xattr.c

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/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2006  NEC Corporation
 *
 * Created by KaiGai Kohei <[email protected]>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#define JFFS2_XATTR_IS_CORRUPTED    1

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/crc32.h>
#include <linux/jffs2.h>
#include <linux/xattr.h>
#include <linux/mtd/mtd.h>
#include "nodelist.h"
/* -------- xdatum related functions ----------------
 * xattr_datum_hashkey(xprefix, xname, xvalue, xsize)
 *   is used to calcurate xdatum hashkey. The reminder of hashkey into XATTRINDEX_HASHSIZE is
 *   the index of the xattr name/value pair cache (c->xattrindex).
 * is_xattr_datum_unchecked(c, xd)
 *   returns 1, if xdatum contains any unchecked raw nodes. if all raw nodes are not
 *   unchecked, it returns 0.
 * unload_xattr_datum(c, xd)
 *   is used to release xattr name/value pair and detach from c->xattrindex.
 * reclaim_xattr_datum(c)
 *   is used to reclaim xattr name/value pairs on the xattr name/value pair cache when
 *   memory usage by cache is over c->xdatum_mem_threshold. Currently, this threshold
 *   is hard coded as 32KiB.
 * do_verify_xattr_datum(c, xd)
 *   is used to load the xdatum informations without name/value pair from the medium.
 *   It's necessary once, because those informations are not collected during mounting
 *   process when EBS is enabled.
 *   0 will be returned, if success. An negative return value means recoverable error, and
 *   positive return value means unrecoverable error. Thus, caller must remove this xdatum
 *   and xref when it returned positive value.
 * do_load_xattr_datum(c, xd)
 *   is used to load name/value pair from the medium.
 *   The meanings of return value is same as do_verify_xattr_datum().
 * load_xattr_datum(c, xd)
 *   is used to be as a wrapper of do_verify_xattr_datum() and do_load_xattr_datum().
 *   If xd need to call do_verify_xattr_datum() at first, it's called before calling
 *   do_load_xattr_datum(). The meanings of return value is same as do_verify_xattr_datum().
 * save_xattr_datum(c, xd)
 *   is used to write xdatum to medium. xd->version will be incremented.
 * create_xattr_datum(c, xprefix, xname, xvalue, xsize)
 *   is used to create new xdatum and write to medium.
 * unrefer_xattr_datum(c, xd)
 *   is used to delete a xdatum. When nobody refers this xdatum, JFFS2_XFLAGS_DEAD
 *   is set on xd->flags and chained xattr_dead_list or release it immediately.
 *   In the first case, the garbage collector release it later.
 * -------------------------------------------------- */
static uint32_t xattr_datum_hashkey(int xprefix, const char *xname, const char *xvalue, int xsize)
{
    int name_len = strlen(xname);

    return crc32(xprefix, xname, name_len) ^ crc32(xprefix, xvalue, xsize);
}

static int is_xattr_datum_unchecked(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
    struct jffs2_raw_node_ref *raw;
    int rc = 0;

    spin_lock(&c->erase_completion_lock);
    for (raw=xd->node; raw != (void *)xd; raw=raw->next_in_ino) {
        if (ref_flags(raw) == REF_UNCHECKED) {
            rc = 1;
            break;
        }
    }
    spin_unlock(&c->erase_completion_lock);
    return rc;
}

static void unload_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
    /* must be called under down_write(xattr_sem) */
    D1(dbg_xattr("%s: xid=%u, version=%u\n", __func__, xd->xid, xd->version));
    if (xd->xname) {
        c->xdatum_mem_usage -= (xd->name_len + 1 + xd->value_len);
        kfree(xd->xname);
    }

    list_del_init(&xd->xindex);
    xd->hashkey = 0;
    xd->xname = NULL;
    xd->xvalue = NULL;
}

static void reclaim_xattr_datum(struct jffs2_sb_info *c)
{
    /* must be called under down_write(xattr_sem) */
    struct jffs2_xattr_datum *xd, *_xd;
    uint32_t target, before;
    static int index = 0;
    int count;

    if (c->xdatum_mem_threshold > c->xdatum_mem_usage)
        return;

    before = c->xdatum_mem_usage;
    target = c->xdatum_mem_usage * 4 / 5; /* 20% reduction */
    for (count = 0; count < XATTRINDEX_HASHSIZE; count++) {
        list_for_each_entry_safe(xd, _xd, &c->xattrindex[index], xindex) {
            if (xd->flags & JFFS2_XFLAGS_HOT) {
                xd->flags &= ~JFFS2_XFLAGS_HOT;
            } else if (!(xd->flags & JFFS2_XFLAGS_BIND)) {
                unload_xattr_datum(c, xd);
            }
            if (c->xdatum_mem_usage <= target)
                goto out;
        }
        index = (index+1) % XATTRINDEX_HASHSIZE;
    }
 out:
    JFFS2_NOTICE("xdatum_mem_usage from %u byte to %u byte (%u byte reclaimed)\n",
             before, c->xdatum_mem_usage, before - c->xdatum_mem_usage);
}

static int do_verify_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
    /* must be called under down_write(xattr_sem) */
    struct jffs2_eraseblock *jeb;
    struct jffs2_raw_node_ref *raw;
    struct jffs2_raw_xattr rx;
    size_t readlen;
    uint32_t crc, offset, totlen;
    int rc;

    spin_lock(&c->erase_completion_lock);
    offset = ref_offset(xd->node);
    if (ref_flags(xd->node) == REF_PRISTINE)
        goto complete;
    spin_unlock(&c->erase_completion_lock);

