[JFFS2][XATTR] XATTR support on JFFS2 (version. 5)

This attached patches provide xattr support including POSIX-ACL and
SELinux support on JFFS2 (version.5).

There are some significant differences from previous version posted
at last December.
The biggest change is addition of EBS(Erase Block Summary) support.
Currently, both kernel and usermode utility (sumtool) can recognize
xattr nodes which have JFFS2_NODETYPE_XATTR/_XREF nodetype.

In addition, some bugs are fixed.
- A potential race condition was fixed.
- Unexpected fail when updating a xattr by same name/value pair was fixed.
- A bug when removing xattr name/value pair was fixed.

The fundamental structures (such as using two new nodetypes and exclusion
mechanism by rwsem) are unchanged. But most of implementation were reviewed
and updated if necessary.
Espacially, we had to change several internal implementations related to
load_xattr_datum() to avoid a potential race condition.

[1/2] xattr_on_jffs2.kernel.version-5.patch
[2/2] xattr_on_jffs2.utils.version-5.patch

Signed-off-by: KaiGai Kohei <kaigai@ak.jp.nec.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 1271 insertions, 0 deletions

diff --git a/fs/jffs2/xattr.c b/fs/jffs2/xattr.c
new file mode 100644
index 0000000..c9a185c
--- /dev/null
+++ b/fs/jffs2/xattr.c
@@ -0,0 +1,1271 @@
+/* -------------------------------------------------------------------------
+ *  File: fs/jffs2/xattr.c
+ *  XATTR support on JFFS2 FileSystem
+ *
+ *  Implemented by KaiGai Kohei <kaigai@ak.jp.nec.com>
+ *  Copyright (C) 2006 NEC Corporation
+ *
+ *  For licensing information, see the file 'LICENCE' in the jffs2 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).
+ * 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.
+ * delete_xattr_datum_node(c, xd)
+ *   is used to delete a jffs2 node is dominated by xdatum. When EBS(Erase Block Summary) is
+ *   enabled, it overwrites the obsolete node by myself.
+ * delete_xattr_datum(c, xd)
+ *   is used to delete jffs2_xattr_datum object. It must be called with 0-value of reference
+ *   counter. (It means how many jffs2_xattr_ref object refers this xdatum.)
+ * 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, phys_ofs)
+ *   is used to write xdatum to medium. xd->version will be incremented.
+ * create_xattr_datum(c, xprefix, xname, xvalue, xsize, phys_ofs)
+ *   is used to create new xdatum and write to medium.
+ * -------------------------------------------------- */
+
+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 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 void delete_xattr_datum_node(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
+{
+	/* must be called under down_write(xattr_sem) */
+	struct jffs2_raw_xattr rx;
+	uint32_t length;
+	int rc;
+
+	if (!xd->node) {
+		JFFS2_WARNING("xdatum (xid=%u) is removed twice.\n", xd->xid);
+		return;
+	}
+	if (jffs2_sum_active()) {
+		memset(&rx, 0xff, sizeof(struct jffs2_raw_xattr));
+		rc = jffs2_flash_read(c, ref_offset(xd->node),
+				      sizeof(struct jffs2_unknown_node),
+				      &length, (char *)&rx);
+		if (rc || length != sizeof(struct jffs2_unknown_node)) {
+			JFFS2_ERROR("jffs2_flash_read()=%d, req=%u, read=%u at %#08x\n",
+				    rc, sizeof(struct jffs2_unknown_node),
+				    length, ref_offset(xd->node));
+		}
+		rc = jffs2_flash_write(c, ref_offset(xd->node), sizeof(rx),
+				       &length, (char *)&rx);
+		if (rc || length != sizeof(struct jffs2_raw_xattr)) {
+			JFFS2_ERROR("jffs2_flash_write()=%d, req=%u, wrote=%u ar %#08x\n",
+				    rc, sizeof(rx), length, ref_offset(xd->node));
+		}
+	}
+	spin_lock(&c->erase_completion_lock);
+	xd->node->next_in_ino = NULL;
+	spin_unlock(&c->erase_completion_lock);
+	jffs2_mark_node_obsolete(c, xd->node);
+	xd->node = NULL;
+}
+
+static void delete_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
+{
+	/* must be called under down_write(xattr_sem) */
+	BUG_ON(xd->refcnt);
+
