scan.c

uclinux的jffs2文件系统

		curofs += retlen&~3;
	}

	D1(printk(KERN_DEBUG "Empty flash detected from 0x%08x to 0x%08x\n", *startofs, curofs));
	kfree(buf);
	*startofs = curofs;
	return 0;
}

static struct jffs2_inode_cache *jffs2_scan_make_ino_cache(struct jffs2_sb_info *c, __u32 ino)
{
	struct jffs2_inode_cache *ic;

	ic = jffs2_get_ino_cache(c, ino);
	if (ic)
		return ic;

	ic = jffs2_alloc_inode_cache();
	if (!ic) {
		printk(KERN_NOTICE "jffs2_scan_make_inode_cache(): allocation of inode cache failed\n");
		return NULL;
	}
	memset(ic, 0, sizeof(*ic));
	ic->scan = kmalloc(sizeof(struct jffs2_scan_info), GFP_KERNEL);
	if (!ic->scan) {
		printk(KERN_NOTICE "jffs2_scan_make_inode_cache(): allocation of scan info for inode cache failed\n");
		jffs2_free_inode_cache(ic);
		return NULL;
	}
	memset(ic->scan, 0, sizeof(*ic->scan));
	ic->ino = ino;
	ic->nodes = (void *)ic;
	jffs2_add_ino_cache(c, ic);
	if (ino == 1)
		ic->nlink=1;
	return ic;
}

static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, __u32 *ofs)
{
	struct jffs2_raw_node_ref *raw;
	struct jffs2_full_dnode *fn;
	struct jffs2_tmp_dnode_info *tn, **tn_list;
	struct jffs2_inode_cache *ic;
	struct jffs2_raw_inode ri;
	__u32 crc;
	__u16 oldnodetype;
	int ret;
	ssize_t retlen;

	D1(printk(KERN_DEBUG "jffs2_scan_inode_node(): Node at 0x%08x\n", *ofs));

	ret = c->mtd->read(c->mtd, *ofs, sizeof(ri), &retlen, (char *)&ri);
	if (ret) {
		printk(KERN_NOTICE "jffs2_scan_inode_node(): Read error at 0x%08x: %d\n", *ofs, ret);
		return ret;
	}
	if (retlen != sizeof(ri)) {
		printk(KERN_NOTICE "Short read: 0x%x bytes at 0x%08x instead of requested %x\n", 
		       retlen, *ofs, sizeof(ri));
		return -EIO;
	}

	/* We sort of assume that the node was accurate when it was 
	   first written to the medium :) */
	oldnodetype = ri.nodetype;
	ri.nodetype |= JFFS2_NODE_ACCURATE;
	crc = crc32(0, &ri, sizeof(ri)-8);
	ri.nodetype = oldnodetype;

	if(crc != ri.node_crc) {
		printk(KERN_NOTICE "jffs2_scan_inode_node(): CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
		       *ofs, ri.node_crc, crc);
		/* FIXME: Why do we believe totlen? */
		DIRTY_SPACE(4);
		*ofs += 4;
		return 0;
	}
	/* There was a bug where we wrote hole nodes out with csize/dsize
	   swapped. Deal with it */
	if (ri.compr == JFFS2_COMPR_ZERO && !ri.dsize && ri.csize) {
		ri.dsize = ri.csize;
		ri.csize = 0;
	}

	if (ri.csize) {
		/* Check data CRC too */
		unsigned char *dbuf;
		__u32 crc;

		dbuf = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
		if (!dbuf) {
			printk(KERN_NOTICE "jffs2_scan_inode_node(): allocation of temporary data buffer for CRC check failed\n");
			return -ENOMEM;
		}
		ret = c->mtd->read(c->mtd, *ofs+sizeof(ri), ri.csize, &retlen, dbuf);
		if (ret) {
			printk(KERN_NOTICE "jffs2_scan_inode_node(): Read error at 0x%08x: %d\n", *ofs+sizeof(ri), ret);
			kfree(dbuf);
			return ret;
		}
		if (retlen != ri.csize) {
			printk(KERN_NOTICE "Short read: 0x%x bytes at 0x%08x instead of requested %x\n", 
			       retlen, *ofs+ sizeof(ri), ri.csize);
			kfree(dbuf);
			return -EIO;
		}
		crc = crc32(0, dbuf, ri.csize);
		kfree(dbuf);
		if (crc != ri.data_crc) {
			printk(KERN_NOTICE "jffs2_scan_inode_node(): Data CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
			       *ofs, ri.data_crc, crc);
			DIRTY_SPACE(PAD(ri.totlen));
			*ofs += PAD(ri.totlen);
			return 0;
		}
	}