    rc = jffs2_flash_read(c, offset, sizeof(rx), &readlen, (char *)&rx);
    if (rc || readlen != sizeof(rx)) {
        JFFS2_WARNING("jffs2_flash_read()=%d, req=%zu, read=%zu at %#08x\n",
                  rc, sizeof(rx), readlen, offset);
        return rc ? rc : -EIO;
    }
    crc = crc32(0, &rx, sizeof(rx) - 4);
    if (crc != je32_to_cpu(rx.node_crc)) {
        JFFS2_ERROR("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
                offset, je32_to_cpu(rx.hdr_crc), crc);
        xd->flags |= JFFS2_XFLAGS_INVALID;
        return JFFS2_XATTR_IS_CORRUPTED;
    }
    totlen = PAD(sizeof(rx) + rx.name_len + 1 + je16_to_cpu(rx.value_len));
    if (je16_to_cpu(rx.magic) != JFFS2_MAGIC_BITMASK
        || je16_to_cpu(rx.nodetype) != JFFS2_NODETYPE_XATTR
        || je32_to_cpu(rx.totlen) != totlen
        || je32_to_cpu(rx.xid) != xd->xid
        || je32_to_cpu(rx.version) != xd->version) {
        JFFS2_ERROR("inconsistent xdatum at %#08x, magic=%#04x/%#04x, "
                "nodetype=%#04x/%#04x, totlen=%u/%u, xid=%u/%u, version=%u/%u\n",
                offset, je16_to_cpu(rx.magic), JFFS2_MAGIC_BITMASK,
                je16_to_cpu(rx.nodetype), JFFS2_NODETYPE_XATTR,
                je32_to_cpu(rx.totlen), totlen,
                je32_to_cpu(rx.xid), xd->xid,
                je32_to_cpu(rx.version), xd->version);
        xd->flags |= JFFS2_XFLAGS_INVALID;
        return JFFS2_XATTR_IS_CORRUPTED;
    }
    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);

    spin_lock(&c->erase_completion_lock);
 complete:
    for (raw=xd->node; raw != (void *)xd; raw=raw->next_in_ino) {
        jeb = &c->blocks[ref_offset(raw) / c->sector_size];
        totlen = PAD(ref_totlen(c, jeb, raw));
        if (ref_flags(raw) == REF_UNCHECKED) {
            c->unchecked_size -= totlen; c->used_size += totlen;
            jeb->unchecked_size -= totlen; jeb->used_size += totlen;
        }
        raw->flash_offset = ref_offset(raw) | ((xd->node==raw) ? REF_PRISTINE : REF_NORMAL);
    }
    spin_unlock(&c->erase_completion_lock);

    /* unchecked xdatum is chained with c->xattr_unchecked */
    list_del_init(&xd->xindex);

    dbg_xattr("success on verfying xdatum (xid=%u, version=%u)\n",
          xd->xid, xd->version);

    return 0;
}

static int do_load_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
    /* must be called under down_write(xattr_sem) */
    char *data;
    size_t readlen;
    uint32_t crc, length;
    int i, ret, retry = 0;

    BUG_ON(ref_flags(xd->node) != REF_PRISTINE);
    BUG_ON(!list_empty(&xd->xindex));
 retry:
    length = xd->name_len + 1 + xd->value_len;
    data = kmalloc(length, GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    ret = jffs2_flash_read(c, ref_offset(xd->node)+sizeof(struct jffs2_raw_xattr),
                   length, &readlen, data);

    if (ret || length!=readlen) {
        JFFS2_WARNING("jffs2_flash_read() returned %d, request=%d, readlen=%zu, at %#08x\n",
                  ret, length, readlen, ref_offset(xd->node));
        kfree(data);
        return ret ? ret : -EIO;
    }

    data[xd->name_len] = '\0';
    crc = crc32(0, data, length);
    if (crc != xd->data_crc) {
        JFFS2_WARNING("node CRC failed (JFFS2_NODETYPE_XATTR)"
                  " at %#08x, read: 0x%08x calculated: 0x%08x\n",
                  ref_offset(xd->node), xd->data_crc, crc);
        kfree(data);
        xd->flags |= JFFS2_XFLAGS_INVALID;
        return JFFS2_XATTR_IS_CORRUPTED;
    }

    xd->flags |= JFFS2_XFLAGS_HOT;
    xd->xname = data;
    xd->xvalue = data + xd->name_len+1;

    c->xdatum_mem_usage += length;

    xd->hashkey = xattr_datum_hashkey(xd->xprefix, xd->xname, xd->xvalue, xd->value_len);
    i = xd->hashkey % XATTRINDEX_HASHSIZE;
    list_add(&xd->xindex, &c->xattrindex[i]);
    if (!retry) {
        retry = 1;
        reclaim_xattr_datum(c);
        if (!xd->xname)
            goto retry;
    }

    dbg_xattr("success on loading xdatum (xid=%u, xprefix=%u, xname='%s')\n",
          xd->xid, xd->xprefix, xd->xname);

    return 0;
}

static int load_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
    /* must be called under down_write(xattr_sem);
     * rc < 0 : recoverable error, try again
     * rc = 0 : success
     * rc > 0 : Unrecoverable error, this node should be deleted.
     */
    int rc = 0;

    BUG_ON(xd->flags & JFFS2_XFLAGS_DEAD);
    if (xd->xname)
        return 0;
    if (xd->flags & JFFS2_XFLAGS_INVALID)
        return JFFS2_XATTR_IS_CORRUPTED;
    if (unlikely(is_xattr_datum_unchecked(c, xd)))
        rc = do_verify_xattr_datum(c, xd);
    if (!rc)
        rc = do_load_xattr_datum(c, xd);
    return rc;
}

static int save_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
    /* must be called under down_write(xattr_sem) */
    struct jffs2_raw_xattr rx;
    struct kvec vecs[2];
    size_t length;
    int rc, totlen;
    uint32_t phys_ofs = write_ofs(c);

    BUG_ON(!xd->xname);
    BUG_ON(xd->flags & (JFFS2_XFLAGS_DEAD|JFFS2_XFLAGS_INVALID));

    vecs[0].iov_base = &rx;
    vecs[0].iov_len = sizeof(rx);
    vecs[1].iov_base = xd->xname;
    vecs[1].iov_len = xd->name_len + 1 + xd->value_len;
    totlen = vecs[0].iov_len + vecs[1].iov_len;

