scan.c

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/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 *
 * Created by David Woodhouse <[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/sched.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/pagemap.h>
#include <linux/crc32.h>
#include <linux/compiler.h>
#include "nodelist.h"
#include "summary.h"
#include "debug.h"

#define DEFAULT_EMPTY_SCAN_SIZE 256

#define noisy_printk(noise, fmt, ...)                   \
do {                                    \
    if (*(noise)) {                         \
        pr_notice(fmt, ##__VA_ARGS__);              \
        (*(noise))--;                       \
        if (!(*(noise)))                    \
            pr_notice("Further such events for this erase block will not be printed\n"); \
    }                               \
} while (0)

static uint32_t pseudo_random;

static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                  unsigned char *buf, uint32_t buf_size, struct jffs2_summary *s);

/* These helper functions _must_ increase ofs and also do the dirty/used space accounting.
 * Returning an error will abort the mount - bad checksums etc. should just mark the space
 * as dirty.
 */
static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                 struct jffs2_raw_inode *ri, uint32_t ofs, struct jffs2_summary *s);
static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                 struct jffs2_raw_dirent *rd, uint32_t ofs, struct jffs2_summary *s);

static inline int min_free(struct jffs2_sb_info *c)
{
    uint32_t min = 2 * sizeof(struct jffs2_raw_inode);
#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
    if (!jffs2_can_mark_obsolete(c) && min < c->wbuf_pagesize)
        return c->wbuf_pagesize;
#endif
    return min;

}

static inline uint32_t EMPTY_SCAN_SIZE(uint32_t sector_size) {
    if (sector_size < DEFAULT_EMPTY_SCAN_SIZE)
        return sector_size;
    else
        return DEFAULT_EMPTY_SCAN_SIZE;
}

static int file_dirty(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)
{
    int ret;

    if ((ret = jffs2_prealloc_raw_node_refs(c, jeb, 1)))
        return ret;
    if ((ret = jffs2_scan_dirty_space(c, jeb, jeb->free_size)))
        return ret;
    /* Turned wasted size into dirty, since we apparently 
       think it's recoverable now. */
    jeb->dirty_size += jeb->wasted_size;
    c->dirty_size += jeb->wasted_size;
    c->wasted_size -= jeb->wasted_size;
    jeb->wasted_size = 0;
    if (VERYDIRTY(c, jeb->dirty_size)) {
        list_add(&jeb->list, &c->very_dirty_list);
    } else {
        list_add(&jeb->list, &c->dirty_list);
    }
    return 0;
}

int jffs2_scan_medium(struct jffs2_sb_info *c)
{
    int i, ret;
    uint32_t empty_blocks = 0, bad_blocks = 0;
    unsigned char *flashbuf = NULL;
    uint32_t buf_size = 0;
    struct jffs2_summary *s = NULL; /* summary info collected by the scan process */
#ifndef __ECOS
    size_t pointlen, try_size;

    ret = mtd_point(c->mtd, 0, c->mtd->size, &pointlen,
            (void **)&flashbuf, NULL);
    if (!ret && pointlen < c->mtd->size) {
        /* Don't muck about if it won't let us point to the whole flash */
        jffs2_dbg(1, "MTD point returned len too short: 0x%zx\n",
              pointlen);
        mtd_unpoint(c->mtd, 0, pointlen);
        flashbuf = NULL;
    }
    if (ret && ret != -EOPNOTSUPP)
        jffs2_dbg(1, "MTD point failed %d\n", ret);
#endif
    if (!flashbuf) {
        /* For NAND it's quicker to read a whole eraseblock at a time,
           apparently */
        if (jffs2_cleanmarker_oob(c))
            try_size = c->sector_size;
        else
            try_size = PAGE_SIZE;

        jffs2_dbg(1, "Trying to allocate readbuf of %zu "
              "bytes\n", try_size);

        flashbuf = mtd_kmalloc_up_to(c->mtd, &try_size);
        if (!flashbuf)
            return -ENOMEM;

        jffs2_dbg(1, "Allocated readbuf of %zu bytes\n",
              try_size);

        buf_size = (uint32_t)try_size;
    }

    if (jffs2_sum_active()) {
        s = kzalloc(sizeof(struct jffs2_summary), GFP_KERNEL);
        if (!s) {
            JFFS2_WARNING("Can't allocate memory for summary\n");
            ret = -ENOMEM;
            goto out;
        }
    }

    for (i=0; i<c->nr_blocks; i++) {
        struct jffs2_eraseblock *jeb = &c->blocks[i];

        cond_resched();

        /* reset summary info for next eraseblock scan */
        jffs2_sum_reset_collected(s);

        ret = jffs2_scan_eraseblock(c, jeb, buf_size?flashbuf:(flashbuf+jeb->offset),
                        buf_size, s);

        if (ret < 0)
            goto out;

        jffs2_dbg_acct_paranoia_check_nolock(c, jeb);

