written, tot_written;
+
+        tot_written = 0;
+        /* Get an index LEB with lots of obsolete index nodes */
+        lnum = ubifs_find_dirty_idx_leb(c);
+        if (lnum < 0)
+                /*
+                 * There also may be dirt in the index head that could be
+                 * filled, however we do not check there at present.
+                 */
+                return lnum; /* Error code */
+        *p = lnum;
+        dbg_gc("LEB %d", lnum);
+        /*
+         * Scan the index LEB.  We use the generic scan for this even though
+         * it is more comprehensive and less efficient than is needed for this
+         * purpose.
+         */
+        sleb = ubifs_scan(c, lnum, 0, c->ileb_buf);
+        c->ileb_len = 0;
+        if (IS_ERR(sleb))
+                return PTR_ERR(sleb);
+        gap_start = 0;
+        list_for_each_entry(snod, &sleb->nodes, list) {
+                struct ubifs_idx_node *idx;
+                int in_use, level;
+
+                ubifs_assert(snod->type == UBIFS_IDX_NODE);
+                idx = snod->node;
+                key_read(c, ubifs_idx_key(c, idx), &snod->key);
+                level = le16_to_cpu(idx->level);
+                /* Determine if the index node is in use (not obsolete) */
+                in_use = is_idx_node_in_use(c, &snod->key, level, lnum,
+                                            snod->offs);
+                if (in_use < 0) {
+                        ubifs_scan_destroy(sleb);
+                        return in_use; /* Error code */
+                }
+                if (in_use) {
+                        if (in_use == 1)
+                                dirt += ALIGN(snod->len, 8);
+                        /*
+                         * The obsolete index nodes form gaps that can be
+                         * overwritten.  This gap has ended because we have
+                         * found an index node that is still in use
+                         * i.e. not obsolete
+                         */
+                        gap_end = snod->offs;
+                        /* Try to fill gap */
+                        written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
+                        if (written < 0) {
+                                ubifs_scan_destroy(sleb);
+                                return written; /* Error code */
+                        }
+                        tot_written += written;
+                        gap_start = ALIGN(snod->offs + snod->len, 8);
+                }
+        }
+        ubifs_scan_destroy(sleb);
+        c->ileb_len = c->leb_size;
+        gap_end = c->leb_size;
+        /* Try to fill gap */
+        written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
+        if (written < 0)
+                return written; /* Error code */
+        tot_written += written;
+        if (tot_written == 0) {
+                struct ubifs_lprops lp;
+
+                dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
+                err = ubifs_read_one_lp(c, lnum, &lp);
+                if (err)
+                        return err;
+                if (lp.free == c->leb_size) {
+                        /*
+                         * We must have snatched this LEB from the idx_gc list
+                         * so we need to correct the free and dirty space.
+                         */
+                        err = ubifs_change_one_lp(c, lnum,
+                                                  c->leb_size - c->ileb_len,
+                                                  dirt, 0, 0, 0);
+                        if (err)
+                                return err;
+                }
+                return 0;
+        }
+        err = ubifs_change_one_lp(c, lnum, c->leb_size - c->ileb_len, dirt,
+                                  0, 0, 0);
+        if (err)
+                return err;
+        err = ubifs_leb_change(c, lnum, c->ileb_buf, c->ileb_len,
+                               UBI_SHORTTERM);
+        if (err)
+                return err;
+        dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
+        return tot_written;
+}
+
+/**
+ * get_leb_cnt - calculate the number of empty LEBs needed to commit.
+ * @c: UBIFS file-system description object
+ * @cnt: number of znodes to commit
+ *
+ * This function returns the number of empty LEBs needed to commit @cnt znodes
+ * to the current index head.  The number is not exact and may be more than
+ * needed.
+ */
+static int get_leb_cnt(struct ubifs_info *c, int cnt)
+{
+        int d;
+
+        /* Assume maximum index node size (i.e. overestimate space needed) */
+        cnt -= (c->leb_size - c->ihead_offs) / c->max_idx_node_sz;
+        if (cnt < 0)
+                cnt = 0;
+        d = c->leb_size / c->max_idx_node_sz;
+        return DIV_ROUND_UP(cnt, d);
+}
+
+/**
+ * layout_in_gaps - in-the-gaps method of committing TNC.
