Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

[linux-2.6/linux-mips.git] / fs / jffs2 / xattr.c

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2006  NEC Corporation
 *
 * Created by KaiGai Kohei <kaigai@ak.jp.nec.com>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#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 -EIO;
        }
        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 -EIO;
        }
        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_XREF)"
                              " 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 -EIO;
        }

        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 -EIO;
        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.
 * -------------------------------------------------- */
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 -EIO;
        }
        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 -EIO;
        }
        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;
}

/* -------- 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);
}