dm-log.c

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	lc->recovering_bits = vmalloc(bitset_size);
	if (!lc->recovering_bits) {
		DMWARN("couldn't allocate sync bitset");
		vfree(lc->sync_bits);
		if (!dev)
			vfree(lc->clean_bits);
		vfree(lc->disk_header);
		kfree(lc);
		return -ENOMEM;
	}
	memset(lc->recovering_bits, 0, bitset_size);
	lc->sync_search = 0;
	log->context = lc;

	return 0;
}

static int core_ctr(struct dirty_log *log, struct dm_target *ti,
		    unsigned int argc, char **argv)
{
	return create_log_context(log, ti, argc, argv, NULL);
}

static void destroy_log_context(struct log_c *lc)
{
	vfree(lc->sync_bits);
	vfree(lc->recovering_bits);
	kfree(lc);
}

static void core_dtr(struct dirty_log *log)
{
	struct log_c *lc = (struct log_c *) log->context;

	vfree(lc->clean_bits);
	destroy_log_context(lc);
}

/*----------------------------------------------------------------
 * disk log constructor/destructor
 *
 * argv contains log_device region_size followed optionally by [no]sync
 *--------------------------------------------------------------*/
static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
		    unsigned int argc, char **argv)
{
	int r;
	struct dm_dev *dev;

	if (argc < 2 || argc > 3) {
		DMWARN("wrong number of arguments to disk mirror log");
		return -EINVAL;
	}

	r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
			  FMODE_READ | FMODE_WRITE, &dev);
	if (r)
		return r;

	r = create_log_context(log, ti, argc - 1, argv + 1, dev);
	if (r) {
		dm_put_device(ti, dev);
		return r;
	}

	return 0;
}

static void disk_dtr(struct dirty_log *log)
{
	struct log_c *lc = (struct log_c *) log->context;

	dm_put_device(lc->ti, lc->log_dev);
	vfree(lc->disk_header);
	dm_io_client_destroy(lc->io_req.client);
	destroy_log_context(lc);
}

static int count_bits32(uint32_t *addr, unsigned size)
{
	int count = 0, i;

	for (i = 0; i < size; i++) {
		count += hweight32(*(addr+i));
	}
	return count;
}

static void fail_log_device(struct log_c *lc)
{
	if (lc->log_dev_failed)
		return;

	lc->log_dev_failed = 1;
	dm_table_event(lc->ti->table);
}

static int disk_resume(struct dirty_log *log)
{
	int r;
	unsigned i;
	struct log_c *lc = (struct log_c *) log->context;
	size_t size = lc->bitset_uint32_count * sizeof(uint32_t);

	/* read the disk header */
	r = read_header(lc);
	if (r) {
		DMWARN("%s: Failed to read header on mirror log device",
		       lc->log_dev->name);
		fail_log_device(lc);
		/*
		 * If the log device cannot be read, we must assume
		 * all regions are out-of-sync.  If we simply return
		 * here, the state will be uninitialized and could
		 * lead us to return 'in-sync' status for regions
		 * that are actually 'out-of-sync'.
		 */
		lc->header.nr_regions = 0;
	}

	/* set or clear any new bits -- device has grown */
	if (lc->sync == NOSYNC)
		for (i = lc->header.nr_regions; i < lc->region_count; i++)
			/* FIXME: amazingly inefficient */
			log_set_bit(lc, lc->clean_bits, i);
	else
		for (i = lc->header.nr_regions; i < lc->region_count; i++)
			/* FIXME: amazingly inefficient */
			log_clear_bit(lc, lc->clean_bits, i);

	/* clear any old bits -- device has shrunk */
	for (i = lc->region_count; i % (sizeof(*lc->clean_bits) << BYTE_SHIFT); i++)
		log_clear_bit(lc, lc->clean_bits, i);

	/* copy clean across to sync */
	memcpy(lc->sync_bits, lc->clean_bits, size);
	lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
	lc->sync_search = 0;

	/* set the correct number of regions in the header */
	lc->header.nr_regions = lc->region_count;

	/* write the new header */
	r = write_header(lc);
	if (r) {
		DMWARN("%s: Failed to write header on mirror log device",
		       lc->log_dev->name);
		fail_log_device(lc);
	}

	return r;
}

static uint32_t core_get_region_size(struct dirty_log *log)
{
	struct log_c *lc = (struct log_c *) log->context;
	return lc->region_size;
}

static int core_resume(struct dirty_log *log)
{
	struct log_c *lc = (struct log_c *) log->context;
	lc->sync_search = 0;
	return 0;
}

static int core_is_clean(struct dirty_log *log, region_t region)
{
	struct log_c *lc = (struct log_c *) log->context;
	return log_test_bit(lc->clean_bits, region);
}

static int core_in_sync(struct dirty_log *log, region_t region, int block)
{
	struct log_c *lc = (struct log_c *) log->context;
	return log_test_bit(lc->sync_bits, region);
}

static int core_flush(struct dirty_log *log)
{
	/* no op */
	return 0;
}

static int disk_flush(struct dirty_log *log)
{
	int r;
	struct log_c *lc = (struct log_c *) log->context;

