scan.c

基于linux-2.6.28的mtd驱动

			return -EINVAL;
		}

		/*
		 * Now we have to drop the older one and preserve the newer
		 * one.
		 */
		cmp_res = compare_lebs(ubi, seb, pnum, vid_hdr);
		if (cmp_res < 0)
			return cmp_res;

		if (cmp_res & 1) {
			/*
			 * This logical eraseblock is newer then the one
			 * found earlier.
			 */
			err = validate_vid_hdr(vid_hdr, sv, pnum);
			if (err)
				return err;

			if (cmp_res & 4)
				err = add_to_list(si, seb->pnum, seb->ec,
						  &si->corr);
			else
				err = add_to_list(si, seb->pnum, seb->ec,
						  &si->erase);
			if (err)
				return err;

			seb->ec = ec;
			seb->pnum = pnum;
			seb->scrub = ((cmp_res & 2) || bitflips);
			seb->sqnum = sqnum;

			if (sv->highest_lnum == lnum)
				sv->last_data_size =
					be32_to_cpu(vid_hdr->data_size);

			return 0;
		} else {
			/*
			 * This logical eraseblock is older then the one found
			 * previously.
			 */
			if (cmp_res & 4)
				return add_to_list(si, pnum, ec, &si->corr);
			else
				return add_to_list(si, pnum, ec, &si->erase);
		}
	}

	/*
	 * We've met this logical eraseblock for the first time, add it to the
	 * scanning information.
	 */

	err = validate_vid_hdr(vid_hdr, sv, pnum);
	if (err)
		return err;

	seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
	if (!seb)
		return -ENOMEM;

	seb->ec = ec;
	seb->pnum = pnum;
	seb->lnum = lnum;
	seb->sqnum = sqnum;
	seb->scrub = bitflips;

	if (sv->highest_lnum <= lnum) {
		sv->highest_lnum = lnum;
		sv->last_data_size = be32_to_cpu(vid_hdr->data_size);
	}

	sv->leb_count += 1;
	rb_link_node(&seb->u.rb, parent, p);
	rb_insert_color(&seb->u.rb, &sv->root);
	return 0;
}

/**
 * ubi_scan_find_sv - find volume in the scanning information.
 * @si: scanning information
 * @vol_id: the requested volume ID
 *
 * This function returns a pointer to the volume description or %NULL if there
 * are no data about this volume in the scanning information.
 */
struct ubi_scan_volume *ubi_scan_find_sv(const struct ubi_scan_info *si,
					 int vol_id)
{
	struct ubi_scan_volume *sv;
	struct rb_node *p = si->volumes.rb_node;

	while (p) {
		sv = rb_entry(p, struct ubi_scan_volume, rb);

		if (vol_id == sv->vol_id)
			return sv;

		if (vol_id > sv->vol_id)
			p = p->rb_left;
		else
			p = p->rb_right;
	}

	return NULL;
}

/**
 * ubi_scan_find_seb - find LEB in the volume scanning information.
 * @sv: a pointer to the volume scanning information
 * @lnum: the requested logical eraseblock
 *
 * This function returns a pointer to the scanning logical eraseblock or %NULL
 * if there are no data about it in the scanning volume information.
 */
struct ubi_scan_leb *ubi_scan_find_seb(const struct ubi_scan_volume *sv,
				       int lnum)
{
	struct ubi_scan_leb *seb;
	struct rb_node *p = sv->root.rb_node;

	while (p) {
		seb = rb_entry(p, struct ubi_scan_leb, u.rb);

		if (lnum == seb->lnum)
			return seb;

		if (lnum > seb->lnum)
			p = p->rb_left;
		else
			p = p->rb_right;
	}

	return NULL;
}

/**
 * ubi_scan_rm_volume - delete scanning information about a volume.
 * @si: scanning information
 * @sv: the volume scanning information to delete
 */
void ubi_scan_rm_volume(struct ubi_scan_info *si, struct ubi_scan_volume *sv)
{
	struct rb_node *rb;
	struct ubi_scan_leb *seb;

	dbg_bld("remove scanning information about volume %d", sv->vol_id);

	while ((rb = rb_first(&sv->root))) {
		seb = rb_entry(rb, struct ubi_scan_leb, u.rb);
		rb_erase(&seb->u.rb, &sv->root);
		list_add_tail(&seb->u.list, &si->erase);
	}