    /* Setup raw-xattr */
    memset(&rx, 0, sizeof(rx));
    rx.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
    rx.nodetype = cpu_to_je16(JFFS2_NODETYPE_XATTR);
    rx.totlen = cpu_to_je32(PAD(totlen));
    rx.hdr_crc = cpu_to_je32(crc32(0, &rx, sizeof(struct jffs2_unknown_node) - 4));

    rx.xid = cpu_to_je32(xd->xid);
    rx.version = cpu_to_je32(++xd->version);
    rx.xprefix = xd->xprefix;
    rx.name_len = xd->name_len;
    rx.value_len = cpu_to_je16(xd->value_len);
    rx.data_crc = cpu_to_je32(crc32(0, vecs[1].iov_base, vecs[1].iov_len));
    rx.node_crc = cpu_to_je32(crc32(0, &rx, sizeof(struct jffs2_raw_xattr) - 4));

    rc = jffs2_flash_writev(c, vecs, 2, phys_ofs, &length, 0);
    if (rc || totlen != length) {
        JFFS2_WARNING("jffs2_flash_writev()=%d, req=%u, wrote=%zu, at %#08x\n",
                  rc, totlen, length, phys_ofs);
        rc = rc ? rc : -EIO;
        if (length)
            jffs2_add_physical_node_ref(c, phys_ofs | REF_OBSOLETE, PAD(totlen), NULL);

        return rc;
    }
    /* success */
    jffs2_add_physical_node_ref(c, phys_ofs | REF_PRISTINE, PAD(totlen), (void *)xd);

    dbg_xattr("success on saving xdatum (xid=%u, version=%u, xprefix=%u, xname='%s')\n",
          xd->xid, xd->version, xd->xprefix, xd->xname);

    return 0;
}

static struct jffs2_xattr_datum *create_xattr_datum(struct jffs2_sb_info *c,
                            int xprefix, const char *xname,
                            const char *xvalue, int xsize)
{
    /* must be called under down_write(xattr_sem) */
    struct jffs2_xattr_datum *xd;
    uint32_t hashkey, name_len;
    char *data;
    int i, rc;

    /* Search xattr_datum has same xname/xvalue by index */
    hashkey = xattr_datum_hashkey(xprefix, xname, xvalue, xsize);
    i = hashkey % XATTRINDEX_HASHSIZE;
    list_for_each_entry(xd, &c->xattrindex[i], xindex) {
        if (xd->hashkey==hashkey
            && xd->xprefix==xprefix
            && xd->value_len==xsize
            && !strcmp(xd->xname, xname)
            && !memcmp(xd->xvalue, xvalue, xsize)) {
            atomic_inc(&xd->refcnt);
            return xd;
        }
    }

    /* Not found, Create NEW XATTR-Cache */
    name_len = strlen(xname);

    xd = jffs2_alloc_xattr_datum();
    if (!xd)
        return ERR_PTR(-ENOMEM);

    data = kmalloc(name_len + 1 + xsize, GFP_KERNEL);
    if (!data) {
        jffs2_free_xattr_datum(xd);
        return ERR_PTR(-ENOMEM);
    }
    strcpy(data, xname);
    memcpy(data + name_len + 1, xvalue, xsize);

    atomic_set(&xd->refcnt, 1);
    xd->xid = ++c->highest_xid;
    xd->flags |= JFFS2_XFLAGS_HOT;
    xd->xprefix = xprefix;

    xd->hashkey = hashkey;
    xd->xname = data;
    xd->xvalue = data + name_len + 1;
    xd->name_len = name_len;
    xd->value_len = xsize;
    xd->data_crc = crc32(0, data, xd->name_len + 1 + xd->value_len);

    rc = save_xattr_datum(c, xd);
    if (rc) {
        kfree(xd->xname);
        jffs2_free_xattr_datum(xd);
        return ERR_PTR(rc);
    }

    /* Insert Hash Index */
    i = hashkey % XATTRINDEX_HASHSIZE;
    list_add(&xd->xindex, &c->xattrindex[i]);

    c->xdatum_mem_usage += (xd->name_len + 1 + xd->value_len);
    reclaim_xattr_datum(c);

    return xd;
}

static void unrefer_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
    /* must be called under down_write(xattr_sem) */
    if (atomic_dec_and_lock(&xd->refcnt, &c->erase_completion_lock)) {
        unload_xattr_datum(c, xd);
        xd->flags |= JFFS2_XFLAGS_DEAD;
        if (xd->node == (void *)xd) {
            BUG_ON(!(xd->flags & JFFS2_XFLAGS_INVALID));
            jffs2_free_xattr_datum(xd);
        } else {
            list_add(&xd->xindex, &c->xattr_dead_list);
        }
        spin_unlock(&c->erase_completion_lock);

        dbg_xattr("xdatum(xid=%u, version=%u) was removed.\n",
              xd->xid, xd->version);
    }
}

/* -------- xref related functions ------------------
 * verify_xattr_ref(c, ref)
 *   is used to load xref information from medium. Because summary data does not
 *   contain xid/ino, it's necessary to verify once while mounting process.
 * save_xattr_ref(c, ref)
 *   is used to write xref to medium. If delete marker is marked, it write
 *   a delete marker of xref into medium.
 * create_xattr_ref(c, ic, xd)
 *   is used to create a new xref and write to medium.
 * delete_xattr_ref(c, ref)
 *   is used to delete jffs2_xattr_ref. It marks xref XREF_DELETE_MARKER,
 *   and allows GC to reclaim those physical nodes.
 * jffs2_xattr_delete_inode(c, ic)
 *   is called to remove xrefs related to obsolete inode when inode is unlinked.
 * jffs2_xattr_free_inode(c, ic)
 *   is called to release xattr related objects when unmounting. 
 * check_xattr_ref_inode(c, ic)
 *   is used to confirm inode does not have duplicate xattr name/value pair.
 * jffs2_xattr_do_crccheck_inode(c, ic)
 *   is used to force xattr data integrity check during the initial gc scan.
 * -------------------------------------------------- */
static int verify_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref)
{
    struct jffs2_eraseblock *jeb;
    struct jffs2_raw_node_ref *raw;
    struct jffs2_raw_xref rr;
    size_t readlen;
    uint32_t crc, offset, totlen;
    int rc;

    spin_lock(&c->erase_completion_lock);
    if (ref_flags(ref->node) != REF_UNCHECKED)
        goto complete;
    offset = ref_offset(ref->node);
    spin_unlock(&c->erase_completion_lock);

