int jffs2_sum_write_sumnode(struct jffs2_sb_info *c)
{
	struct jffs2_raw_node_ref *summary_ref;
	int datasize, infosize, padsize, ret;
	struct jffs2_eraseblock *jeb;

	dbg_summary("called\n");

	jeb = c->nextblock;

	if (!c->summary->sum_num || !c->summary->sum_list_head) {
		JFFS2_WARNING("Empty summary info!!!\n");
		BUG();
	}

	datasize = c->summary->sum_size + sizeof(struct jffs2_sum_marker);
	infosize = sizeof(struct jffs2_raw_summary) + datasize;
	padsize = jeb->free_size - infosize;
	infosize += padsize;
	datasize += padsize;

	/* Is there enough space for summary? */
	if (padsize < 0) {
		/* don't try to write out summary for this jeb */
		jffs2_sum_disable_collecting(c->summary);

		JFFS2_WARNING("Not enough space for summary, padsize = %d\n", padsize);
		return 0;
	}

	ret = jffs2_sum_write_data(c, jeb, infosize, datasize, padsize);
	if (ret)
		return 0; /* can't write out summary, block is marked as NOSUM_SIZE */

	/* for ACCT_PARANOIA_CHECK */
	spin_unlock(&c->erase_completion_lock);
	summary_ref = jffs2_alloc_raw_node_ref();
	spin_lock(&c->erase_completion_lock);

	if (!summary_ref) {
		JFFS2_NOTICE("Failed to allocate node ref for summary\n");
		return -ENOMEM;
	}

	summary_ref->next_in_ino = NULL;
	summary_ref->next_phys = NULL;
	summary_ref->flash_offset = (jeb->offset + c->sector_size - jeb->free_size) | REF_NORMAL;
	summary_ref->__totlen = infosize;

	if (!jeb->first_node)
		jeb->first_node = summary_ref;
	if (jeb->last_node)
		jeb->last_node->next_phys = summary_ref;
	jeb->last_node = summary_ref;

	USED_SPACE(infosize);

	return 0;
}

int jffs2_sum_write_sumnode(struct jffs2_sb_info *c)
{
	int datasize, infosize, padsize;
	struct jffs2_eraseblock *jeb;
	int ret = 0;

	dbg_summary("called\n");

	spin_unlock(&c->erase_completion_lock);

	jeb = c->nextblock;
	jffs2_prealloc_raw_node_refs(c, jeb, 1);

	if (!c->summary->sum_num || !c->summary->sum_list_head) {
		JFFS2_WARNING("Empty summary info!!!\n");
		BUG();
	}

	datasize = c->summary->sum_size + sizeof(struct jffs2_sum_marker);
	infosize = sizeof(struct jffs2_raw_summary) + datasize;
	padsize = jeb->free_size - infosize;
	infosize += padsize;
	datasize += padsize;

	ret = jffs2_sum_write_data(c, jeb, infosize, datasize, padsize);
	spin_lock(&c->erase_completion_lock);
	return ret;
}

static int jffs2_sum_add_mem(struct jffs2_summary *s, union jffs2_sum_mem *item)
{
	if (!s->sum_list_head)
		s->sum_list_head = (union jffs2_sum_mem *) item;
	if (s->sum_list_tail)
		s->sum_list_tail->u.next = (union jffs2_sum_mem *) item;
	s->sum_list_tail = (union jffs2_sum_mem *) item;

	switch (je16_to_cpu(item->u.nodetype)) {
		case JFFS2_NODETYPE_INODE:
			s->sum_size += JFFS2_SUMMARY_INODE_SIZE;
			s->sum_num++;
			dbg_summary("inode (%u) added to summary\n",
						je32_to_cpu(item->i.inode));
			break;
		case JFFS2_NODETYPE_DIRENT:
			s->sum_size += JFFS2_SUMMARY_DIRENT_SIZE(item->d.nsize);
			s->sum_num++;
			dbg_summary("dirent (%u) added to summary\n",
						je32_to_cpu(item->d.ino));
			break;
		default:
			JFFS2_WARNING("UNKNOWN node type %u\n",
					    je16_to_cpu(item->u.nodetype));
			return 1;
	}
	return 0;
}

static int jffs2_scan_xref_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
				struct jffs2_raw_xref *rr, uint32_t ofs,
				struct jffs2_summary *s)
{
	struct jffs2_xattr_ref *ref;
	uint32_t crc;
	int err;

	crc = crc32(0, rr, sizeof(*rr) - 4);
	if (crc != je32_to_cpu(rr->node_crc)) {
		JFFS2_WARNING("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
			      ofs, je32_to_cpu(rr->node_crc), crc);
		if ((err = jffs2_scan_dirty_space(c, jeb, PAD(je32_to_cpu(rr->totlen)))))
			return err;
		return 0;
	}

	if (PAD(sizeof(struct jffs2_raw_xref)) != je32_to_cpu(rr->totlen)) {
		JFFS2_WARNING("node length mismatch at %#08x, read=%u, calc=%zd\n",
			      ofs, je32_to_cpu(rr->totlen),
			      PAD(sizeof(struct jffs2_raw_xref)));
		if ((err = jffs2_scan_dirty_space(c, jeb, je32_to_cpu(rr->totlen))))
			return err;
		return 0;
	}

	ref = jffs2_alloc_xattr_ref();
	if (!ref)
		return -ENOMEM;