+	unload_xattr_datum(c, xd);
+	if (xd->node) {
+		delete_xattr_datum_node(c, xd);
+		xd->node = NULL;
+	}
+	jffs2_free_xattr_datum(xd);
+}
+
+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_xattr rx;
+	size_t readlen;
+	uint32_t crc, totlen;
+	int rc;
+
+	BUG_ON(!xd->node);
+	BUG_ON(ref_flags(xd->node) != REF_UNCHECKED);
+
+	rc = jffs2_flash_read(c, ref_offset(xd->node), sizeof(rx), &readlen, (char *)&rx);
+	if (rc || readlen != sizeof(rx)) {
+		JFFS2_WARNING("jffs2_flash_read()=%d, req=%u, read=%u at %#08x\n",
+			      rc, sizeof(rx), readlen, ref_offset(xd->node));
+		return rc ? rc : -EIO;
+	}
+	crc = crc32(0, &rx, sizeof(rx) - 4);
+	if (crc != je32_to_cpu(rx.node_crc)) {
+		if (je32_to_cpu(rx.node_crc) != 0xffffffff)
+			JFFS2_ERROR("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
+				    ref_offset(xd->node), je32_to_cpu(rx.hdr_crc), crc);
+		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",
+			    ref_offset(xd->node), 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);
+		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);
+
+	/* This JFFS2_NODETYPE_XATTR node is checked */
+	jeb = &c->blocks[ref_offset(xd->node) / c->sector_size];
+	totlen = PAD(je32_to_cpu(rx.totlen));
+
+	spin_lock(&c->erase_completion_lock);
+	c->unchecked_size -= totlen; c->used_size += totlen;
+	jeb->unchecked_size -= totlen; jeb->used_size += totlen;
+	xd->node->flash_offset = ref_offset(xd->node) | REF_PRISTINE;
+	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(!xd->node);
+	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=%d, 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);
+		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->xname);
+	if (!xd->node)
+		return EIO;
+	if (unlikely(ref_flags(xd->node) != REF_PRISTINE)) {
+		rc = do_verify_xattr_datum(c, xd);
+		if (rc > 0) {
+			list_del_init(&xd->xindex);
+			delete_xattr_datum_node(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, uint32_t phys_ofs)
+{
+	/* must be called under down_write(xattr_sem) */
+	struct jffs2_raw_xattr rx;
+	struct jffs2_raw_node_ref *raw;
+	struct kvec vecs[2];
+	uint32_t length;
+	int rc, totlen;
+
+	BUG_ON(!xd->xname);
+
+	vecs[0].iov_base = &rx;
+	vecs[0].iov_len = PAD(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;
+
+	raw = jffs2_alloc_raw_node_ref();
+	if (!raw)
+		return -ENOMEM;
+	raw->flash_offset = phys_ofs;
+	raw->__totlen = PAD(totlen);
+	raw->next_phys = NULL;
+	raw->next_in_ino = (void *)xd;
+
+	/* Setup raw-xattr */
+	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=%u, at %#08x\n",
+			      rc, totlen, length, phys_ofs);
+		rc = rc ? rc : -EIO;
+		if (length) {
+			raw->flash_offset |= REF_OBSOLETE;
+			raw->next_in_ino = NULL;
+			jffs2_add_physical_node_ref(c, raw);
+			jffs2_mark_node_obsolete(c, raw);
+		} else {
+			jffs2_free_raw_node_ref(raw);
+		}
+		return rc;
+	}
+	BUG_ON(raw->__totlen < sizeof(struct jffs2_raw_xattr));
+	/* success */
+	raw->flash_offset |= REF_PRISTINE;
+	jffs2_add_physical_node_ref(c, raw);
+	if (xd->node)
+		delete_xattr_datum_node(c, xd);
+	xd->node = raw;
+
+	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,
+						    uint32_t phys_ofs)
+{
+	/* 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)) {
+			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);
+
+	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, phys_ofs);
+	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;
+}
+
+/* -------- xdatum 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.
+ * delete_xattr_ref_node(c, ref)
+ *   is used to delete a jffs2 node is dominated by xref. When EBS is enabled,
+ *   it overwrites the obsolete node by myself. 
+ * delete_xattr_ref(c, ref)
+ *   is used to delete jffs2_xattr_ref object. If the reference counter of xdatum
+ *   is refered by this xref become 0, delete_xattr_datum() is called later.
+ * save_xattr_ref(c, ref, phys_ofs)
+ *   is used to write xref to medium.
