C++ DMWARN函数代码示例

static int ca_load(struct count_array *ca, struct dm_space_map *sm)
{
	int r;
	uint32_t count;
	dm_block_t nr_blocks, i;

	r = dm_sm_get_nr_blocks(sm, &nr_blocks);
	if (r)
		return r;

	BUG_ON(ca->nr != nr_blocks);

	DMWARN("Loading debug space map from disk.  This may take some time");
	for (i = 0; i < nr_blocks; i++) {
		r = dm_sm_get_count(sm, i, &count);
		if (r) {
			DMERR("load failed");
			return r;
		}

		ca_set_count(ca, i, count);
	}
	DMWARN("Load complete");

	return 0;
}

/*
 * get_type
 * @type_name
 *
 * Attempt to retrieve the dm_dirty_log_type by name.  If not already
 * available, attempt to load the appropriate module.
 *
 * Log modules are named "dm-log-" followed by the 'type_name'.
 * Modules may contain multiple types.
 * This function will first try the module "dm-log-<type_name>",
 * then truncate 'type_name' on the last '-' and try again.
 *
 * For example, if type_name was "clustered-disk", it would search
 * 'dm-log-clustered-disk' then 'dm-log-clustered'.
 *
 * Returns: dirty_log_type* on success, NULL on failure
 */
static struct dm_dirty_log_type *get_type(const char *type_name)
{
	char *p, *type_name_dup;
	struct dm_dirty_log_type *log_type;

	if (!type_name)
		return NULL;

	log_type = _get_dirty_log_type(type_name);
	if (log_type)
		return log_type;

	type_name_dup = kstrdup(type_name, GFP_KERNEL);
	if (!type_name_dup) {
		DMWARN("No memory left to attempt log module load for \"%s\"",
		       type_name);
		return NULL;
	}

	while (request_module("dm-log-%s", type_name_dup) ||
	       !(log_type = _get_dirty_log_type(type_name))) {
		p = strrchr(type_name_dup, '-');
		if (!p)
			break;
		p[0] = '\0';
	}

	if (!log_type)
		DMWARN("Module for logging type \"%s\" not found.", type_name);

	kfree(type_name_dup);

	return log_type;
}

static int persistent_read_metadata(struct exception_store *store)
{
	int r, new_snapshot;
	struct pstore *ps = get_info(store);

	/*
	 * Read the snapshot header.
	 */
	r = read_header(ps, &new_snapshot);
	if (r)
		return r;

	/*
	 * Do we need to setup a new snapshot ?
	 */
	if (new_snapshot) {
		r = write_header(ps);
		if (r) {
			DMWARN("write_header failed");
			return r;
		}

		r = zero_area(ps, 0);
		if (r) {
			DMWARN("zero_area(0) failed");
			return r;
		}

	} else {
		/*
		 * Sanity checks.
		 */
		if (!ps->valid) {
			DMWARN("snapshot is marked invalid");
			return -EINVAL;
		}

		if (ps->version != SNAPSHOT_DISK_VERSION) {
			DMWARN("unable to handle snapshot disk version %d",
			       ps->version);
			return -EINVAL;
		}

		/*
		 * Read the metadata.
		 */
		r = read_exceptions(ps);
		if (r)
			return r;
	}

	return 0;
}

static int build_constructor_string(struct dm_target *ti,
				    unsigned argc, char **argv,
				    char **ctr_str)
{
	int i, str_size;
	char *str = NULL;

	*ctr_str = NULL;

	/*
	 * Determine overall size of the string.
	 */
	for (i = 0, str_size = 0; i < argc; i++)
		str_size += strlen(argv[i]) + 1; /* +1 for space between args */

	str_size += 20; /* Max number of chars in a printed u64 number */

	str = kzalloc(str_size, GFP_KERNEL);
	if (!str) {
		DMWARN("Unable to allocate memory for constructor string");
		return -ENOMEM;
	}

	str_size = sprintf(str, "%llu", (unsigned long long)ti->len);
	for (i = 0; i < argc; i++)
		str_size += sprintf(str + str_size, " %s", argv[i]);