	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);
	ref->next = c->xref_temp;
	c->xref_temp = ref;

	jffs2_link_node_ref(c, jeb, ofs | REF_PRISTINE, PAD(je32_to_cpu(rr->totlen)), (void *)ref);

	if (jffs2_sum_active())
		jffs2_sum_add_xref_mem(s, rr, ofs - jeb->offset);
	dbg_xattr("scan xref at %#08x (xid=%u, ino=%u)\n",
		  ofs, ref->xid, ref->ino);
	return 0;
}

int jffs2_sum_init(struct jffs2_sb_info *c)
{
	c->summary = kzalloc(sizeof(struct jffs2_summary), GFP_KERNEL);

	if (!c->summary) {
		JFFS2_WARNING("Can't allocate memory for summary information!\n");
		return -ENOMEM;
	}

	c->summary->sum_buf = vmalloc(c->sector_size);

	if (!c->summary->sum_buf) {
		JFFS2_WARNING("Can't allocate buffer for writing out summary information!\n");
		kfree(c->summary);
		return -ENOMEM;
	}

	dbg_summary("returned successfully\n");

	return 0;
}

int jffs2_sum_write_sumnode(struct jffs2_sb_info *c)
{
	int datasize, infosize, padsize;
	struct jffs2_eraseblock *jeb;
	int ret;

	dbg_summary("called\n");

	spin_unlock(&c->erase_completion_lock);

	jeb = c->nextblock;
	jffs2_prealloc_raw_node_refs(c, jeb, 1);

	if (!c->summary->sum_num || !c->summary->sum_list_head) {
		JFFS2_WARNING("Empty summary info!!!\n");
		BUG();
	}

	datasize = c->summary->sum_size + sizeof(struct jffs2_sum_marker);
	infosize = sizeof(struct jffs2_raw_summary) + datasize;
	padsize = jeb->free_size - infosize;
	infosize += padsize;
	datasize += padsize;

	/* Is there enough space for summary? */
	if (padsize < 0) {
		/* don't try to write out summary for this jeb */
		jffs2_sum_disable_collecting(c->summary);

		JFFS2_WARNING("Not enough space for summary, padsize = %d\n", padsize);
		spin_lock(&c->erase_completion_lock);
		return 0;
	}

	ret = jffs2_sum_write_data(c, jeb, infosize, datasize, padsize);
	spin_lock(&c->erase_completion_lock);
	return ret;
}

int jffs2_sum_init(struct jffs2_sb_info *c)
{
	uint32_t sum_size = min_t(uint32_t, c->sector_size, MAX_SUMMARY_SIZE);

	c->summary = kzalloc(sizeof(struct jffs2_summary), GFP_KERNEL);

	if (!c->summary) {
		JFFS2_WARNING("Can't allocate memory for summary information!\n");
		return -ENOMEM;
	}

	c->summary->sum_buf = kmalloc(sum_size, GFP_KERNEL);

	if (!c->summary->sum_buf) {
		JFFS2_WARNING("Can't allocate buffer for writing out summary information!\n");
		kfree(c->summary);
		return -ENOMEM;
	}

	dbg_summary("returned successfully\n");

	return 0;
}

static int jffs2_sum_add_mem(struct jffs2_summary *s, union jffs2_sum_mem *item)
{
	if (!s->sum_list_head)
		s->sum_list_head = (union jffs2_sum_mem *) item;
	if (s->sum_list_tail)
		s->sum_list_tail->u.next = (union jffs2_sum_mem *) item;
	s->sum_list_tail = (union jffs2_sum_mem *) item;

	switch (je16_to_cpu(item->u.nodetype)) {
		case JFFS2_NODETYPE_INODE:
			s->sum_size += JFFS2_SUMMARY_INODE_SIZE;
			s->sum_num++;
			dbg_summary("inode (%u) added to summary\n",
						je32_to_cpu(item->i.inode));
			break;
		case JFFS2_NODETYPE_DIRENT:
			s->sum_size += JFFS2_SUMMARY_DIRENT_SIZE(item->d.nsize);
			s->sum_num++;
			dbg_summary("dirent (%u) added to summary\n",
						je32_to_cpu(item->d.ino));
			break;
#ifdef CONFIG_JFFS2_FS_XATTR
		case JFFS2_NODETYPE_XATTR:
			s->sum_size += JFFS2_SUMMARY_XATTR_SIZE;
			s->sum_num++;
			dbg_summary("xattr (xid=%u, version=%u) added to summary\n",
				    je32_to_cpu(item->x.xid), je32_to_cpu(item->x.version));
			break;
		case JFFS2_NODETYPE_XREF:
			s->sum_size += JFFS2_SUMMARY_XREF_SIZE;
			s->sum_num++;
			dbg_summary("xref added to summary\n");
			break;
#endif
		default:
			JFFS2_WARNING("UNKNOWN node type %u\n",
					    je16_to_cpu(item->u.nodetype));
			return 1;
	}
	return 0;
}

//.........这里部分代码省略.........
				goto no_mem;

			temp->nodetype = node->i.nodetype;
			temp->inode = node->i.ino;
			temp->version = node->i.version;
			temp->offset = cpu_to_je32(ofs);
			temp->totlen = node->i.totlen;
			temp->next = NULL;

			return jffs2_sum_add_mem(c->summary, (union jffs2_sum_mem *)temp);
		}

		case JFFS2_NODETYPE_DIRENT: {
			struct jffs2_sum_dirent_mem *temp =
				kmalloc(sizeof(struct jffs2_sum_dirent_mem) + node->d.nsize, GFP_KERNEL);

			if (!temp)
				goto no_mem;

			temp->nodetype = node->d.nodetype;
			temp->totlen = node->d.totlen;
			temp->offset = cpu_to_je32(ofs);
			temp->pino = node->d.pino;
			temp->version = node->d.version;
			temp->ino = node->d.ino;
			temp->nsize = node->d.nsize;
			temp->type = node->d.type;
			temp->next = NULL;

			switch (count) {
				case 1:
					memcpy(temp->name,node->d.name,node->d.nsize);
					break;

				case 2:
					memcpy(temp->name,invecs[1].iov_base,node->d.nsize);
					break;