+ * create_xattr_ref(c, ic, xd, phys_ofs)
+ *   is used to create a new xref and write to medium.
+ * 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_ilist(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_xref rr;
+	size_t readlen;
+	uint32_t crc, totlen;
+	int rc;
+
+	BUG_ON(ref_flags(ref->node) != REF_UNCHECKED);
+
+	rc = jffs2_flash_read(c, ref_offset(ref->node), sizeof(rr), &readlen, (char *)&rr);
+	if (rc || sizeof(rr) != readlen) {
+		JFFS2_WARNING("jffs2_flash_read()=%d, req=%u, read=%u, at %#08x\n",
+			      rc, sizeof(rr), readlen, ref_offset(ref->node));
+		return rc ? rc : -EIO;
+	}
+	/* obsolete node */
+	crc = crc32(0, &rr, sizeof(rr) - 4);
+	if (crc != je32_to_cpu(rr.node_crc)) {
+		if (je32_to_cpu(rr.node_crc) != 0xffffffff)
+			JFFS2_ERROR("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
+				    ref_offset(ref->node), 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/%u\n",
+			    ref_offset(ref->node), 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);
+
+	/* fixup superblock/eraseblock info */
+	jeb = &c->blocks[ref_offset(ref->node) / c->sector_size];
+	totlen = PAD(sizeof(rr));
+
+	spin_lock(&c->erase_completion_lock);
+	c->unchecked_size -= totlen; c->used_size += totlen;
+	jeb->unchecked_size -= totlen; jeb->used_size += totlen;
+	ref->node->flash_offset = ref_offset(ref->node) | REF_PRISTINE;
+	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 void delete_xattr_ref_node(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref)
+{
+	struct jffs2_raw_xref rr;
+	uint32_t length;
+	int rc;
+
+	if (jffs2_sum_active()) {
+		memset(&rr, 0xff, sizeof(rr));
+		rc = jffs2_flash_read(c, ref_offset(ref->node),
+				      sizeof(struct jffs2_unknown_node),
+				      &length, (char *)&rr);
+		if (rc || length != sizeof(struct jffs2_unknown_node)) {
+			JFFS2_ERROR("jffs2_flash_read()=%d, req=%u, read=%u at %#08x\n",
+				    rc, sizeof(struct jffs2_unknown_node),
+				    length, ref_offset(ref->node));
+		}
+		rc = jffs2_flash_write(c, ref_offset(ref->node), sizeof(rr),
+				       &length, (char *)&rr);
+		if (rc || length != sizeof(struct jffs2_raw_xref)) {
+			JFFS2_ERROR("jffs2_flash_write()=%d, req=%u, wrote=%u at %#08x\n",
+				    rc, sizeof(rr), length, ref_offset(ref->node));
+		}
+	}
+	spin_lock(&c->erase_completion_lock);
+	ref->node->next_in_ino = NULL;
+	spin_unlock(&c->erase_completion_lock);
+	jffs2_mark_node_obsolete(c, ref->node);
+	ref->node = NULL;
+}
+
+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;
+
+	BUG_ON(!ref->node);
+	delete_xattr_ref_node(c, ref);
+
+	list_del(&ref->ilist);
+	xd = ref->xd;
+	xd->refcnt--;
+	if (!xd->refcnt)
+		delete_xattr_datum(c, xd);
+	jffs2_free_xattr_ref(ref);
+}
+
+static int save_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref, uint32_t phys_ofs)
+{
+	/* must be called under down_write(xattr_sem) */
+	struct jffs2_raw_node_ref *raw;
+	struct jffs2_raw_xref rr;
+	uint32_t length;
+	int ret;
+
+	raw = jffs2_alloc_raw_node_ref();
+	if (!raw)
+		return -ENOMEM;
+	raw->flash_offset = phys_ofs;
+	raw->__totlen = PAD(sizeof(rr));
+	raw->next_phys = NULL;
+	raw->next_in_ino = (void *)ref;
+
+	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));
+
+	rr.ino = cpu_to_je32(ref->ic->ino);
+	rr.xid = cpu_to_je32(ref->xd->xid);
+	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=%u, retlen=%u, at %#08x\n",
+			      ret, sizeof(rr), length, phys_ofs);
+		ret = ret ? ret : -EIO;
+		if (length) {
+			raw->flash_offset |= REF_OBSOLETE;
