log.c

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/*
 * 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: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 */

/*
 * This file is a part of UBIFS journal implementation and contains various
 * functions which manipulate the log. The log is a fixed area on the flash
 * which does not contain any data but refers to buds. The log is a part of the
 * journal.
 */

#include "ubifs.h"

static int dbg_check_bud_bytes(struct ubifs_info *c);

struct ubifs_bud *ubifs_search_bud(struct ubifs_info *c, int lnum)
{
    struct rb_node *p;
    struct ubifs_bud *bud;

    spin_lock(&c->buds_lock);
    p = c->buds.rb_node;
    while (p) {
        bud = rb_entry(p, struct ubifs_bud, rb);
        if (lnum < bud->lnum)
            p = p->rb_left;
        else if (lnum > bud->lnum)
            p = p->rb_right;
        else {
            spin_unlock(&c->buds_lock);
            return bud;
        }
    }
    spin_unlock(&c->buds_lock);
    return NULL;
}

struct ubifs_wbuf *ubifs_get_wbuf(struct ubifs_info *c, int lnum)
{
    struct rb_node *p;
    struct ubifs_bud *bud;
    int jhead;

    if (!c->jheads)
        return NULL;

    spin_lock(&c->buds_lock);
    p = c->buds.rb_node;
    while (p) {
        bud = rb_entry(p, struct ubifs_bud, rb);
        if (lnum < bud->lnum)
            p = p->rb_left;
        else if (lnum > bud->lnum)
            p = p->rb_right;
        else {
            jhead = bud->jhead;
            spin_unlock(&c->buds_lock);
            return &c->jheads[jhead].wbuf;
        }
    }
    spin_unlock(&c->buds_lock);
    return NULL;
}

static inline long long empty_log_bytes(const struct ubifs_info *c)
{
    long long h, t;

    h = (long long)c->lhead_lnum * c->leb_size + c->lhead_offs;
    t = (long long)c->ltail_lnum * c->leb_size;

    if (h >= t)
        return c->log_bytes - h + t;
    else
        return t - h;
}

void ubifs_add_bud(struct ubifs_info *c, struct ubifs_bud *bud)
{
    struct rb_node **p, *parent = NULL;
    struct ubifs_bud *b;
    struct ubifs_jhead *jhead;

    spin_lock(&c->buds_lock);
    p = &c->buds.rb_node;
    while (*p) {
        parent = *p;
        b = rb_entry(parent, struct ubifs_bud, rb);
        ubifs_assert(bud->lnum != b->lnum);
        if (bud->lnum < b->lnum)
            p = &(*p)->rb_left;
        else
            p = &(*p)->rb_right;
    }

    rb_link_node(&bud->rb, parent, p);
    rb_insert_color(&bud->rb, &c->buds);
    if (c->jheads) {
        jhead = &c->jheads[bud->jhead];
        list_add_tail(&bud->list, &jhead->buds_list);
    } else
        ubifs_assert(c->replaying && c->ro_mount);

    /*
     * Note, although this is a new bud, we anyway account this space now,
     * before any data has been written to it, because this is about to
     * guarantee fixed mount time, and this bud will anyway be read and
     * scanned.
     */
    c->bud_bytes += c->leb_size - bud->start;

    dbg_log("LEB %d:%d, jhead %s, bud_bytes %lld", bud->lnum,
        bud->start, dbg_jhead(bud->jhead), c->bud_bytes);
    spin_unlock(&c->buds_lock);
}

int ubifs_add_bud_to_log(struct ubifs_info *c, int jhead, int lnum, int offs)
{
    int err;
    struct ubifs_bud *bud;
    struct ubifs_ref_node *ref;

    bud = kmalloc(sizeof(struct ubifs_bud), GFP_NOFS);
    if (!bud)
        return -ENOMEM;
    ref = kzalloc(c->ref_node_alsz, GFP_NOFS);
    if (!ref) {
        kfree(bud);
        return -ENOMEM;
    }

    mutex_lock(&c->log_mutex);
    ubifs_assert(!c->ro_media && !c->ro_mount);
    if (c->ro_error) {
        err = -EROFS;
        goto out_unlock;
    }