	*ctr_str = str;
	return str_size;
}

static int __init dm_dirty_log_init(void)
{
	int r;

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

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

	return r;
}

static int read_header(struct pstore *ps, int *new_snapshot)
{
	int r;
	struct disk_header *dh;

	r = chunk_io(ps, 0, READ);
	if (r)
		return r;

	dh = (struct disk_header *) ps->area;

	if (le32_to_cpu(dh->magic) == 0) {
		*new_snapshot = 1;

	} else if (le32_to_cpu(dh->magic) == SNAP_MAGIC) {
		*new_snapshot = 0;
		ps->valid = le32_to_cpu(dh->valid);
		ps->version = le32_to_cpu(dh->version);
		ps->chunk_size = le32_to_cpu(dh->chunk_size);

	} else {
		DMWARN("Invalid/corrupt snapshot");
		r = -ENXIO;
	}

	return r;
}

static void table_destroy(struct dm_table *t)
{
	unsigned int i;

	/* free the indexes (see dm_table_complete) */
	if (t->depth >= 2)
		vfree(t->index[t->depth - 2]);

	/* free the targets */
	for (i = 0; i < t->num_targets; i++) {
		struct dm_target *tgt = t->targets + i;

		if (tgt->type->dtr)
			tgt->type->dtr(tgt);

		dm_put_target_type(tgt->type);
	}

	vfree(t->highs);

	/* free the device list */
	if (t->devices.next != &t->devices) {
		DMWARN("devices still present during destroy: "
		       "dm_table_remove_device calls missing");

		free_devices(&t->devices);
	}

	kfree(t);
}

static int read_header(struct log_c *log)
{
	int r;
	unsigned long ebits;

	r = dm_io_sync_vm(1, &log->header_location, READ,
			  log->disk_header, &ebits);
	if (r)
		return r;

	header_from_disk(&log->header, log->disk_header);

	/* New log required? */
	if (log->sync != DEFAULTSYNC || log->header.magic != MIRROR_MAGIC) {
		log->header.magic = MIRROR_MAGIC;
		log->header.version = MIRROR_DISK_VERSION;
		log->header.nr_regions = 0;
	}

#ifdef __LITTLE_ENDIAN
	if (log->header.version == 1)
		log->header.version = 2;
#endif

	if (log->header.version != MIRROR_DISK_VERSION) {
		DMWARN("incompatible disk log version");
		return -EINVAL;
	}

	return 0;
}

/*
 * Functions to lock and unlock any filesystem running on the
 * device.
 */
static int lock_fs(struct mapped_device *md)
{
	int r = -ENOMEM;

	md->frozen_bdev = bdget_disk(md->disk, 0);
	if (!md->frozen_bdev) {
		DMWARN("bdget failed in lock_fs");
		goto out;
	}

	WARN_ON(md->frozen_sb);

	md->frozen_sb = freeze_bdev(md->frozen_bdev);
	if (IS_ERR(md->frozen_sb)) {
		r = PTR_ERR(md->frozen_sb);
		goto out_bdput;
	}

	/* don't bdput right now, we don't want the bdev
	 * to go away while it is locked.  We'll bdput
	 * in unlock_fs
	 */
	return 0;

out_bdput:
	bdput(md->frozen_bdev);
	md->frozen_sb = NULL;
	md->frozen_bdev = NULL;
out:
	return r;
}

/*
 * hp_sw_end_io - Completion handler for HP path activation.
 * @req: path activation request
 * @error: scsi-ml error
 *
 *  Check sense data, free request structure, and notify dm that
 *  pg initialization has completed.
 *
 * Context: scsi-ml softirq
 *
 */
static void hp_sw_end_io(struct request *req, int error)
{
    struct dm_path *path = req->end_io_data;
    unsigned err_flags = 0;

    if (!error) {
        DMDEBUG("%s path activation command - success",
            path->dev->name);
        goto out;
    }

    if (hp_sw_error_is_retryable(req)) {
        DMDEBUG("%s path activation command - retry",
            path->dev->name);
        err_flags = MP_RETRY;
        goto out;
    }