    rc = jffs2_flash_read(c, offset, sizeof(rr), &readlen, (char *)&rr);
    if (rc || sizeof(rr) != readlen) {
        JFFS2_WARNING("jffs2_flash_read()=%d, req=%zu, read=%zu, at %#08x\n",
                  rc, sizeof(rr), readlen, offset);
        return rc ? rc : -EIO;
    }
    /* obsolete node */
    crc = crc32(0, &rr, sizeof(rr) - 4);
    if (crc != je32_to_cpu(rr.node_crc)) {
        JFFS2_ERROR("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
                offset, je32_to_cpu(rr.node_crc), crc);
        return JFFS2_XATTR_IS_CORRUPTED;
    }
    if (je16_to_cpu(rr.magic) != JFFS2_MAGIC_BITMASK
        || je16_to_cpu(rr.nodetype) != JFFS2_NODETYPE_XREF
        || je32_to_cpu(rr.totlen) != PAD(sizeof(rr))) {
        JFFS2_ERROR("inconsistent xref at %#08x, magic=%#04x/%#04x, "
                "nodetype=%#04x/%#04x, totlen=%u/%zu\n",
                offset, je16_to_cpu(rr.magic), JFFS2_MAGIC_BITMASK,
                je16_to_cpu(rr.nodetype), JFFS2_NODETYPE_XREF,
                je32_to_cpu(rr.totlen), PAD(sizeof(rr)));
        return JFFS2_XATTR_IS_CORRUPTED;
    }
    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);

    spin_lock(&c->erase_completion_lock);
 complete:
    for (raw=ref->node; raw != (void *)ref; raw=raw->next_in_ino) {
        jeb = &c->blocks[ref_offset(raw) / c->sector_size];
        totlen = PAD(ref_totlen(c, jeb, raw));
        if (ref_flags(raw) == REF_UNCHECKED) {
            c->unchecked_size -= totlen; c->used_size += totlen;
            jeb->unchecked_size -= totlen; jeb->used_size += totlen;
        }
        raw->flash_offset = ref_offset(raw) | ((ref->node==raw) ? REF_PRISTINE : REF_NORMAL);
    }
    spin_unlock(&c->erase_completion_lock);

    dbg_xattr("success on verifying xref (ino=%u, xid=%u) at %#08x\n",
          ref->ino, ref->xid, ref_offset(ref->node));
    return 0;
}

static int save_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref)
{
    /* must be called under down_write(xattr_sem) */
    struct jffs2_raw_xref rr;
    size_t length;
    uint32_t xseqno, phys_ofs = write_ofs(c);
    int ret;

    rr.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
    rr.nodetype = cpu_to_je16(JFFS2_NODETYPE_XREF);
    rr.totlen = cpu_to_je32(PAD(sizeof(rr)));
    rr.hdr_crc = cpu_to_je32(crc32(0, &rr, sizeof(struct jffs2_unknown_node) - 4));

    xseqno = (c->highest_xseqno += 2);
    if (is_xattr_ref_dead(ref)) {
        xseqno |= XREF_DELETE_MARKER;
        rr.ino = cpu_to_je32(ref->ino);
        rr.xid = cpu_to_je32(ref->xid);
    } else {
        rr.ino = cpu_to_je32(ref->ic->ino);
        rr.xid = cpu_to_je32(ref->xd->xid);
    }
    rr.xseqno = cpu_to_je32(xseqno);
    rr.node_crc = cpu_to_je32(crc32(0, &rr, sizeof(rr) - 4));

    ret = jffs2_flash_write(c, phys_ofs, sizeof(rr), &length, (char *)&rr);
    if (ret || sizeof(rr) != length) {
        JFFS2_WARNING("jffs2_flash_write() returned %d, request=%zu, retlen=%zu, at %#08x\n",
                  ret, sizeof(rr), length, phys_ofs);
        ret = ret ? ret : -EIO;
        if (length)
            jffs2_add_physical_node_ref(c, phys_ofs | REF_OBSOLETE, PAD(sizeof(rr)), NULL);

        return ret;
    }
    /* success */
    ref->xseqno = xseqno;
    jffs2_add_physical_node_ref(c, phys_ofs | REF_PRISTINE, PAD(sizeof(rr)), (void *)ref);

    dbg_xattr("success on saving xref (ino=%u, xid=%u)\n", ref->ic->ino, ref->xd->xid);

    return 0;
}

static struct jffs2_xattr_ref *create_xattr_ref(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic,
                        struct jffs2_xattr_datum *xd)
{
    /* must be called under down_write(xattr_sem) */
    struct jffs2_xattr_ref *ref;
    int ret;

    ref = jffs2_alloc_xattr_ref();
    if (!ref)
        return ERR_PTR(-ENOMEM);
    ref->ic = ic;
    ref->xd = xd;

    ret = save_xattr_ref(c, ref);
    if (ret) {
        jffs2_free_xattr_ref(ref);
        return ERR_PTR(ret);
    }

    /* Chain to inode */
    ref->next = ic->xref;
    ic->xref = ref;

    return ref; /* success */
}

static void delete_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref)
{
    /* must be called under down_write(xattr_sem) */
    struct jffs2_xattr_datum *xd;

    xd = ref->xd;
    ref->xseqno |= XREF_DELETE_MARKER;
    ref->ino = ref->ic->ino;
    ref->xid = ref->xd->xid;
    spin_lock(&c->erase_completion_lock);
    ref->next = c->xref_dead_list;
    c->xref_dead_list = ref;
    spin_unlock(&c->erase_completion_lock);

    dbg_xattr("xref(ino=%u, xid=%u, xseqno=%u) was removed.\n",
          ref->ino, ref->xid, ref->xseqno);

    unrefer_xattr_datum(c, xd);
}

void jffs2_xattr_delete_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic)
{
    /* It's called from jffs2_evict_inode() on inode removing.
       When an inode with XATTR is removed, those XATTRs must be removed. */
    struct jffs2_xattr_ref *ref, *_ref;

    if (!ic || ic->pino_nlink > 0)
        return;

    down_write(&c->xattr_sem);
    for (ref = ic->xref; ref; ref = _ref) {
        _ref = ref->next;
        delete_xattr_ref(c, ref);
    }
    ic->xref = NULL;
    up_write(&c->xattr_sem);
}

void jffs2_xattr_free_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic)
{
    /* It's called from jffs2_free_ino_caches() until unmounting FS. */
    struct jffs2_xattr_datum *xd;
    struct jffs2_xattr_ref *ref, *_ref;

    down_write(&c->xattr_sem);
    for (ref = ic->xref; ref; ref = _ref) {
        _ref = ref->next;
        xd = ref->xd;
        if (atomic_dec_and_test(&xd->refcnt)) {
            unload_xattr_datum(c, xd);
            jffs2_free_xattr_datum(xd);
        }
        jffs2_free_xattr_ref(ref);
    }
    ic->xref = NULL;
    up_write(&c->xattr_sem);
}