    /* Make sure we have enough space in the log */
    if (empty_log_bytes(c) - c->ref_node_alsz < c->min_log_bytes) {
        dbg_log("not enough log space - %lld, required %d",
            empty_log_bytes(c), c->min_log_bytes);
        ubifs_commit_required(c);
        err = -EAGAIN;
        goto out_unlock;
    }

    /*
     * Make sure the amount of space in buds will not exceed the
     * 'c->max_bud_bytes' limit, because we want to guarantee mount time
     * limits.
     *
     * It is not necessary to hold @c->buds_lock when reading @c->bud_bytes
     * because we are holding @c->log_mutex. All @c->bud_bytes take place
     * when both @c->log_mutex and @c->bud_bytes are locked.
     */
    if (c->bud_bytes + c->leb_size - offs > c->max_bud_bytes) {
        dbg_log("bud bytes %lld (%lld max), require commit",
            c->bud_bytes, c->max_bud_bytes);
        ubifs_commit_required(c);
        err = -EAGAIN;
        goto out_unlock;
    }

    /*
     * If the journal is full enough - start background commit. Note, it is
     * OK to read 'c->cmt_state' without spinlock because integer reads
     * are atomic in the kernel.
     */
    if (c->bud_bytes >= c->bg_bud_bytes &&
        c->cmt_state == COMMIT_RESTING) {
        dbg_log("bud bytes %lld (%lld max), initiate BG commit",
            c->bud_bytes, c->max_bud_bytes);
        ubifs_request_bg_commit(c);
    }

    bud->lnum = lnum;
    bud->start = offs;
    bud->jhead = jhead;

    ref->ch.node_type = UBIFS_REF_NODE;
    ref->lnum = cpu_to_le32(bud->lnum);
    ref->offs = cpu_to_le32(bud->start);
    ref->jhead = cpu_to_le32(jhead);

    if (c->lhead_offs > c->leb_size - c->ref_node_alsz) {
        c->lhead_lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
        c->lhead_offs = 0;
    }

    if (c->lhead_offs == 0) {
        /* Must ensure next log LEB has been unmapped */
        err = ubifs_leb_unmap(c, c->lhead_lnum);
        if (err)
            goto out_unlock;
    }

    if (bud->start == 0) {
        /*
         * Before writing the LEB reference which refers an empty LEB
         * to the log, we have to make sure it is mapped, because
         * otherwise we'd risk to refer an LEB with garbage in case of
         * an unclean reboot, because the target LEB might have been
         * unmapped, but not yet physically erased.
         */
        err = ubifs_leb_map(c, bud->lnum);
        if (err)
            goto out_unlock;
    }

    dbg_log("write ref LEB %d:%d",
        c->lhead_lnum, c->lhead_offs);
    err = ubifs_write_node(c, ref, UBIFS_REF_NODE_SZ, c->lhead_lnum,
                   c->lhead_offs);
    if (err)
        goto out_unlock;

    c->lhead_offs += c->ref_node_alsz;

    ubifs_add_bud(c, bud);

    mutex_unlock(&c->log_mutex);
    kfree(ref);
    return 0;

out_unlock:
    mutex_unlock(&c->log_mutex);
    kfree(ref);
    kfree(bud);
    return err;
}

static void remove_buds(struct ubifs_info *c)
{
    struct rb_node *p;

    ubifs_assert(list_empty(&c->old_buds));
    c->cmt_bud_bytes = 0;
    spin_lock(&c->buds_lock);
    p = rb_first(&c->buds);
    while (p) {
        struct rb_node *p1 = p;
        struct ubifs_bud *bud;
        struct ubifs_wbuf *wbuf;