        /* Now decide which list to put it on */
        switch(ret) {
        case BLK_STATE_ALLFF:
            /*
             * Empty block.   Since we can't be sure it
             * was entirely erased, we just queue it for erase
             * again.  It will be marked as such when the erase
             * is complete.  Meanwhile we still count it as empty
             * for later checks.
             */
            empty_blocks++;
            list_add(&jeb->list, &c->erase_pending_list);
            c->nr_erasing_blocks++;
            break;

        case BLK_STATE_CLEANMARKER:
            /* Only a CLEANMARKER node is valid */
            if (!jeb->dirty_size) {
                /* It's actually free */
                list_add(&jeb->list, &c->free_list);
                c->nr_free_blocks++;
            } else {
                /* Dirt */
                jffs2_dbg(1, "Adding all-dirty block at 0x%08x to erase_pending_list\n",
                      jeb->offset);
                list_add(&jeb->list, &c->erase_pending_list);
                c->nr_erasing_blocks++;
            }
            break;

        case BLK_STATE_CLEAN:
            /* Full (or almost full) of clean data. Clean list */
            list_add(&jeb->list, &c->clean_list);
            break;

        case BLK_STATE_PARTDIRTY:
            /* Some data, but not full. Dirty list. */
            /* We want to remember the block with most free space
            and stick it in the 'nextblock' position to start writing to it. */
            if (jeb->free_size > min_free(c) &&
                    (!c->nextblock || c->nextblock->free_size < jeb->free_size)) {
                /* Better candidate for the next writes to go to */
                if (c->nextblock) {
                    ret = file_dirty(c, c->nextblock);
                    if (ret)
                        goto out;
                    /* deleting summary information of the old nextblock */
                    jffs2_sum_reset_collected(c->summary);
                }
                /* update collected summary information for the current nextblock */
                jffs2_sum_move_collected(c, s);
                jffs2_dbg(1, "%s(): new nextblock = 0x%08x\n",
                      __func__, jeb->offset);
                c->nextblock = jeb;
            } else {
                ret = file_dirty(c, jeb);
                if (ret)
                    goto out;
            }
            break;

        case BLK_STATE_ALLDIRTY:
            /* Nothing valid - not even a clean marker. Needs erasing. */
            /* For now we just put it on the erasing list. We'll start the erases later */
            jffs2_dbg(1, "Erase block at 0x%08x is not formatted. It will be erased\n",
                  jeb->offset);
            list_add(&jeb->list, &c->erase_pending_list);
            c->nr_erasing_blocks++;
            break;

        case BLK_STATE_BADBLOCK:
            jffs2_dbg(1, "Block at 0x%08x is bad\n", jeb->offset);
            list_add(&jeb->list, &c->bad_list);
            c->bad_size += c->sector_size;
            c->free_size -= c->sector_size;
            bad_blocks++;
            break;
        default:
            pr_warn("%s(): unknown block state\n", __func__);
            BUG();
        }
    }

    /* Nextblock dirty is always seen as wasted, because we cannot recycle it now */
    if (c->nextblock && (c->nextblock->dirty_size)) {
        c->nextblock->wasted_size += c->nextblock->dirty_size;
        c->wasted_size += c->nextblock->dirty_size;
        c->dirty_size -= c->nextblock->dirty_size;
        c->nextblock->dirty_size = 0;
    }
#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
    if (!jffs2_can_mark_obsolete(c) && c->wbuf_pagesize && c->nextblock && (c->nextblock->free_size % c->wbuf_pagesize)) {
        /* If we're going to start writing into a block which already
           contains data, and the end of the data isn't page-aligned,
           skip a little and align it. */

        uint32_t skip = c->nextblock->free_size % c->wbuf_pagesize;

        jffs2_dbg(1, "%s(): Skipping %d bytes in nextblock to ensure page alignment\n",
              __func__, skip);
        jffs2_prealloc_raw_node_refs(c, c->nextblock, 1);
        jffs2_scan_dirty_space(c, c->nextblock, skip);
    }
#endif
    if (c->nr_erasing_blocks) {
        if ( !c->used_size && ((c->nr_free_blocks+empty_blocks+bad_blocks)!= c->nr_blocks || bad_blocks == c->nr_blocks) ) {
            pr_notice("Cowardly refusing to erase blocks on filesystem with no valid JFFS2 nodes\n");
            pr_notice("empty_blocks %d, bad_blocks %d, c->nr_blocks %d\n",
                  empty_blocks, bad_blocks, c->nr_blocks);
            ret = -EIO;
            goto out;
        }
        spin_lock(&c->erase_completion_lock);
        jffs2_garbage_collect_trigger(c);
        spin_unlock(&c->erase_completion_lock);
    }
    ret = 0;
 out:
    if (buf_size)
        kfree(flashbuf);
#ifndef __ECOS
    else
        mtd_unpoint(c->mtd, 0, c->mtd->size);
#endif
    kfree(s);
    return ret;
}

static int jffs2_fill_scan_buf(struct jffs2_sb_info *c, void *buf,
                   uint32_t ofs, uint32_t len)
{
    int ret;
    size_t retlen;

    ret = jffs2_flash_read(c, ofs, len, &retlen, buf);
    if (ret) {
        jffs2_dbg(1, "mtd->read(0x%x bytes from 0x%x) returned %d\n",
              len, ofs, ret);
        return ret;
    }
    if (retlen < len) {
        jffs2_dbg(1, "Read at 0x%x gave only 0x%zx bytes\n",
              ofs, retlen);
        return -EIO;
    }
    return 0;
}

int jffs2_scan_classify_jeb(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)
{
    if ((jeb->used_size + jeb->unchecked_size) == PAD(c->cleanmarker_size) && !jeb->dirty_size
        && (!jeb->first_node || !ref_next(jeb->first_node)) )
        return BLK_STATE_CLEANMARKER;

