dcssblk.c

来自「优龙2410linux2.6.8内核源代码」· C语言 代码 · 共 700 行 · 第 1/2 页

	 */
	down_read(&dcssblk_devices_sem);
	dev_info = dcssblk_get_device_by_name(local_buf);
	up_read(&dcssblk_devices_sem);
	if (dev_info != NULL) {
		PRINT_WARN("Segment %s already loaded!\n", local_buf);
		rc = -EEXIST;
		goto out;
	}
	/*
	 * get a struct dcssblk_dev_info
	 */
	dev_info = kmalloc(sizeof(struct dcssblk_dev_info), GFP_KERNEL);
	if (dev_info == NULL) {
		rc = -ENOMEM;
		goto out;
	}
	memset(dev_info, 0, sizeof(struct dcssblk_dev_info));

	strcpy(dev_info->segment_name, local_buf);
	strlcpy(dev_info->dev.bus_id, local_buf, BUS_ID_SIZE);
	dev_info->dev.release = dcssblk_release_segment;
	INIT_LIST_HEAD(&dev_info->lh);

	dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
	if (dev_info->gd == NULL) {
		rc = -ENOMEM;
		goto free_dev_info;
	}
	dev_info->gd->major = dcssblk_major;
	dev_info->gd->fops = &dcssblk_devops;
	dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
	dev_info->gd->queue = dev_info->dcssblk_queue;
	dev_info->gd->private_data = dev_info;
	dev_info->gd->driverfs_dev = &dev_info->dev;
	/*
	 * load the segment
	 */
	rc = segment_load(local_buf, SEGMENT_SHARED_RO,
				&dev_info->start, &dev_info->end);
	if (rc < 0) {
		PRINT_ERR("Segment %s not loaded, rc=%d\n", local_buf, rc);
		goto dealloc_gendisk;
	}
	seg_byte_size = (dev_info->end - dev_info->start + 1);
	set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
	PRINT_INFO("Loaded segment %s from %p to %p, size = %lu Byte, "
		   "capacity = %lu sectors (512 Byte)\n", local_buf,
		   	(void *) dev_info->start, (void *) dev_info->end,
			seg_byte_size, seg_byte_size >> 9);

	dev_info->segment_type = rc;
	dev_info->save_pending = 0;
	dev_info->is_shared = 1;
	dev_info->dev.parent = dcssblk_root_dev;

	/*
	 * get minor, add to list
	 */
	down_write(&dcssblk_devices_sem);
	rc = dcssblk_assign_free_minor(dev_info);
	if (rc) {
		up_write(&dcssblk_devices_sem);
		PRINT_ERR("No free minor number available! "
			  "Unloading segment...\n");
		goto unload_seg;
	}
	sprintf(dev_info->gd->disk_name, "dcssblk%d",
		dev_info->gd->first_minor);
	list_add_tail(&dev_info->lh, &dcssblk_devices);

	if (!try_module_get(THIS_MODULE)) {
		rc = -ENODEV;
		goto list_del;
	}
	/*
	 * register the device
	 */
	rc = device_register(&dev_info->dev);
	if (rc) {
		PRINT_ERR("Segment %s could not be registered RC=%d\n",
				local_buf, rc);
		module_put(THIS_MODULE);
		goto list_del;
	}
	get_device(&dev_info->dev);
	rc = device_create_file(&dev_info->dev, &dev_attr_shared);
	if (rc)
		goto unregister_dev;
	rc = device_create_file(&dev_info->dev, &dev_attr_save);
	if (rc)
		goto unregister_dev;

	add_disk(dev_info->gd);

	blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
	blk_queue_hardsect_size(dev_info->dcssblk_queue, 4096);

	switch (dev_info->segment_type) {
		case SEGMENT_SHARED_RO:
		case SEGMENT_EXCLUSIVE_RO:
			set_disk_ro(dev_info->gd,1);
			break;
		case SEGMENT_SHARED_RW:
		case SEGMENT_EXCLUSIVE_RW:
			set_disk_ro(dev_info->gd,0);
			break;
	}
	PRINT_DEBUG("Segment %s loaded successfully\n", local_buf);
	up_write(&dcssblk_devices_sem);
	rc = count;
	goto out;

unregister_dev:
	PRINT_ERR("device_create_file() failed!\n");
	list_del(&dev_info->lh);
	blk_put_queue(dev_info->dcssblk_queue);
	dev_info->gd->queue = NULL;
	put_disk(dev_info->gd);
	device_unregister(&dev_info->dev);
	segment_unload(dev_info->segment_name);
	put_device(&dev_info->dev);
	up_write(&dcssblk_devices_sem);
	goto out;
list_del:
	list_del(&dev_info->lh);
	up_write(&dcssblk_devices_sem);
unload_seg:
	segment_unload(local_buf);
dealloc_gendisk:
	blk_put_queue(dev_info->dcssblk_queue);
	dev_info->gd->queue = NULL;
	put_disk(dev_info->gd);
free_dev_info:
	kfree(dev_info);
out:
	kfree(local_buf);
out_nobuf:
	return rc;
}