	rb_erase(&sv->rb, &si->volumes);
	kfree(sv);
	si->vols_found -= 1;
}

/**
 * ubi_scan_erase_peb - erase a physical eraseblock.
 * @ubi: UBI device description object
 * @si: scanning information
 * @pnum: physical eraseblock number to erase;
 * @ec: erase counter value to write (%UBI_SCAN_UNKNOWN_EC if it is unknown)
 *
 * This function erases physical eraseblock 'pnum', and writes the erase
 * counter header to it. This function should only be used on UBI device
 * initialization stages, when the EBA sub-system had not been yet initialized.
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
int ubi_scan_erase_peb(struct ubi_device *ubi, const struct ubi_scan_info *si,
		       int pnum, int ec)
{
	int err;
	struct ubi_ec_hdr *ec_hdr;

	if ((long long)ec >= UBI_MAX_ERASECOUNTER) {
		/*
		 * Erase counter overflow. Upgrade UBI and use 64-bit
		 * erase counters internally.
		 */
		ubi_err("erase counter overflow at PEB %d, EC %d", pnum, ec);
		return -EINVAL;
	}

	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
	if (!ec_hdr)
		return -ENOMEM;

	ec_hdr->ec = cpu_to_be64(ec);

	err = ubi_io_sync_erase(ubi, pnum, 0);
	if (err < 0)
		goto out_free;

	err = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);

out_free:
	kfree(ec_hdr);
	return err;
}

/**
 * ubi_scan_get_free_peb - get a free physical eraseblock.
 * @ubi: UBI device description object
 * @si: scanning information
 *
 * This function returns a free physical eraseblock. It is supposed to be
 * called on the UBI initialization stages when the wear-leveling sub-system is
 * not initialized yet. This function picks a physical eraseblocks from one of
 * the lists, writes the EC header if it is needed, and removes it from the
 * list.
 *
 * This function returns scanning physical eraseblock information in case of
 * success and an error code in case of failure.
 */
struct ubi_scan_leb *ubi_scan_get_free_peb(struct ubi_device *ubi,
					   struct ubi_scan_info *si)
{
	int err = 0, i;
	struct ubi_scan_leb *seb;

	if (!list_empty(&si->free)) {
		seb = list_entry(si->free.next, struct ubi_scan_leb, u.list);
		list_del(&seb->u.list);
		dbg_bld("return free PEB %d, EC %d", seb->pnum, seb->ec);
		return seb;
	}

	for (i = 0; i < 2; i++) {
		struct list_head *head;
		struct ubi_scan_leb *tmp_seb;

		if (i == 0)
			head = &si->erase;
		else
			head = &si->corr;

		/*
		 * We try to erase the first physical eraseblock from the @head
		 * list and pick it if we succeed, or try to erase the
		 * next one if not. And so forth. We don't want to take care
		 * about bad eraseblocks here - they'll be handled later.
		 */
		list_for_each_entry_safe(seb, tmp_seb, head, u.list) {
			if (seb->ec == UBI_SCAN_UNKNOWN_EC)
				seb->ec = si->mean_ec;

			err = ubi_scan_erase_peb(ubi, si, seb->pnum, seb->ec+1);
			if (err)
				continue;

			seb->ec += 1;
			list_del(&seb->u.list);
			dbg_bld("return PEB %d, EC %d", seb->pnum, seb->ec);
			return seb;
		}
	}

	ubi_err("no eraseblocks found");
	return ERR_PTR(-ENOSPC);
}

/**
 * process_eb - read, check UBI headers, and add them to scanning information.
 * @ubi: UBI device description object
 * @si: scanning information
 * @pnum: the physical eraseblock number
 *
 * This function returns a zero if the physical eraseblock was successfully
 * handled and a negative error code in case of failure.
 */
static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
		      int pnum)
{
	long long uninitialized_var(ec);
	int err, bitflips = 0, vol_id, ec_corr = 0;

	dbg_bld("scan PEB %d", pnum);

