summary.c

Go to the documentation of this file.

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2004  Ferenc Havasi <[email protected]>,
 *           Zoltan Sogor <[email protected]>,
 *           Patrik Kluba <[email protected]>,
 *           University of Szeged, Hungary
 *         2006  KaiGai Kohei <[email protected]>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/pagemap.h>
#include <linux/crc32.h>
#include <linux/compiler.h>
#include <linux/vmalloc.h>
#include "nodelist.h"
#include "debug.h"

int jffs2_sum_init(struct jffs2_sb_info *c)
{
    uint32_t sum_size = min_t(uint32_t, c->sector_size, MAX_SUMMARY_SIZE);

    c->summary = kzalloc(sizeof(struct jffs2_summary), GFP_KERNEL);

    if (!c->summary) {
        JFFS2_WARNING("Can't allocate memory for summary information!\n");
        return -ENOMEM;
    }

    c->summary->sum_buf = kmalloc(sum_size, GFP_KERNEL);

    if (!c->summary->sum_buf) {
        JFFS2_WARNING("Can't allocate buffer for writing out summary information!\n");
        kfree(c->summary);
        return -ENOMEM;
    }

    dbg_summary("returned successfully\n");

    return 0;
}

void jffs2_sum_exit(struct jffs2_sb_info *c)
{
    dbg_summary("called\n");

    jffs2_sum_disable_collecting(c->summary);

    kfree(c->summary->sum_buf);
    c->summary->sum_buf = NULL;

    kfree(c->summary);
    c->summary = NULL;
}

static int jffs2_sum_add_mem(struct jffs2_summary *s, union jffs2_sum_mem *item)
{
    if (!s->sum_list_head)
        s->sum_list_head = (union jffs2_sum_mem *) item;
    if (s->sum_list_tail)
        s->sum_list_tail->u.next = (union jffs2_sum_mem *) item;
    s->sum_list_tail = (union jffs2_sum_mem *) item;

    switch (je16_to_cpu(item->u.nodetype)) {
        case JFFS2_NODETYPE_INODE:
            s->sum_size += JFFS2_SUMMARY_INODE_SIZE;
            s->sum_num++;
            dbg_summary("inode (%u) added to summary\n",
                        je32_to_cpu(item->i.inode));
            break;
        case JFFS2_NODETYPE_DIRENT:
            s->sum_size += JFFS2_SUMMARY_DIRENT_SIZE(item->d.nsize);
            s->sum_num++;
            dbg_summary("dirent (%u) added to summary\n",
                        je32_to_cpu(item->d.ino));
            break;
#ifdef CONFIG_JFFS2_FS_XATTR
        case JFFS2_NODETYPE_XATTR:
            s->sum_size += JFFS2_SUMMARY_XATTR_SIZE;
            s->sum_num++;
            dbg_summary("xattr (xid=%u, version=%u) added to summary\n",
                    je32_to_cpu(item->x.xid), je32_to_cpu(item->x.version));
            break;
        case JFFS2_NODETYPE_XREF:
            s->sum_size += JFFS2_SUMMARY_XREF_SIZE;
            s->sum_num++;
            dbg_summary("xref added to summary\n");
            break;
#endif
        default:
            JFFS2_WARNING("UNKNOWN node type %u\n",
                        je16_to_cpu(item->u.nodetype));
            return 1;
    }
    return 0;
}


/* The following 3 functions are called from scan.c to collect summary info for not closed jeb */

int jffs2_sum_add_padding_mem(struct jffs2_summary *s, uint32_t size)
{
    dbg_summary("called with %u\n", size);
    s->sum_padded += size;
    return 0;
}

int jffs2_sum_add_inode_mem(struct jffs2_summary *s, struct jffs2_raw_inode *ri,
                uint32_t ofs)
{
    struct jffs2_sum_inode_mem *temp = kmalloc(sizeof(struct jffs2_sum_inode_mem), GFP_KERNEL);

    if (!temp)
        return -ENOMEM;