+ * @c: UBIFS file-system description object
+ * @cnt: number of dirty znodes to commit.
+ *
+ * This function lays out new index nodes for dirty znodes using in-the-gaps
+ * method of TNC commit.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int layout_in_gaps(struct ubifs_info *c, int cnt)
+{
+        int err, leb_needed_cnt, written, *p;
+
+        dbg_gc("%d znodes to write", cnt);
+
+        c->gap_lebs = kmalloc(sizeof(int) * (c->lst.idx_lebs + 1), GFP_NOFS);
+        if (!c->gap_lebs)
+                return -ENOMEM;
+
+        p = c->gap_lebs;
+        do {
+                ubifs_assert(p < c->gap_lebs + sizeof(int) * c->lst.idx_lebs);
+                written = layout_leb_in_gaps(c, p);
+                if (written < 0) {
+                        err = written;
+                        if (err == -ENOSPC) {
+                                if (!dbg_force_in_the_gaps_enabled) {
+                                        /*
+                                         * Do not print scary warnings if the
+                                         * debugging option which forces
+                                         * in-the-gaps is enabled.
+                                         */
+                                        ubifs_err("out of space");
+                                        spin_lock(&c->space_lock);
+                                        dbg_dump_budg(c);
+                                        spin_unlock(&c->space_lock);
+                                        dbg_dump_lprops(c);
+                                }
+                                /* Try to commit anyway */
+                                err = 0;
+                                break;
+                        }
+                        kfree(c->gap_lebs);
+                        c->gap_lebs = NULL;
+                        return err;
+                }
+                p++;
+                cnt -= written;
+                leb_needed_cnt = get_leb_cnt(c, cnt);
+                dbg_gc("%d znodes remaining, need %d LEBs, have %d", cnt,
+                       leb_needed_cnt, c->ileb_cnt);
+        } while (leb_needed_cnt > c->ileb_cnt);
+
+        *p = -1;
+        return 0;
+}
+
+/**
+ * layout_in_empty_space - layout index nodes in empty space.
+ * @c: UBIFS file-system description object
+ *
+ * This function lays out new index nodes for dirty znodes using empty LEBs.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int layout_in_empty_space(struct ubifs_info *c)
+{
+        struct ubifs_znode *znode, *cnext, *zp;
+        int lnum, offs, len, next_len, buf_len, buf_offs, used, avail;
+        int wlen, blen, err;
+
+        cnext = c->enext;
+        if (!cnext)
+                return 0;
+
+        lnum = c->ihead_lnum;
+        buf_offs = c->ihead_offs;
+
+        buf_len = ubifs_idx_node_sz(c, c->fanout);
+        buf_len = ALIGN(buf_len, c->min_io_size);
+        used = 0;
+        avail = buf_len;
+
+        /* Ensure there is enough room for first write */
+        next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
+        if (buf_offs + next_len > c->leb_size)
+                lnum = -1;
+
+        while (1) {
+                znode = cnext;
+
+                len = ubifs_idx_node_sz(c, znode->child_cnt);
+
+                /* Determine the index node position */
+                if (lnum == -1) {
+                        if (c->ileb_nxt >= c->ileb_cnt) {
+                                ubifs_err("out of space");
+                                return -ENOSPC;
+                        }
+                        lnum = c->ilebs[c->ileb_nxt++];
+                        buf_offs = 0;
+                        used = 0;
+                        avail = buf_len;
+                }
+
+                offs = buf_offs + used;
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+                znode->lnum = lnum;
+                znode->offs = offs;
+                znode->len = len;
+#endif
+
+                /* Update the parent */
+                zp = znode->parent;
+                if (zp) {
+                        struct ubifs_zbranch *zbr;
+                        int i;
+
+                        i = znode->iip;
+                        zbr = &zp->zbranch[i];
+                        zbr->lnum = lnum;
+                        zbr->offs = offs;
+                        zbr->len = len;
+                } else {
+                        c->zroot.lnum = lnum;
+                        c->zroot.offs = offs;
+                        c->zroot.len = len;
+                }
+                c->calc_idx_sz += ALIGN(len, 8);
+
+                /*
+                 * Once lprops is updated, we can decrease the dirty znode count
+                 * but it is easier to just do it here.