static int check_xattr_ref_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic)
{
    /* success of check_xattr_ref_inode() means that inode (ic) dose not have
     * duplicate name/value pairs. If duplicate name/value pair would be found,
     * one will be removed.
     */
    struct jffs2_xattr_ref *ref, *cmp, **pref, **pcmp;
    int rc = 0;

    if (likely(ic->flags & INO_FLAGS_XATTR_CHECKED))
        return 0;
    down_write(&c->xattr_sem);
 retry:
    rc = 0;
    for (ref=ic->xref, pref=&ic->xref; ref; pref=&ref->next, ref=ref->next) {
        if (!ref->xd->xname) {
            rc = load_xattr_datum(c, ref->xd);
            if (unlikely(rc > 0)) {
                *pref = ref->next;
                delete_xattr_ref(c, ref);
                goto retry;
            } else if (unlikely(rc < 0))
                goto out;
        }
        for (cmp=ref->next, pcmp=&ref->next; cmp; pcmp=&cmp->next, cmp=cmp->next) {
            if (!cmp->xd->xname) {
                ref->xd->flags |= JFFS2_XFLAGS_BIND;
                rc = load_xattr_datum(c, cmp->xd);
                ref->xd->flags &= ~JFFS2_XFLAGS_BIND;
                if (unlikely(rc > 0)) {
                    *pcmp = cmp->next;
                    delete_xattr_ref(c, cmp);
                    goto retry;
                } else if (unlikely(rc < 0))
                    goto out;
            }
            if (ref->xd->xprefix == cmp->xd->xprefix
                && !strcmp(ref->xd->xname, cmp->xd->xname)) {
                if (ref->xseqno > cmp->xseqno) {
                    *pcmp = cmp->next;
                    delete_xattr_ref(c, cmp);
                } else {
                    *pref = ref->next;
                    delete_xattr_ref(c, ref);
                }
                goto retry;
            }
        }
    }
    ic->flags |= INO_FLAGS_XATTR_CHECKED;
 out:
    up_write(&c->xattr_sem);

    return rc;
}

void jffs2_xattr_do_crccheck_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic)
{
    check_xattr_ref_inode(c, ic);
}

/* -------- xattr subsystem functions ---------------
 * jffs2_init_xattr_subsystem(c)
 *   is used to initialize semaphore and list_head, and some variables.
 * jffs2_find_xattr_datum(c, xid)
 *   is used to lookup xdatum while scanning process.
 * jffs2_clear_xattr_subsystem(c)
 *   is used to release any xattr related objects.
 * jffs2_build_xattr_subsystem(c)
 *   is used to associate xdatum and xref while super block building process.
 * jffs2_setup_xattr_datum(c, xid, version)
 *   is used to insert xdatum while scanning process.
 * -------------------------------------------------- */
void jffs2_init_xattr_subsystem(struct jffs2_sb_info *c)
{
    int i;

    for (i=0; i < XATTRINDEX_HASHSIZE; i++)
        INIT_LIST_HEAD(&c->xattrindex[i]);
    INIT_LIST_HEAD(&c->xattr_unchecked);
    INIT_LIST_HEAD(&c->xattr_dead_list);
    c->xref_dead_list = NULL;
    c->xref_temp = NULL;

    init_rwsem(&c->xattr_sem);
    c->highest_xid = 0;
    c->highest_xseqno = 0;
    c->xdatum_mem_usage = 0;
    c->xdatum_mem_threshold = 32 * 1024;    /* Default 32KB */
}

static struct jffs2_xattr_datum *jffs2_find_xattr_datum(struct jffs2_sb_info *c, uint32_t xid)
{
    struct jffs2_xattr_datum *xd;
    int i = xid % XATTRINDEX_HASHSIZE;

    /* It's only used in scanning/building process. */
    BUG_ON(!(c->flags & (JFFS2_SB_FLAG_SCANNING|JFFS2_SB_FLAG_BUILDING)));

    list_for_each_entry(xd, &c->xattrindex[i], xindex) {
        if (xd->xid==xid)
            return xd;
    }
    return NULL;
}

void jffs2_clear_xattr_subsystem(struct jffs2_sb_info *c)
{
    struct jffs2_xattr_datum *xd, *_xd;
    struct jffs2_xattr_ref *ref, *_ref;
    int i;

    for (ref=c->xref_temp; ref; ref = _ref) {
        _ref = ref->next;
        jffs2_free_xattr_ref(ref);
    }

    for (ref=c->xref_dead_list; ref; ref = _ref) {
        _ref = ref->next;
        jffs2_free_xattr_ref(ref);
    }

    for (i=0; i < XATTRINDEX_HASHSIZE; i++) {
        list_for_each_entry_safe(xd, _xd, &c->xattrindex[i], xindex) {
            list_del(&xd->xindex);
            if (xd->xname)
                kfree(xd->xname);
            jffs2_free_xattr_datum(xd);
        }
    }

    list_for_each_entry_safe(xd, _xd, &c->xattr_dead_list, xindex) {
        list_del(&xd->xindex);
        jffs2_free_xattr_datum(xd);
    }
    list_for_each_entry_safe(xd, _xd, &c->xattr_unchecked, xindex) {
        list_del(&xd->xindex);
        jffs2_free_xattr_datum(xd);
    }
}

#define XREF_TMPHASH_SIZE   (128)
void jffs2_build_xattr_subsystem(struct jffs2_sb_info *c)
{
    struct jffs2_xattr_ref *ref, *_ref;
    struct jffs2_xattr_ref *xref_tmphash[XREF_TMPHASH_SIZE];
    struct jffs2_xattr_datum *xd, *_xd;
    struct jffs2_inode_cache *ic;
    struct jffs2_raw_node_ref *raw;
    int i, xdatum_count = 0, xdatum_unchecked_count = 0, xref_count = 0;
    int xdatum_orphan_count = 0, xref_orphan_count = 0, xref_dead_count = 0;

    BUG_ON(!(c->flags & JFFS2_SB_FLAG_BUILDING));

    /* Phase.1 : Merge same xref */
    for (i=0; i < XREF_TMPHASH_SIZE; i++)
        xref_tmphash[i] = NULL;
    for (ref=c->xref_temp; ref; ref=_ref) {
        struct jffs2_xattr_ref *tmp;