    temp->nodetype = ri->nodetype;
    temp->inode = ri->ino;
    temp->version = ri->version;
    temp->offset = cpu_to_je32(ofs); /* relative offset from the beginning of the jeb */
    temp->totlen = ri->totlen;
    temp->next = NULL;

    return jffs2_sum_add_mem(s, (union jffs2_sum_mem *)temp);
}

int jffs2_sum_add_dirent_mem(struct jffs2_summary *s, struct jffs2_raw_dirent *rd,
                uint32_t ofs)
{
    struct jffs2_sum_dirent_mem *temp =
        kmalloc(sizeof(struct jffs2_sum_dirent_mem) + rd->nsize, GFP_KERNEL);

    if (!temp)
        return -ENOMEM;

    temp->nodetype = rd->nodetype;
    temp->totlen = rd->totlen;
    temp->offset = cpu_to_je32(ofs);    /* relative from the beginning of the jeb */
    temp->pino = rd->pino;
    temp->version = rd->version;
    temp->ino = rd->ino;
    temp->nsize = rd->nsize;
    temp->type = rd->type;
    temp->next = NULL;

    memcpy(temp->name, rd->name, rd->nsize);

    return jffs2_sum_add_mem(s, (union jffs2_sum_mem *)temp);
}

#ifdef CONFIG_JFFS2_FS_XATTR
int jffs2_sum_add_xattr_mem(struct jffs2_summary *s, struct jffs2_raw_xattr *rx, uint32_t ofs)
{
    struct jffs2_sum_xattr_mem *temp;

    temp = kmalloc(sizeof(struct jffs2_sum_xattr_mem), GFP_KERNEL);
    if (!temp)
        return -ENOMEM;

    temp->nodetype = rx->nodetype;
    temp->xid = rx->xid;
    temp->version = rx->version;
    temp->offset = cpu_to_je32(ofs);
    temp->totlen = rx->totlen;
    temp->next = NULL;

    return jffs2_sum_add_mem(s, (union jffs2_sum_mem *)temp);
}

int jffs2_sum_add_xref_mem(struct jffs2_summary *s, struct jffs2_raw_xref *rr, uint32_t ofs)
{
    struct jffs2_sum_xref_mem *temp;

    temp = kmalloc(sizeof(struct jffs2_sum_xref_mem), GFP_KERNEL);
    if (!temp)
        return -ENOMEM;

    temp->nodetype = rr->nodetype;
    temp->offset = cpu_to_je32(ofs);
    temp->next = NULL;

    return jffs2_sum_add_mem(s, (union jffs2_sum_mem *)temp);
}
#endif
/* Cleanup every collected summary information */

static void jffs2_sum_clean_collected(struct jffs2_summary *s)
{
    union jffs2_sum_mem *temp;

    if (!s->sum_list_head) {
        dbg_summary("already empty\n");
    }
    while (s->sum_list_head) {
        temp = s->sum_list_head;
        s->sum_list_head = s->sum_list_head->u.next;
        kfree(temp);
    }
    s->sum_list_tail = NULL;
    s->sum_padded = 0;
    s->sum_num = 0;
}

void jffs2_sum_reset_collected(struct jffs2_summary *s)
{
    dbg_summary("called\n");
    jffs2_sum_clean_collected(s);
    s->sum_size = 0;
}

void jffs2_sum_disable_collecting(struct jffs2_summary *s)
{
    dbg_summary("called\n");
    jffs2_sum_clean_collected(s);
    s->sum_size = JFFS2_SUMMARY_NOSUM_SIZE;
}

int jffs2_sum_is_disabled(struct jffs2_summary *s)
{
    return (s->sum_size == JFFS2_SUMMARY_NOSUM_SIZE);
}