+                 */
+                atomic_long_dec(&c->dirty_zn_cnt);
+
+                /*
+                 * Calculate the next index node length to see if there is
+                 * enough room for it
+                 */
+                cnext = znode->cnext;
+                if (cnext == c->cnext)
+                        next_len = 0;
+                else
+                        next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
+
+                if (c->min_io_size == 1) {
+                        buf_offs += ALIGN(len, 8);
+                        if (next_len) {
+                                if (buf_offs + next_len <= c->leb_size)
+                                        continue;
+                                err = ubifs_update_one_lp(c, lnum, 0,
+                                                c->leb_size - buf_offs, 0, 0);
+                                if (err)
+                                        return err;
+                                lnum = -1;
+                                continue;
+                        }
+                        err = ubifs_update_one_lp(c, lnum,
+                                        c->leb_size - buf_offs, 0, 0, 0);
+                        if (err)
+                                return err;
+                        break;
+                }
+
+                /* Update buffer positions */
+                wlen = used + len;
+                used += ALIGN(len, 8);
+                avail -= ALIGN(len, 8);
+
+                if (next_len != 0 &&
+                    buf_offs + used + next_len <= c->leb_size &&
+                    avail > 0)
+                        continue;
+
+                if (avail <= 0 && next_len &&
+                    buf_offs + used + next_len <= c->leb_size)
+                        blen = buf_len;
+                else
+                        blen = ALIGN(wlen, c->min_io_size);
+
+                /* The buffer is full or there are no more znodes to do */
+                buf_offs += blen;
+                if (next_len) {
+                        if (buf_offs + next_len > c->leb_size) {
+                                err = ubifs_update_one_lp(c, lnum,
+                                        c->leb_size - buf_offs, blen - used,
+                                        0, 0);
+                                if (err)
+                                        return err;
+                                lnum = -1;
+                        }
+                        used -= blen;
+                        if (used < 0)
+                                used = 0;
+                        avail = buf_len - used;
+                        continue;
+                }
+                err = ubifs_update_one_lp(c, lnum, c->leb_size - buf_offs,
+                                          blen - used, 0, 0);
+                if (err)
+                        return err;
+                break;
+        }
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+        c->new_ihead_lnum = lnum;
+        c->new_ihead_offs = buf_offs;
+#endif
+
+        return 0;
+}
+
+/**
+ * layout_commit - determine positions of index nodes to commit.
+ * @c: UBIFS file-system description object
+ * @no_space: indicates that insufficient empty LEBs were allocated
+ * @cnt: number of znodes to commit
+ *
+ * Calculate and update the positions of index nodes to commit.  If there were
+ * an insufficient number of empty LEBs allocated, then index nodes are placed
+ * into the gaps created by obsolete index nodes in non-empty index LEBs.  For
+ * this purpose, an obsolete index node is one that was not in the index as at
+ * the end of the last commit.  To write "in-the-gaps" requires that those index
+ * LEBs are updated atomically in-place.
+ */
+static int layout_commit(struct ubifs_info *c, int no_space, int cnt)
+{
+        int err;
+
+        if (no_space) {
+                err = layout_in_gaps(c, cnt);
+                if (err)
+                        return err;
+        }
+        err = layout_in_empty_space(c);
+        return err;
+}
+
+/**
+ * find_first_dirty - find first dirty znode.