	/* Wheee. It worked */
	raw = jffs2_alloc_raw_node_ref();
	if (!raw) {
		printk(KERN_NOTICE "jffs2_scan_inode_node(): allocation of node reference failed\n");
		return -ENOMEM;
	}
	tn = jffs2_alloc_tmp_dnode_info();
	if (!tn) {
		jffs2_free_raw_node_ref(raw);
		return -ENOMEM;
	}
	fn = jffs2_alloc_full_dnode();
	if (!fn) {
		jffs2_free_tmp_dnode_info(tn);
		jffs2_free_raw_node_ref(raw);
		return -ENOMEM;
	}
	ic = jffs2_scan_make_ino_cache(c, ri.ino);
	if (!ic) {
		jffs2_free_full_dnode(fn);
		jffs2_free_tmp_dnode_info(tn);
		jffs2_free_raw_node_ref(raw);
		return -ENOMEM;
	}

	/* Build the data structures and file them for later */
	raw->flash_offset = *ofs;
	raw->totlen = PAD(ri.totlen);
	raw->next_phys = NULL;
	raw->next_in_ino = ic->nodes;
	ic->nodes = raw;
	if (!jeb->first_node)
		jeb->first_node = raw;
	if (jeb->last_node)
		jeb->last_node->next_phys = raw;
	jeb->last_node = raw;

	D1(printk(KERN_DEBUG "Node is ino #%u, version %d. Range 0x%x-0x%x\n", 
		  ri.ino, ri.version, ri.offset, ri.offset+ri.dsize));

	pseudo_random += ri.version;

	for (tn_list = &ic->scan->tmpnodes; *tn_list; tn_list = &((*tn_list)->next)) {
		if ((*tn_list)->version < ri.version)
			continue;
		if ((*tn_list)->version > ri.version) 
			break;
		/* Wheee. We've found another instance of the same version number.
		   We should obsolete one of them. 
		*/
		D1(printk(KERN_DEBUG "Duplicate version %d found in ino #%u. Previous one is at 0x%08x\n", ri.version, ic->ino, (*tn_list)->fn->raw->flash_offset &~3));
		if (!jeb->used_size) {
			D1(printk(KERN_DEBUG "No valid nodes yet found in this eraseblock 0x%08x, so obsoleting the new instance at 0x%08x\n", 
				  jeb->offset, raw->flash_offset & ~3));
			ri.nodetype &= ~JFFS2_NODE_ACCURATE;
			/* Perhaps we could also mark it as such on the medium. Maybe later */
		}
		break;
	}

	if (ri.nodetype & JFFS2_NODE_ACCURATE) {
		memset(fn,0,sizeof(*fn));

		fn->ofs = ri.offset;
		fn->size = ri.dsize;
		fn->frags = 0;
		fn->raw = raw;

		tn->next = NULL;
		tn->fn = fn;
		tn->version = ri.version;

		USED_SPACE(PAD(ri.totlen));
		jffs2_add_tn_to_list(tn, &ic->scan->tmpnodes);
		/* Make sure the one we just added is the _last_ in the list
		   with this version number, so the older ones get obsoleted */
		while (tn->next && tn->next->version == tn->version) {

			D1(printk(KERN_DEBUG "Shifting new node at 0x%08x after other node at 0x%08x for version %d in list\n",
				  fn->raw->flash_offset&~3, tn->next->fn->raw->flash_offset &~3, ri.version));

			if(tn->fn != fn)
				BUG();
			tn->fn = tn->next->fn;
			tn->next->fn = fn;
			tn = tn->next;
		}
	} else {
		jffs2_free_full_dnode(fn);
		jffs2_free_tmp_dnode_info(tn);
		raw->flash_offset |= 1;
		DIRTY_SPACE(PAD(ri.totlen));
	}		
	*ofs += PAD(ri.totlen);
	return 0;
}

static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, __u32 *ofs)
{
	struct jffs2_raw_node_ref *raw;
	struct jffs2_full_dirent *fd;
	struct jffs2_inode_cache *ic;
	struct jffs2_raw_dirent rd;
	__u16 oldnodetype;
	int ret;
	__u32 crc;
	ssize_t retlen;

	D1(printk(KERN_DEBUG "jffs2_scan_dirent_node(): Node at 0x%08x\n", *ofs));

	ret = c->mtd->read(c->mtd, *ofs, sizeof(rd), &retlen, (char *)&rd);
	if (ret) {
		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Read error at 0x%08x: %d\n", *ofs, ret);
		return ret;
	}
	if (retlen != sizeof(rd)) {
		printk(KERN_NOTICE "Short read: 0x%x bytes at 0x%08x instead of requested %x\n", 
		       retlen, *ofs, sizeof(rd));
		return -EIO;
	}