/* Move the collected summary information into sb (called from scan.c) */

void jffs2_sum_move_collected(struct jffs2_sb_info *c, struct jffs2_summary *s)
{
    dbg_summary("oldsize=0x%x oldnum=%u => newsize=0x%x newnum=%u\n",
                c->summary->sum_size, c->summary->sum_num,
                s->sum_size, s->sum_num);

    c->summary->sum_size = s->sum_size;
    c->summary->sum_num = s->sum_num;
    c->summary->sum_padded = s->sum_padded;
    c->summary->sum_list_head = s->sum_list_head;
    c->summary->sum_list_tail = s->sum_list_tail;

    s->sum_list_head = s->sum_list_tail = NULL;
}

/* Called from wbuf.c to collect writed node info */

int jffs2_sum_add_kvec(struct jffs2_sb_info *c, const struct kvec *invecs,
                unsigned long count, uint32_t ofs)
{
    union jffs2_node_union *node;
    struct jffs2_eraseblock *jeb;

    if (c->summary->sum_size == JFFS2_SUMMARY_NOSUM_SIZE) {
        dbg_summary("Summary is disabled for this jeb! Skipping summary info!\n");
        return 0;
    }

    node = invecs[0].iov_base;
    jeb = &c->blocks[ofs / c->sector_size];
    ofs -= jeb->offset;

    switch (je16_to_cpu(node->u.nodetype)) {
        case JFFS2_NODETYPE_INODE: {
            struct jffs2_sum_inode_mem *temp =
                kmalloc(sizeof(struct jffs2_sum_inode_mem), GFP_KERNEL);

            if (!temp)
                goto no_mem;

            temp->nodetype = node->i.nodetype;
            temp->inode = node->i.ino;
            temp->version = node->i.version;
            temp->offset = cpu_to_je32(ofs);
            temp->totlen = node->i.totlen;
            temp->next = NULL;

            return jffs2_sum_add_mem(c->summary, (union jffs2_sum_mem *)temp);
        }

        case JFFS2_NODETYPE_DIRENT: {
            struct jffs2_sum_dirent_mem *temp =
                kmalloc(sizeof(struct jffs2_sum_dirent_mem) + node->d.nsize, GFP_KERNEL);

            if (!temp)
                goto no_mem;

            temp->nodetype = node->d.nodetype;
            temp->totlen = node->d.totlen;
            temp->offset = cpu_to_je32(ofs);
            temp->pino = node->d.pino;
            temp->version = node->d.version;
            temp->ino = node->d.ino;
            temp->nsize = node->d.nsize;
            temp->type = node->d.type;
            temp->next = NULL;

            switch (count) {
                case 1:
                    memcpy(temp->name,node->d.name,node->d.nsize);
                    break;

                case 2:
                    memcpy(temp->name,invecs[1].iov_base,node->d.nsize);
                    break;

                default:
                    BUG();  /* impossible count value */
                    break;
            }

            return jffs2_sum_add_mem(c->summary, (union jffs2_sum_mem *)temp);
        }
#ifdef CONFIG_JFFS2_FS_XATTR
        case JFFS2_NODETYPE_XATTR: {
            struct jffs2_sum_xattr_mem *temp;
            temp = kmalloc(sizeof(struct jffs2_sum_xattr_mem), GFP_KERNEL);
            if (!temp)
                goto no_mem;

            temp->nodetype = node->x.nodetype;
            temp->xid = node->x.xid;
            temp->version = node->x.version;
            temp->totlen = node->x.totlen;
            temp->offset = cpu_to_je32(ofs);
            temp->next = NULL;

            return jffs2_sum_add_mem(c->summary, (union jffs2_sum_mem *)temp);
        }
        case JFFS2_NODETYPE_XREF: {
            struct jffs2_sum_xref_mem *temp;
            temp = kmalloc(sizeof(struct jffs2_sum_xref_mem), GFP_KERNEL);
            if (!temp)
                goto no_mem;
            temp->nodetype = node->r.nodetype;
            temp->offset = cpu_to_je32(ofs);
            temp->next = NULL;

            return jffs2_sum_add_mem(c->summary, (union jffs2_sum_mem *)temp);
        }
#endif
        case JFFS2_NODETYPE_PADDING:
            dbg_summary("node PADDING\n");
            c->summary->sum_padded += je32_to_cpu(node->u.totlen);
            break;