+ * @znode: znode to begin searching from
+ */
+static struct ubifs_znode *find_first_dirty(struct ubifs_znode *znode)
+{
+        int i, cont;
+
+        if (!znode)
+                return NULL;
+
+        while (1) {
+                if (znode->level == 0) {
+                        if (ubifs_zn_dirty(znode))
+                                return znode;
+                        return NULL;
+                }
+                cont = 0;
+                for (i = 0; i < znode->child_cnt; i++) {
+                        struct ubifs_zbranch *zbr = &znode->zbranch[i];
+
+                        if (zbr->znode && ubifs_zn_dirty(zbr->znode)) {
+                                znode = zbr->znode;
+                                cont = 1;
+                                break;
+                        }
+                }
+                if (!cont) {
+                        if (ubifs_zn_dirty(znode))
+                                return znode;
+                        return NULL;
+                }
+        }
+}
+
+/**
+ * find_next_dirty - find next dirty znode.
+ * @znode: znode to begin searching from
+ */
+static struct ubifs_znode *find_next_dirty(struct ubifs_znode *znode)
+{
+        int n = znode->iip + 1;
+
+        znode = znode->parent;
+        if (!znode)
+                return NULL;
+        for (; n < znode->child_cnt; n++) {
+                struct ubifs_zbranch *zbr = &znode->zbranch[n];
+
+                if (zbr->znode && ubifs_zn_dirty(zbr->znode))
+                        return find_first_dirty(zbr->znode);
+        }
+        return znode;
+}
+
+/**
+ * get_znodes_to_commit - create list of dirty znodes to commit.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns the number of znodes to commit.
+ */
+static int get_znodes_to_commit(struct ubifs_info *c)
+{
+        struct ubifs_znode *znode, *cnext;
+        int cnt = 0;
+
+        c->cnext = find_first_dirty(c->zroot.znode);
+        znode = c->enext = c->cnext;
+        if (!znode) {
+                dbg_cmt("no znodes to commit");
+                return 0;
+        }
+        cnt += 1;
+        while (1) {
+                ubifs_assert(!test_bit(COW_ZNODE, &znode->flags));
+                __set_bit(COW_ZNODE, &znode->flags);
+                znode->alt = 0;
+                cnext = find_next_dirty(znode);
+                if (!cnext) {
+                        znode->cnext = c->cnext;
+                        break;
+                }
+                znode->cnext = cnext;
+                znode = cnext;
+                cnt += 1;
+        }
+        dbg_cmt("committing %d znodes", cnt);
+        ubifs_assert(cnt == atomic_long_read(&c->dirty_zn_cnt));
+        return cnt;
+}
+
+/**
+ * alloc_idx_lebs - allocate empty LEBs to be used to commit.
+ * @c: UBIFS file-system description object
+ * @cnt: number of znodes to commit
+ *
+ * This function returns %-ENOSPC if it cannot allocate a sufficient number of
+ * empty LEBs.  %0 is returned on success, otherwise a negative error code
+ * is returned.
+ */
+static int alloc_idx_lebs(struct ubifs_info *c, int cnt)
+{
+        int i, leb_cnt, lnum;
+
+        c->ileb_cnt = 0;
+        c->ileb_nxt = 0;
+        leb_cnt = get_leb_cnt(c, cnt);
+        dbg_cmt("need about %d empty LEBS for TNC commit", leb_cnt);
+        if (!leb_cnt)
+                return 0;
+        c->ilebs = kmalloc(leb_cnt * sizeof(int), GFP_NOFS);
+        if (!c->ilebs)
+                return -ENOMEM;
+        for (i = 0; i < leb_cnt; i++) {
+                lnum = ubifs_find_free_leb_for_idx(c);
+                if (lnum < 0)
+                        return lnum;
+                c->ilebs[c->ileb_cnt++] = lnum;
+                dbg_cmt("LEB %d", lnum);
+        }
+        if (dbg_force_in_the_gaps())
+                return -ENOSPC;
+        return 0;
+}
+
+/**
+ * free_unused_idx_lebs - free unused LEBs that were allocated for the commit.
+ * @c: UBIFS file-system description object
+ *
+ * It is possible that we allocate more empty LEBs for the commit than we need.