        _ref = ref->next;
        if (ref_flags(ref->node) != REF_PRISTINE) {
            if (verify_xattr_ref(c, ref)) {
                BUG_ON(ref->node->next_in_ino != (void *)ref);
                ref->node->next_in_ino = NULL;
                jffs2_mark_node_obsolete(c, ref->node);
                jffs2_free_xattr_ref(ref);
                continue;
            }
        }

        i = (ref->ino ^ ref->xid) % XREF_TMPHASH_SIZE;
        for (tmp=xref_tmphash[i]; tmp; tmp=tmp->next) {
            if (tmp->ino == ref->ino && tmp->xid == ref->xid)
                break;
        }
        if (tmp) {
            raw = ref->node;
            if (ref->xseqno > tmp->xseqno) {
                tmp->xseqno = ref->xseqno;
                raw->next_in_ino = tmp->node;
                tmp->node = raw;
            } else {
                raw->next_in_ino = tmp->node->next_in_ino;
                tmp->node->next_in_ino = raw;
            }
            jffs2_free_xattr_ref(ref);
            continue;
        } else {
            ref->next = xref_tmphash[i];
            xref_tmphash[i] = ref;
        }
    }
    c->xref_temp = NULL;

    /* Phase.2 : Bind xref with inode_cache and xattr_datum */
    for (i=0; i < XREF_TMPHASH_SIZE; i++) {
        for (ref=xref_tmphash[i]; ref; ref=_ref) {
            xref_count++;
            _ref = ref->next;
            if (is_xattr_ref_dead(ref)) {
                ref->next = c->xref_dead_list;
                c->xref_dead_list = ref;
                xref_dead_count++;
                continue;
            }
            /* At this point, ref->xid and ref->ino contain XID and inode number.
               ref->xd and ref->ic are not valid yet. */
            xd = jffs2_find_xattr_datum(c, ref->xid);
            ic = jffs2_get_ino_cache(c, ref->ino);
            if (!xd || !ic || !ic->pino_nlink) {
                dbg_xattr("xref(ino=%u, xid=%u, xseqno=%u) is orphan.\n",
                      ref->ino, ref->xid, ref->xseqno);
                ref->xseqno |= XREF_DELETE_MARKER;
                ref->next = c->xref_dead_list;
                c->xref_dead_list = ref;
                xref_orphan_count++;
                continue;
            }
            ref->xd = xd;
            ref->ic = ic;
            atomic_inc(&xd->refcnt);
            ref->next = ic->xref;
            ic->xref = ref;
        }
    }

    /* Phase.3 : Link unchecked xdatum to xattr_unchecked list */
    for (i=0; i < XATTRINDEX_HASHSIZE; i++) {
        list_for_each_entry_safe(xd, _xd, &c->xattrindex[i], xindex) {
            xdatum_count++;
            list_del_init(&xd->xindex);
            if (!atomic_read(&xd->refcnt)) {
                dbg_xattr("xdatum(xid=%u, version=%u) is orphan.\n",
                      xd->xid, xd->version);
                xd->flags |= JFFS2_XFLAGS_DEAD;
                list_add(&xd->xindex, &c->xattr_unchecked);
                xdatum_orphan_count++;
                continue;
            }
            if (is_xattr_datum_unchecked(c, xd)) {
                dbg_xattr("unchecked xdatum(xid=%u, version=%u)\n",
                      xd->xid, xd->version);
                list_add(&xd->xindex, &c->xattr_unchecked);
                xdatum_unchecked_count++;
            }
        }
    }
    /* build complete */
    JFFS2_NOTICE("complete building xattr subsystem, %u of xdatum"
             " (%u unchecked, %u orphan) and "
             "%u of xref (%u dead, %u orphan) found.\n",
             xdatum_count, xdatum_unchecked_count, xdatum_orphan_count,
             xref_count, xref_dead_count, xref_orphan_count);
}

struct jffs2_xattr_datum *jffs2_setup_xattr_datum(struct jffs2_sb_info *c,
                          uint32_t xid, uint32_t version)
{
    struct jffs2_xattr_datum *xd;

    xd = jffs2_find_xattr_datum(c, xid);
    if (!xd) {
        xd = jffs2_alloc_xattr_datum();
        if (!xd)
            return ERR_PTR(-ENOMEM);
        xd->xid = xid;
        xd->version = version;
        if (xd->xid > c->highest_xid)
            c->highest_xid = xd->xid;
        list_add_tail(&xd->xindex, &c->xattrindex[xid % XATTRINDEX_HASHSIZE]);
    }
    return xd;
}

/* -------- xattr subsystem functions ---------------
 * xprefix_to_handler(xprefix)
 *   is used to translate xprefix into xattr_handler.
 * jffs2_listxattr(dentry, buffer, size)
 *   is an implementation of listxattr handler on jffs2.
 * do_jffs2_getxattr(inode, xprefix, xname, buffer, size)
 *   is an implementation of getxattr handler on jffs2.
 * do_jffs2_setxattr(inode, xprefix, xname, buffer, size, flags)
 *   is an implementation of setxattr handler on jffs2.
 * -------------------------------------------------- */
const struct xattr_handler *jffs2_xattr_handlers[] = {
    &jffs2_user_xattr_handler,
#ifdef CONFIG_JFFS2_FS_SECURITY
    &jffs2_security_xattr_handler,
#endif
#ifdef CONFIG_JFFS2_FS_POSIX_ACL
    &jffs2_acl_access_xattr_handler,
    &jffs2_acl_default_xattr_handler,
#endif
    &jffs2_trusted_xattr_handler,
    NULL
};

static const struct xattr_handler *xprefix_to_handler(int xprefix) {
    const struct xattr_handler *ret;

    switch (xprefix) {
    case JFFS2_XPREFIX_USER:
        ret = &jffs2_user_xattr_handler;
        break;
#ifdef CONFIG_JFFS2_FS_SECURITY
    case JFFS2_XPREFIX_SECURITY:
        ret = &jffs2_security_xattr_handler;
        break;
#endif
#ifdef CONFIG_JFFS2_FS_POSIX_ACL
    case JFFS2_XPREFIX_ACL_ACCESS:
        ret = &jffs2_acl_access_xattr_handler;
        break;
    case JFFS2_XPREFIX_ACL_DEFAULT:
        ret = &jffs2_acl_default_xattr_handler;
        break;
#endif
    case JFFS2_XPREFIX_TRUSTED:
        ret = &jffs2_trusted_xattr_handler;
        break;
    default:
        ret = NULL;
        break;
    }
    return ret;
}