        case JFFS2_NODETYPE_CLEANMARKER:
            dbg_summary("node CLEANMARKER\n");
            break;

        case JFFS2_NODETYPE_SUMMARY:
            dbg_summary("node SUMMARY\n");
            break;

        default:
            /* If you implement a new node type you should also implement
               summary support for it or disable summary.
            */
            BUG();
            break;
    }

    return 0;

no_mem:
    JFFS2_WARNING("MEMORY ALLOCATION ERROR!");
    return -ENOMEM;
}

static struct jffs2_raw_node_ref *sum_link_node_ref(struct jffs2_sb_info *c,
                            struct jffs2_eraseblock *jeb,
                            uint32_t ofs, uint32_t len,
                            struct jffs2_inode_cache *ic)
{
    /* If there was a gap, mark it dirty */
    if ((ofs & ~3) > c->sector_size - jeb->free_size) {
        /* Ew. Summary doesn't actually tell us explicitly about dirty space */
        jffs2_scan_dirty_space(c, jeb, (ofs & ~3) - (c->sector_size - jeb->free_size));
    }

    return jffs2_link_node_ref(c, jeb, jeb->offset + ofs, len, ic);
}

/* Process the stored summary information - helper function for jffs2_sum_scan_sumnode() */

static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                struct jffs2_raw_summary *summary, uint32_t *pseudo_random)
{
    struct jffs2_inode_cache *ic;
    struct jffs2_full_dirent *fd;
    void *sp;
    int i, ino;
    int err;

    sp = summary->sum;

    for (i=0; i<je32_to_cpu(summary->sum_num); i++) {
        dbg_summary("processing summary index %d\n", i);

        cond_resched();

        /* Make sure there's a spare ref for dirty space */
        err = jffs2_prealloc_raw_node_refs(c, jeb, 2);
        if (err)
            return err;

        switch (je16_to_cpu(((struct jffs2_sum_unknown_flash *)sp)->nodetype)) {
            case JFFS2_NODETYPE_INODE: {
                struct jffs2_sum_inode_flash *spi;
                spi = sp;

                ino = je32_to_cpu(spi->inode);

                dbg_summary("Inode at 0x%08x-0x%08x\n",
                        jeb->offset + je32_to_cpu(spi->offset),
                        jeb->offset + je32_to_cpu(spi->offset) + je32_to_cpu(spi->totlen));

                ic = jffs2_scan_make_ino_cache(c, ino);
                if (!ic) {
                    JFFS2_NOTICE("scan_make_ino_cache failed\n");
                    return -ENOMEM;
                }

                sum_link_node_ref(c, jeb, je32_to_cpu(spi->offset) | REF_UNCHECKED,
                          PAD(je32_to_cpu(spi->totlen)), ic);

                *pseudo_random += je32_to_cpu(spi->version);

                sp += JFFS2_SUMMARY_INODE_SIZE;

                break;
            }

            case JFFS2_NODETYPE_DIRENT: {
                struct jffs2_sum_dirent_flash *spd;
                int checkedlen;
                spd = sp;

                dbg_summary("Dirent at 0x%08x-0x%08x\n",
                        jeb->offset + je32_to_cpu(spd->offset),
                        jeb->offset + je32_to_cpu(spd->offset) + je32_to_cpu(spd->totlen));


                /* This should never happen, but https://dev.laptop.org/ticket/4184 */
                checkedlen = strnlen(spd->name, spd->nsize);
                if (!checkedlen) {
                    pr_err("Dirent at %08x has zero at start of name. Aborting mount.\n",
                           jeb->offset +
                           je32_to_cpu(spd->offset));
                    return -EIO;
                }
                if (checkedlen < spd->nsize) {
                    pr_err("Dirent at %08x has zeroes in name. Truncating to %d chars\n",
                           jeb->offset +
                           je32_to_cpu(spd->offset),
                           checkedlen);
                }


                fd = jffs2_alloc_full_dirent(checkedlen+1);
                if (!fd)
                    return -ENOMEM;

                memcpy(&fd->name, spd->name, checkedlen);
                fd->name[checkedlen] = 0;