    /* move blocks with max 4 byte dirty space to cleanlist */
    else if (!ISDIRTY(c->sector_size - (jeb->used_size + jeb->unchecked_size))) {
        c->dirty_size -= jeb->dirty_size;
        c->wasted_size += jeb->dirty_size;
        jeb->wasted_size += jeb->dirty_size;
        jeb->dirty_size = 0;
        return BLK_STATE_CLEAN;
    } else if (jeb->used_size || jeb->unchecked_size)
        return BLK_STATE_PARTDIRTY;
    else
        return BLK_STATE_ALLDIRTY;
}

#ifdef CONFIG_JFFS2_FS_XATTR
static int jffs2_scan_xattr_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                 struct jffs2_raw_xattr *rx, uint32_t ofs,
                 struct jffs2_summary *s)
{
    struct jffs2_xattr_datum *xd;
    uint32_t xid, version, totlen, crc;
    int err;

    crc = crc32(0, rx, sizeof(struct jffs2_raw_xattr) - 4);
    if (crc != je32_to_cpu(rx->node_crc)) {
        JFFS2_WARNING("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
                  ofs, je32_to_cpu(rx->node_crc), crc);
        if ((err = jffs2_scan_dirty_space(c, jeb, je32_to_cpu(rx->totlen))))
            return err;
        return 0;
    }

    xid = je32_to_cpu(rx->xid);
    version = je32_to_cpu(rx->version);

    totlen = PAD(sizeof(struct jffs2_raw_xattr)
            + rx->name_len + 1 + je16_to_cpu(rx->value_len));
    if (totlen != je32_to_cpu(rx->totlen)) {
        JFFS2_WARNING("node length mismatch at %#08x, read=%u, calc=%u\n",
                  ofs, je32_to_cpu(rx->totlen), totlen);
        if ((err = jffs2_scan_dirty_space(c, jeb, je32_to_cpu(rx->totlen))))
            return err;
        return 0;
    }

    xd = jffs2_setup_xattr_datum(c, xid, version);
    if (IS_ERR(xd))
        return PTR_ERR(xd);

    if (xd->version > version) {
        struct jffs2_raw_node_ref *raw
            = jffs2_link_node_ref(c, jeb, ofs | REF_PRISTINE, totlen, NULL);
        raw->next_in_ino = xd->node->next_in_ino;
        xd->node->next_in_ino = raw;
    } else {
        xd->version = version;
        xd->xprefix = rx->xprefix;
        xd->name_len = rx->name_len;
        xd->value_len = je16_to_cpu(rx->value_len);
        xd->data_crc = je32_to_cpu(rx->data_crc);

        jffs2_link_node_ref(c, jeb, ofs | REF_PRISTINE, totlen, (void *)xd);
    }

    if (jffs2_sum_active())
        jffs2_sum_add_xattr_mem(s, rx, ofs - jeb->offset);
    dbg_xattr("scanning xdatum at %#08x (xid=%u, version=%u)\n",
          ofs, xd->xid, xd->version);
    return 0;
}

static int jffs2_scan_xref_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                struct jffs2_raw_xref *rr, uint32_t ofs,
                struct jffs2_summary *s)
{
    struct jffs2_xattr_ref *ref;
    uint32_t crc;
    int err;

    crc = crc32(0, rr, sizeof(*rr) - 4);
    if (crc != je32_to_cpu(rr->node_crc)) {
        JFFS2_WARNING("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
                  ofs, je32_to_cpu(rr->node_crc), crc);
        if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(rr->totlen)))))
            return err;
        return 0;
    }

    if (PAD(sizeof(struct jffs2_raw_xref)) != je32_to_cpu(rr->totlen)) {
        JFFS2_WARNING("node length mismatch at %#08x, read=%u, calc=%zd\n",
                  ofs, je32_to_cpu(rr->totlen),
                  PAD(sizeof(struct jffs2_raw_xref)));
        if ((err = jffs2_scan_dirty_space(c, jeb, je32_to_cpu(rr->totlen))))
            return err;
        return 0;
    }

    ref = jffs2_alloc_xattr_ref();
    if (!ref)
        return -ENOMEM;

    /* BEFORE jffs2_build_xattr_subsystem() called, 
     * and AFTER xattr_ref is marked as a dead xref,
     * ref->xid is used to store 32bit xid, xd is not used
     * ref->ino is used to store 32bit inode-number, ic is not used
     * Thoes variables are declared as union, thus using those
     * are exclusive. In a similar way, ref->next is temporarily
     * used to chain all xattr_ref object. It's re-chained to
     * jffs2_inode_cache in jffs2_build_xattr_subsystem() correctly.
     */
    ref->ino = je32_to_cpu(rr->ino);
    ref->xid = je32_to_cpu(rr->xid);
    ref->xseqno = je32_to_cpu(rr->xseqno);
    if (ref->xseqno > c->highest_xseqno)
        c->highest_xseqno = (ref->xseqno & ~XREF_DELETE_MARKER);
    ref->next = c->xref_temp;
    c->xref_temp = ref;

    jffs2_link_node_ref(c, jeb, ofs | REF_PRISTINE, PAD(je32_to_cpu(rr->totlen)), (void *)ref);

    if (jffs2_sum_active())
        jffs2_sum_add_xref_mem(s, rr, ofs - jeb->offset);
    dbg_xattr("scan xref at %#08x (xid=%u, ino=%u)\n",
          ofs, ref->xid, ref->ino);
    return 0;
}
#endif