ssize_t jffs2_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
    struct inode *inode = dentry->d_inode;
    struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
    struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
    struct jffs2_inode_cache *ic = f->inocache;
    struct jffs2_xattr_ref *ref, **pref;
    struct jffs2_xattr_datum *xd;
    const struct xattr_handler *xhandle;
    ssize_t len, rc;
    int retry = 0;

    rc = check_xattr_ref_inode(c, ic);
    if (unlikely(rc))
        return rc;

    down_read(&c->xattr_sem);
 retry:
    len = 0;
    for (ref=ic->xref, pref=&ic->xref; ref; pref=&ref->next, ref=ref->next) {
        BUG_ON(ref->ic != ic);
        xd = ref->xd;
        if (!xd->xname) {
            /* xdatum is unchached */
            if (!retry) {
                retry = 1;
                up_read(&c->xattr_sem);
                down_write(&c->xattr_sem);
                goto retry;
            } else {
                rc = load_xattr_datum(c, xd);
                if (unlikely(rc > 0)) {
                    *pref = ref->next;
                    delete_xattr_ref(c, ref);
                    goto retry;
                } else if (unlikely(rc < 0))
                    goto out;
            }
        }
        xhandle = xprefix_to_handler(xd->xprefix);
        if (!xhandle)
            continue;
        if (buffer) {
            rc = xhandle->list(dentry, buffer+len, size-len,
                       xd->xname, xd->name_len, xd->flags);
        } else {
            rc = xhandle->list(dentry, NULL, 0, xd->xname,
                       xd->name_len, xd->flags);
        }
        if (rc < 0)
            goto out;
        len += rc;
    }
    rc = len;
 out:
    if (!retry) {
        up_read(&c->xattr_sem);
    } else {
        up_write(&c->xattr_sem);
    }
    return rc;
}

int do_jffs2_getxattr(struct inode *inode, int xprefix, const char *xname,
              char *buffer, size_t size)
{
    struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
    struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
    struct jffs2_inode_cache *ic = f->inocache;
    struct jffs2_xattr_datum *xd;
    struct jffs2_xattr_ref *ref, **pref;
    int rc, retry = 0;

    rc = check_xattr_ref_inode(c, ic);
    if (unlikely(rc))
        return rc;

    down_read(&c->xattr_sem);
 retry:
    for (ref=ic->xref, pref=&ic->xref; ref; pref=&ref->next, ref=ref->next) {
        BUG_ON(ref->ic!=ic);

        xd = ref->xd;
        if (xd->xprefix != xprefix)
            continue;
        if (!xd->xname) {
            /* xdatum is unchached */
            if (!retry) {
                retry = 1;
                up_read(&c->xattr_sem);
                down_write(&c->xattr_sem);
                goto retry;
            } else {
                rc = load_xattr_datum(c, xd);
                if (unlikely(rc > 0)) {
                    *pref = ref->next;
                    delete_xattr_ref(c, ref);
                    goto retry;
                } else if (unlikely(rc < 0)) {
                    goto out;
                }
            }
        }
        if (!strcmp(xname, xd->xname)) {
            rc = xd->value_len;
            if (buffer) {
                if (size < rc) {
                    rc = -ERANGE;
                } else {
                    memcpy(buffer, xd->xvalue, rc);
                }
            }
            goto out;
        }
    }
    rc = -ENODATA;
 out:
    if (!retry) {
        up_read(&c->xattr_sem);
    } else {
        up_write(&c->xattr_sem);
    }
    return rc;
}

int do_jffs2_setxattr(struct inode *inode, int xprefix, const char *xname,
              const char *buffer, size_t size, int flags)
{
    struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
    struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
    struct jffs2_inode_cache *ic = f->inocache;
    struct jffs2_xattr_datum *xd;
    struct jffs2_xattr_ref *ref, *newref, **pref;
    uint32_t length, request;
    int rc;

    rc = check_xattr_ref_inode(c, ic);
    if (unlikely(rc))
        return rc;

    request = PAD(sizeof(struct jffs2_raw_xattr) + strlen(xname) + 1 + size);
    rc = jffs2_reserve_space(c, request, &length,
                 ALLOC_NORMAL, JFFS2_SUMMARY_XATTR_SIZE);
    if (rc) {
        JFFS2_WARNING("jffs2_reserve_space()=%d, request=%u\n", rc, request);
        return rc;
    }

    /* Find existing xattr */
    down_write(&c->xattr_sem);
 retry:
    for (ref=ic->xref, pref=&ic->xref; ref; pref=&ref->next, ref=ref->next) {
        xd = ref->xd;
        if (xd->xprefix != xprefix)
            continue;
        if (!xd->xname) {
            rc = load_xattr_datum(c, xd);
            if (unlikely(rc > 0)) {
                *pref = ref->next;
                delete_xattr_ref(c, ref);
                goto retry;
            } else if (unlikely(rc < 0))
                goto out;
        }
        if (!strcmp(xd->xname, xname)) {
            if (flags & XATTR_CREATE) {
                rc = -EEXIST;
                goto out;
            }
            if (!buffer) {
                ref->ino = ic->ino;
                ref->xid = xd->xid;
                ref->xseqno |= XREF_DELETE_MARKER;
                rc = save_xattr_ref(c, ref);
                if (!rc) {
                    *pref = ref->next;
                    spin_lock(&c->erase_completion_lock);
                    ref->next = c->xref_dead_list;
                    c->xref_dead_list = ref;
                    spin_unlock(&c->erase_completion_lock);
                    unrefer_xattr_datum(c, xd);
                } else {
                    ref->ic = ic;
                    ref->xd = xd;
                    ref->xseqno &= ~XREF_DELETE_MARKER;
                }
                goto out;
            }
            goto found;
        }
    }
    /* not found */
    if (flags & XATTR_REPLACE) {
        rc = -ENODATA;
        goto out;
    }
    if (!buffer) {
        rc = -ENODATA;
        goto out;
    }
 found:
    xd = create_xattr_datum(c, xprefix, xname, buffer, size);
    if (IS_ERR(xd)) {
        rc = PTR_ERR(xd);
        goto out;
    }
    up_write(&c->xattr_sem);
    jffs2_complete_reservation(c);