				default:
					BUG();	/* impossible count value */
					break;
			}

			return jffs2_sum_add_mem(c->summary, (union jffs2_sum_mem *)temp);
		}
#ifdef CONFIG_JFFS2_FS_XATTR
		case JFFS2_NODETYPE_XATTR: {
			struct jffs2_sum_xattr_mem *temp;
			temp = kmalloc(sizeof(struct jffs2_sum_xattr_mem), GFP_KERNEL);
			if (!temp)
				goto no_mem;

			temp->nodetype = node->x.nodetype;
			temp->xid = node->x.xid;
			temp->version = node->x.version;
			temp->totlen = node->x.totlen;
			temp->offset = cpu_to_je32(ofs);
			temp->next = NULL;

			return jffs2_sum_add_mem(c->summary, (union jffs2_sum_mem *)temp);
		}
		case JFFS2_NODETYPE_XREF: {
			struct jffs2_sum_xref_mem *temp;
			temp = kmalloc(sizeof(struct jffs2_sum_xref_mem), GFP_KERNEL);
			if (!temp)
				goto no_mem;
			temp->nodetype = node->r.nodetype;
			temp->offset = cpu_to_je32(ofs);
			temp->next = NULL;

			return jffs2_sum_add_mem(c->summary, (union jffs2_sum_mem *)temp);
		}
#endif
		case JFFS2_NODETYPE_PADDING:
			dbg_summary("node PADDING\n");
			c->summary->sum_padded += je32_to_cpu(node->u.totlen);
			break;

		case JFFS2_NODETYPE_CLEANMARKER:
			dbg_summary("node CLEANMARKER\n");
			break;

		case JFFS2_NODETYPE_SUMMARY:
			dbg_summary("node SUMMARY\n");
			break;

		default:
			/* If you implement a new node type you should also implement
			   summary support for it or disable summary.
			*/
			BUG();
			break;
	}

	return 0;

no_mem:
	JFFS2_WARNING("MEMORY ALLOCATION ERROR!");
	return -ENOMEM;
}

int jffs2_scan_medium(struct jffs2_sb_info *c)
{
	int i, ret;
	uint32_t empty_blocks = 0, bad_blocks = 0;
	unsigned char *flashbuf = NULL;
	uint32_t buf_size = 0;
	struct jffs2_summary *s = NULL; 
#ifndef __ECOS
	size_t pointlen, try_size;

	ret = mtd_point(c->mtd, 0, c->mtd->size, &pointlen,
			(void **)&flashbuf, NULL);
	if (!ret && pointlen < c->mtd->size) {
		
		jffs2_dbg(1, "MTD point returned len too short: 0x%zx\n",
			  pointlen);
		mtd_unpoint(c->mtd, 0, pointlen);
		flashbuf = NULL;
	}
	if (ret && ret != -EOPNOTSUPP)
		jffs2_dbg(1, "MTD point failed %d\n", ret);
#endif
	if (!flashbuf) {
		if (jffs2_cleanmarker_oob(c))
			try_size = c->sector_size;
		else
			try_size = PAGE_SIZE;

		jffs2_dbg(1, "Trying to allocate readbuf of %zu "
			  "bytes\n", try_size);

		flashbuf = mtd_kmalloc_up_to(c->mtd, &try_size);
		if (!flashbuf)
			return -ENOMEM;

		jffs2_dbg(1, "Allocated readbuf of %zu bytes\n",
			  try_size);

		buf_size = (uint32_t)try_size;
	}

	if (jffs2_sum_active()) {
		s = kzalloc(sizeof(struct jffs2_summary), GFP_KERNEL);
		if (!s) {
			JFFS2_WARNING("Can't allocate memory for summary\n");
			ret = -ENOMEM;
			goto out;
		}
	}

	for (i=0; i<c->nr_blocks; i++) {
		struct jffs2_eraseblock *jeb = &c->blocks[i];

		cond_resched();

		
		jffs2_sum_reset_collected(s);

		ret = jffs2_scan_eraseblock(c, jeb, buf_size?flashbuf:(flashbuf+jeb->offset),
						buf_size, s);

		if (ret < 0)
			goto out;

		jffs2_dbg_acct_paranoia_check_nolock(c, jeb);

		
		switch(ret) {
		case BLK_STATE_ALLFF:
			empty_blocks++;
			list_add(&jeb->list, &c->erase_pending_list);
			c->nr_erasing_blocks++;
			break;

		case BLK_STATE_CLEANMARKER:
			
			if (!jeb->dirty_size) {
				
				list_add(&jeb->list, &c->free_list);
				c->nr_free_blocks++;
			} else {
				
				jffs2_dbg(1, "Adding all-dirty block at 0x%08x to erase_pending_list\n",
					  jeb->offset);
				list_add(&jeb->list, &c->erase_pending_list);
				c->nr_erasing_blocks++;
			}
			break;

		case BLK_STATE_CLEAN:
			
			list_add(&jeb->list, &c->clean_list);
			break;

		case BLK_STATE_PARTDIRTY:
			
			if (jeb->free_size > min_free(c) &&
					(!c->nextblock || c->nextblock->free_size < jeb->free_size)) {
				
				if (c->nextblock) {
//.........这里部分代码省略.........

/* Get tmp_dnode_info and full_dirent for all non-obsolete nodes associated
   with this ino, returning the former in order of version */
static int jffs2_get_inode_nodes(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
				 struct rb_root *tnp, struct jffs2_full_dirent **fdp,
				 uint32_t *highest_version, uint32_t *latest_mctime,
				 uint32_t *mctime_ver)
{
	struct jffs2_raw_node_ref *ref, *valid_ref;
	struct rb_root ret_tn = RB_ROOT;
	struct jffs2_full_dirent *ret_fd = NULL;
	unsigned char *buf = NULL;
	union jffs2_node_union *node;
	size_t retlen;
	int len, err;