/* Called with 'buf_size == 0' if buf is in fact a pointer _directly_ into
   the flash, XIP-style */
static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                  unsigned char *buf, uint32_t buf_size, struct jffs2_summary *s) {
    struct jffs2_unknown_node *node;
    struct jffs2_unknown_node crcnode;
    uint32_t ofs, prevofs, max_ofs;
    uint32_t hdr_crc, buf_ofs, buf_len;
    int err;
    int noise = 0;


#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
    int cleanmarkerfound = 0;
#endif

    ofs = jeb->offset;
    prevofs = jeb->offset - 1;

    jffs2_dbg(1, "%s(): Scanning block at 0x%x\n", __func__, ofs);

#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
    if (jffs2_cleanmarker_oob(c)) {
        int ret;

        if (mtd_block_isbad(c->mtd, jeb->offset))
            return BLK_STATE_BADBLOCK;

        ret = jffs2_check_nand_cleanmarker(c, jeb);
        jffs2_dbg(2, "jffs_check_nand_cleanmarker returned %d\n", ret);

        /* Even if it's not found, we still scan to see
           if the block is empty. We use this information
           to decide whether to erase it or not. */
        switch (ret) {
        case 0:     cleanmarkerfound = 1; break;
        case 1:     break;
        default:    return ret;
        }
    }
#endif

    if (jffs2_sum_active()) {
        struct jffs2_sum_marker *sm;
        void *sumptr = NULL;
        uint32_t sumlen;
          
        if (!buf_size) {
            /* XIP case. Just look, point at the summary if it's there */
            sm = (void *)buf + c->sector_size - sizeof(*sm);
            if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC) {
                sumptr = buf + je32_to_cpu(sm->offset);
                sumlen = c->sector_size - je32_to_cpu(sm->offset);
            }
        } else {
            /* If NAND flash, read a whole page of it. Else just the end */
            if (c->wbuf_pagesize)
                buf_len = c->wbuf_pagesize;
            else
                buf_len = sizeof(*sm);

            /* Read as much as we want into the _end_ of the preallocated buffer */
            err = jffs2_fill_scan_buf(c, buf + buf_size - buf_len, 
                          jeb->offset + c->sector_size - buf_len,
                          buf_len);             
            if (err)
                return err;

            sm = (void *)buf + buf_size - sizeof(*sm);
            if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC) {
                sumlen = c->sector_size - je32_to_cpu(sm->offset);
                sumptr = buf + buf_size - sumlen;

                /* Now, make sure the summary itself is available */
                if (sumlen > buf_size) {
                    /* Need to kmalloc for this. */
                    sumptr = kmalloc(sumlen, GFP_KERNEL);
                    if (!sumptr)
                        return -ENOMEM;
                    memcpy(sumptr + sumlen - buf_len, buf + buf_size - buf_len, buf_len);
                }
                if (buf_len < sumlen) {
                    /* Need to read more so that the entire summary node is present */
                    err = jffs2_fill_scan_buf(c, sumptr, 
                                  jeb->offset + c->sector_size - sumlen,
                                  sumlen - buf_len);                
                    if (err)
                        return err;
                }
            }

        }

        if (sumptr) {
            err = jffs2_sum_scan_sumnode(c, jeb, sumptr, sumlen, &pseudo_random);

            if (buf_size && sumlen > buf_size)
                kfree(sumptr);
            /* If it returns with a real error, bail. 
               If it returns positive, that's a block classification
               (i.e. BLK_STATE_xxx) so return that too.
               If it returns zero, fall through to full scan. */
            if (err)
                return err;
        }
    }

    buf_ofs = jeb->offset;

    if (!buf_size) {
        /* This is the XIP case -- we're reading _directly_ from the flash chip */
        buf_len = c->sector_size;
    } else {
        buf_len = EMPTY_SCAN_SIZE(c->sector_size);
        err = jffs2_fill_scan_buf(c, buf, buf_ofs, buf_len);
        if (err)
            return err;
    }

    /* We temporarily use 'ofs' as a pointer into the buffer/jeb */
    ofs = 0;
    max_ofs = EMPTY_SCAN_SIZE(c->sector_size);
    /* Scan only EMPTY_SCAN_SIZE of 0xFF before declaring it's empty */
    while(ofs < max_ofs && *(uint32_t *)(&buf[ofs]) == 0xFFFFFFFF)
        ofs += 4;

    if (ofs == max_ofs) {
#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
        if (jffs2_cleanmarker_oob(c)) {
            /* scan oob, take care of cleanmarker */
            int ret = jffs2_check_oob_empty(c, jeb, cleanmarkerfound);
            jffs2_dbg(2, "jffs2_check_oob_empty returned %d\n",
                  ret);
            switch (ret) {
            case 0:     return cleanmarkerfound ? BLK_STATE_CLEANMARKER : BLK_STATE_ALLFF;
            case 1:     return BLK_STATE_ALLDIRTY;
            default:    return ret;
            }
        }
#endif
        jffs2_dbg(1, "Block at 0x%08x is empty (erased)\n",
              jeb->offset);
        if (c->cleanmarker_size == 0)
            return BLK_STATE_CLEANMARKER;   /* don't bother with re-erase */
        else
            return BLK_STATE_ALLFF; /* OK to erase if all blocks are like this */
    }
    if (ofs) {
        jffs2_dbg(1, "Free space at %08x ends at %08x\n", jeb->offset,
              jeb->offset + ofs);
        if ((err = jffs2_prealloc_raw_node_refs(c, jeb, 1)))
            return err;
        if ((err = jffs2_scan_dirty_space(c, jeb, ofs)))
            return err;
    }