    DMWARN("%s path activation fail - error=0x%x",
           path->dev->name, error);
    err_flags = MP_FAIL_PATH;

out:
    req->end_io_data = NULL;
    __blk_put_request(req->q, req);
    dm_pg_init_complete(path, err_flags);
}

/**ltl
 * 功能: 将目标设备加入到列表中
 * 参数: t	->映射表
 *		ti	->映射目标
 *		path	->映射目标<major:minor>
 * 		start-> 映射目标相对低层设备的起始偏移量(类似磁盘分区的起始地址)
 *		len	-> 此目标设备在dm设备的长度
 *		mode	-> rw
 *		result-> 底层设备对象
 * 返回值:
 * 说明:
 */
static int __table_get_device(struct dm_table *t, struct dm_target *ti,
			      const char *path, sector_t start, sector_t len,
			      int mode, struct dm_dev **result)
{
	int r;
	dev_t dev;
	struct dm_dev *dd;
	unsigned int major, minor;

	BUG_ON(!t);
	/* 获取主设备号和次设备号 */
	if (sscanf(path, "%u:%u", &major, &minor) == 2) {
		/* Extract the major/minor numbers */
		dev = MKDEV(major, minor);
		if (MAJOR(dev) != major || MINOR(dev) != minor)
			return -EOVERFLOW;
	} else {
		/* convert the path to a device */
		if ((r = lookup_device(path, &dev))) /* 根据设备路径/dev/sdb获取<major:minor> */
			return r;
	}
	/* 在列表中查找映射目标 */
	dd = find_device(&t->devices, dev);
	if (!dd) {
		dd = kmalloc(sizeof(*dd), GFP_KERNEL);
		if (!dd)
			return -ENOMEM;

		dd->mode = mode;
		dd->bdev = NULL;
		/* 打开设备 */
		if ((r = open_dev(dd, dev, t->md))) {
			kfree(dd);
			return r;
		}

		format_dev_t(dd->name, dev); /* 主设备号次设备号 */

		atomic_set(&dd->count, 0);
		/* 将目标设备插入到映射表中 */
		list_add(&dd->list, &t->devices);

	} else if (dd->mode != (mode | dd->mode)) {
		r = upgrade_mode(dd, mode, t->md);
		if (r)
			return r;
	}
	atomic_inc(&dd->count);
	/* 检查区域是否超过设备 */
	if (!check_device_area(dd, start, len)) {
		DMWARN("device %s too small for target", path);
		dm_put_device(ti, dd);
		return -EINVAL;
	}

	*result = dd;

	return 0;
}

/*----------------------------------------------------------------
 * 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;
	size_t size;
	struct log_c *lc;
	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 = core_ctr(log, ti, argc - 1, argv + 1);
	if (r) {
		dm_put_device(ti, dev);
		return r;
	}

	lc = (struct log_c *) log->context;
	lc->log_dev = dev;

	/* setup the disk header fields */
	lc->header_location.bdev = lc->log_dev->bdev;
	lc->header_location.sector = 0;
	lc->header_location.count = 1;

	/*
	 * We can't read less than this amount, even though we'll
	 * not be using most of this space.
	 */
	lc->disk_header = vmalloc(1 << SECTOR_SHIFT);
	if (!lc->disk_header)
		goto bad;