+			raw->next_in_ino = NULL;
+			jffs2_add_physical_node_ref(c, raw);
+			jffs2_mark_node_obsolete(c, raw);
+		} else {
+			jffs2_free_raw_node_ref(raw);
+		}
+		return ret;
+	}
+	raw->flash_offset |= REF_PRISTINE;
+
+	jffs2_add_physical_node_ref(c, raw);
+	if (ref->node)
+		delete_xattr_ref_node(c, ref);
+	ref->node = raw;
+
+	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, uint32_t phys_ofs)
+{
+	/* 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, phys_ofs);
+	if (ret) {
+		jffs2_free_xattr_ref(ref);
+		return ERR_PTR(ret);
+	}
+
+	/* Chain to inode */
+	list_add(&ref->ilist, &ic->ilist);
+
+	return ref; /* success */
+}
+
+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);
+	list_for_each_entry_safe(ref, _ref, &ic->ilist, ilist)
+		delete_xattr_ref(c, ref);
+	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);
+	list_for_each_entry_safe(ref, _ref, &ic->ilist, ilist) {
+		list_del(&ref->ilist);
+		xd = ref->xd;
+		xd->refcnt--;
+		if (!xd->refcnt) {
+			unload_xattr_datum(c, xd);
+			jffs2_free_xattr_datum(xd);
+		}
+		jffs2_free_xattr_ref(ref);
+	}
+	up_write(&c->xattr_sem);
+}
+
+static int check_xattr_ref_ilist(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic)
+{
+	/* success of check_xattr_ref_ilist() 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;
+	int rc = 0;
+
+	if (likely(ic->flags & INO_FLAGS_XATTR_CHECKED))
+		return 0;
+	down_write(&c->xattr_sem);
+ retry:
+	rc = 0;
+	list_for_each_entry(ref, &ic->ilist, ilist) {
+		if (!ref->xd->xname) {
+			rc = load_xattr_datum(c, ref->xd);
+			if (unlikely(rc > 0)) {
+				delete_xattr_ref(c, ref);
+				goto retry;
+			} else if (unlikely(rc < 0))
+				goto out;
+		}
+		cmp = ref;
+		list_for_each_entry_continue(cmp, &ic->ilist, ilist) {
+			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)) {
+					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)) {
+				delete_xattr_ref(c, cmp);
+				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_temp);
+	INIT_LIST_HEAD(&c->xattr_unchecked);
+
+	init_rwsem(&c->xattr_sem);
+	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;
+
+	list_for_each_entry_safe(ref, _ref, &c->xattr_temp, ilist)
+		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);
+		}
+	}
+}
+
+void jffs2_build_xattr_subsystem(struct jffs2_sb_info *c)
+{
+	struct jffs2_xattr_ref *ref, *_ref;
+	struct jffs2_xattr_datum *xd, *_xd;
+	struct jffs2_inode_cache *ic;
+	int i, xdatum_count =0, xdatum_unchecked_count = 0, xref_count = 0;
+
+	BUG_ON(!(c->flags & JFFS2_SB_FLAG_BUILDING));
+
+	/* Phase.1 */
+	list_for_each_entry_safe(ref, _ref, &c->xattr_temp, ilist) {
+		list_del_init(&ref->ilist);
+		/* checking REF_UNCHECKED nodes */
+		if (ref_flags(ref->node) != REF_PRISTINE) {
+			if (verify_xattr_ref(c, ref)) {
+				delete_xattr_ref_node(c, ref);
+				jffs2_free_xattr_ref(ref);
+				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) {
+			if (ref_flags(ref->node) != REF_UNCHECKED)
+				JFFS2_WARNING("xref(ino=%u, xid=%u) is orphan. \n",
+					      ref->ino, ref->xid);
+			delete_xattr_ref_node(c, ref);
+			jffs2_free_xattr_ref(ref);
+			continue;
+		}
+		ref->xd = xd;
+		ref->ic = ic;
+		xd->refcnt++;
+		list_add_tail(&ref->ilist, &ic->ilist);
+		xref_count++;
+	}
+	/* After this, ref->xid/ino are NEVER used. */
+
+	/* Phase.2 */
+	for (i=0; i < XATTRINDEX_HASHSIZE; i++) {
+		list_for_each_entry_safe(xd, _xd, &c->xattrindex[i], xindex) {
+			list_del_init(&xd->xindex);
+			if (!xd->refcnt) {
+				if (ref_flags(xd->node) != REF_UNCHECKED)
