readinode.c

linux 内核源代码

					   highest_version, because this one is only
					   counting _valid_ nodes which could give the
					   latest inode metadata */
					high_ver = this->version;
					rii->latest_ref = this->fn->raw;
				}
				dbg_readinode("Add %p (v %d, 0x%x-0x%x, ov %d) to fragtree\n",
					     this, this->version, this->fn->ofs,
					     this->fn->ofs+this->fn->size, this->overlapped);

				ret = jffs2_add_full_dnode_to_inode(c, f, this->fn);
				if (ret) {
					/* Free the nodes in vers_root; let the caller
					   deal with the rest */
					JFFS2_ERROR("Add node to tree failed %d\n", ret);
					while (1) {
						vers_next = tn_prev(this);
						if (check_tn_node(c, this))
							jffs2_mark_node_obsolete(c, this->fn->raw);
						jffs2_free_full_dnode(this->fn);
						jffs2_free_tmp_dnode_info(this);
						this = vers_next;
						if (!this)
							break;
						eat_last(&ver_root, &vers_next->rb);
					}
					return ret;
				}
				jffs2_free_tmp_dnode_info(this);
			}
			this = vers_next;
		}
	}
	return 0;
}

static void jffs2_free_tmp_dnode_info_list(struct rb_root *list)
{
	struct rb_node *this;
	struct jffs2_tmp_dnode_info *tn;

	this = list->rb_node;

	/* Now at bottom of tree */
	while (this) {
		if (this->rb_left)
			this = this->rb_left;
		else if (this->rb_right)
			this = this->rb_right;
		else {
			tn = rb_entry(this, struct jffs2_tmp_dnode_info, rb);
			jffs2_free_full_dnode(tn->fn);
			jffs2_free_tmp_dnode_info(tn);

			this = rb_parent(this);
			if (!this)
				break;

			if (this->rb_left == &tn->rb)
				this->rb_left = NULL;
			else if (this->rb_right == &tn->rb)
				this->rb_right = NULL;
			else BUG();
		}
	}
	list->rb_node = NULL;
}

static void jffs2_free_full_dirent_list(struct jffs2_full_dirent *fd)
{
	struct jffs2_full_dirent *next;

	while (fd) {
		next = fd->next;
		jffs2_free_full_dirent(fd);
		fd = next;
	}
}

/* Returns first valid node after 'ref'. May return 'ref' */
static struct jffs2_raw_node_ref *jffs2_first_valid_node(struct jffs2_raw_node_ref *ref)
{
	while (ref && ref->next_in_ino) {
		if (!ref_obsolete(ref))
			return ref;
		dbg_noderef("node at 0x%08x is obsoleted. Ignoring.\n", ref_offset(ref));
		ref = ref->next_in_ino;
	}
	return NULL;
}

/*
 * Helper function for jffs2_get_inode_nodes().
 * It is called every time an directory entry node is found.
 *
 * Returns: 0 on success;
 * 	    negative error code on failure.
 */
static inline int read_direntry(struct jffs2_sb_info *c, struct jffs2_raw_node_ref *ref,
				struct jffs2_raw_dirent *rd, size_t read,
				struct jffs2_readinode_info *rii)
{
	struct jffs2_full_dirent *fd;
	uint32_t crc;

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

	crc = crc32(0, rd, sizeof(*rd) - 8);
	if (unlikely(crc != je32_to_cpu(rd->node_crc))) {
		JFFS2_NOTICE("header CRC failed on dirent node at %#08x: read %#08x, calculated %#08x\n",
			     ref_offset(ref), je32_to_cpu(rd->node_crc), crc);
		jffs2_mark_node_obsolete(c, ref);
		return 0;
	}

	/* If we've never checked the CRCs on this node, check them now */
	if (ref_flags(ref) == REF_UNCHECKED) {
		struct jffs2_eraseblock *jeb;
		int len;

		/* Sanity check */
		if (unlikely(PAD((rd->nsize + sizeof(*rd))) != PAD(je32_to_cpu(rd->totlen)))) {
			JFFS2_ERROR("illegal nsize in node at %#08x: nsize %#02x, totlen %#04x\n",
				    ref_offset(ref), rd->nsize, je32_to_cpu(rd->totlen));
			jffs2_mark_node_obsolete(c, ref);
			return 0;
		}

		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;
		ref->flash_offset = ref_offset(ref) | dirent_node_state(rd);
		spin_unlock(&c->erase_completion_lock);
	}

	fd = jffs2_alloc_full_dirent(rd->nsize + 1);
	if (unlikely(!fd))
		return -ENOMEM;

	fd->raw = ref;
	fd->version = je32_to_cpu(rd->version);
	fd->ino = je32_to_cpu(rd->ino);
	fd->type = rd->type;

	if (fd->version > rii->highest_version)
		rii->highest_version = fd->version;

