scan.c

jffs2源代码基于2。6内核

		}
		if (je16_to_cpu(node->magic) == JFFS2_OLD_MAGIC_BITMASK) {
			printk(KERN_WARNING "Old JFFS2 bitmask found at 0x%08x\n", ofs);
			printk(KERN_WARNING "You cannot use older JFFS2 filesystems with newer kernels\n");
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}
		if (je16_to_cpu(node->magic) != JFFS2_MAGIC_BITMASK) {
			/* OK. We're out of possibilities. Whinge and move on */
			noisy_printk(&noise, "jffs2_scan_eraseblock(): Magic bitmask 0x%04x not found at 0x%08x: 0x%04x instead\n", 
				     JFFS2_MAGIC_BITMASK, ofs, 
				     je16_to_cpu(node->magic));
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}
		/* We seem to have a node of sorts. Check the CRC */
		crcnode.magic = node->magic;
		crcnode.nodetype = cpu_to_je16( je16_to_cpu(node->nodetype) | JFFS2_NODE_ACCURATE);
		crcnode.totlen = node->totlen;
		hdr_crc = crc32(0, &crcnode, sizeof(crcnode)-4);

		if (hdr_crc != je32_to_cpu(node->hdr_crc)) {
			noisy_printk(&noise, "jffs2_scan_eraseblock(): Node at 0x%08x {0x%04x, 0x%04x, 0x%08x) has invalid CRC 0x%08x (calculated 0x%08x)\n",
				     ofs, je16_to_cpu(node->magic),
				     je16_to_cpu(node->nodetype), 
				     je32_to_cpu(node->totlen),
				     je32_to_cpu(node->hdr_crc),
				     hdr_crc);
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}

		if (ofs + je32_to_cpu(node->totlen) > 
		    jeb->offset + c->sector_size) {
			/* Eep. Node goes over the end of the erase block. */
			printk(KERN_WARNING "Node at 0x%08x with length 0x%08x would run over the end of the erase block\n",
			       ofs, je32_to_cpu(node->totlen));
			printk(KERN_WARNING "Perhaps the file system was created with the wrong erase size?\n");
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}

		if (!(je16_to_cpu(node->nodetype) & JFFS2_NODE_ACCURATE)) {
			/* Wheee. This is an obsoleted node */
			D2(printk(KERN_DEBUG "Node at 0x%08x is obsolete. Skipping\n", ofs));
			DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
			ofs += PAD(je32_to_cpu(node->totlen));
			continue;
		}

		switch(je16_to_cpu(node->nodetype)) {
		case JFFS2_NODETYPE_INODE:
			if (buf_ofs + buf_len < ofs + sizeof(struct jffs2_raw_inode)) {
				buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
				D1(printk(KERN_DEBUG "Fewer than %zd bytes (inode node) left to end of buf. Reading 0x%x at 0x%08x\n",
					  sizeof(struct jffs2_raw_inode), buf_len, ofs));
				err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
				if (err)
					return err;
				buf_ofs = ofs;
				node = (void *)buf;
			}
			err = jffs2_scan_inode_node(c, jeb, (void *)node, ofs);
			if (err) return err;
			ofs += PAD(je32_to_cpu(node->totlen));
			break;
			
		case JFFS2_NODETYPE_DIRENT:
			if (buf_ofs + buf_len < ofs + je32_to_cpu(node->totlen)) {
				buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
				D1(printk(KERN_DEBUG "Fewer than %d bytes (dirent node) left to end of buf. Reading 0x%x at 0x%08x\n",
					  je32_to_cpu(node->totlen), buf_len, ofs));
				err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
				if (err)
					return err;
				buf_ofs = ofs;
				node = (void *)buf;
			}
			err = jffs2_scan_dirent_node(c, jeb, (void *)node, ofs);
			if (err) return err;
			ofs += PAD(je32_to_cpu(node->totlen));
			break;

		case JFFS2_NODETYPE_CLEANMARKER:
			D1(printk(KERN_DEBUG "CLEANMARKER node found at 0x%08x\n", ofs));
			if (je32_to_cpu(node->totlen) != c->cleanmarker_size) {
				printk(KERN_NOTICE "CLEANMARKER node found at 0x%08x has totlen 0x%x != normal 0x%x\n", 
				       ofs, je32_to_cpu(node->totlen), c->cleanmarker_size);
				DIRTY_SPACE(PAD(sizeof(struct jffs2_unknown_node)));
				ofs += PAD(sizeof(struct jffs2_unknown_node));
			} else if (jeb->first_node) {
				printk(KERN_NOTICE "CLEANMARKER node found at 0x%08x, not first node in block (0x%08x)\n", ofs, jeb->offset);
				DIRTY_SPACE(PAD(sizeof(struct jffs2_unknown_node)));
				ofs += PAD(sizeof(struct jffs2_unknown_node));
			} else {
				struct jffs2_raw_node_ref *marker_ref = jffs2_alloc_raw_node_ref();
				if (!marker_ref) {
					printk(KERN_NOTICE "Failed to allocate node ref for clean marker\n");
					return -ENOMEM;
				}
				marker_ref->next_in_ino = NULL;
				marker_ref->next_phys = NULL;
				marker_ref->flash_offset = ofs | REF_NORMAL;
				marker_ref->__totlen = c->cleanmarker_size;
				jeb->first_node = jeb->last_node = marker_ref;
			     