+ * This functions frees the surplus.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int free_unused_idx_lebs(struct ubifs_info *c)
+{
+        int i, err = 0, lnum, er;
+
+        for (i = c->ileb_nxt; i < c->ileb_cnt; i++) {
+                lnum = c->ilebs[i];
+                dbg_cmt("LEB %d", lnum);
+                er = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
+                                         LPROPS_INDEX | LPROPS_TAKEN, 0);
+                if (!err)
+                        err = er;
+        }
+        return err;
+}
+
+/**
+ * free_idx_lebs - free unused LEBs after commit end.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int free_idx_lebs(struct ubifs_info *c)
+{
+        int err;
+
+        err = free_unused_idx_lebs(c);
+        kfree(c->ilebs);
+        c->ilebs = NULL;
+        return err;
+}
+
+/**
+ * ubifs_tnc_start_commit - start TNC commit.
+ * @c: UBIFS file-system description object
+ * @zroot: new index root position is returned here
+ *
+ * This function prepares the list of indexing nodes to commit and lays out
+ * their positions on flash. If there is not enough free space it uses the
+ * in-gap commit method. Returns zero in case of success and a negative error
+ * code in case of failure.
+ */
+int ubifs_tnc_start_commit(struct ubifs_info *c, struct ubifs_zbranch *zroot)
+{
+        int err = 0, cnt;
+
+        mutex_lock(&c->tnc_mutex);
+        err = dbg_check_tnc(c, 1);
+        if (err)
+                goto out;
+        cnt = get_znodes_to_commit(c);
+        if (cnt != 0) {
+                int no_space = 0;
+
+                err = alloc_idx_lebs(c, cnt);
+                if (err == -ENOSPC)
+                        no_space = 1;
+                else if (err)
+                        goto out_free;
+                err = layout_commit(c, no_space, cnt);
+                if (err)
+                        goto out_free;
+                ubifs_assert(atomic_long_read(&c->dirty_zn_cnt) == 0);
+                err = free_unused_idx_lebs(c);
+                if (err)
+                        goto out;
+        }
+        destroy_old_idx(c);
+        memcpy(zroot, &c->zroot, sizeof(struct ubifs_zbranch));
+
+        err = ubifs_save_dirty_idx_lnums(c);
+        if (err)
+                goto out;
+
+        spin_lock(&c->space_lock);
+        /*
+         * Although we have not finished committing yet, update size of the
+         * committed index ('c->old_idx_sz') and zero out the index growth
+         * budget. It is OK to do this now, because we've reserved all the
+         * space which is needed to commit the index, and it is save for the
+         * budgeting subsystem to assume the index is already committed,
+         * even though it is not.
+         */
+        c->old_idx_sz = c->calc_idx_sz;
+        c->budg_uncommitted_idx = 0;
+        spin_unlock(&c->space_lock);
+        mutex_unlock(&c->tnc_mutex);
+
+        dbg_cmt("number of index LEBs %d", c->lst.idx_lebs);
+        dbg_cmt("size of index %llu", c->calc_idx_sz);
+        return err;
+
+out_free:
+        free_idx_lebs(c);
+out:
+        mutex_unlock(&c->tnc_mutex);
+        return err;
+}
+
+/**
+ * write_index - write index nodes.
+ * @c: UBIFS file-system description object
+ *
+ * This function writes the index nodes whose positions were laid out in the
+ * layout_in_empty_space function.
+ */
+static int write_index(struct ubifs_info *c)
+{
+        struct ubifs_idx_node *idx;
+        struct ubifs_znode *znode, *cnext;
+        int i, lnum, offs, len, next_len, buf_len, buf_offs, used;
+        int avail, wlen, err, lnum_pos = 0;
+
+        cnext = c->enext;
+        if (!cnext)
+                return 0;
+
+        /*
+         * Always write index nodes to the index head so that index nodes and
+         * other types of nodes are never mixed in the same erase block.