                ic = jffs2_scan_make_ino_cache(c, je32_to_cpu(spd->pino));
                if (!ic) {
                    jffs2_free_full_dirent(fd);
                    return -ENOMEM;
                }

                fd->raw = sum_link_node_ref(c, jeb,  je32_to_cpu(spd->offset) | REF_UNCHECKED,
                                PAD(je32_to_cpu(spd->totlen)), ic);

                fd->next = NULL;
                fd->version = je32_to_cpu(spd->version);
                fd->ino = je32_to_cpu(spd->ino);
                fd->nhash = full_name_hash(fd->name, checkedlen);
                fd->type = spd->type;

                jffs2_add_fd_to_list(c, fd, &ic->scan_dents);

                *pseudo_random += je32_to_cpu(spd->version);

                sp += JFFS2_SUMMARY_DIRENT_SIZE(spd->nsize);

                break;
            }
#ifdef CONFIG_JFFS2_FS_XATTR
            case JFFS2_NODETYPE_XATTR: {
                struct jffs2_xattr_datum *xd;
                struct jffs2_sum_xattr_flash *spx;

                spx = (struct jffs2_sum_xattr_flash *)sp;
                dbg_summary("xattr at %#08x-%#08x (xid=%u, version=%u)\n", 
                        jeb->offset + je32_to_cpu(spx->offset),
                        jeb->offset + je32_to_cpu(spx->offset) + je32_to_cpu(spx->totlen),
                        je32_to_cpu(spx->xid), je32_to_cpu(spx->version));

                xd = jffs2_setup_xattr_datum(c, je32_to_cpu(spx->xid),
                                je32_to_cpu(spx->version));
                if (IS_ERR(xd))
                    return PTR_ERR(xd);
                if (xd->version > je32_to_cpu(spx->version)) {
                    /* node is not the newest one */
                    struct jffs2_raw_node_ref *raw
                        = sum_link_node_ref(c, jeb, je32_to_cpu(spx->offset) | REF_UNCHECKED,
                                    PAD(je32_to_cpu(spx->totlen)), NULL);
                    raw->next_in_ino = xd->node->next_in_ino;
                    xd->node->next_in_ino = raw;
                } else {
                    xd->version = je32_to_cpu(spx->version);
                    sum_link_node_ref(c, jeb, je32_to_cpu(spx->offset) | REF_UNCHECKED,
                              PAD(je32_to_cpu(spx->totlen)), (void *)xd);
                }
                *pseudo_random += je32_to_cpu(spx->xid);
                sp += JFFS2_SUMMARY_XATTR_SIZE;

                break;
            }
            case JFFS2_NODETYPE_XREF: {
                struct jffs2_xattr_ref *ref;
                struct jffs2_sum_xref_flash *spr;

                spr = (struct jffs2_sum_xref_flash *)sp;
                dbg_summary("xref at %#08x-%#08x\n",
                        jeb->offset + je32_to_cpu(spr->offset),
                        jeb->offset + je32_to_cpu(spr->offset) + 
                        (uint32_t)PAD(sizeof(struct jffs2_raw_xref)));

                ref = jffs2_alloc_xattr_ref();
                if (!ref) {
                    JFFS2_NOTICE("allocation of xattr_datum failed\n");
                    return -ENOMEM;
                }
                ref->next = c->xref_temp;
                c->xref_temp = ref;

                sum_link_node_ref(c, jeb, je32_to_cpu(spr->offset) | REF_UNCHECKED,
                          PAD(sizeof(struct jffs2_raw_xref)), (void *)ref);

                *pseudo_random += ref->node->flash_offset;
                sp += JFFS2_SUMMARY_XREF_SIZE;

                break;
            }
#endif
            default : {
                uint16_t nodetype = je16_to_cpu(((struct jffs2_sum_unknown_flash *)sp)->nodetype);
                JFFS2_WARNING("Unsupported node type %x found in summary! Exiting...\n", nodetype);
                if ((nodetype & JFFS2_COMPAT_MASK) == JFFS2_FEATURE_INCOMPAT)
                    return -EIO;