	/* only write if the log has changed */
	if (!lc->touched)
		return 0;

	r = write_header(lc);
	if (r)
		fail_log_device(lc);
	else
		lc->touched = 0;

	return r;
}

static void core_mark_region(struct dirty_log *log, region_t region)
{
	struct log_c *lc = (struct log_c *) log->context;
	log_clear_bit(lc, lc->clean_bits, region);
}

static void core_clear_region(struct dirty_log *log, region_t region)
{
	struct log_c *lc = (struct log_c *) log->context;
	log_set_bit(lc, lc->clean_bits, region);
}

static int core_get_resync_work(struct dirty_log *log, region_t *region)
{
	struct log_c *lc = (struct log_c *) log->context;

	if (lc->sync_search >= lc->region_count)
		return 0;

	do {
		*region = ext2_find_next_zero_bit(
					     (unsigned long *) lc->sync_bits,
					     lc->region_count,
					     lc->sync_search);
		lc->sync_search = *region + 1;

		if (*region >= lc->region_count)
			return 0;

	} while (log_test_bit(lc->recovering_bits, *region));

	log_set_bit(lc, lc->recovering_bits, *region);
	return 1;
}

static void core_set_region_sync(struct dirty_log *log, region_t region,
				 int in_sync)
{
	struct log_c *lc = (struct log_c *) log->context;

	log_clear_bit(lc, lc->recovering_bits, region);
	if (in_sync) {
		log_set_bit(lc, lc->sync_bits, region);
                lc->sync_count++;
        } else if (log_test_bit(lc->sync_bits, region)) {
		lc->sync_count--;
		log_clear_bit(lc, lc->sync_bits, region);
	}
}

static region_t core_get_sync_count(struct dirty_log *log)
{
        struct log_c *lc = (struct log_c *) log->context;

        return lc->sync_count;
}

#define	DMEMIT_SYNC \
	if (lc->sync != DEFAULTSYNC) \
		DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")

static int core_status(struct dirty_log *log, status_type_t status,
		       char *result, unsigned int maxlen)
{
	int sz = 0;
	struct log_c *lc = log->context;

	switch(status) {
	case STATUSTYPE_INFO:
		DMEMIT("1 %s", log->type->name);
		break;

	case STATUSTYPE_TABLE:
		DMEMIT("%s %u %u ", log->type->name,
		       lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
		DMEMIT_SYNC;
	}

	return sz;
}

static int disk_status(struct dirty_log *log, status_type_t status,
		       char *result, unsigned int maxlen)
{
	int sz = 0;
	struct log_c *lc = log->context;

	switch(status) {
	case STATUSTYPE_INFO:
		DMEMIT("3 %s %s %c", log->type->name, lc->log_dev->name,
		       lc->log_dev_failed ? 'D' : 'A');
		break;

	case STATUSTYPE_TABLE:
		DMEMIT("%s %u %s %u ", log->type->name,
		       lc->sync == DEFAULTSYNC ? 2 : 3, lc->log_dev->name,
		       lc->region_size);
		DMEMIT_SYNC;
	}

	return sz;
}

static struct dirty_log_type _core_type = {
	.name = "core",
	.module = THIS_MODULE,
	.ctr = core_ctr,
	.dtr = core_dtr,
	.resume = core_resume,
	.get_region_size = core_get_region_size,
	.is_clean = core_is_clean,
	.in_sync = core_in_sync,
	.flush = core_flush,
	.mark_region = core_mark_region,
	.clear_region = core_clear_region,
	.get_resync_work = core_get_resync_work,
	.set_region_sync = core_set_region_sync,
	.get_sync_count = core_get_sync_count,
	.status = core_status,
};

static struct dirty_log_type _disk_type = {
	.name = "disk",
	.module = THIS_MODULE,
	.ctr = disk_ctr,
	.dtr = disk_dtr,
	.postsuspend = disk_flush,
	.resume = disk_resume,
	.get_region_size = core_get_region_size,
	.is_clean = core_is_clean,
	.in_sync = core_in_sync,
	.flush = disk_flush,
	.mark_region = core_mark_region,
	.clear_region = core_clear_region,
	.get_resync_work = core_get_resync_work,
	.set_region_sync = core_set_region_sync,
	.get_sync_count = core_get_sync_count,
	.status = disk_status,
};

int __init dm_dirty_log_init(void)
{
	int r;

	r = dm_register_dirty_log_type(&_core_type);
	if (r)
		DMWARN("couldn't register core log");

	r = dm_register_dirty_log_type(&_disk_type);
	if (r) {
		DMWARN("couldn't register disk type");
		dm_unregister_dirty_log_type(&_core_type);
	}

	return r;
}

void dm_dirty_log_exit(void)
{
	dm_unregister_dirty_log_type(&_disk_type);
	dm_unregister_dirty_log_type(&_core_type);
}

EXPORT_SYMBOL(dm_register_dirty_log_type);
EXPORT_SYMBOL(dm_unregister_dirty_log_type);
EXPORT_SYMBOL(dm_create_dirty_log);
EXPORT_SYMBOL(dm_destroy_dirty_log);