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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. Currentry, 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", __FUNCTION__, 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_clear_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->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 taht 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->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.
 * -------------------------------------------------- */
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 struct xattr_handler *xprefix_to_handler(int xprefix) {
      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;
      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(inode, buffer+len, size-len, xd->xname, xd->name_len);
            } else {
                  rc = xhandle->list(inode, NULL, 0, xd->xname, xd->name_len);
            }
            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",
                        __FUNCTION__, 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);
}

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