    /* Now ofs is a complete physical flash offset as it always was... */
    ofs += jeb->offset;

    noise = 10;

    dbg_summary("no summary found in jeb 0x%08x. Apply original scan.\n",jeb->offset);

scan_more:
    while(ofs < jeb->offset + c->sector_size) {

        jffs2_dbg_acct_paranoia_check_nolock(c, jeb);

        /* Make sure there are node refs available for use */
        err = jffs2_prealloc_raw_node_refs(c, jeb, 2);
        if (err)
            return err;

        cond_resched();

        if (ofs & 3) {
            pr_warn("Eep. ofs 0x%08x not word-aligned!\n", ofs);
            ofs = PAD(ofs);
            continue;
        }
        if (ofs == prevofs) {
            pr_warn("ofs 0x%08x has already been seen. Skipping\n",
                ofs);
            if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
                return err;
            ofs += 4;
            continue;
        }
        prevofs = ofs;

        if (jeb->offset + c->sector_size < ofs + sizeof(*node)) {
            jffs2_dbg(1, "Fewer than %zd bytes left to end of block. (%x+%x<%x+%zx) Not reading\n",
                  sizeof(struct jffs2_unknown_node),
                  jeb->offset, c->sector_size, ofs,
                  sizeof(*node));
            if ((err = jffs2_scan_dirty_space(c, jeb, (jeb->offset + c->sector_size)-ofs)))
                return err;
            break;
        }

        if (buf_ofs + buf_len < ofs + sizeof(*node)) {
            buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
            jffs2_dbg(1, "Fewer than %zd bytes (node header) left to end of buf. Reading 0x%x at 0x%08x\n",
                  sizeof(struct jffs2_unknown_node),
                  buf_len, ofs);
            err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
            if (err)
                return err;
            buf_ofs = ofs;
        }

        node = (struct jffs2_unknown_node *)&buf[ofs-buf_ofs];

        if (*(uint32_t *)(&buf[ofs-buf_ofs]) == 0xffffffff) {
            uint32_t inbuf_ofs;
            uint32_t empty_start, scan_end;

            empty_start = ofs;
            ofs += 4;
            scan_end = min_t(uint32_t, EMPTY_SCAN_SIZE(c->sector_size)/8, buf_len);

            jffs2_dbg(1, "Found empty flash at 0x%08x\n", ofs);
        more_empty:
            inbuf_ofs = ofs - buf_ofs;
            while (inbuf_ofs < scan_end) {
                if (unlikely(*(uint32_t *)(&buf[inbuf_ofs]) != 0xffffffff)) {
                    pr_warn("Empty flash at 0x%08x ends at 0x%08x\n",
                        empty_start, ofs);
                    if ((err = jffs2_scan_dirty_space(c, jeb, ofs-empty_start)))
                        return err;
                    goto scan_more;
                }

                inbuf_ofs+=4;
                ofs += 4;
            }
            /* Ran off end. */
            jffs2_dbg(1, "Empty flash to end of buffer at 0x%08x\n",
                  ofs);

            /* If we're only checking the beginning of a block with a cleanmarker,
               bail now */
            if (buf_ofs == jeb->offset && jeb->used_size == PAD(c->cleanmarker_size) &&
                c->cleanmarker_size && !jeb->dirty_size && !ref_next(jeb->first_node)) {
                jffs2_dbg(1, "%d bytes at start of block seems clean... assuming all clean\n",
                      EMPTY_SCAN_SIZE(c->sector_size));
                return BLK_STATE_CLEANMARKER;
            }
            if (!buf_size && (scan_end != buf_len)) {/* XIP/point case */
                scan_end = buf_len;
                goto more_empty;
            }
            
            /* See how much more there is to read in this eraseblock... */
            buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
            if (!buf_len) {
                /* No more to read. Break out of main loop without marking
                   this range of empty space as dirty (because it's not) */
                jffs2_dbg(1, "Empty flash at %08x runs to end of block. Treating as free_space\n",
                      empty_start);
                break;
            }
            /* point never reaches here */
            scan_end = buf_len;
            jffs2_dbg(1, "Reading another 0x%x at 0x%08x\n",
                  buf_len, ofs);
            err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
            if (err)
                return err;
            buf_ofs = ofs;
            goto more_empty;
        }

        if (ofs == jeb->offset && je16_to_cpu(node->magic) == KSAMTIB_CIGAM_2SFFJ) {
            pr_warn("Magic bitmask is backwards at offset 0x%08x. Wrong endian filesystem?\n",
                ofs);
            if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
                return err;
            ofs += 4;
            continue;
        }
        if (je16_to_cpu(node->magic) == JFFS2_DIRTY_BITMASK) {
            jffs2_dbg(1, "Dirty bitmask at 0x%08x\n", ofs);
            if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
                return err;
            ofs += 4;
            continue;
        }
        if (je16_to_cpu(node->magic) == JFFS2_OLD_MAGIC_BITMASK) {
            pr_warn("Old JFFS2 bitmask found at 0x%08x\n", ofs);
            pr_warn("You cannot use older JFFS2 filesystems with newer kernels\n");
            if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
                return err;
            ofs += 4;
            continue;
        }
        if (je16_to_cpu(node->magic) != JFFS2_MAGIC_BITMASK) {
            /* OK. We're out of possibilities. Whinge and move on */
            noisy_printk(&noise, "%s(): Magic bitmask 0x%04x not found at 0x%08x: 0x%04x instead\n",
                     __func__,
                     JFFS2_MAGIC_BITMASK, ofs,
                     je16_to_cpu(node->magic));
            if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
                return err;
            ofs += 4;
            continue;
        }
        /* We seem to have a node of sorts. Check the CRC */
        crcnode.magic = node->magic;
        crcnode.nodetype = cpu_to_je16( je16_to_cpu(node->nodetype) | JFFS2_NODE_ACCURATE);
        crcnode.totlen = node->totlen;
        hdr_crc = crc32(0, &crcnode, sizeof(crcnode)-4);