    /* create xattr_ref */
    request = PAD(sizeof(struct jffs2_raw_xref));
    rc = jffs2_reserve_space(c, request, &length,
                 ALLOC_NORMAL, JFFS2_SUMMARY_XREF_SIZE);
    down_write(&c->xattr_sem);
    if (rc) {
        JFFS2_WARNING("jffs2_reserve_space()=%d, request=%u\n", rc, request);
        unrefer_xattr_datum(c, xd);
        up_write(&c->xattr_sem);
        return rc;
    }
    if (ref)
        *pref = ref->next;
    newref = create_xattr_ref(c, ic, xd);
    if (IS_ERR(newref)) {
        if (ref) {
            ref->next = ic->xref;
            ic->xref = ref;
        }
        rc = PTR_ERR(newref);
        unrefer_xattr_datum(c, xd);
    } else if (ref) {
        delete_xattr_ref(c, ref);
    }
 out:
    up_write(&c->xattr_sem);
    jffs2_complete_reservation(c);
    return rc;
}

/* -------- garbage collector functions -------------
 * jffs2_garbage_collect_xattr_datum(c, xd, raw)
 *   is used to move xdatum into new node.
 * jffs2_garbage_collect_xattr_ref(c, ref, raw)
 *   is used to move xref into new node.
 * jffs2_verify_xattr(c)
 *   is used to call do_verify_xattr_datum() before garbage collecting.
 * jffs2_release_xattr_datum(c, xd)
 *   is used to release an in-memory object of xdatum.
 * jffs2_release_xattr_ref(c, ref)
 *   is used to release an in-memory object of xref.
 * -------------------------------------------------- */
int jffs2_garbage_collect_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd,
                      struct jffs2_raw_node_ref *raw)
{
    uint32_t totlen, length, old_ofs;
    int rc = 0;

    down_write(&c->xattr_sem);
    if (xd->node != raw)
        goto out;
    if (xd->flags & (JFFS2_XFLAGS_DEAD|JFFS2_XFLAGS_INVALID))
        goto out;

    rc = load_xattr_datum(c, xd);
    if (unlikely(rc)) {
        rc = (rc > 0) ? 0 : rc;
        goto out;
    }
    old_ofs = ref_offset(xd->node);
    totlen = PAD(sizeof(struct jffs2_raw_xattr)
            + xd->name_len + 1 + xd->value_len);
    rc = jffs2_reserve_space_gc(c, totlen, &length, JFFS2_SUMMARY_XATTR_SIZE);
    if (rc) {
        JFFS2_WARNING("jffs2_reserve_space_gc()=%d, request=%u\n", rc, totlen);
        goto out;
    }
    rc = save_xattr_datum(c, xd);
    if (!rc)
        dbg_xattr("xdatum (xid=%u, version=%u) GC'ed from %#08x to %08x\n",
              xd->xid, xd->version, old_ofs, ref_offset(xd->node));
 out:
    if (!rc)
        jffs2_mark_node_obsolete(c, raw);
    up_write(&c->xattr_sem);
    return rc;
}

int jffs2_garbage_collect_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref,
                    struct jffs2_raw_node_ref *raw)
{
    uint32_t totlen, length, old_ofs;
    int rc = 0;

    down_write(&c->xattr_sem);
    BUG_ON(!ref->node);

    if (ref->node != raw)
        goto out;
    if (is_xattr_ref_dead(ref) && (raw->next_in_ino == (void *)ref))
        goto out;

    old_ofs = ref_offset(ref->node);
    totlen = ref_totlen(c, c->gcblock, ref->node);

    rc = jffs2_reserve_space_gc(c, totlen, &length, JFFS2_SUMMARY_XREF_SIZE);
    if (rc) {
        JFFS2_WARNING("%s: jffs2_reserve_space_gc() = %d, request = %u\n",
                  __func__, rc, totlen);
        rc = rc ? rc : -EBADFD;
        goto out;
    }
    rc = save_xattr_ref(c, ref);
    if (!rc)
        dbg_xattr("xref (ino=%u, xid=%u) GC'ed from %#08x to %08x\n",
              ref->ic->ino, ref->xd->xid, old_ofs, ref_offset(ref->node));
 out:
    if (!rc)
        jffs2_mark_node_obsolete(c, raw);
    up_write(&c->xattr_sem);
    return rc;
}

int jffs2_verify_xattr(struct jffs2_sb_info *c)
{
    struct jffs2_xattr_datum *xd, *_xd;
    struct jffs2_eraseblock *jeb;
    struct jffs2_raw_node_ref *raw;
    uint32_t totlen;
    int rc;

    down_write(&c->xattr_sem);
    list_for_each_entry_safe(xd, _xd, &c->xattr_unchecked, xindex) {
        rc = do_verify_xattr_datum(c, xd);
        if (rc < 0)
            continue;
        list_del_init(&xd->xindex);
        spin_lock(&c->erase_completion_lock);
        for (raw=xd->node; raw != (void *)xd; raw=raw->next_in_ino) {
            if (ref_flags(raw) != REF_UNCHECKED)
                continue;
            jeb = &c->blocks[ref_offset(raw) / c->sector_size];
            totlen = PAD(ref_totlen(c, jeb, raw));
            c->unchecked_size -= totlen; c->used_size += totlen;
            jeb->unchecked_size -= totlen; jeb->used_size += totlen;
            raw->flash_offset = ref_offset(raw)
                | ((xd->node == (void *)raw) ? REF_PRISTINE : REF_NORMAL);
        }
        if (xd->flags & JFFS2_XFLAGS_DEAD)
            list_add(&xd->xindex, &c->xattr_dead_list);
        spin_unlock(&c->erase_completion_lock);
    }
    up_write(&c->xattr_sem);
    return list_empty(&c->xattr_unchecked) ? 1 : 0;
}

void jffs2_release_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
    /* must be called under spin_lock(&c->erase_completion_lock) */
    if (atomic_read(&xd->refcnt) || xd->node != (void *)xd)
        return;

    list_del(&xd->xindex);
    jffs2_free_xattr_datum(xd);
}

void jffs2_release_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref)
{
    /* must be called under spin_lock(&c->erase_completion_lock) */
    struct jffs2_xattr_ref *tmp, **ptmp;

    if (ref->node != (void *)ref)
        return;

    for (tmp=c->xref_dead_list, ptmp=&c->xref_dead_list; tmp; ptmp=&tmp->next, tmp=tmp->next) {
        if (ref == tmp) {
            *ptmp = tmp->next;
            break;
        }
    }
    jffs2_free_xattr_ref(ref);
}