+					JFFS2_WARNING("orphan xdatum(xid=%u, version=%u) at %#08x\n",
+						      xd->xid, xd->version, ref_offset(xd->node));
+				delete_xattr_datum(c, xd);
+				continue;
+			}
+			if (ref_flags(xd->node) != REF_PRISTINE) {
+				dbg_xattr("unchecked xdatum(xid=%u) at %#08x\n",
+					  xd->xid, ref_offset(xd->node));
+				list_add(&xd->xindex, &c->xattr_unchecked);
+				xdatum_unchecked_count++;
+			}
+			xdatum_count++;
+		}
+	}
+	/* build complete */
+	JFFS2_NOTICE("complete building xattr subsystem, %u of xdatum (%u unchecked) and "
+		     "%u of xref found.\n", xdatum_count, xdatum_unchecked_count, xref_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;
+
+	_xd = jffs2_find_xattr_datum(c, xid);
+	if (_xd) {
+		dbg_xattr("duplicate xdatum (xid=%u, version=%u/%u) at %#08x\n",
+			  xid, version, _xd->version, ref_offset(_xd->node));
+		if (version < _xd->version)
+			return ERR_PTR(-EEXIST);
+	}
+	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]);
+
+	if (_xd) {
+		list_del_init(&_xd->xindex);
+		delete_xattr_datum_node(c, _xd);
+		jffs2_free_xattr_datum(_xd);
+	}
+	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;
+	struct jffs2_xattr_datum *xd;
+	struct xattr_handler *xhandle;
+	ssize_t len, rc;
+	int retry = 0;
+
+	rc = check_xattr_ref_ilist(c, ic);
+	if (unlikely(rc))
+		return rc;
+
+	down_read(&c->xattr_sem);
+ retry:
+	len = 0;
+	list_for_each_entry(ref, &ic->ilist, ilist) {
+		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)) {
+					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;
+	int rc, retry = 0;
+
+	rc = check_xattr_ref_ilist(c, ic);
+	if (unlikely(rc))
+		return rc;
+
+	down_read(&c->xattr_sem);
+ retry:
+	list_for_each_entry(ref, &ic->ilist, ilist) {
+		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)) {
+					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;
+	uint32_t phys_ofs, length, request;
+	int rc;
+
+	rc = check_xattr_ref_ilist(c, ic);
+	if (unlikely(rc))
+		return rc;
+
+	request = PAD(sizeof(struct jffs2_raw_xattr) + strlen(xname) + 1 + size);
+	rc = jffs2_reserve_space(c, request, &phys_ofs, &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:
+	list_for_each_entry(ref, &ic->ilist, ilist) {
+		xd = ref->xd;
+		if (xd->xprefix != xprefix)
+			continue;
+		if (!xd->xname) {
+			rc = load_xattr_datum(c, xd);
+			if (unlikely(rc > 0)) {
+				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) {
+				delete_xattr_ref(c, ref);
+				rc = 0;
+				goto out;
+			}
+			goto found;
+		}
+	}
+	/* not found */
+	ref = NULL;
+	if (flags & XATTR_REPLACE) {
+		rc = -ENODATA;
+		goto out;
+	}
+	if (!buffer) {
+		rc = -EINVAL;
+		goto out;
+	}
+ found:
+	xd = create_xattr_datum(c, xprefix, xname, buffer, size, phys_ofs);
+	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, &phys_ofs, &length,
+				 ALLOC_NORMAL, JFFS2_SUMMARY_XREF_SIZE);
+	if (rc) {
+		JFFS2_WARNING("jffs2_reserve_space()=%d, request=%u\n", rc, request);
+		down_write(&c->xattr_sem);
+		xd->refcnt--;
+		if (!xd->refcnt)
+			delete_xattr_datum(c, xd);
+		up_write(&c->xattr_sem);
+		return rc;
+	}
+	down_write(&c->xattr_sem);
+	newref = create_xattr_ref(c, ic, xd, phys_ofs);
+	if (IS_ERR(newref)) {
+		rc = PTR_ERR(newref);
+		xd->refcnt--;
+		if (!xd->refcnt)
+			delete_xattr_datum(c, xd);
+	} else if (ref) {
+		/* If replaced xattr_ref exists */
+		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)
+ *   is used to move xdatum into new node.
+ * jffs2_garbage_collect_xattr_ref(c, ref)
+ *   is used to move xref into new node.