        if (hdr_crc != je32_to_cpu(node->hdr_crc)) {
            noisy_printk(&noise, "%s(): Node at 0x%08x {0x%04x, 0x%04x, 0x%08x) has invalid CRC 0x%08x (calculated 0x%08x)\n",
                     __func__,
                     ofs, je16_to_cpu(node->magic),
                     je16_to_cpu(node->nodetype),
                     je32_to_cpu(node->totlen),
                     je32_to_cpu(node->hdr_crc),
                     hdr_crc);
            if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
                return err;
            ofs += 4;
            continue;
        }

        if (ofs + je32_to_cpu(node->totlen) > jeb->offset + c->sector_size) {
            /* Eep. Node goes over the end of the erase block. */
            pr_warn("Node at 0x%08x with length 0x%08x would run over the end of the erase block\n",
                ofs, je32_to_cpu(node->totlen));
            pr_warn("Perhaps the file system was created with the wrong erase size?\n");
            if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
                return err;
            ofs += 4;
            continue;
        }

        if (!(je16_to_cpu(node->nodetype) & JFFS2_NODE_ACCURATE)) {
            /* Wheee. This is an obsoleted node */
            jffs2_dbg(2, "Node at 0x%08x is obsolete. Skipping\n",
                  ofs);
            if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(node->totlen)))))
                return err;
            ofs += PAD(je32_to_cpu(node->totlen));
            continue;
        }

        switch(je16_to_cpu(node->nodetype)) {
        case JFFS2_NODETYPE_INODE:
            if (buf_ofs + buf_len < ofs + sizeof(struct jffs2_raw_inode)) {
                buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
                jffs2_dbg(1, "Fewer than %zd bytes (inode node) left to end of buf. Reading 0x%x at 0x%08x\n",
                      sizeof(struct jffs2_raw_inode),
                      buf_len, ofs);
                err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
                if (err)
                    return err;
                buf_ofs = ofs;
                node = (void *)buf;
            }
            err = jffs2_scan_inode_node(c, jeb, (void *)node, ofs, s);
            if (err) return err;
            ofs += PAD(je32_to_cpu(node->totlen));
            break;

        case JFFS2_NODETYPE_DIRENT:
            if (buf_ofs + buf_len < ofs + je32_to_cpu(node->totlen)) {
                buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
                jffs2_dbg(1, "Fewer than %d bytes (dirent node) left to end of buf. Reading 0x%x at 0x%08x\n",
                      je32_to_cpu(node->totlen), buf_len,
                      ofs);
                err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
                if (err)
                    return err;
                buf_ofs = ofs;
                node = (void *)buf;
            }
            err = jffs2_scan_dirent_node(c, jeb, (void *)node, ofs, s);
            if (err) return err;
            ofs += PAD(je32_to_cpu(node->totlen));
            break;

#ifdef CONFIG_JFFS2_FS_XATTR
        case JFFS2_NODETYPE_XATTR:
            if (buf_ofs + buf_len < ofs + je32_to_cpu(node->totlen)) {
                buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
                jffs2_dbg(1, "Fewer than %d bytes (xattr node) left to end of buf. Reading 0x%x at 0x%08x\n",
                      je32_to_cpu(node->totlen), buf_len,
                      ofs);
                err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
                if (err)
                    return err;
                buf_ofs = ofs;
                node = (void *)buf;
            }
            err = jffs2_scan_xattr_node(c, jeb, (void *)node, ofs, s);
            if (err)
                return err;
            ofs += PAD(je32_to_cpu(node->totlen));
            break;
        case JFFS2_NODETYPE_XREF:
            if (buf_ofs + buf_len < ofs + je32_to_cpu(node->totlen)) {
                buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
                jffs2_dbg(1, "Fewer than %d bytes (xref node) left to end of buf. Reading 0x%x at 0x%08x\n",
                      je32_to_cpu(node->totlen), buf_len,
                      ofs);
                err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
                if (err)
                    return err;
                buf_ofs = ofs;
                node = (void *)buf;
            }
            err = jffs2_scan_xref_node(c, jeb, (void *)node, ofs, s);
            if (err)
                return err;
            ofs += PAD(je32_to_cpu(node->totlen));
            break;
#endif  /* CONFIG_JFFS2_FS_XATTR */

        case JFFS2_NODETYPE_CLEANMARKER:
            jffs2_dbg(1, "CLEANMARKER node found at 0x%08x\n", ofs);
            if (je32_to_cpu(node->totlen) != c->cleanmarker_size) {
                pr_notice("CLEANMARKER node found at 0x%08x has totlen 0x%x != normal 0x%x\n",
                      ofs, je32_to_cpu(node->totlen),
                      c->cleanmarker_size);
                if ((err = jffs2_scan_dirty_space(c, jeb, PAD(sizeof(struct jffs2_unknown_node)))))
                    return err;
                ofs += PAD(sizeof(struct jffs2_unknown_node));
            } else if (jeb->first_node) {
                pr_notice("CLEANMARKER node found at 0x%08x, not first node in block (0x%08x)\n",
                      ofs, jeb->offset);
                if ((err = jffs2_scan_dirty_space(c, jeb, PAD(sizeof(struct jffs2_unknown_node)))))
                    return err;
                ofs += PAD(sizeof(struct jffs2_unknown_node));
            } else {
                jffs2_link_node_ref(c, jeb, ofs | REF_NORMAL, c->cleanmarker_size, NULL);