	*mctime_ver = 0;

	dbg_readinode("ino #%u\n", f->inocache->ino);

	if (jffs2_is_writebuffered(c)) {
		/*
		 * If we have the write buffer, we assume the minimal I/O unit
		 * is c->wbuf_pagesize. We implement some optimizations which in
		 * this case and we need a temporary buffer of size =
		 * 2*c->wbuf_pagesize bytes (see comments in read_dnode()).
		 * Basically, we want to read not only the node header, but the
		 * whole wbuf (NAND page in case of NAND) or 2, if the node
		 * header overlaps the border between the 2 wbufs.
		 */
		len = 2*c->wbuf_pagesize;
	} else {
		/*
		 * When there is no write buffer, the size of the temporary
		 * buffer is the size of the larges node header.
		 */
		len = sizeof(union jffs2_node_union);
	}

	/* FIXME: in case of NOR and available ->point() this
	 * needs to be fixed. */
	buf = kmalloc(len, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	spin_lock(&c->erase_completion_lock);
	valid_ref = jffs2_first_valid_node(f->inocache->nodes);
	if (!valid_ref && f->inocache->ino != 1)
		JFFS2_WARNING("Eep. No valid nodes for ino #%u.\n", f->inocache->ino);
	while (valid_ref) {
		unsigned char *bufstart;

		/* We can hold a pointer to a non-obsolete node without the spinlock,
		   but _obsolete_ nodes may disappear at any time, if the block
		   they're in gets erased. So if we mark 'ref' obsolete while we're
		   not holding the lock, it can go away immediately. For that reason,
		   we find the next valid node first, before processing 'ref'.
		*/
		ref = valid_ref;
		valid_ref = jffs2_first_valid_node(ref->next_in_ino);
		spin_unlock(&c->erase_completion_lock);

		cond_resched();

		/*
		 * At this point we don't know the type of the node we're going
		 * to read, so we do not know the size of its header. In order
		 * to minimize the amount of flash IO we assume the node has
		 * size = JFFS2_MIN_NODE_HEADER.
		 */
		if (jffs2_is_writebuffered(c)) {
			/*
			 * We treat 'buf' as 2 adjacent wbufs. We want to
			 * adjust bufstart such as it points to the
			 * beginning of the node within this wbuf.
			 */
			bufstart = buf + (ref_offset(ref) % c->wbuf_pagesize);
			/* We will read either one wbuf or 2 wbufs. */
			len = c->wbuf_pagesize - (bufstart - buf);
			if (JFFS2_MIN_NODE_HEADER + (int)(bufstart - buf) > c->wbuf_pagesize) {
				/* The header spans the border of the first wbuf */
				len += c->wbuf_pagesize;
			}
		} else {
			bufstart = buf;
			len = JFFS2_MIN_NODE_HEADER;
		}

		dbg_readinode("read %d bytes at %#08x(%d).\n", len, ref_offset(ref), ref_flags(ref));

		/* FIXME: point() */
		err = jffs2_flash_read(c, ref_offset(ref), len,
				       &retlen, bufstart);
		if (err) {
			JFFS2_ERROR("can not read %d bytes from 0x%08x, " "error code: %d.\n", len, ref_offset(ref), err);
			goto free_out;
		}

		if (retlen < len) {
			JFFS2_ERROR("short read at %#08x: %d instead of %d.\n", ref_offset(ref), retlen, len);
			err = -EIO;
//.........这里部分代码省略.........

static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c,
					struct jffs2_inode_info *f,
					struct jffs2_raw_inode *latest_node)
{
	struct jffs2_tmp_dnode_info *tn;
	struct rb_root tn_list;
	struct rb_node *rb, *repl_rb;
	struct jffs2_full_dirent *fd_list;
	struct jffs2_full_dnode *fn, *first_fn = NULL;
	uint32_t crc;
	uint32_t latest_mctime, mctime_ver;
	size_t retlen;
	int ret;

	dbg_readinode("ino #%u nlink is %d\n", f->inocache->ino, f->inocache->nlink);

	/* Grab all nodes relevant to this ino */
	ret = jffs2_get_inode_nodes(c, f, &tn_list, &fd_list, &f->highest_version, &latest_mctime, &mctime_ver);

	if (ret) {
		JFFS2_ERROR("cannot read nodes for ino %u, returned error is %d\n", f->inocache->ino, ret);
		if (f->inocache->state == INO_STATE_READING)
			jffs2_set_inocache_state(c, f->inocache, INO_STATE_CHECKEDABSENT);
		return ret;
	}
	f->dents = fd_list;

	rb = rb_first(&tn_list);

	while (rb) {
		cond_resched();
		tn = rb_entry(rb, struct jffs2_tmp_dnode_info, rb);
		fn = tn->fn;
		ret = 1;
		dbg_readinode("consider node ver %u, phys offset "
			"%#08x(%d), range %u-%u.\n", tn->version,
			ref_offset(fn->raw), ref_flags(fn->raw),
			fn->ofs, fn->ofs + fn->size);

		if (fn->size) {
			ret = jffs2_add_older_frag_to_fragtree(c, f, tn);
			/* TODO: the error code isn't checked, check it */
			jffs2_dbg_fragtree_paranoia_check_nolock(f);
			BUG_ON(ret < 0);
			if (!first_fn && ret == 0)
				first_fn = fn;
		} else if (!first_fn) {
			first_fn = fn;
			f->metadata = fn;
			ret = 0; /* Prevent freeing the metadata update node */
		} else
			jffs2_mark_node_obsolete(c, fn->raw);

		BUG_ON(rb->rb_left);
		if (rb->rb_parent && rb->rb_parent->rb_left == rb) {
			/* We were then left-hand child of our parent. We need
			 * to move our own right-hand child into our place. */
			repl_rb = rb->rb_right;
			if (repl_rb)
				repl_rb->rb_parent = rb->rb_parent;
		} else
			repl_rb = NULL;

		rb = rb_next(rb);