                /* For compatible node types, just fall back to the full scan */
                c->wasted_size -= jeb->wasted_size;
                c->free_size += c->sector_size - jeb->free_size;
                c->used_size -= jeb->used_size;
                c->dirty_size -= jeb->dirty_size;
                jeb->wasted_size = jeb->used_size = jeb->dirty_size = 0;
                jeb->free_size = c->sector_size;

                jffs2_free_jeb_node_refs(c, jeb);
                return -ENOTRECOVERABLE;
            }
        }
    }
    return 0;
}

/* Process the summary node - called from jffs2_scan_eraseblock() */
int jffs2_sum_scan_sumnode(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
               struct jffs2_raw_summary *summary, uint32_t sumsize,
               uint32_t *pseudo_random)
{
    struct jffs2_unknown_node crcnode;
    int ret, ofs;
    uint32_t crc;

    ofs = c->sector_size - sumsize;

    dbg_summary("summary found for 0x%08x at 0x%08x (0x%x bytes)\n",
            jeb->offset, jeb->offset + ofs, sumsize);

    /* OK, now check for node validity and CRC */
    crcnode.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
    crcnode.nodetype = cpu_to_je16(JFFS2_NODETYPE_SUMMARY);
    crcnode.totlen = summary->totlen;
    crc = crc32(0, &crcnode, sizeof(crcnode)-4);

    if (je32_to_cpu(summary->hdr_crc) != crc) {
        dbg_summary("Summary node header is corrupt (bad CRC or "
                "no summary at all)\n");
        goto crc_err;
    }

    if (je32_to_cpu(summary->totlen) != sumsize) {
        dbg_summary("Summary node is corrupt (wrong erasesize?)\n");
        goto crc_err;
    }

    crc = crc32(0, summary, sizeof(struct jffs2_raw_summary)-8);

    if (je32_to_cpu(summary->node_crc) != crc) {
        dbg_summary("Summary node is corrupt (bad CRC)\n");
        goto crc_err;
    }

    crc = crc32(0, summary->sum, sumsize - sizeof(struct jffs2_raw_summary));

    if (je32_to_cpu(summary->sum_crc) != crc) {
        dbg_summary("Summary node data is corrupt (bad CRC)\n");
        goto crc_err;
    }

    if ( je32_to_cpu(summary->cln_mkr) ) {

        dbg_summary("Summary : CLEANMARKER node \n");

        ret = jffs2_prealloc_raw_node_refs(c, jeb, 1);
        if (ret)
            return ret;

        if (je32_to_cpu(summary->cln_mkr) != c->cleanmarker_size) {
            dbg_summary("CLEANMARKER node has totlen 0x%x != normal 0x%x\n",
                je32_to_cpu(summary->cln_mkr), c->cleanmarker_size);
            if ((ret = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(summary->cln_mkr)))))
                return ret;
        } else if (jeb->first_node) {
            dbg_summary("CLEANMARKER node not first node in block "
                    "(0x%08x)\n", jeb->offset);
            if ((ret = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(summary->cln_mkr)))))
                return ret;
        } else {
            jffs2_link_node_ref(c, jeb, jeb->offset | REF_NORMAL,
                        je32_to_cpu(summary->cln_mkr), NULL);
        }
    }

    ret = jffs2_sum_process_sum_data(c, jeb, summary, pseudo_random);
    /* -ENOTRECOVERABLE isn't a fatal error -- it means we should do a full
       scan of this eraseblock. So return zero */
    if (ret == -ENOTRECOVERABLE)
        return 0;
    if (ret)
        return ret;     /* real error */