				USED_SPACE(PAD(c->cleanmarker_size));
				ofs += PAD(c->cleanmarker_size);
			}
			break;

		case JFFS2_NODETYPE_PADDING:
			DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
			ofs += PAD(je32_to_cpu(node->totlen));
			break;

		default:
			switch (je16_to_cpu(node->nodetype) & JFFS2_COMPAT_MASK) {
			case JFFS2_FEATURE_ROCOMPAT:
				printk(KERN_NOTICE "Read-only compatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs);
			        c->flags |= JFFS2_SB_FLAG_RO;
				if (!(jffs2_is_readonly(c)))
					return -EROFS;
				DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
				ofs += PAD(je32_to_cpu(node->totlen));
				break;

			case JFFS2_FEATURE_INCOMPAT:
				printk(KERN_NOTICE "Incompatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs);
				return -EINVAL;

			case JFFS2_FEATURE_RWCOMPAT_DELETE:
				D1(printk(KERN_NOTICE "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs));
				DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
				ofs += PAD(je32_to_cpu(node->totlen));
				break;

			case JFFS2_FEATURE_RWCOMPAT_COPY:
				D1(printk(KERN_NOTICE "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs));
				USED_SPACE(PAD(je32_to_cpu(node->totlen)));
				ofs += PAD(je32_to_cpu(node->totlen));
				break;
			}
		}
	}


	D1(printk(KERN_DEBUG "Block at 0x%08x: free 0x%08x, dirty 0x%08x, unchecked 0x%08x, used 0x%08x\n", jeb->offset, 
		  jeb->free_size, jeb->dirty_size, jeb->unchecked_size, jeb->used_size));

	/* mark_node_obsolete can add to wasted !! */
	if (jeb->wasted_size) {
		jeb->dirty_size += jeb->wasted_size;
		c->dirty_size += jeb->wasted_size;
		c->wasted_size -= jeb->wasted_size;
		jeb->wasted_size = 0;
	}

	if ((jeb->used_size + jeb->unchecked_size) == PAD(c->cleanmarker_size) && !jeb->dirty_size 
		&& (!jeb->first_node || !jeb->first_node->next_in_ino) )
		return BLK_STATE_CLEANMARKER;
		
	/* move blocks with max 4 byte dirty space to cleanlist */	
	else if (!ISDIRTY(c->sector_size - (jeb->used_size + jeb->unchecked_size))) {
		c->dirty_size -= jeb->dirty_size;
		c->wasted_size += jeb->dirty_size; 
		jeb->wasted_size += jeb->dirty_size;
		jeb->dirty_size = 0;
		return BLK_STATE_CLEAN;
	} else if (jeb->used_size || jeb->unchecked_size)
		return BLK_STATE_PARTDIRTY;
	else
		return BLK_STATE_ALLDIRTY;
}

static struct jffs2_inode_cache *jffs2_scan_make_ino_cache(struct jffs2_sb_info *c, uint32_t ino)
{
	struct jffs2_inode_cache *ic;

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

	if (ino > c->highest_ino)
		c->highest_ino = ino;

	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->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, 
				 struct jffs2_raw_inode *ri, uint32_t ofs)
{
	struct jffs2_raw_node_ref *raw;
	struct jffs2_inode_cache *ic;
	uint32_t ino = je32_to_cpu(ri->ino);

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

	/* We do very little here now. Just check the ino# to which we should attribute
	   this node; we can do all the CRC checking etc. later. There's a tradeoff here -- 
	   we used to scan the flash once only, reading everything we want from it into
	   memory, then building all our in-core data structures and freeing the extra
	   information. Now we allow the first part of the mount to complete a lot quicker,
	   but we have to go _back_ to the flash in order to finish the CRC checking, etc. 
	   Which means that the _full_ amount of time to get to proper write mode with GC
	   operational may actually be _longer_ than before. Sucks to be me. */

	raw = jffs2_alloc_raw_node_ref();
	if (!raw) {
		printk(KERN_NOTICE "jffs2_scan_inode_node(): allocation of node reference failed\n");
		return -ENOMEM;
	}

	ic = jffs2_get_ino_cache(c, ino);
	if (!ic) {
		/* Inocache get failed. Either we read a bogus ino# or it's just genuinely the
		   first node we found for this inode. Do a CRC check to protect against the former
		   case */
		uint32_t crc = crc32(0, ri, sizeof(*ri)-8);

		if (crc != je32_to_cpu(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, je32_to_cpu(ri->node_crc), crc);
			/* We believe totlen because the CRC on the node _header_ was OK, just the node itself failed. */
			DIRTY_SPACE(PAD(je32_to_cpu(ri->totlen)));
			jffs2_free_raw_node_ref(raw);
			return 0;
		}
		ic = jffs2_scan_make_ino_cache(c, ino);
		if (!ic) {
			jffs2_free_raw_node_ref(raw);
			return -ENOMEM;
		}
	}