        p = rb_next(p);
        bud = rb_entry(p1, struct ubifs_bud, rb);
        wbuf = &c->jheads[bud->jhead].wbuf;

        if (wbuf->lnum == bud->lnum) {
            /*
             * Do not remove buds which are pointed to by journal
             * heads (non-closed buds).
             */
            c->cmt_bud_bytes += wbuf->offs - bud->start;
            dbg_log("preserve %d:%d, jhead %s, bud bytes %d, cmt_bud_bytes %lld",
                bud->lnum, bud->start, dbg_jhead(bud->jhead),
                wbuf->offs - bud->start, c->cmt_bud_bytes);
            bud->start = wbuf->offs;
        } else {
            c->cmt_bud_bytes += c->leb_size - bud->start;
            dbg_log("remove %d:%d, jhead %s, bud bytes %d, cmt_bud_bytes %lld",
                bud->lnum, bud->start, dbg_jhead(bud->jhead),
                c->leb_size - bud->start, c->cmt_bud_bytes);
            rb_erase(p1, &c->buds);
            /*
             * If the commit does not finish, the recovery will need
             * to replay the journal, in which case the old buds
             * must be unchanged. Do not release them until post
             * commit i.e. do not allow them to be garbage
             * collected.
             */
            list_move(&bud->list, &c->old_buds);
        }
    }
    spin_unlock(&c->buds_lock);
}

int ubifs_log_start_commit(struct ubifs_info *c, int *ltail_lnum)
{
    void *buf;
    struct ubifs_cs_node *cs;
    struct ubifs_ref_node *ref;
    int err, i, max_len, len;

    err = dbg_check_bud_bytes(c);
    if (err)
        return err;

    max_len = UBIFS_CS_NODE_SZ + c->jhead_cnt * UBIFS_REF_NODE_SZ;
    max_len = ALIGN(max_len, c->min_io_size);
    buf = cs = kmalloc(max_len, GFP_NOFS);
    if (!buf)
        return -ENOMEM;

    cs->ch.node_type = UBIFS_CS_NODE;
    cs->cmt_no = cpu_to_le64(c->cmt_no);
    ubifs_prepare_node(c, cs, UBIFS_CS_NODE_SZ, 0);

    /*
     * Note, we do not lock 'c->log_mutex' because this is the commit start
     * phase and we are exclusively using the log. And we do not lock
     * write-buffer because nobody can write to the file-system at this
     * phase.
     */

    len = UBIFS_CS_NODE_SZ;
    for (i = 0; i < c->jhead_cnt; i++) {
        int lnum = c->jheads[i].wbuf.lnum;
        int offs = c->jheads[i].wbuf.offs;

        if (lnum == -1 || offs == c->leb_size)
            continue;

        dbg_log("add ref to LEB %d:%d for jhead %s",
            lnum, offs, dbg_jhead(i));
        ref = buf + len;
        ref->ch.node_type = UBIFS_REF_NODE;
        ref->lnum = cpu_to_le32(lnum);
        ref->offs = cpu_to_le32(offs);
        ref->jhead = cpu_to_le32(i);

        ubifs_prepare_node(c, ref, UBIFS_REF_NODE_SZ, 0);
        len += UBIFS_REF_NODE_SZ;
    }

    ubifs_pad(c, buf + len, ALIGN(len, c->min_io_size) - len);

    /* Switch to the next log LEB */
    if (c->lhead_offs) {
        c->lhead_lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
        c->lhead_offs = 0;
    }

    if (c->lhead_offs == 0) {
        /* Must ensure next LEB has been unmapped */
        err = ubifs_leb_unmap(c, c->lhead_lnum);
        if (err)
            goto out;
    }

    len = ALIGN(len, c->min_io_size);
    dbg_log("writing commit start at LEB %d:0, len %d", c->lhead_lnum, len);
    err = ubifs_leb_write(c, c->lhead_lnum, cs, 0, len);
    if (err)
        goto out;