	/* Pick out the mctime of the latest dirent */
	if(fd->version > rii->mctime_ver && je32_to_cpu(rd->mctime)) {
		rii->mctime_ver = fd->version;
		rii->latest_mctime = je32_to_cpu(rd->mctime);
	}

	/*
	 * Copy as much of the name as possible from the raw
	 * dirent we've already read from the flash.
	 */
	if (read > sizeof(*rd))
		memcpy(&fd->name[0], &rd->name[0],
		       min_t(uint32_t, rd->nsize, (read - sizeof(*rd)) ));

	/* Do we need to copy any more of the name directly from the flash? */
	if (rd->nsize + sizeof(*rd) > read) {
		/* FIXME: point() */
		int err;
		int already = read - sizeof(*rd);

		err = jffs2_flash_read(c, (ref_offset(ref)) + read,
				rd->nsize - already, &read, &fd->name[already]);
		if (unlikely(read != rd->nsize - already) && likely(!err))
			return -EIO;

		if (unlikely(err)) {
			JFFS2_ERROR("read remainder of name: error %d\n", err);
			jffs2_free_full_dirent(fd);
			return -EIO;
		}
	}

	fd->nhash = full_name_hash(fd->name, rd->nsize);
	fd->next = NULL;
	fd->name[rd->nsize] = '\0';

	/*
	 * Wheee. We now have a complete jffs2_full_dirent structure, with
	 * the name in it and everything. Link it into the list
	 */
	jffs2_add_fd_to_list(c, fd, &rii->fds);

	return 0;
}

/*
 * Helper function for jffs2_get_inode_nodes().
 * It is called every time an inode node is found.
 *
 * Returns: 0 on success (possibly after marking a bad node 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, int rdlen,
			     struct jffs2_readinode_info *rii)
{
	struct jffs2_tmp_dnode_info *tn;
	uint32_t len, csize;
	int ret = 0;
	uint32_t crc;

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

	crc = crc32(0, rd, sizeof(*rd) - 8);
	if (unlikely(crc != je32_to_cpu(rd->node_crc))) {
		JFFS2_NOTICE("node CRC failed on dnode at %#08x: read %#08x, calculated %#08x\n",
			     ref_offset(ref), je32_to_cpu(rd->node_crc), crc);
		jffs2_mark_node_obsolete(c, ref);
		return 0;
	}

	tn = jffs2_alloc_tmp_dnode_info();
	if (!tn) {
		JFFS2_ERROR("failed to allocate tn (%zu 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) {

		/* 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));
			jffs2_mark_node_obsolete(c, 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));
				jffs2_mark_node_obsolete(c, ref);
				goto free_out;
			}

		} else if (csize == 0) {
			/*
			 * We checked the header CRC. If the node has no data, adjust
			 * the space accounting now. For other nodes this will be done
			 * later either when the node is marked obsolete or when its
			 * data is checked.
			 */
			struct jffs2_eraseblock *jeb;

			dbg_readinode("the node has no data.\n");
			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;
			ref->flash_offset = ref_offset(ref) | REF_NORMAL;
			spin_unlock(&c->erase_completion_lock);
		}
	}

	tn->fn = jffs2_alloc_full_dnode();
	if (!tn->fn) {
		JFFS2_ERROR("alloc fn failed\n");
		ret = -ENOMEM;
		goto free_out;
	}

	tn->version = je32_to_cpu(rd->version);
	tn->fn->ofs = je32_to_cpu(rd->offset);
	tn->data_crc = je32_to_cpu(rd->data_crc);
	tn->csize = csize;
	tn->fn->raw = ref;
	tn->overlapped = 0;

	if (tn->version > rii->highest_version)
		rii->highest_version = tn->version;

	/* There was a bug where we wrote hole nodes out with
	   csize/dsize swapped. Deal with it */
	if (rd->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(rd->dsize) && csize)
		tn->fn->size = csize;
	else // normal case...
		tn->fn->size = je32_to_cpu(rd->dsize);

	dbg_readinode("dnode @%08x: ver %u, offset %#04x, dsize %#04x, csize %#04x\n",
		  ref_offset(ref), je32_to_cpu(rd->version), je32_to_cpu(rd->offset), je32_to_cpu(rd->dsize), csize);

	ret = jffs2_add_tn_to_tree(c, rii, tn);

	if (ret) {
		jffs2_free_full_dnode(tn->fn);
	free_out:
		jffs2_free_tmp_dnode_info(tn);
		return ret;
	}
#ifdef JFFS2_DBG_READINODE_MESSAGES
	dbg_readinode("After adding ver %d:\n", je32_to_cpu(rd->version));
	tn = tn_first(&rii->tn_root);
	while (tn) {
		dbg_readinode("%p: v %d r 0x%x-0x%x ov %d\n",
			     tn, tn->version, tn->fn->ofs,
			     tn->fn->ofs+tn->fn->size, tn->overlapped);
		tn = tn_next(tn);
	}
#endif
	return 0;
}