                ofs += PAD(c->cleanmarker_size);
            }
            break;

        case JFFS2_NODETYPE_PADDING:
            if (jffs2_sum_active())
                jffs2_sum_add_padding_mem(s, je32_to_cpu(node->totlen));
            if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(node->totlen)))))
                return err;
            ofs += PAD(je32_to_cpu(node->totlen));
            break;

        default:
            switch (je16_to_cpu(node->nodetype) & JFFS2_COMPAT_MASK) {
            case JFFS2_FEATURE_ROCOMPAT:
                pr_notice("Read-only compatible feature node (0x%04x) found at offset 0x%08x\n",
                      je16_to_cpu(node->nodetype), ofs);
                c->flags |= JFFS2_SB_FLAG_RO;
                if (!(jffs2_is_readonly(c)))
                    return -EROFS;
                if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(node->totlen)))))
                    return err;
                ofs += PAD(je32_to_cpu(node->totlen));
                break;

            case JFFS2_FEATURE_INCOMPAT:
                pr_notice("Incompatible feature node (0x%04x) found at offset 0x%08x\n",
                      je16_to_cpu(node->nodetype), ofs);
                return -EINVAL;

            case JFFS2_FEATURE_RWCOMPAT_DELETE:
                jffs2_dbg(1, "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n",
                      je16_to_cpu(node->nodetype), ofs);
                if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(node->totlen)))))
                    return err;
                ofs += PAD(je32_to_cpu(node->totlen));
                break;

            case JFFS2_FEATURE_RWCOMPAT_COPY: {
                jffs2_dbg(1, "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n",
                      je16_to_cpu(node->nodetype), ofs);

                jffs2_link_node_ref(c, jeb, ofs | REF_PRISTINE, PAD(je32_to_cpu(node->totlen)), NULL);

                /* We can't summarise nodes we don't grok */
                jffs2_sum_disable_collecting(s);
                ofs += PAD(je32_to_cpu(node->totlen));
                break;
                }
            }
        }
    }

    if (jffs2_sum_active()) {
        if (PAD(s->sum_size + JFFS2_SUMMARY_FRAME_SIZE) > jeb->free_size) {
            dbg_summary("There is not enough space for "
                "summary information, disabling for this jeb!\n");
            jffs2_sum_disable_collecting(s);
        }
    }

    jffs2_dbg(1, "Block at 0x%08x: free 0x%08x, dirty 0x%08x, unchecked 0x%08x, used 0x%08x, wasted 0x%08x\n",
          jeb->offset, jeb->free_size, jeb->dirty_size,
          jeb->unchecked_size, jeb->used_size, jeb->wasted_size);
    
    /* mark_node_obsolete can add to wasted !! */
    if (jeb->wasted_size) {
        jeb->dirty_size += jeb->wasted_size;
        c->dirty_size += jeb->wasted_size;
        c->wasted_size -= jeb->wasted_size;
        jeb->wasted_size = 0;
    }

    return jffs2_scan_classify_jeb(c, jeb);
}

struct jffs2_inode_cache *jffs2_scan_make_ino_cache(struct jffs2_sb_info *c, uint32_t ino)
{
    struct jffs2_inode_cache *ic;

    ic = jffs2_get_ino_cache(c, ino);
    if (ic)
        return ic;

    if (ino > c->highest_ino)
        c->highest_ino = ino;

    ic = jffs2_alloc_inode_cache();
    if (!ic) {
        pr_notice("%s(): allocation of inode cache failed\n", __func__);
        return NULL;
    }
    memset(ic, 0, sizeof(*ic));

    ic->ino = ino;
    ic->nodes = (void *)ic;
    jffs2_add_ino_cache(c, ic);
    if (ino == 1)
        ic->pino_nlink = 1;
    return ic;
}

static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                 struct jffs2_raw_inode *ri, uint32_t ofs, struct jffs2_summary *s)
{
    struct jffs2_inode_cache *ic;
    uint32_t crc, ino = je32_to_cpu(ri->ino);

    jffs2_dbg(1, "%s(): Node at 0x%08x\n", __func__, ofs);

    /* We do very little here now. Just check the ino# to which we should attribute
       this node; we can do all the CRC checking etc. later. There's a tradeoff here --
       we used to scan the flash once only, reading everything we want from it into
       memory, then building all our in-core data structures and freeing the extra
       information. Now we allow the first part of the mount to complete a lot quicker,
       but we have to go _back_ to the flash in order to finish the CRC checking, etc.
       Which means that the _full_ amount of time to get to proper write mode with GC
       operational may actually be _longer_ than before. Sucks to be me. */

    /* Check the node CRC in any case. */
    crc = crc32(0, ri, sizeof(*ri)-8);
    if (crc != je32_to_cpu(ri->node_crc)) {
        pr_notice("%s(): CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
              __func__, ofs, je32_to_cpu(ri->node_crc), crc);
        /*
         * We believe totlen because the CRC on the node
         * _header_ was OK, just the node itself failed.
         */
        return jffs2_scan_dirty_space(c, jeb,
                          PAD(je32_to_cpu(ri->totlen)));
    }

    ic = jffs2_get_ino_cache(c, ino);
    if (!ic) {
        ic = jffs2_scan_make_ino_cache(c, ino);
        if (!ic)
            return -ENOMEM;
    }