	/* Skip bad physical eraseblocks */
	err = ubi_io_is_bad(ubi, pnum);
	if (err < 0)
		return err;
	else if (err) {
		/*
		 * FIXME: this is actually duty of the I/O sub-system to
		 * initialize this, but MTD does not provide enough
		 * information.
		 */
		si->bad_peb_count += 1;
		return 0;
	}

	err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
	if (err < 0)
		return err;
	else if (err == UBI_IO_BITFLIPS)
		bitflips = 1;
	else if (err == UBI_IO_PEB_EMPTY)
		return add_to_list(si, pnum, UBI_SCAN_UNKNOWN_EC, &si->erase);
	else if (err == UBI_IO_BAD_EC_HDR) {
		/*
		 * We have to also look at the VID header, possibly it is not
		 * corrupted. Set %bitflips flag in order to make this PEB be
		 * moved and EC be re-created.
		 */
		ec_corr = 1;
		ec = UBI_SCAN_UNKNOWN_EC;
		bitflips = 1;
	}

	si->is_empty = 0;

	if (!ec_corr) {
		/* Make sure UBI version is OK */
		if (ech->version != UBI_VERSION) {
			ubi_err("this UBI version is %d, image version is %d",
				UBI_VERSION, (int)ech->version);
			return -EINVAL;
		}

		ec = be64_to_cpu(ech->ec);
		if (ec > UBI_MAX_ERASECOUNTER) {
			/*
			 * Erase counter overflow. The EC headers have 64 bits
			 * reserved, but we anyway make use of only 31 bit
			 * values, as this seems to be enough for any existing
			 * flash. Upgrade UBI and use 64-bit erase counters
			 * internally.
			 */
			ubi_err("erase counter overflow, max is %d",
				UBI_MAX_ERASECOUNTER);
			ubi_dbg_dump_ec_hdr(ech);
			return -EINVAL;
		}
	}

	/* OK, we've done with the EC header, let's look at the VID header */

	err = ubi_io_read_vid_hdr(ubi, pnum, vidh, 0);
	if (err < 0)
		return err;
	else if (err == UBI_IO_BITFLIPS)
		bitflips = 1;
	else if (err == UBI_IO_BAD_VID_HDR ||
		 (err == UBI_IO_PEB_FREE && ec_corr)) {
		/* VID header is corrupted */
		err = add_to_list(si, pnum, ec, &si->corr);
		if (err)
			return err;
		goto adjust_mean_ec;
	} else if (err == UBI_IO_PEB_FREE) {
		/* No VID header - the physical eraseblock is free */
		err = add_to_list(si, pnum, ec, &si->free);
		if (err)
			return err;
		goto adjust_mean_ec;
	}

	vol_id = be32_to_cpu(vidh->vol_id);
	if (vol_id > UBI_MAX_VOLUMES && vol_id != UBI_LAYOUT_VOLUME_ID) {
		int lnum = be32_to_cpu(vidh->lnum);

		/* Unsupported internal volume */
		switch (vidh->compat) {
		case UBI_COMPAT_DELETE:
			ubi_msg("\"delete\" compatible internal volume %d:%d"
				" found, remove it", vol_id, lnum);
			err = add_to_list(si, pnum, ec, &si->corr);
			if (err)
				return err;
			break;

		case UBI_COMPAT_RO:
			ubi_msg("read-only compatible internal volume %d:%d"
				" found, switch to read-only mode",
				vol_id, lnum);
			ubi->ro_mode = 1;
			break;

		case UBI_COMPAT_PRESERVE:
			ubi_msg("\"preserve\" compatible internal volume %d:%d"
				" found", vol_id, lnum);
			err = add_to_list(si, pnum, ec, &si->alien);
			if (err)
				return err;
			si->alien_peb_count += 1;
			return 0;

		case UBI_COMPAT_REJECT:
			ubi_err("incompatible internal volume %d:%d found",
				vol_id, lnum);
			return -EINVAL;
		}
	}

	/* Both UBI headers seem to be fine */
	err = ubi_scan_add_used(ubi, si, pnum, ec, vidh, bitflips);
	if (err)
		return err;

adjust_mean_ec:
	if (!ec_corr) {
		si->ec_sum += ec;
		si->ec_count += 1;
		if (ec > si->max_ec)
			si->max_ec = ec;
		if (ec < si->min_ec)
			si->min_ec = ec;
	}

	return 0;
}

/**
 * ubi_scan - scan an MTD device.
 * @ubi: UBI device description object
 *
 * This function does full scanning of an MTD device and returns complete
 * information about it. In case of failure, an error code is returned.
 */
struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
{
	int err, pnum;
	struct rb_node *rb1, *rb2;
	struct ubi_scan_volume *sv;
	struct ubi_scan_leb *seb;
	struct ubi_scan_info *si;

	si = kzalloc(sizeof(struct ubi_scan_info), GFP_KERNEL);
	if (!si)
		return ERR_PTR(-ENOMEM);