+ * jffs2_garbage_collect_xattr(c, ic)
+ *   is used to call appropriate garbage collector function, if argument
+ *   pointer (ic) is the reference of xdatum/xref.
+ * jffs2_verify_xattr(c)
+ *   is used to call do_verify_xattr_datum() before garbage collecting.
+ * -------------------------------------------------- */
+static int jffs2_garbage_collect_xattr_datum(struct jffs2_sb_info *c,
+					     struct jffs2_xattr_datum *xd)
+{
+	/* must be called under down_write(xattr_sem), and called from GC thread */
+	uint32_t phys_ofs, totlen, length, old_ofs;
+	int rc;
+
+	BUG_ON(!xd->node);
+
+	old_ofs = ref_offset(xd->node);
+	totlen = ref_totlen(c, c->gcblock, xd->node);
+	if (totlen < sizeof(struct jffs2_raw_xattr))
+		return -EINVAL;
+
+	if (!xd->xname) {
+		rc = load_xattr_datum(c, xd);
+		if (unlikely(rc > 0)) {
+			delete_xattr_datum_node(c, xd);
+			return 0;
+		} else if (unlikely(rc < 0))
+			return -EINVAL;
+	}
+	rc = jffs2_reserve_space_gc(c, totlen, &phys_ofs, &length, JFFS2_SUMMARY_XATTR_SIZE);
+	if (rc || length < totlen) {
+		JFFS2_WARNING("jffs2_reserve_space()=%d, request=%u\n", rc, totlen);
+		return rc ? rc : -EBADFD;
+	}
+	rc = save_xattr_datum(c, xd, phys_ofs);
+	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));
+	return rc;
+}
+
+
+static int jffs2_garbage_collect_xattr_ref(struct jffs2_sb_info *c,
+					   struct jffs2_xattr_ref *ref)
+{
+	/* must be called under down(alloc_sem) */
+	uint32_t phys_ofs, totlen, length, old_ofs;
+	int rc;
+
+	BUG_ON(!ref->node);
+
+	old_ofs = ref_offset(ref->node);
+	totlen = ref_totlen(c, c->gcblock, ref->node);
+	if (totlen != sizeof(struct jffs2_raw_xref))
+		return -EINVAL;
+	rc = jffs2_reserve_space_gc(c, totlen, &phys_ofs, &length, JFFS2_SUMMARY_XREF_SIZE);
+	if (rc || length < totlen) {
+		JFFS2_WARNING("%s: jffs2_reserve_space() = %d, request = %u\n",
+			      __FUNCTION__, rc, totlen);
+		return rc ? rc : -EBADFD;
+	}
+	rc = save_xattr_ref(c, ref, phys_ofs);
+	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));
+	return rc;
+}
+
+int jffs2_garbage_collect_xattr(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic)
+{
+	struct jffs2_xattr_datum *xd;
+	struct jffs2_xattr_ref *ref;
+	int ret;
+
+	switch (ic->class) {
+	case RAWNODE_CLASS_XATTR_DATUM:
+		spin_unlock(&c->erase_completion_lock);
+
+		down_write(&c->xattr_sem);
+		xd = (struct jffs2_xattr_datum *)ic;
+		ret = xd ? jffs2_garbage_collect_xattr_datum(c, xd) : 0;
+		up_write(&c->xattr_sem);
+		break;
+	case RAWNODE_CLASS_XATTR_REF:
+		spin_unlock(&c->erase_completion_lock);
+
+		down_write(&c->xattr_sem);
+		ref = (struct jffs2_xattr_ref *)ic;
+		ret = ref ? jffs2_garbage_collect_xattr_ref(c, ref) : 0;
+		up_write(&c->xattr_sem);
+		break;
+	default:
+		/* This node is not xattr_datum/xattr_ref */
+		ret = 1;
+		break;
+	}
+	return ret;
+}
+
+int jffs2_verify_xattr(struct jffs2_sb_info *c)
+{
+	struct jffs2_xattr_datum *xd, *_xd;
+	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) {
+			list_del_init(&xd->xindex);
+			break;
+		} else if (rc > 0) {
+			list_del_init(&xd->xindex);
+			delete_xattr_datum_node(c, xd);
+		}
+	}
+	up_write(&c->xattr_sem);
+
+	return list_empty(&c->xattr_unchecked) ? 1 : 0;
+}