/*
 * Helper function for jffs2_get_inode_nodes().
 * It is called every time an unknown node is found.
 *
 * Returns: 0 on success;
 * 	    negative error code on failure.
 */
static inline int read_unknown(struct jffs2_sb_info *c, struct jffs2_raw_node_ref *ref, struct jffs2_unknown_node *un)
{
	/* We don't mark unknown nodes as REF_UNCHECKED */
	if (ref_flags(ref) == REF_UNCHECKED) {
		JFFS2_ERROR("REF_UNCHECKED but unknown node at %#08x\n",
			    ref_offset(ref));
		JFFS2_ERROR("Node is {%04x,%04x,%08x,%08x}. Please report this error.\n",
			    je16_to_cpu(un->magic), je16_to_cpu(un->nodetype),
			    je32_to_cpu(un->totlen), je32_to_cpu(un->hdr_crc));
		jffs2_mark_node_obsolete(c, ref);
		return 0;
	}

	un->nodetype = cpu_to_je16(JFFS2_NODE_ACCURATE | je16_to_cpu(un->nodetype));

	switch(je16_to_cpu(un->nodetype) & JFFS2_COMPAT_MASK) {

	case JFFS2_FEATURE_INCOMPAT:
		JFFS2_ERROR("unknown INCOMPAT nodetype %#04X at %#08x\n",
			    je16_to_cpu(un->nodetype), ref_offset(ref));
		/* EEP */
		BUG();
		break;

	case JFFS2_FEATURE_ROCOMPAT:
		JFFS2_ERROR("unknown ROCOMPAT nodetype %#04X at %#08x\n",
			    je16_to_cpu(un->nodetype), ref_offset(ref));
		BUG_ON(!(c->flags & JFFS2_SB_FLAG_RO));
		break;

	case JFFS2_FEATURE_RWCOMPAT_COPY:
		JFFS2_NOTICE("unknown RWCOMPAT_COPY nodetype %#04X at %#08x\n",
			     je16_to_cpu(un->nodetype), ref_offset(ref));
		break;

	case JFFS2_FEATURE_RWCOMPAT_DELETE:
		JFFS2_NOTICE("unknown RWCOMPAT_DELETE nodetype %#04X at %#08x\n",
			     je16_to_cpu(un->nodetype), ref_offset(ref));
		jffs2_mark_node_obsolete(c, ref);
		return 0;
	}

	return 0;
}

/*
 * Helper function for jffs2_get_inode_nodes().
 * The function detects whether more data should be read and reads it if yes.
 *
 * Returns: 0 on succes;
 * 	    negative error code on failure.
 */
static int read_more(struct jffs2_sb_info *c, struct jffs2_raw_node_ref *ref,
		     int needed_len, int *rdlen, unsigned char *buf)
{
	int err, to_read = needed_len - *rdlen;
	size_t retlen;
	uint32_t offs;

	if (jffs2_is_writebuffered(c)) {
		int rem = to_read % c->wbuf_pagesize;

		if (rem)
			to_read += c->wbuf_pagesize - rem;
	}

	/* We need to read more data */
	offs = ref_offset(ref) + *rdlen;

	dbg_readinode("read more %d bytes\n", to_read);

	err = jffs2_flash_read(c, offs, to_read, &retlen, buf + *rdlen);
	if (err) {
		JFFS2_ERROR("can not read %d bytes from 0x%08x, "
			"error code: %d.\n", to_read, offs, err);
		return err;
	}

	if (retlen < to_read) {
		JFFS2_ERROR("short read at %#08x: %zu instead of %d.\n",
				offs, retlen, to_read);
		return -EIO;
	}

	*rdlen += to_read;
	return 0;
}

/* Get tmp_dnode_info and full_dirent for all non-obsolete nodes associated
   with this ino. Perform a preliminary ordering on data nodes, throwing away
   those which are completely obsoleted by newer ones. The naïve approach we
   use to take of just returning them _all_ in version order will cause us to
   run out of memory in certain degenerate cases. */
static int jffs2_get_inode_nodes(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
				 struct jffs2_readinode_info *rii)
{
	struct jffs2_raw_node_ref *ref, *valid_ref;
	unsigned char *buf = NULL;
	union jffs2_node_union *node;