    /* for PARANOIA_CHECK */
    ret = jffs2_prealloc_raw_node_refs(c, jeb, 2);
    if (ret)
        return ret;

    sum_link_node_ref(c, jeb, ofs | REF_NORMAL, sumsize, NULL);

    if (unlikely(jeb->free_size)) {
        JFFS2_WARNING("Free size 0x%x bytes in eraseblock @0x%08x with summary?\n",
                  jeb->free_size, jeb->offset);
        jeb->wasted_size += jeb->free_size;
        c->wasted_size += jeb->free_size;
        c->free_size -= jeb->free_size;
        jeb->free_size = 0;
    }

    return jffs2_scan_classify_jeb(c, jeb);

crc_err:
    JFFS2_WARNING("Summary node crc error, skipping summary information.\n");

    return 0;
}

/* Write summary data to flash - helper function for jffs2_sum_write_sumnode() */

static int jffs2_sum_write_data(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                uint32_t infosize, uint32_t datasize, int padsize)
{
    struct jffs2_raw_summary isum;
    union jffs2_sum_mem *temp;
    struct jffs2_sum_marker *sm;
    struct kvec vecs[2];
    uint32_t sum_ofs;
    void *wpage;
    int ret;
    size_t retlen;

    if (padsize + datasize > MAX_SUMMARY_SIZE) {
        /* It won't fit in the buffer. Abort summary for this jeb */
        jffs2_sum_disable_collecting(c->summary);

        JFFS2_WARNING("Summary too big (%d data, %d pad) in eraseblock at %08x\n",
                  datasize, padsize, jeb->offset);
        /* Non-fatal */
        return 0;
    }
    /* Is there enough space for summary? */
    if (padsize < 0) {
        /* don't try to write out summary for this jeb */
        jffs2_sum_disable_collecting(c->summary);

        JFFS2_WARNING("Not enough space for summary, padsize = %d\n",
                  padsize);
        /* Non-fatal */
        return 0;
    }

    memset(c->summary->sum_buf, 0xff, datasize);
    memset(&isum, 0, sizeof(isum));

    isum.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
    isum.nodetype = cpu_to_je16(JFFS2_NODETYPE_SUMMARY);
    isum.totlen = cpu_to_je32(infosize);
    isum.hdr_crc = cpu_to_je32(crc32(0, &isum, sizeof(struct jffs2_unknown_node) - 4));
    isum.padded = cpu_to_je32(c->summary->sum_padded);
    isum.cln_mkr = cpu_to_je32(c->cleanmarker_size);
    isum.sum_num = cpu_to_je32(c->summary->sum_num);
    wpage = c->summary->sum_buf;

    while (c->summary->sum_num) {
        temp = c->summary->sum_list_head;

        switch (je16_to_cpu(temp->u.nodetype)) {
            case JFFS2_NODETYPE_INODE: {
                struct jffs2_sum_inode_flash *sino_ptr = wpage;

                sino_ptr->nodetype = temp->i.nodetype;
                sino_ptr->inode = temp->i.inode;
                sino_ptr->version = temp->i.version;
                sino_ptr->offset = temp->i.offset;
                sino_ptr->totlen = temp->i.totlen;

                wpage += JFFS2_SUMMARY_INODE_SIZE;

                break;
            }

            case JFFS2_NODETYPE_DIRENT: {
                struct jffs2_sum_dirent_flash *sdrnt_ptr = wpage;

                sdrnt_ptr->nodetype = temp->d.nodetype;
                sdrnt_ptr->totlen = temp->d.totlen;
                sdrnt_ptr->offset = temp->d.offset;
                sdrnt_ptr->pino = temp->d.pino;
                sdrnt_ptr->version = temp->d.version;
                sdrnt_ptr->ino = temp->d.ino;
                sdrnt_ptr->nsize = temp->d.nsize;
                sdrnt_ptr->type = temp->d.type;

                memcpy(sdrnt_ptr->name, temp->d.name,
                            temp->d.nsize);

                wpage += JFFS2_SUMMARY_DIRENT_SIZE(temp->d.nsize);

                break;
            }
#ifdef CONFIG_JFFS2_FS_XATTR
            case JFFS2_NODETYPE_XATTR: {
                struct jffs2_sum_xattr_flash *sxattr_ptr = wpage;