    *ltail_lnum = c->lhead_lnum;

    c->lhead_offs += len;
    if (c->lhead_offs == c->leb_size) {
        c->lhead_lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
        c->lhead_offs = 0;
    }

    remove_buds(c);

    /*
     * We have started the commit and now users may use the rest of the log
     * for new writes.
     */
    c->min_log_bytes = 0;

out:
    kfree(buf);
    return err;
}

int ubifs_log_end_commit(struct ubifs_info *c, int ltail_lnum)
{
    int err;

    /*
     * At this phase we have to lock 'c->log_mutex' because UBIFS allows FS
     * writes during commit. Its only short "commit" start phase when
     * writers are blocked.
     */
    mutex_lock(&c->log_mutex);

    dbg_log("old tail was LEB %d:0, new tail is LEB %d:0",
        c->ltail_lnum, ltail_lnum);

    c->ltail_lnum = ltail_lnum;
    /*
     * The commit is finished and from now on it must be guaranteed that
     * there is always enough space for the next commit.
     */
    c->min_log_bytes = c->leb_size;

    spin_lock(&c->buds_lock);
    c->bud_bytes -= c->cmt_bud_bytes;
    spin_unlock(&c->buds_lock);

    err = dbg_check_bud_bytes(c);

    mutex_unlock(&c->log_mutex);
    return err;
}

int ubifs_log_post_commit(struct ubifs_info *c, int old_ltail_lnum)
{
    int lnum, err = 0;

    while (!list_empty(&c->old_buds)) {
        struct ubifs_bud *bud;

        bud = list_entry(c->old_buds.next, struct ubifs_bud, list);
        err = ubifs_return_leb(c, bud->lnum);
        if (err)
            return err;
        list_del(&bud->list);
        kfree(bud);
    }
    mutex_lock(&c->log_mutex);
    for (lnum = old_ltail_lnum; lnum != c->ltail_lnum;
         lnum = ubifs_next_log_lnum(c, lnum)) {
        dbg_log("unmap log LEB %d", lnum);
        err = ubifs_leb_unmap(c, lnum);
        if (err)
            goto out;
    }
out:
    mutex_unlock(&c->log_mutex);
    return err;
}

struct done_ref {
    struct rb_node rb;
    int lnum;
};

static int done_already(struct rb_root *done_tree, int lnum)
{
    struct rb_node **p = &done_tree->rb_node, *parent = NULL;
    struct done_ref *dr;

    while (*p) {
        parent = *p;
        dr = rb_entry(parent, struct done_ref, rb);
        if (lnum < dr->lnum)
            p = &(*p)->rb_left;
        else if (lnum > dr->lnum)
            p = &(*p)->rb_right;
        else
            return 1;
    }

    dr = kzalloc(sizeof(struct done_ref), GFP_NOFS);
    if (!dr)
        return -ENOMEM;

    dr->lnum = lnum;

    rb_link_node(&dr->rb, parent, p);
    rb_insert_color(&dr->rb, done_tree);

    return 0;
}

static void destroy_done_tree(struct rb_root *done_tree)
{
    struct rb_node *this = done_tree->rb_node;
    struct done_ref *dr;

    while (this) {
        if (this->rb_left) {
            this = this->rb_left;
            continue;
        } else if (this->rb_right) {
            this = this->rb_right;
            continue;
        }
        dr = rb_entry(this, struct done_ref, rb);
        this = rb_parent(this);
        if (this) {
            if (this->rb_left == &dr->rb)
                this->rb_left = NULL;
            else
                this->rb_right = NULL;
        }
        kfree(dr);
    }
}

static int add_node(struct ubifs_info *c, void *buf, int *lnum, int *offs,
            void *node)
{
    struct ubifs_ch *ch = node;
    int len = le32_to_cpu(ch->len), remains = c->leb_size - *offs;

    if (len > remains) {
        int sz = ALIGN(*offs, c->min_io_size), err;