		/* Remove the spent tn from the tree; don't bother rebalancing
		 * but put our right-hand child in our own place. */
		if (tn->rb.rb_parent) {
			if (tn->rb.rb_parent->rb_left == &tn->rb)
				tn->rb.rb_parent->rb_left = repl_rb;
			else if (tn->rb.rb_parent->rb_right == &tn->rb)
				tn->rb.rb_parent->rb_right = repl_rb;
			else BUG();
		} else if (tn->rb.rb_right)
			tn->rb.rb_right->rb_parent = NULL;

		jffs2_free_tmp_dnode_info(tn);
		if (ret) {
			dbg_readinode("delete dnode %u-%u.\n",
				fn->ofs, fn->ofs + fn->size);
			jffs2_free_full_dnode(fn);
		}
	}
	jffs2_dbg_fragtree_paranoia_check_nolock(f);

	BUG_ON(first_fn && ref_obsolete(first_fn->raw));

	fn = first_fn;
	if (unlikely(!first_fn)) {
		/* No data nodes for this inode. */
		if (f->inocache->ino != 1) {
			JFFS2_WARNING("no data nodes found for ino #%u\n", f->inocache->ino);
			if (!fd_list) {
				if (f->inocache->state == INO_STATE_READING)
					jffs2_set_inocache_state(c, f->inocache, INO_STATE_CHECKEDABSENT);
				return -EIO;
			}
			JFFS2_NOTICE("but it has children so we fake some modes for it\n");
		}
		latest_node->mode = cpu_to_jemode(S_IFDIR|S_IRUGO|S_IWUSR|S_IXUGO);
//.........这里部分代码省略.........

/*
 * Helper function for jffs2_get_inode_nodes().
 * It is called every time an inode node is found.
 *
 * Returns: 0 on succes;
 * 	    1 if the node should be marked obsolete;
 * 	    negative error code on failure.
 */
static inline int read_dnode(struct jffs2_sb_info *c, struct jffs2_raw_node_ref *ref,
			     struct jffs2_raw_inode *rd, struct rb_root *tnp, int rdlen,
			     uint32_t *latest_mctime, uint32_t *mctime_ver)
{
	struct jffs2_tmp_dnode_info *tn;
	uint32_t len, csize;
	int ret = 1;

	/* Obsoleted. This cannot happen, surely? dwmw2 20020308 */
	BUG_ON(ref_obsolete(ref));

	tn = jffs2_alloc_tmp_dnode_info();
	if (!tn) {
		JFFS2_ERROR("failed to allocate tn (%d bytes).\n", sizeof(*tn));
		return -ENOMEM;
	}

	tn->partial_crc = 0;
	csize = je32_to_cpu(rd->csize);

	/* If we've never checked the CRCs on this node, check them now */
	if (ref_flags(ref) == REF_UNCHECKED) {
		uint32_t crc;

		crc = crc32(0, rd, sizeof(*rd) - 8);
		if (unlikely(crc != je32_to_cpu(rd->node_crc))) {
			JFFS2_NOTICE("header CRC failed on node at %#08x: read %#08x, calculated %#08x\n",
					ref_offset(ref), je32_to_cpu(rd->node_crc), crc);
			goto free_out;
		}

		/* Sanity checks */
		if (unlikely(je32_to_cpu(rd->offset) > je32_to_cpu(rd->isize)) ||
		    unlikely(PAD(je32_to_cpu(rd->csize) + sizeof(*rd)) != PAD(je32_to_cpu(rd->totlen)))) {
				JFFS2_WARNING("inode node header CRC is corrupted at %#08x\n", ref_offset(ref));
				jffs2_dbg_dump_node(c, ref_offset(ref));
			goto free_out;
		}

		if (jffs2_is_writebuffered(c) && csize != 0) {
			/* At this point we are supposed to check the data CRC
			 * of our unchecked node. But thus far, we do not
			 * know whether the node is valid or obsolete. To
			 * figure this out, we need to walk all the nodes of
			 * the inode and build the inode fragtree. We don't
			 * want to spend time checking data of nodes which may
			 * later be found to be obsolete. So we put off the full
			 * data CRC checking until we have read all the inode
			 * nodes and have started building the fragtree.
			 *
			 * The fragtree is being built starting with nodes
			 * having the highest version number, so we'll be able
			 * to detect whether a node is valid (i.e., it is not
			 * overlapped by a node with higher version) or not.
			 * And we'll be able to check only those nodes, which
			 * are not obsolete.
			 *
			 * Of course, this optimization only makes sense in case
			 * of NAND flashes (or other flashes whith
			 * !jffs2_can_mark_obsolete()), since on NOR flashes
			 * nodes are marked obsolete physically.
			 *
			 * Since NAND flashes (or other flashes with
			 * jffs2_is_writebuffered(c)) are anyway read by
			 * fractions of c->wbuf_pagesize, and we have just read
			 * the node header, it is likely that the starting part
			 * of the node data is also read when we read the
			 * header. So we don't mind to check the CRC of the
			 * starting part of the data of the node now, and check
			 * the second part later (in jffs2_check_node_data()).
			 * Of course, we will not need to re-read and re-check
			 * the NAND page which we have just read. This is why we
			 * read the whole NAND page at jffs2_get_inode_nodes(),
			 * while we needed only the node header.
			 */
			unsigned char *buf;

			/* 'buf' will point to the start of data */
			buf = (unsigned char *)rd + sizeof(*rd);
			/* len will be the read data length */
			len = min_t(uint32_t, rdlen - sizeof(*rd), csize);
			tn->partial_crc = crc32(0, buf, len);

			dbg_readinode("Calculates CRC (%#08x) for %d bytes, csize %d\n", tn->partial_crc, len, csize);

			/* If we actually calculated the whole data CRC
			 * and it is wrong, drop the node. */
			if (len >= csize && unlikely(tn->partial_crc != je32_to_cpu(rd->data_crc))) {
				JFFS2_NOTICE("wrong data CRC in data node at 0x%08x: read %#08x, calculated %#08x.\n",
					ref_offset(ref), tn->partial_crc, je32_to_cpu(rd->data_crc));
				goto free_out;
			}
//.........这里部分代码省略.........