                temp = c->summary->sum_list_head;
                sxattr_ptr->nodetype = temp->x.nodetype;
                sxattr_ptr->xid = temp->x.xid;
                sxattr_ptr->version = temp->x.version;
                sxattr_ptr->offset = temp->x.offset;
                sxattr_ptr->totlen = temp->x.totlen;

                wpage += JFFS2_SUMMARY_XATTR_SIZE;
                break;
            }
            case JFFS2_NODETYPE_XREF: {
                struct jffs2_sum_xref_flash *sxref_ptr = wpage;

                temp = c->summary->sum_list_head;
                sxref_ptr->nodetype = temp->r.nodetype;
                sxref_ptr->offset = temp->r.offset;

                wpage += JFFS2_SUMMARY_XREF_SIZE;
                break;
            }
#endif
            default : {
                if ((je16_to_cpu(temp->u.nodetype) & JFFS2_COMPAT_MASK)
                    == JFFS2_FEATURE_RWCOMPAT_COPY) {
                    dbg_summary("Writing unknown RWCOMPAT_COPY node type %x\n",
                            je16_to_cpu(temp->u.nodetype));
                    jffs2_sum_disable_collecting(c->summary);
                } else {
                    BUG();  /* unknown node in summary information */
                }
            }
        }

        c->summary->sum_list_head = temp->u.next;
        kfree(temp);

        c->summary->sum_num--;
    }

    jffs2_sum_reset_collected(c->summary);

    wpage += padsize;

    sm = wpage;
    sm->offset = cpu_to_je32(c->sector_size - jeb->free_size);
    sm->magic = cpu_to_je32(JFFS2_SUM_MAGIC);

    isum.sum_crc = cpu_to_je32(crc32(0, c->summary->sum_buf, datasize));
    isum.node_crc = cpu_to_je32(crc32(0, &isum, sizeof(isum) - 8));

    vecs[0].iov_base = &isum;
    vecs[0].iov_len = sizeof(isum);
    vecs[1].iov_base = c->summary->sum_buf;
    vecs[1].iov_len = datasize;

    sum_ofs = jeb->offset + c->sector_size - jeb->free_size;

    dbg_summary("writing out data to flash to pos : 0x%08x\n", sum_ofs);

    ret = jffs2_flash_writev(c, vecs, 2, sum_ofs, &retlen, 0);

    if (ret || (retlen != infosize)) {

        JFFS2_WARNING("Write of %u bytes at 0x%08x failed. returned %d, retlen %zd\n",
                  infosize, sum_ofs, ret, retlen);

        if (retlen) {
            /* Waste remaining space */
            spin_lock(&c->erase_completion_lock);
            jffs2_link_node_ref(c, jeb, sum_ofs | REF_OBSOLETE, infosize, NULL);
            spin_unlock(&c->erase_completion_lock);
        }

        c->summary->sum_size = JFFS2_SUMMARY_NOSUM_SIZE;

        return 0;
    }

    spin_lock(&c->erase_completion_lock);
    jffs2_link_node_ref(c, jeb, sum_ofs | REF_NORMAL, infosize, NULL);
    spin_unlock(&c->erase_completion_lock);

    return 0;
}

/* Write out summary information - called from jffs2_do_reserve_space */

int jffs2_sum_write_sumnode(struct jffs2_sb_info *c)
{
    int datasize, infosize, padsize;
    struct jffs2_eraseblock *jeb;
    int ret = 0;

    dbg_summary("called\n");

    spin_unlock(&c->erase_completion_lock);

    jeb = c->nextblock;
    jffs2_prealloc_raw_node_refs(c, jeb, 1);

    if (!c->summary->sum_num || !c->summary->sum_list_head) {
        JFFS2_WARNING("Empty summary info!!!\n");
        BUG();
    }

    datasize = c->summary->sum_size + sizeof(struct jffs2_sum_marker);
    infosize = sizeof(struct jffs2_raw_summary) + datasize;
    padsize = jeb->free_size - infosize;
    infosize += padsize;
    datasize += padsize;

    ret = jffs2_sum_write_data(c, jeb, infosize, datasize, padsize);
    spin_lock(&c->erase_completion_lock);
    return ret;
}