        ubifs_pad(c, buf + *offs, sz - *offs);
        err = ubifs_leb_change(c, *lnum, buf, sz);
        if (err)
            return err;
        *lnum = ubifs_next_log_lnum(c, *lnum);
        *offs = 0;
    }
    memcpy(buf + *offs, node, len);
    *offs += ALIGN(len, 8);
    return 0;
}

int ubifs_consolidate_log(struct ubifs_info *c)
{
    struct ubifs_scan_leb *sleb;
    struct ubifs_scan_node *snod;
    struct rb_root done_tree = RB_ROOT;
    int lnum, err, first = 1, write_lnum, offs = 0;
    void *buf;

    dbg_rcvry("log tail LEB %d, log head LEB %d", c->ltail_lnum,
          c->lhead_lnum);
    buf = vmalloc(c->leb_size);
    if (!buf)
        return -ENOMEM;
    lnum = c->ltail_lnum;
    write_lnum = lnum;
    while (1) {
        sleb = ubifs_scan(c, lnum, 0, c->sbuf, 0);
        if (IS_ERR(sleb)) {
            err = PTR_ERR(sleb);
            goto out_free;
        }
        list_for_each_entry(snod, &sleb->nodes, list) {
            switch (snod->type) {
            case UBIFS_REF_NODE: {
                struct ubifs_ref_node *ref = snod->node;
                int ref_lnum = le32_to_cpu(ref->lnum);

                err = done_already(&done_tree, ref_lnum);
                if (err < 0)
                    goto out_scan;
                if (err != 1) {
                    err = add_node(c, buf, &write_lnum,
                               &offs, snod->node);
                    if (err)
                        goto out_scan;
                }
                break;
            }
            case UBIFS_CS_NODE:
                if (!first)
                    break;
                err = add_node(c, buf, &write_lnum, &offs,
                           snod->node);
                if (err)
                    goto out_scan;
                first = 0;
                break;
            }
        }
        ubifs_scan_destroy(sleb);
        if (lnum == c->lhead_lnum)
            break;
        lnum = ubifs_next_log_lnum(c, lnum);
    }
    if (offs) {
        int sz = ALIGN(offs, c->min_io_size);

        ubifs_pad(c, buf + offs, sz - offs);
        err = ubifs_leb_change(c, write_lnum, buf, sz);
        if (err)
            goto out_free;
        offs = ALIGN(offs, c->min_io_size);
    }
    destroy_done_tree(&done_tree);
    vfree(buf);
    if (write_lnum == c->lhead_lnum) {
        ubifs_err("log is too full");
        return -EINVAL;
    }
    /* Unmap remaining LEBs */
    lnum = write_lnum;
    do {
        lnum = ubifs_next_log_lnum(c, lnum);
        err = ubifs_leb_unmap(c, lnum);
        if (err)
            return err;
    } while (lnum != c->lhead_lnum);
    c->lhead_lnum = write_lnum;
    c->lhead_offs = offs;
    dbg_rcvry("new log head at %d:%d", c->lhead_lnum, c->lhead_offs);
    return 0;

out_scan:
    ubifs_scan_destroy(sleb);
out_free:
    destroy_done_tree(&done_tree);
    vfree(buf);
    return err;
}

static int dbg_check_bud_bytes(struct ubifs_info *c)
{
    int i, err = 0;
    struct ubifs_bud *bud;
    long long bud_bytes = 0;

    if (!dbg_is_chk_gen(c))
        return 0;

    spin_lock(&c->buds_lock);
    for (i = 0; i < c->jhead_cnt; i++)
        list_for_each_entry(bud, &c->jheads[i].buds_list, list)
            bud_bytes += c->leb_size - bud->start;

    if (c->bud_bytes != bud_bytes) {
        ubifs_err("bad bud_bytes %lld, calculated %lld",
              c->bud_bytes, bud_bytes);
        err = -EINVAL;
    }
    spin_unlock(&c->buds_lock);

    return err;
}