	/* setup the disk bitset fields */
	lc->bits_location.bdev = lc->log_dev->bdev;
	lc->bits_location.sector = LOG_OFFSET;

	size = dm_round_up(lc->bitset_uint32_count * sizeof(uint32_t),
			   1 << SECTOR_SHIFT);
	lc->bits_location.count = size >> SECTOR_SHIFT;
	lc->disk_bits = vmalloc(size);
	if (!lc->disk_bits) {
		vfree(lc->disk_header);
		goto bad;
	}
	return 0;

 bad:
	dm_put_device(ti, lc->log_dev);
	core_dtr(log);
	return -ENOMEM;
}

static void persistent_drop(struct exception_store *store)
{
	struct pstore *ps = get_info(store);

	ps->valid = 0;
	if (write_header(ps))
		DMWARN("write header failed");
}

/*
 * Add a device to the list, or just increment the usage count if
 * it's already present.
 */
static int __table_get_device(struct dm_table *t, struct dm_target *ti,
			      const char *path, sector_t start, sector_t len,
			      int mode, struct dm_dev **result)
{
	int r;
	dev_t dev;
	struct dm_dev *dd;
	unsigned int major, minor;

	if (!t)
		BUG();

	if (sscanf(path, "%u:%u", &major, &minor) == 2) {
		/* Extract the major/minor numbers */
		dev = MKDEV(major, minor);
		if (MAJOR(dev) != major || MINOR(dev) != minor)
			return -EOVERFLOW;
	} else {
		/* convert the path to a device */
		if ((r = lookup_device(path, &dev)))
			return r;
	}

	dd = find_device(&t->devices, dev);
	if (!dd) {
		dd = kmalloc(sizeof(*dd), GFP_KERNEL);
		if (!dd)
			return -ENOMEM;

		dd->mode = mode;
		dd->bdev = NULL;

		if ((r = open_dev(dd, dev))) {
			kfree(dd);
			return r;
		}

		atomic_set(&dd->count, 0);
		list_add(&dd->list, &t->devices);

	} else if (dd->mode != (mode | dd->mode)) {
		r = upgrade_mode(dd, mode);
		if (r)
			return r;
	}
	atomic_inc(&dd->count);

	if (!check_device_area(dd, start, len)) {
		DMWARN("device %s too small for target", path);
		dm_put_device(ti, dd);
		return -EINVAL;
	}

	*result = dd;

	return 0;
}

/*
 * Returns:
 * DM_MAPIO_*       : the request has been processed as indicated
 * DM_MAPIO_REQUEUE : the original request needs to be immediately requeued
 * < 0              : the request was completed due to failure
 */
static int map_request(struct dm_rq_target_io *tio)
{
	int r;
	struct dm_target *ti = tio->ti;
	struct mapped_device *md = tio->md;
	struct request *rq = tio->orig;
	struct request *clone = NULL;
	blk_status_t ret;

	r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
check_again:
	switch (r) {
	case DM_MAPIO_SUBMITTED:
		/* The target has taken the I/O to submit by itself later */
		break;
	case DM_MAPIO_REMAPPED:
		if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
			/* -ENOMEM */
			ti->type->release_clone_rq(clone);
			return DM_MAPIO_REQUEUE;
		}

		/* The target has remapped the I/O so dispatch it */
		trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
				     blk_rq_pos(rq));
		ret = dm_dispatch_clone_request(clone, rq);
		if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
			blk_rq_unprep_clone(clone);
			tio->ti->type->release_clone_rq(clone);
			tio->clone = NULL;
			if (!rq->q->mq_ops)
				r = DM_MAPIO_DELAY_REQUEUE;
			else
				r = DM_MAPIO_REQUEUE;
			goto check_again;
		}
		break;
	case DM_MAPIO_REQUEUE:
		/* The target wants to requeue the I/O */
		break;
	case DM_MAPIO_DELAY_REQUEUE:
		/* The target wants to requeue the I/O after a delay */
		dm_requeue_original_request(tio, true);
		break;
	case DM_MAPIO_KILL:
		/* The target wants to complete the I/O */
		dm_kill_unmapped_request(rq, BLK_STS_IOERR);
		break;
	default:
		DMWARN("unimplemented target map return value: %d", r);
		BUG();
	}

	return r;
}