+         */
+        lnum = c->ihead_lnum;
+        buf_offs = c->ihead_offs;
+
+        /* Allocate commit buffer */
+        buf_len = ALIGN(c->max_idx_node_sz, c->min_io_size);
+        used = 0;
+        avail = buf_len;
+
+        /* Ensure there is enough room for first write */
+        next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
+        if (buf_offs + next_len > c->leb_size) {
+                err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0, 0,
+                                          LPROPS_TAKEN);
+                if (err)
+                        return err;
+                lnum = -1;
+        }
+
+        while (1) {
+                cond_resched();
+
+                znode = cnext;
+                idx = c->cbuf + used;
+
+                /* Make index node */
+                idx->ch.node_type = UBIFS_IDX_NODE;
+                idx->child_cnt = cpu_to_le16(znode->child_cnt);
+                idx->level = cpu_to_le16(znode->level);
+                for (i = 0; i < znode->child_cnt; i++) {
+                        struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
+                        struct ubifs_zbranch *zbr = &znode->zbranch[i];
+
+                        key_write_idx(c, &zbr->key, &br->key);
+                        br->lnum = cpu_to_le32(zbr->lnum);
+                        br->offs = cpu_to_le32(zbr->offs);
+                        br->len = cpu_to_le32(zbr->len);
+                        if (!zbr->lnum || !zbr->len) {
+                                ubifs_err("bad ref in znode");
+                                dbg_dump_znode(c, znode);
+                                if (zbr->znode)
+                                        dbg_dump_znode(c, zbr->znode);
+                        }
+                }
+                len = ubifs_idx_node_sz(c, znode->child_cnt);
+                ubifs_prepare_node(c, idx, len, 0);
+
+                /* Determine the index node position */
+                if (lnum == -1) {
+                        lnum = c->ilebs[lnum_pos++];
+                        buf_offs = 0;
+                        used = 0;
+                        avail = buf_len;
+                }
+                offs = buf_offs + used;
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+                if (lnum != znode->lnum || offs != znode->offs ||
+                    len != znode->len) {
+                        ubifs_err("inconsistent znode posn");
+                        return -EINVAL;
+                }
+#endif
+
+                /* Grab some stuff from znode while we still can */
+                cnext = znode->cnext;
+
+                ubifs_assert(ubifs_zn_dirty(znode));
+                ubifs_assert(test_bit(COW_ZNODE, &znode->flags));
+
+                /*
+                 * It is important that other threads should see %DIRTY_ZNODE
+                 * flag cleared before %COW_ZNODE. Specifically, it matters in
+                 * the 'dirty_cow_znode()' function. This is the reason for the
+                 * first barrier. Also, we want the bit changes to be seen to
+                 * other threads ASAP, to avoid unnecesarry copying, which is
+                 * the reason for the second barrier.
+                 */
+                clear_bit(DIRTY_ZNODE, &znode->flags);
+                smp_mb__before_clear_bit();
+                clear_bit(COW_ZNODE, &znode->flags);
+                smp_mb__after_clear_bit();
+
+                /* Do not access znode from this point on */
+
+                /* Update buffer positions */
+                wlen = used + len;
+                used += ALIGN(len, 8);
+                avail -= ALIGN(len, 8);
+
+                /*
+                 * Calculate the next index node length to see if there is
+                 * enough room for it
+                 */
+                if (cnext == c->cnext)
+                        next_len = 0;
+                else
+                        next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
+
+                if (c->min_io_size == 1) {
+                        /*
+                         * Write the prepared index node immediately if there is
+                         * no minimum IO size
+                         */
+                        err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs,
+                                              wlen, UBI_SHORTTERM);
+                        if (err)
+                                return err;
+                        buf_offs += ALIGN(wlen, 8);
+                        if (next_len) {
+                                used = 0;
+                                avail = buf_len;
+                                if (buf_offs + next_len > c->leb_size) {
+                                        err = ubifs_update_one_lp(c, lnum,