static int jffs2_sum_write_data(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
					uint32_t infosize, uint32_t datasize, int padsize)
{
	struct jffs2_raw_summary isum;
	union jffs2_sum_mem *temp;
	struct jffs2_sum_marker *sm;
	struct kvec vecs[2];
	void *wpage;
	int ret;
	size_t retlen;

	memset(c->summary->sum_buf, 0xff, datasize);
	memset(&isum, 0, sizeof(isum));

	isum.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
	isum.nodetype = cpu_to_je16(JFFS2_NODETYPE_SUMMARY);
	isum.totlen = cpu_to_je32(infosize);
	isum.hdr_crc = cpu_to_je32(crc32(0, &isum, sizeof(struct jffs2_unknown_node) - 4));
	isum.padded = cpu_to_je32(c->summary->sum_padded);
	isum.cln_mkr = cpu_to_je32(c->cleanmarker_size);
	isum.sum_num = cpu_to_je32(c->summary->sum_num);
	wpage = c->summary->sum_buf;

	while (c->summary->sum_num) {

		switch (je16_to_cpu(c->summary->sum_list_head->u.nodetype)) {
			case JFFS2_NODETYPE_INODE: {
				struct jffs2_sum_inode_flash *sino_ptr = wpage;

				sino_ptr->nodetype = c->summary->sum_list_head->i.nodetype;
				sino_ptr->inode = c->summary->sum_list_head->i.inode;
				sino_ptr->version = c->summary->sum_list_head->i.version;
				sino_ptr->offset = c->summary->sum_list_head->i.offset;
				sino_ptr->totlen = c->summary->sum_list_head->i.totlen;

				wpage += JFFS2_SUMMARY_INODE_SIZE;

				break;
			}

			case JFFS2_NODETYPE_DIRENT: {
				struct jffs2_sum_dirent_flash *sdrnt_ptr = wpage;

				sdrnt_ptr->nodetype = c->summary->sum_list_head->d.nodetype;
				sdrnt_ptr->totlen = c->summary->sum_list_head->d.totlen;
				sdrnt_ptr->offset = c->summary->sum_list_head->d.offset;
				sdrnt_ptr->pino = c->summary->sum_list_head->d.pino;
				sdrnt_ptr->version = c->summary->sum_list_head->d.version;
				sdrnt_ptr->ino = c->summary->sum_list_head->d.ino;
				sdrnt_ptr->nsize = c->summary->sum_list_head->d.nsize;
				sdrnt_ptr->type = c->summary->sum_list_head->d.type;

				memcpy(sdrnt_ptr->name, c->summary->sum_list_head->d.name,
							c->summary->sum_list_head->d.nsize);

				wpage += JFFS2_SUMMARY_DIRENT_SIZE(c->summary->sum_list_head->d.nsize);

				break;
			}

			default : {
				BUG();	/* unknown node in summary information */
			}
		}

		temp = c->summary->sum_list_head;
		c->summary->sum_list_head = c->summary->sum_list_head->u.next;
		kfree(temp);

		c->summary->sum_num--;
	}

	jffs2_sum_reset_collected(c->summary);

	wpage += padsize;

	sm = wpage;
	sm->offset = cpu_to_je32(c->sector_size - jeb->free_size);
	sm->magic = cpu_to_je32(JFFS2_SUM_MAGIC);

	isum.sum_crc = cpu_to_je32(crc32(0, c->summary->sum_buf, datasize));
	isum.node_crc = cpu_to_je32(crc32(0, &isum, sizeof(isum) - 8));

	vecs[0].iov_base = &isum;
	vecs[0].iov_len = sizeof(isum);
	vecs[1].iov_base = c->summary->sum_buf;
	vecs[1].iov_len = datasize;

	dbg_summary("JFFS2: writing out data to flash to pos : 0x%08x\n",
			jeb->offset + c->sector_size - jeb->free_size);

	spin_unlock(&c->erase_completion_lock);
	ret = jffs2_flash_writev(c, vecs, 2, jeb->offset + c->sector_size -
				jeb->free_size, &retlen, 0);
	spin_lock(&c->erase_completion_lock);


	if (ret || (retlen != infosize)) {
		JFFS2_WARNING("Write of %zd bytes at 0x%08x failed. returned %d, retlen %zd\n",
			infosize, jeb->offset + c->sector_size - jeb->free_size, ret, retlen);
//.........这里部分代码省略.........

//.........这里部分代码省略.........
					return -ENOMEM;
				}

				fd->raw = sum_link_node_ref(c, jeb,  je32_to_cpu(spd->offset) | REF_UNCHECKED,
							    PAD(je32_to_cpu(spd->totlen)), ic);

				fd->next = NULL;
				fd->version = je32_to_cpu(spd->version);
				fd->ino = je32_to_cpu(spd->ino);
				fd->nhash = full_name_hash(NULL, fd->name, checkedlen);
				fd->type = spd->type;

				jffs2_add_fd_to_list(c, fd, &ic->scan_dents);