	/* We sort of assume that the node was accurate when it was 
	   first written to the medium :) */
	oldnodetype = rd.nodetype;
	rd.nodetype |= JFFS2_NODE_ACCURATE;
	crc = crc32(0, &rd, sizeof(rd)-8);
	rd.nodetype = oldnodetype;

	if (crc != rd.node_crc) {
		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Node CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
		       *ofs, rd.node_crc, crc);
		/* FIXME: Why do we believe totlen? */
		DIRTY_SPACE(4);
		*ofs += 4;
		return 0;
	}

	pseudo_random += rd.version;

	fd = jffs2_alloc_full_dirent(rd.nsize+1);
	if (!fd) {
		return -ENOMEM;
}
	ret = c->mtd->read(c->mtd, *ofs + sizeof(rd), rd.nsize, &retlen, &fd->name[0]);
	if (ret) {
		jffs2_free_full_dirent(fd);
		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Read error at 0x%08x: %d\n", 
		       *ofs + sizeof(rd), ret);
		return ret;
	}
	if (retlen != rd.nsize) {
		jffs2_free_full_dirent(fd);
		printk(KERN_NOTICE "Short read: 0x%x bytes at 0x%08x instead of requested %x\n", 
		       retlen, *ofs + sizeof(rd), rd.nsize);
		return -EIO;
	}
	crc = crc32(0, fd->name, rd.nsize);
	if (crc != rd.name_crc) {
		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Name CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
		       *ofs, rd.name_crc, crc);	
		fd->name[rd.nsize]=0;
		D1(printk(KERN_NOTICE "Name for which CRC failed is (now) '%s', ino #%d\n", fd->name, rd.ino));
		jffs2_free_full_dirent(fd);
		/* FIXME: Why do we believe totlen? */
		DIRTY_SPACE(PAD(rd.totlen));
		*ofs += PAD(rd.totlen);
		return 0;
	}
	raw = jffs2_alloc_raw_node_ref();
	if (!raw) {
		jffs2_free_full_dirent(fd);
		printk(KERN_NOTICE "jffs2_scan_dirent_node(): allocation of node reference failed\n");
		return -ENOMEM;
	}
	ic = jffs2_scan_make_ino_cache(c, rd.pino);
	if (!ic) {
		jffs2_free_full_dirent(fd);
		jffs2_free_raw_node_ref(raw);
		return -ENOMEM;
	}
	
	raw->totlen = PAD(rd.totlen);
	raw->flash_offset = *ofs;
	raw->next_phys = NULL;
	raw->next_in_ino = ic->nodes;
	ic->nodes = raw;
	if (!jeb->first_node)
		jeb->first_node = raw;
	if (jeb->last_node)
		jeb->last_node->next_phys = raw;
	jeb->last_node = raw;

	if (rd.nodetype & JFFS2_NODE_ACCURATE) {
		fd->raw = raw;
		fd->next = NULL;
		fd->version = rd.version;
		fd->ino = rd.ino;
		fd->name[rd.nsize]=0;
		fd->nhash = full_name_hash(fd->name, rd.nsize);
		fd->type = rd.type;

		USED_SPACE(PAD(rd.totlen));
		jffs2_add_fd_to_list(c, fd, &ic->scan->dents);
	} else {
		raw->flash_offset |= 1;
		jffs2_free_full_dirent(fd);

		DIRTY_SPACE(PAD(rd.totlen));
	} 
	*ofs += PAD(rd.totlen);
	return 0;
}

static int count_list(struct list_head *l)
{
	uint32_t count = 0;
	struct list_head *tmp;

	list_for_each(tmp, l) {
		count++;
	}
	return count;
}

/* Note: This breaks if list_empty(head). I don't care. You
   might, if you copy this code and use it elsewhere :) */
static void rotate_list(struct list_head *head, uint32_t count)
{
	struct list_head *n = head->next;

	list_del(head);
	while(count--)
		n = n->next;
	list_add(head, n);
}

static void jffs2_rotate_lists(struct jffs2_sb_info *c)
{
	uint32_t x;

	x = count_list(&c->clean_list);
	if (x)
		rotate_list((&c->clean_list), pseudo_random % x);

	x = count_list(&c->dirty_list);
	if (x)
		rotate_list((&c->dirty_list), pseudo_random % x);

	if (c->nr_erasing_blocks)
		rotate_list((&c->erase_pending_list), pseudo_random % c->nr_erasing_blocks);

	if (c->nr_free_blocks) /* Not that it should ever be zero */
		rotate_list((&c->free_list), pseudo_random % c->nr_free_blocks);
}