+                                                LPROPS_NC, 0, 0, LPROPS_TAKEN);
+                                        if (err)
+                                                return err;
+                                        lnum = -1;
+                                }
+                                continue;
+                        }
+                } else {
+                        int blen, nxt_offs = buf_offs + used + next_len;
+
+                        if (next_len && nxt_offs <= c->leb_size) {
+                                if (avail > 0)
+                                        continue;
+                                else
+                                        blen = buf_len;
+                        } else {
+                                wlen = ALIGN(wlen, 8);
+                                blen = ALIGN(wlen, c->min_io_size);
+                                ubifs_pad(c, c->cbuf + wlen, blen - wlen);
+                        }
+                        /*
+                         * The buffer is full or there are no more znodes
+                         * to do
+                         */
+                        err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs,
+                                              blen, UBI_SHORTTERM);
+                        if (err)
+                                return err;
+                        buf_offs += blen;
+                        if (next_len) {
+                                if (nxt_offs > c->leb_size) {
+                                        err = ubifs_update_one_lp(c, lnum,
+                                                LPROPS_NC, 0, 0, LPROPS_TAKEN);
+                                        if (err)
+                                                return err;
+                                        lnum = -1;
+                                }
+                                used -= blen;
+                                if (used < 0)
+                                        used = 0;
+                                avail = buf_len - used;
+                                memmove(c->cbuf, c->cbuf + blen, used);
+                                continue;
+                        }
+                }
+                break;
+        }
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+        if (lnum != c->new_ihead_lnum || buf_offs != c->new_ihead_offs) {
+                ubifs_err("inconsistent ihead");
+                return -EINVAL;
+        }
+#endif
+
+        c->ihead_lnum = lnum;
+        c->ihead_offs = buf_offs;
+
+        return 0;
+}
+
+/**
+ * free_obsolete_znodes - free obsolete znodes.
+ * @c: UBIFS file-system description object
+ *
+ * At the end of commit end, obsolete znodes are freed.
+ */
+static void free_obsolete_znodes(struct ubifs_info *c)
+{
+        struct ubifs_znode *znode, *cnext;
+
+        cnext = c->cnext;
+        do {
+                znode = cnext;
+                cnext = znode->cnext;
+                if (test_bit(OBSOLETE_ZNODE, &znode->flags))
+                        kfree(znode);
+                else {
+                        znode->cnext = NULL;
+                        atomic_long_inc(&c->clean_zn_cnt);
+                        atomic_long_inc(&ubifs_clean_zn_cnt);
+                }
+        } while (cnext != c->cnext);
+}
+
+/**
+ * return_gap_lebs - return LEBs used by the in-gap commit method.
+ * @c: UBIFS file-system description object
+ *
+ * This function clears the "taken" flag for the LEBs which were used by the
+ * "commit in-the-gaps" method.
+ */
+static int return_gap_lebs(struct ubifs_info *c)
+{
+        int *p, err;
+
+        if (!c->gap_lebs)
+                return 0;
+
+        dbg_cmt("");
+        for (p = c->gap_lebs; *p != -1; p++) {
+                err = ubifs_change_one_lp(c, *p, LPROPS_NC, LPROPS_NC, 0,
+                                          LPROPS_TAKEN, 0);
+                if (err)
+                        return err;
+        }
+
+        kfree(c->gap_lebs);
+        c->gap_lebs = NULL;
+        return 0;
+}
+
+/**
+ * ubifs_tnc_end_commit - update the TNC for commit end.
+ * @c: UBIFS file-system description object
+ *
+ * Write the dirty znodes.
+ */
+int ubifs_tnc_end_commit(struct ubifs_info *c)
+{
+        int err;
+
+        if (!c->cnext)
+                return 0;
+
+        err = return_gap_lebs(c);
+        if (err)
+                return err;
+
+        err = write_index(c);
+        if (err)
+                return err;
+
+        mutex_lock(&c->tnc_mutex);
+
+        dbg_cmt("TNC height is %d", c->zroot.znode->level + 1);
+
+        free_obsolete_znodes(c);
+
+        c->cnext = NULL;
+        kfree(c->ilebs);
+        c->ilebs = NULL;
+
+        mutex_unlock(&c->tnc_mutex);
+
+        return 0;
+}