				*pseudo_random += je32_to_cpu(spd->version);

				sp += JFFS2_SUMMARY_DIRENT_SIZE(spd->nsize);

				break;
			}
#ifdef CONFIG_JFFS2_FS_XATTR
			case JFFS2_NODETYPE_XATTR: {
				struct jffs2_xattr_datum *xd;
				struct jffs2_sum_xattr_flash *spx;

				spx = (struct jffs2_sum_xattr_flash *)sp;
				dbg_summary("xattr at %#08x-%#08x (xid=%u, version=%u)\n", 
					    jeb->offset + je32_to_cpu(spx->offset),
					    jeb->offset + je32_to_cpu(spx->offset) + je32_to_cpu(spx->totlen),
					    je32_to_cpu(spx->xid), je32_to_cpu(spx->version));

				xd = jffs2_setup_xattr_datum(c, je32_to_cpu(spx->xid),
								je32_to_cpu(spx->version));
				if (IS_ERR(xd))
					return PTR_ERR(xd);
				if (xd->version > je32_to_cpu(spx->version)) {
					/* node is not the newest one */
					struct jffs2_raw_node_ref *raw
						= sum_link_node_ref(c, jeb, je32_to_cpu(spx->offset) | REF_UNCHECKED,
								    PAD(je32_to_cpu(spx->totlen)), NULL);
					raw->next_in_ino = xd->node->next_in_ino;
					xd->node->next_in_ino = raw;
				} else {
					xd->version = je32_to_cpu(spx->version);
					sum_link_node_ref(c, jeb, je32_to_cpu(spx->offset) | REF_UNCHECKED,
							  PAD(je32_to_cpu(spx->totlen)), (void *)xd);
				}
				*pseudo_random += je32_to_cpu(spx->xid);
				sp += JFFS2_SUMMARY_XATTR_SIZE;

				break;
			}
			case JFFS2_NODETYPE_XREF: {
				struct jffs2_xattr_ref *ref;
				struct jffs2_sum_xref_flash *spr;

				spr = (struct jffs2_sum_xref_flash *)sp;
				dbg_summary("xref at %#08x-%#08x\n",
					    jeb->offset + je32_to_cpu(spr->offset),
					    jeb->offset + je32_to_cpu(spr->offset) + 
					    (uint32_t)PAD(sizeof(struct jffs2_raw_xref)));

				ref = jffs2_alloc_xattr_ref();
				if (!ref) {
					JFFS2_NOTICE("allocation of xattr_datum failed\n");
					return -ENOMEM;
				}
				ref->next = c->xref_temp;
				c->xref_temp = ref;

				sum_link_node_ref(c, jeb, je32_to_cpu(spr->offset) | REF_UNCHECKED,
						  PAD(sizeof(struct jffs2_raw_xref)), (void *)ref);

				*pseudo_random += ref->node->flash_offset;
				sp += JFFS2_SUMMARY_XREF_SIZE;

				break;
			}
#endif
			default : {
				uint16_t nodetype = je16_to_cpu(((struct jffs2_sum_unknown_flash *)sp)->nodetype);
				JFFS2_WARNING("Unsupported node type %x found in summary! Exiting...\n", nodetype);
				if ((nodetype & JFFS2_COMPAT_MASK) == JFFS2_FEATURE_INCOMPAT)
					return -EIO;

				/* For compatible node types, just fall back to the full scan */
				c->wasted_size -= jeb->wasted_size;
				c->free_size += c->sector_size - jeb->free_size;
				c->used_size -= jeb->used_size;
				c->dirty_size -= jeb->dirty_size;
				jeb->wasted_size = jeb->used_size = jeb->dirty_size = 0;
				jeb->free_size = c->sector_size;

				jffs2_free_jeb_node_refs(c, jeb);
				return -ENOTRECOVERABLE;
			}
		}
	}
	return 0;
}

static int jffs2_get_inode_nodes(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
				 struct rb_root *tnp, struct jffs2_full_dirent **fdp,
				 uint32_t *highest_version, uint32_t *latest_mctime,
				 uint32_t *mctime_ver)
{
	struct jffs2_raw_node_ref *ref, *valid_ref;
	struct rb_root ret_tn = RB_ROOT;
	struct jffs2_full_dirent *ret_fd = NULL;
	union jffs2_node_union node;
	size_t retlen;
	int err;

	*mctime_ver = 0;
	
	JFFS2_DBG_READINODE("ino #%u\n", f->inocache->ino);

	spin_lock(&c->erase_completion_lock);

	valid_ref = jffs2_first_valid_node(f->inocache->nodes);

	if (!valid_ref && (f->inocache->ino != 1))
		JFFS2_WARNING("no valid nodes for ino #%u\n", f->inocache->ino);

	while (valid_ref) {
		/* We can hold a pointer to a non-obsolete node without the spinlock,
		   but _obsolete_ nodes may disappear at any time, if the block
		   they're in gets erased. So if we mark 'ref' obsolete while we're
		   not holding the lock, it can go away immediately. For that reason,
		   we find the next valid node first, before processing 'ref'.
		*/
		ref = valid_ref;
		valid_ref = jffs2_first_valid_node(ref->next_in_ino);
		spin_unlock(&c->erase_completion_lock);

		cond_resched();

		/* FIXME: point() */
		err = jffs2_flash_read(c, (ref_offset(ref)), 
				       min_t(uint32_t, ref_totlen(c, NULL, ref), sizeof(node)),
				       &retlen, (void *)&node);
		if (err) {
			JFFS2_ERROR("error %d reading node at 0x%08x in get_inode_nodes()\n", err, ref_offset(ref));
			goto free_out;
		}
			
		switch (je16_to_cpu(node.u.nodetype)) {
			
		case JFFS2_NODETYPE_DIRENT:
			JFFS2_DBG_READINODE("node at %08x (%d) is a dirent node\n", ref_offset(ref), ref_flags(ref));
			
			if (retlen < sizeof(node.d)) {
				JFFS2_ERROR("short read dirent at %#08x\n", ref_offset(ref));
				err = -EIO;
				goto free_out;
			}

			err = read_direntry(c, ref, &node.d, retlen, &ret_fd, (int32_t *)latest_mctime, mctime_ver);
			if (err == 1) {
				jffs2_mark_node_obsolete(c, ref);
				break;
			} else if (unlikely(err))
				goto free_out;
			
			if (je32_to_cpu(node.d.version) > *highest_version)
				*highest_version = je32_to_cpu(node.d.version);

			break;

		case JFFS2_NODETYPE_INODE:
			JFFS2_DBG_READINODE("node at %08x (%d) is a data node\n", ref_offset(ref), ref_flags(ref));
			
			if (retlen < sizeof(node.i)) {
				JFFS2_ERROR("short read dnode at %#08x\n", ref_offset(ref));
				err = -EIO;
				goto free_out;
			}

			err = read_dnode(c, ref, &node.i, retlen, &ret_tn, (int32_t *)latest_mctime, mctime_ver);
			if (err == 1) {
				jffs2_mark_node_obsolete(c, ref);
				break;
			} else if (unlikely(err))
				goto free_out;

			if (je32_to_cpu(node.i.version) > *highest_version)
				*highest_version = je32_to_cpu(node.i.version);
			