	/* Wheee. It worked */

	raw->flash_offset = ofs | REF_UNCHECKED;
	raw->__totlen = PAD(je32_to_cpu(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", 
		  je32_to_cpu(ri->ino), je32_to_cpu(ri->version),
		  je32_to_cpu(ri->offset),
		  je32_to_cpu(ri->offset)+je32_to_cpu(ri->dsize)));

	pseudo_random += je32_to_cpu(ri->version);

	UNCHECKED_SPACE(PAD(je32_to_cpu(ri->totlen)));
	return 0;
}

static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, 
				  struct jffs2_raw_dirent *rd, uint32_t ofs)
{
	struct jffs2_raw_node_ref *raw;
	struct jffs2_full_dirent *fd;
	struct jffs2_inode_cache *ic;
	uint32_t crc;

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

	/* We don't get here unless the node is still valid, so we don't have to
	   mask in the ACCURATE bit any more. */
	crc = crc32(0, rd, sizeof(*rd)-8);

	if (crc != je32_to_cpu(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, je32_to_cpu(rd->node_crc), crc);
		/* We believe totlen because the CRC on the node _header_ was OK, just the node itself failed. */
		DIRTY_SPACE(PAD(je32_to_cpu(rd->totlen)));
		return 0;
	}

	pseudo_random += je32_to_cpu(rd->version);

	fd = jffs2_alloc_full_dirent(rd->nsize+1);
	if (!fd) {
		return -ENOMEM;
	}
	memcpy(&fd->name, rd->name, rd->nsize);
	fd->name[rd->nsize] = 0;

	crc = crc32(0, fd->name, rd->nsize);
	if (crc != je32_to_cpu(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, je32_to_cpu(rd->name_crc), crc);	
		D1(printk(KERN_NOTICE "Name for which CRC failed is (now) '%s', ino #%d\n", fd->name, je32_to_cpu(rd->ino)));
		jffs2_free_full_dirent(fd);
		/* FIXME: Why do we believe totlen? */
		/* We believe totlen because the CRC on the node _header_ was OK, just the name failed. */
		DIRTY_SPACE(PAD(je32_to_cpu(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, je32_to_cpu(rd->pino));
	if (!ic) {
		jffs2_free_full_dirent(fd);
		jffs2_free_raw_node_ref(raw);
		return -ENOMEM;
	}
	
	raw->__totlen = PAD(je32_to_cpu(rd->totlen));
	raw->flash_offset = ofs | REF_PRISTINE;
	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;

	fd->raw = raw;
	fd->next = NULL;
	fd->version = je32_to_cpu(rd->version);
	fd->ino = je32_to_cpu(rd->ino);
	fd->nhash = full_name_hash(fd->name, rd->nsize);
	fd->type = rd->type;
	USED_SPACE(PAD(je32_to_cpu(rd->totlen)));
	jffs2_add_fd_to_list(c, fd, &ic->scan_dents);

	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);
}

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

	x = count_list(&c->clean_list);
	if (x) {
		rotateby = pseudo_random % x;
		D1(printk(KERN_DEBUG "Rotating clean_list by %d\n", rotateby));

		rotate_list((&c->clean_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of clean_list is at %08x\n",
			  list_entry(c->clean_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty clean_list\n"));
	}

	x = count_list(&c->very_dirty_list);
	if (x) {
		rotateby = pseudo_random % x;
		D1(printk(KERN_DEBUG "Rotating very_dirty_list by %d\n", rotateby));

		rotate_list((&c->very_dirty_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of very_dirty_list is at %08x\n",
			  list_entry(c->very_dirty_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty very_dirty_list\n"));
	}

	x = count_list(&c->dirty_list);
	if (x) {
		rotateby = pseudo_random % x;
		D1(printk(KERN_DEBUG "Rotating dirty_list by %d\n", rotateby));

		rotate_list((&c->dirty_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of dirty_list is at %08x\n",
			  list_entry(c->dirty_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty dirty_list\n"));
	}

	x = count_list(&c->erasable_list);
	if (x) {
		rotateby = pseudo_random % x;
		D1(printk(KERN_DEBUG "Rotating erasable_list by %d\n", rotateby));

		rotate_list((&c->erasable_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of erasable_list is at %08x\n",
			  list_entry(c->erasable_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty erasable_list\n"));
	}

	if (c->nr_erasing_blocks) {
		rotateby = pseudo_random % c->nr_erasing_blocks;
		D1(printk(KERN_DEBUG "Rotating erase_pending_list by %d\n", rotateby));

		rotate_list((&c->erase_pending_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of erase_pending_list is at %08x\n",
			  list_entry(c->erase_pending_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty erase_pending_list\n"));
	}

	if (c->nr_free_blocks) {
		rotateby = pseudo_random % c->nr_free_blocks;
		D1(printk(KERN_DEBUG "Rotating free_list by %d\n", rotateby));

		rotate_list((&c->free_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of free_list is at %08x\n",
			  list_entry(c->free_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty free_list\n"));
	}
}