    /* Wheee. It worked */
    jffs2_link_node_ref(c, jeb, ofs | REF_UNCHECKED, PAD(je32_to_cpu(ri->totlen)), ic);

    jffs2_dbg(1, "Node is ino #%u, version %d. Range 0x%x-0x%x\n",
          je32_to_cpu(ri->ino), je32_to_cpu(ri->version),
          je32_to_cpu(ri->offset),
          je32_to_cpu(ri->offset)+je32_to_cpu(ri->dsize));

    pseudo_random += je32_to_cpu(ri->version);

    if (jffs2_sum_active()) {
        jffs2_sum_add_inode_mem(s, ri, ofs - jeb->offset);
    }

    return 0;
}

static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
                  struct jffs2_raw_dirent *rd, uint32_t ofs, struct jffs2_summary *s)
{
    struct jffs2_full_dirent *fd;
    struct jffs2_inode_cache *ic;
    uint32_t checkedlen;
    uint32_t crc;
    int err;

    jffs2_dbg(1, "%s(): Node at 0x%08x\n", __func__, ofs);

    /* We don't get here unless the node is still valid, so we don't have to
       mask in the ACCURATE bit any more. */
    crc = crc32(0, rd, sizeof(*rd)-8);

    if (crc != je32_to_cpu(rd->node_crc)) {
        pr_notice("%s(): Node CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
              __func__, ofs, je32_to_cpu(rd->node_crc), crc);
        /* We believe totlen because the CRC on the node _header_ was OK, just the node itself failed. */
        if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(rd->totlen)))))
            return err;
        return 0;
    }

    pseudo_random += je32_to_cpu(rd->version);

    /* Should never happen. Did. (OLPC trac #4184)*/
    checkedlen = strnlen(rd->name, rd->nsize);
    if (checkedlen < rd->nsize) {
        pr_err("Dirent at %08x has zeroes in name. Truncating to %d chars\n",
               ofs, checkedlen);
    }
    fd = jffs2_alloc_full_dirent(checkedlen+1);
    if (!fd) {
        return -ENOMEM;
    }
    memcpy(&fd->name, rd->name, checkedlen);
    fd->name[checkedlen] = 0;

    crc = crc32(0, fd->name, rd->nsize);
    if (crc != je32_to_cpu(rd->name_crc)) {
        pr_notice("%s(): Name CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
              __func__, ofs, je32_to_cpu(rd->name_crc), crc);
        jffs2_dbg(1, "Name for which CRC failed is (now) '%s', ino #%d\n",
              fd->name, je32_to_cpu(rd->ino));
        jffs2_free_full_dirent(fd);
        /* FIXME: Why do we believe totlen? */
        /* We believe totlen because the CRC on the node _header_ was OK, just the name failed. */
        if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(rd->totlen)))))
            return err;
        return 0;
    }
    ic = jffs2_scan_make_ino_cache(c, je32_to_cpu(rd->pino));
    if (!ic) {
        jffs2_free_full_dirent(fd);
        return -ENOMEM;
    }

    fd->raw = jffs2_link_node_ref(c, jeb, ofs | dirent_node_state(rd),
                      PAD(je32_to_cpu(rd->totlen)), ic);

    fd->next = NULL;
    fd->version = je32_to_cpu(rd->version);
    fd->ino = je32_to_cpu(rd->ino);
    fd->nhash = full_name_hash(fd->name, checkedlen);
    fd->type = rd->type;
    jffs2_add_fd_to_list(c, fd, &ic->scan_dents);

    if (jffs2_sum_active()) {
        jffs2_sum_add_dirent_mem(s, rd, ofs - jeb->offset);
    }

    return 0;
}

static int count_list(struct list_head *l)
{
    uint32_t count = 0;
    struct list_head *tmp;

    list_for_each(tmp, l) {
        count++;
    }
    return count;
}

/* Note: This breaks if list_empty(head). I don't care. You
   might, if you copy this code and use it elsewhere :) */
static void rotate_list(struct list_head *head, uint32_t count)
{
    struct list_head *n = head->next;

    list_del(head);
    while(count--) {
        n = n->next;
    }
    list_add(head, n);
}

void jffs2_rotate_lists(struct jffs2_sb_info *c)
{
    uint32_t x;
    uint32_t rotateby;

    x = count_list(&c->clean_list);
    if (x) {
        rotateby = pseudo_random % x;
        rotate_list((&c->clean_list), rotateby);
    }

    x = count_list(&c->very_dirty_list);
    if (x) {
        rotateby = pseudo_random % x;
        rotate_list((&c->very_dirty_list), rotateby);
    }

    x = count_list(&c->dirty_list);
    if (x) {
        rotateby = pseudo_random % x;
        rotate_list((&c->dirty_list), rotateby);
    }

    x = count_list(&c->erasable_list);
    if (x) {
        rotateby = pseudo_random % x;
        rotate_list((&c->erasable_list), rotateby);
    }

    if (c->nr_erasing_blocks) {
        rotateby = pseudo_random % c->nr_erasing_blocks;
        rotate_list((&c->erase_pending_list), rotateby);
    }

    if (c->nr_free_blocks) {
        rotateby = pseudo_random % c->nr_free_blocks;
        rotate_list((&c->free_list), rotateby);
    }
}