			JFFS2_DBG_READINODE("version %d, highest_version now %d\n",
					je32_to_cpu(node.i.version), *highest_version);

			break;

		default:
			/* Check we've managed to read at least the common node header */
			if (retlen < sizeof(struct jffs2_unknown_node)) {
				JFFS2_ERROR("short read unknown node at %#08x\n", ref_offset(ref));
				return -EIO;
			}

			err = read_unknown(c, ref, &node.u, retlen);
//.........这里部分代码省略.........

/*
 * Helper function for jffs2_get_inode_nodes().
 * It is called every time an inode node is found.
 *
 * Returns: 0 on succes;
 * 	    1 if the node should be marked obsolete;
 * 	    negative error code on failure.
 */
static inline int
read_dnode(struct jffs2_sb_info *c,
	   struct jffs2_raw_node_ref *ref,
	   struct jffs2_raw_inode *rd,
	   uint32_t read,
	   struct rb_root *tnp,
	   int32_t *latest_mctime,
	   uint32_t *mctime_ver)
{
	struct jffs2_eraseblock *jeb;
	struct jffs2_tmp_dnode_info *tn;
	
	/* Obsoleted. This cannot happen, surely? dwmw2 20020308 */
	BUG_ON(ref_obsolete(ref));

	/* If we've never checked the CRCs on this node, check them now */
	if (ref_flags(ref) == REF_UNCHECKED) {
		uint32_t crc, len;

		crc = crc32(0, rd, sizeof(*rd) - 8);
		if (unlikely(crc != je32_to_cpu(rd->node_crc))) {
			JFFS2_NOTICE("header CRC failed on node at %#08x: read %#08x, calculated %#08x\n",
					ref_offset(ref), je32_to_cpu(rd->node_crc), crc);
			return 1;
		}
		
		/* Sanity checks */
		if (unlikely(je32_to_cpu(rd->offset) > je32_to_cpu(rd->isize)) ||
		    unlikely(PAD(je32_to_cpu(rd->csize) + sizeof(*rd)) != PAD(je32_to_cpu(rd->totlen)))) {
				JFFS2_WARNING("inode node header CRC is corrupted at %#08x\n", ref_offset(ref));
				jffs2_dbg_dump_node(c, ref_offset(ref));
			return 1;
		}

		if (rd->compr != JFFS2_COMPR_ZERO && je32_to_cpu(rd->csize)) {
			unsigned char *buf = NULL;
			uint32_t pointed = 0;
			int err;
#ifndef __ECOS
			if (c->mtd->point) {
				err = c->mtd->point (c->mtd, ref_offset(ref) + sizeof(*rd), je32_to_cpu(rd->csize),
						     &read, &buf);
				if (unlikely(read < je32_to_cpu(rd->csize)) && likely(!err)) {
					JFFS2_ERROR("MTD point returned len too short: 0x%zx\n", read);
					c->mtd->unpoint(c->mtd, buf, ref_offset(ref) + sizeof(*rd),
							je32_to_cpu(rd->csize));
				} else if (unlikely(err)){
					JFFS2_ERROR("MTD point failed %d\n", err);
				} else
					pointed = 1; /* succefully pointed to device */
			}
#endif					
			if(!pointed){
				buf = kmalloc(je32_to_cpu(rd->csize), GFP_KERNEL);
				if (!buf)
					return -ENOMEM;
				
				err = jffs2_flash_read(c, ref_offset(ref) + sizeof(*rd), je32_to_cpu(rd->csize),
							&read, buf);
				if (unlikely(read != je32_to_cpu(rd->csize)) && likely(!err))
					err = -EIO;
				if (err) {
					kfree(buf);
					return err;
				}
			}
			crc = crc32(0, buf, je32_to_cpu(rd->csize));
			if(!pointed)
				kfree(buf);
#ifndef __ECOS
			else
				c->mtd->unpoint(c->mtd, buf, ref_offset(ref) + sizeof(*rd), je32_to_cpu(rd->csize));
#endif

			if (crc != je32_to_cpu(rd->data_crc)) {
				JFFS2_NOTICE("data CRC failed on node at %#08x: read %#08x, calculated %#08x\n",
					ref_offset(ref), je32_to_cpu(rd->data_crc), crc);
				return 1;
			}
			
		}

		/* Mark the node as having been checked and fix the accounting accordingly */
		jeb = &c->blocks[ref->flash_offset / c->sector_size];
		len = ref_totlen(c, jeb, ref);

		spin_lock(&c->erase_completion_lock);
		jeb->used_size += len;
		jeb->unchecked_size -= len;
		c->used_size += len;
		c->unchecked_size -= len;

//.........这里部分代码省略.........

/* Process the summary node - called from jffs2_scan_eraseblock() */
int jffs2_sum_scan_sumnode(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
			   struct jffs2_raw_summary *summary, uint32_t sumsize,
			   uint32_t *pseudo_random)
{
	struct jffs2_unknown_node crcnode;
	int ret, ofs;
	uint32_t crc;

	ofs = c->sector_size - sumsize;

	dbg_summary("summary found for 0x%08x at 0x%08x (0x%x bytes)\n",
		    jeb->offset, jeb->offset + ofs, sumsize);

	/* OK, now check for node validity and CRC */
	crcnode.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
	crcnode.nodetype = cpu_to_je16(JFFS2_NODETYPE_SUMMARY);
	c