/*
 * device attribute for removing devices
 */
static ssize_t
dcssblk_remove_store(struct device *dev, const char *buf, size_t count)
{
	struct dcssblk_dev_info *dev_info;
	int rc, i;
	char *local_buf;

	if (dev != dcssblk_root_dev) {
		return -EINVAL;
	}
	local_buf = kmalloc(count + 1, GFP_KERNEL);
	if (local_buf == NULL) {
		return -ENOMEM;
	}
	/*
	 * parse input
	 */
	for (i = 0; ((*(buf+i)!='\0') && (*(buf+i)!='\n') && i < count); i++) {
		local_buf[i] = toupper(buf[i]);
	}
	local_buf[i] = '\0';
	if ((i == 0) || (i > 8)) {
		rc = -ENAMETOOLONG;
		goto out_buf;
	}

	down_write(&dcssblk_devices_sem);
	dev_info = dcssblk_get_device_by_name(local_buf);
	if (dev_info == NULL) {
		up_write(&dcssblk_devices_sem);
		PRINT_WARN("Segment %s is not loaded!\n", local_buf);
		rc = -ENODEV;
		goto out_buf;
	}
	if (atomic_read(&dev_info->use_count) != 0) {
		up_write(&dcssblk_devices_sem);
		PRINT_WARN("Segment %s is in use!\n", local_buf);
		rc = -EBUSY;
		goto out_buf;
	}
	list_del(&dev_info->lh);

	del_gendisk(dev_info->gd);
	blk_put_queue(dev_info->dcssblk_queue);
	dev_info->gd->queue = NULL;
	put_disk(dev_info->gd);
	device_unregister(&dev_info->dev);
	segment_unload(dev_info->segment_name);
	PRINT_DEBUG("Segment %s unloaded successfully\n",
			dev_info->segment_name);
	put_device(&dev_info->dev);
	up_write(&dcssblk_devices_sem);

	rc = count;
out_buf:
	kfree(local_buf);
	return rc;
}

static int
dcssblk_open(struct inode *inode, struct file *filp)
{
	struct dcssblk_dev_info *dev_info;
	int rc;

	dev_info = inode->i_bdev->bd_disk->private_data;
	if (NULL == dev_info) {
		rc = -ENODEV;
		goto out;
	}
	atomic_inc(&dev_info->use_count);
	inode->i_bdev->bd_block_size = 4096;
	rc = 0;
out:
	return rc;
}

static int
dcssblk_release(struct inode *inode, struct file *filp)
{
	struct dcssblk_dev_info *dev_info;
	int rc;

	dev_info = inode->i_bdev->bd_disk->private_data;
	if (NULL == dev_info) {
		rc = -ENODEV;
		goto out;
	}
	down_write(&dcssblk_devices_sem);
	if (atomic_dec_and_test(&dev_info->use_count)
	    && (dev_info->save_pending)) {
		PRINT_INFO("Segment %s became idle and is being saved now\n",
			    dev_info->segment_name);
		segment_replace(dev_info->segment_name);
		dev_info->save_pending = 0;
	}
	up_write(&dcssblk_devices_sem);
	rc = 0;
out:
	return rc;
}

static int
dcssblk_make_request(request_queue_t *q, struct bio *bio)
{
	struct dcssblk_dev_info *dev_info;
	struct bio_vec *bvec;
	unsigned long index;
	unsigned long page_addr;
	unsigned long source_addr;
	unsigned long bytes_done;
	int i;

	bytes_done = 0;
	dev_info = bio->bi_bdev->bd_disk->private_data;
	if (dev_info == NULL)
		goto fail;
	if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
		/* Request is not page-aligned. */
		goto fail;
	if (((bio->bi_size >> 9) + bio->bi_sector)
			> get_capacity(bio->bi_bdev->bd_disk)) {
		/* Request beyond end of DCSS segment. */
		goto fail;
	}
	index = (bio->bi_sector >> 3);
	bio_for_each_segment(bvec, bio, i) {
		page_addr = (unsigned long)
			page_address(bvec->bv_page) + bvec->bv_offset;
		source_addr = dev_info->start + (index<<12) + bytes_done;
		if (unlikely(page_addr & 4095) != 0 || (bvec->bv_len & 4095) != 0)
			// More paranoia.
			goto fail;
		if (bio_data_dir(bio) == READ) {
			memcpy((void*)page_addr, (void*)source_addr,
				bvec->bv_len);
		} else {
			memcpy((void*)source_addr, (void*)page_addr,
				bvec->bv_len);
		}
		bytes_done += bvec->bv_len;
	}
	bio_endio(bio, bytes_done, 0);
	return 0;
fail:
	bio_io_error(bio, bytes_done);
	return 0;
}

/*
 * The init/exit functions.
 */
static void __exit
dcssblk_exit(void)
{
	int rc;

	PRINT_DEBUG("DCSSBLOCK EXIT...\n");
	s390_root_dev_unregister(dcssblk_root_dev);
	rc = unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
	if (rc) {
		PRINT_ERR("unregister_blkdev() failed!\n");
	}
	PRINT_DEBUG("...finished!\n");
}

static int __init
dcssblk_init(void)
{
	int rc;

	PRINT_DEBUG("DCSSBLOCK INIT...\n");
	dcssblk_root_dev = s390_root_dev_register("dcssblk");
	if (IS_ERR(dcssblk_root_dev)) {
		PRINT_ERR("device_register() failed!\n");
		return PTR_ERR(dcssblk_root_dev);
	}
	rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
	if (rc) {
		PRINT_ERR("device_create_file(add) failed!\n");
		s390_root_dev_unregister(dcssblk_root_dev);
		return rc;
	}
	rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
	if (rc) {
		PRINT_ERR("device_create_file(remove) failed!\n");
		s390_root_dev_unregister(dcssblk_root_dev);
		return rc;
	}
	rc = register_blkdev(0, DCSSBLK_NAME);
	if (rc < 0) {
		PRINT_ERR("Can't get dynamic major!\n");
		s390_root_dev_unregister(dcssblk_root_dev);
		return rc;
	}
	dcssblk_major = rc;
	init_rwsem(&dcssblk_devices_sem);
	PRINT_DEBUG("...finished!\n");
	return 0;
}

module_init(dcssblk_init);
module_exit(dcssblk_exit);

MODULE_LICENSE("GPL");