/*
   * 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
  ", __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)
  ",
  		     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
  ",

  			      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
  ",
  			    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
  ",

  			    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)
  ",
  		  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
  ",

  			      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
  ",
  			      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')
  ",
  		  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 = ℞

  	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
  ",

  			      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')
  ",
  		  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.
  ",
  			  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
  ",

  			      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
  ",
  			    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
  ",

  			    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
  ",
  		  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
  ",

  			      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)
  ", 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.
  ",
  		  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.
  ",
  					  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.
  ",
  					  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)
  ",
  					  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.
  ",
  		     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
  ", 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
  ", 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
  ", 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
  ",
  			  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
  ",

  			      __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
  ",
  			  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);

  }