[net-next-2.6.git] / drivers / s390 / char / tape_block.c

/*
 *  drivers/s390/char/tape_block.c
 *    block device frontend for tape device driver
 *
 *  S390 and zSeries version
 *    Copyright (C) 2001,2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Carsten Otte <cotte@de.ibm.com>
 *		 Tuan Ngo-Anh <ngoanh@de.ibm.com>
 *		 Martin Schwidefsky <schwidefsky@de.ibm.com>
 *		 Stefan Bader <shbader@de.ibm.com>
 */

#include <linux/fs.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/buffer_head.h>

#include <asm/debug.h>

#define TAPE_DBF_AREA	tape_core_dbf

#include "tape.h"

#define PRINTK_HEADER "TAPE_BLOCK: "

#define TAPEBLOCK_MAX_SEC	100
#define TAPEBLOCK_MIN_REQUEUE	3

/*
 * 2003/11/25  Stefan Bader <shbader@de.ibm.com>
 *
 * In 2.5/2.6 the block device request function is very likely to be called
 * with disabled interrupts (e.g. generic_unplug_device). So the driver can't
 * just call any function that tries to allocate CCW requests from that con-
 * text since it might sleep. There are two choices to work around this:
 *	a) do not allocate with kmalloc but use its own memory pool
 *      b) take requests from the queue outside that context, knowing that
 *         allocation might sleep
 */

/*
 * file operation structure for tape block frontend
 */
static int tapeblock_open(struct inode *, struct file *);
static int tapeblock_release(struct inode *, struct file *);
static int tapeblock_ioctl(struct inode *, struct file *, unsigned int,
				unsigned long);
static int tapeblock_medium_changed(struct gendisk *);
static int tapeblock_revalidate_disk(struct gendisk *);

static struct block_device_operations tapeblock_fops = {
	.owner		 = THIS_MODULE,
	.open		 = tapeblock_open,
	.release	 = tapeblock_release,
	.ioctl           = tapeblock_ioctl,
	.media_changed   = tapeblock_medium_changed,
	.revalidate_disk = tapeblock_revalidate_disk,
};

static int tapeblock_major = 0;

static void
tapeblock_trigger_requeue(struct tape_device *device)
{
	/* Protect against rescheduling. */
	if (atomic_compare_and_swap(0, 1, &device->blk_data.requeue_scheduled))
		return;
	schedule_work(&device->blk_data.requeue_task);
}

/*
 * Post finished request.
 */
static inline void
tapeblock_end_request(struct request *req, int uptodate)
{
	if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
		BUG();
	end_that_request_last(req);
}

static void
__tapeblock_end_request(struct tape_request *ccw_req, void *data)
{
	struct tape_device *device;
	struct request *req;

	DBF_LH(6, "__tapeblock_end_request()\n");

	device = ccw_req->device;
	req = (struct request *) data;
	tapeblock_end_request(req, ccw_req->rc == 0);
	if (ccw_req->rc == 0)
		/* Update position. */
		device->blk_data.block_position =
			(req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
	else
		/* We lost the position information due to an error. */
		device->blk_data.block_position = -1;
	device->discipline->free_bread(ccw_req);
	if (!list_empty(&device->req_queue) ||
	    elv_next_request(device->blk_data.request_queue))
		tapeblock_trigger_requeue(device);
}

/*
 * Feed the tape device CCW queue with requests supplied in a list.
 */
static inline int
tapeblock_start_request(struct tape_device *device, struct request *req)
{
	struct tape_request *	ccw_req;
	int			rc;

	DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);

	ccw_req = device->discipline->bread(device, req);
	if (IS_ERR(ccw_req)) {
		DBF_EVENT(1, "TBLOCK: bread failed\n");
		tapeblock_end_request(req, 0);
		return PTR_ERR(ccw_req);
	}
	ccw_req->callback = __tapeblock_end_request;
	ccw_req->callback_data = (void *) req;
	ccw_req->retries = TAPEBLOCK_RETRIES;

	rc = tape_do_io_async(device, ccw_req);
	if (rc) {
		/*
		 * Start/enqueueing failed. No retries in
		 * this case.
		 */
		tapeblock_end_request(req, 0);
		device->discipline->free_bread(ccw_req);
	}

	return rc;
}

/*
 * Move requests from the block device request queue to the tape device ccw
 * queue.
 */
static void
tapeblock_requeue(void *data) {
	struct tape_device *	device;
	request_queue_t *	queue;
	int			nr_queued;
	struct request *	req;
	struct list_head *	l;
	int			rc;

	device = (struct tape_device *) data;
	if (!device)
		return;

	spin_lock_irq(get_ccwdev_lock(device->cdev));
	queue  = device->blk_data.request_queue;

	/* Count number of requests on ccw queue. */
	nr_queued = 0;
	list_for_each(l, &device->req_queue)
		nr_queued++;
	spin_unlock(get_ccwdev_lock(device->cdev));

	spin_lock(&device->blk_data.request_queue_lock);
	while (
		!blk_queue_plugged(queue) &&
		elv_next_request(queue)   &&
		nr_queued < TAPEBLOCK_MIN_REQUEUE
	) {
		req = elv_next_request(queue);
		if (rq_data_dir(req) == WRITE) {
			DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
			blkdev_dequeue_request(req);
			tapeblock_end_request(req, 0);
			continue;
		}
		spin_unlock_irq(&device->blk_data.request_queue_lock);
		rc = tapeblock_start_request(device, req);
		spin_lock_irq(&device->blk_data.request_queue_lock);
		blkdev_dequeue_request(req);
		nr_queued++;
	}
	spin_unlock_irq(&device->blk_data.request_queue_lock);
	atomic_set(&device->blk_data.requeue_scheduled, 0);
}

/*
 * Tape request queue function. Called from ll_rw_blk.c
 */
static void
tapeblock_request_fn(request_queue_t *queue)
{
	struct tape_device *device;

	device = (struct tape_device *) queue->queuedata;
	DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
	if (device == NULL)
		BUG();

	tapeblock_trigger_requeue(device);
}

/*
 * This function is called for every new tapedevice
 */
int
tapeblock_setup_device(struct tape_device * device)
{
	struct tape_blk_data *	blkdat;
	struct gendisk *	disk;
	int			rc;

	blkdat = &device->blk_data;
	spin_lock_init(&blkdat->request_queue_lock);
	atomic_set(&blkdat->requeue_scheduled, 0);

	blkdat->request_queue = blk_init_queue(
		tapeblock_request_fn,
		&blkdat->request_queue_lock
	);
	if (!blkdat->request_queue)
		return -ENOMEM;

	elevator_exit(blkdat->request_queue->elevator);
	rc = elevator_init(blkdat->request_queue, "noop");
	if (rc)
		goto cleanup_queue;

	blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
	blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
	blk_queue_max_phys_segments(blkdat->request_queue, -1L);
	blk_queue_max_hw_segments(blkdat->request_queue, -1L);
	blk_queue_max_segment_size(blkdat->request_queue, -1L);
	blk_queue_segment_boundary(blkdat->request_queue, -1L);

	disk = alloc_disk(1);
	if (!disk) {
		rc = -ENOMEM;
		goto cleanup_queue;
	}

	disk->major = tapeblock_major;
	disk->first_minor = device->first_minor;
	disk->fops = &tapeblock_fops;
	disk->private_data = tape_get_device_reference(device);
	disk->queue = blkdat->request_queue;
	set_capacity(disk, 0);
	sprintf(disk->disk_name, "btibm%d",
		device->first_minor / TAPE_MINORS_PER_DEV);

	blkdat->disk = disk;
	blkdat->medium_changed = 1;
	blkdat->request_queue->queuedata = tape_get_device_reference(device);

	add_disk(disk);

	INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
		tape_get_device_reference(device));

	return 0;

cleanup_queue:
	blk_cleanup_queue(blkdat->request_queue);
	blkdat->request_queue = NULL;

	return rc;
}

void
tapeblock_cleanup_device(struct tape_device *device)
{
	flush_scheduled_work();
	device->blk_data.requeue_task.data = tape_put_device(device);

	if (!device->blk_data.disk) {
		PRINT_ERR("(%s): No gendisk to clean up!\n",
			device->cdev->dev.bus_id);
		goto cleanup_queue;
	}

	del_gendisk(device->blk_data.disk);
	device->blk_data.disk->private_data =
		tape_put_device(device->blk_data.disk->private_data);
	put_disk(device->blk_data.disk);

	device->blk_data.disk = NULL;
cleanup_queue:
	device->blk_data.request_queue->queuedata = tape_put_device(device);

	blk_cleanup_queue(device->blk_data.request_queue);
	device->blk_data.request_queue = NULL;
}

/*
 * Detect number of blocks of the tape.
 * FIXME: can we extent this to detect the blocks size as well ?
 */
static int
tapeblock_revalidate_disk(struct gendisk *disk)
{
	struct tape_device *	device;
	unsigned int		nr_of_blks;
	int			rc;

	device = (struct tape_device *) disk->private_data;
	if (!device)
		BUG();

	if (!device->blk_data.medium_changed)
		return 0;

	PRINT_INFO("Detecting media size...\n");
	rc = tape_mtop(device, MTFSFM, 1);
	if (rc)
		return rc;

	rc = tape_mtop(device, MTTELL, 1);
	if (rc < 0)
		return rc;

	DBF_LH(3, "Image file ends at %d\n", rc);
	nr_of_blks = rc;

	/* This will fail for the first file. Catch the error by checking the
	 * position. */
	tape_mtop(device, MTBSF, 1);

	rc = tape_mtop(device, MTTELL, 1);
	if (rc < 0)
		return rc;

	if (rc > nr_of_blks)
		return -EINVAL;

	DBF_LH(3, "Image file starts at %d\n", rc);
	device->bof = rc;
	nr_of_blks -= rc;

	PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
	set_capacity(device->blk_data.disk,
		nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));

	device->blk_data.block_position = 0;
	device->blk_data.medium_changed = 0;
	return 0;
}

static int
tapeblock_medium_changed(struct gendisk *disk)
{
	struct tape_device *device;

	device = (struct tape_device *) disk->private_data;
	DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
		device, device->blk_data.medium_changed);

	return device->blk_data.medium_changed;
}

/*
 * Block frontend tape device open function.
 */
static int
tapeblock_open(struct inode *inode, struct file *filp)
{
	struct gendisk *	disk;
	struct tape_device *	device;
	int			rc;

	disk   = inode->i_bdev->bd_disk;
	device = tape_get_device_reference(disk->private_data);

	if (device->required_tapemarks) {
		DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
		PRINT_ERR("TBLOCK: Refusing to open tape with missing"
			" end of file marks.\n");
		rc = -EPERM;
		goto put_device;
	}

	rc = tape_open(device);
	if (rc)
		goto put_device;

	rc = tapeblock_revalidate_disk(disk);
	if (rc)
		goto release;

	/*
	 * Note: The reference to <device> is hold until the release function
	 *       is called.
	 */
	tape_state_set(device, TS_BLKUSE);
	return 0;

release:
	tape_release(device);
 put_device:
	tape_put_device(device);
	return rc;
}

/*
 * Block frontend tape device release function.
 *
 * Note: One reference to the tape device was made by the open function. So
 *       we just get the pointer here and release the reference.
 */
static int
tapeblock_release(struct inode *inode, struct file *filp)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct tape_device *device = disk->private_data;

	tape_state_set(device, TS_IN_USE);
	tape_release(device);
	tape_put_device(device);

	return 0;
}

/*
 * Support of some generic block device IOCTLs.
 */
static int
tapeblock_ioctl(
	struct inode *		inode,
	struct file *		file,
	unsigned int		command,
	unsigned long		arg
) {
	int rc;
	int minor;
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct tape_device *device = disk->private_data;

	rc     = 0;
	disk   = inode->i_bdev->bd_disk;
	if (!disk)
		BUG();
	device = disk->private_data;
	if (!device)
		BUG();
	minor  = iminor(inode);

	DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
	DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);

	switch (command) {
		/* Refuse some IOCTL calls without complaining (mount). */
		case 0x5310:		/* CDROMMULTISESSION */
			rc = -EINVAL;
			break;
		default:
			PRINT_WARN("invalid ioctl 0x%x\n", command);
			rc = -EINVAL;
	}

	return rc;
}

/*
 * Initialize block device frontend.
 */
int
tapeblock_init(void)
{
	int rc;

	/* Register the tape major number to the kernel */
	rc = register_blkdev(tapeblock_major, "tBLK");
	if (rc < 0)
		return rc;

	if (tapeblock_major == 0)
		tapeblock_major = rc;
	PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
	return 0;
}

/*
 * Deregister major for block device frontend
 */
void
tapeblock_exit(void)
{
	unregister_blkdev(tapeblock_major, "tBLK");
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* drivers/s390/char/tape_block.c
	3	* block device frontend for tape device driver
	4	*
	5	* S390 and zSeries version
	6	* Copyright (C) 2001,2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
	7	* Author(s): Carsten Otte <cotte@de.ibm.com>
	8	* Tuan Ngo-Anh <ngoanh@de.ibm.com>
	9	* Martin Schwidefsky <schwidefsky@de.ibm.com>
	10	* Stefan Bader <shbader@de.ibm.com>
	11	*/
	12
	13	#include <linux/fs.h>
	14	#include <linux/config.h>
	15	#include <linux/module.h>
	16	#include <linux/blkdev.h>
	17	#include <linux/interrupt.h>
	18	#include <linux/buffer_head.h>
	19
	20	#include <asm/debug.h>
	21
	22	#define TAPE_DBF_AREA tape_core_dbf
	23
	24	#include "tape.h"
	25
	26	#define PRINTK_HEADER "TAPE_BLOCK: "
	27
	28	#define TAPEBLOCK_MAX_SEC 100
	29	#define TAPEBLOCK_MIN_REQUEUE 3
	30
	31	/*
	32	* 2003/11/25 Stefan Bader <shbader@de.ibm.com>
	33	*
	34	* In 2.5/2.6 the block device request function is very likely to be called
	35	* with disabled interrupts (e.g. generic_unplug_device). So the driver can't
	36	* just call any function that tries to allocate CCW requests from that con-
	37	* text since it might sleep. There are two choices to work around this:
	38	* a) do not allocate with kmalloc but use its own memory pool
	39	* b) take requests from the queue outside that context, knowing that
	40	* allocation might sleep
	41	*/
	42
	43	/*
	44	* file operation structure for tape block frontend
	45	*/
	46	static int tapeblock_open(struct inode , struct file );
	47	static int tapeblock_release(struct inode , struct file );
	48	static int tapeblock_ioctl(struct inode , struct file , unsigned int,
	49	unsigned long);
	50	static int tapeblock_medium_changed(struct gendisk *);
	51	static int tapeblock_revalidate_disk(struct gendisk *);
	52
	53	static struct block_device_operations tapeblock_fops = {
	54	.owner = THIS_MODULE,
	55	.open = tapeblock_open,
	56	.release = tapeblock_release,
	57	.ioctl = tapeblock_ioctl,
	58	.media_changed = tapeblock_medium_changed,
	59	.revalidate_disk = tapeblock_revalidate_disk,
	60	};
	61
	62	static int tapeblock_major = 0;
	63
	64	static void
65	tapeblock_trigger_requeue(struct tape_device *device)
66	{
67	/* Protect against rescheduling. */
68	if (atomic_compare_and_swap(0, 1, &device->blk_data.requeue_scheduled))
69	return;
70	schedule_work(&device->blk_data.requeue_task);
71	}
72
73	/*
74	* Post finished request.
75	*/
76	static inline void
77	tapeblock_end_request(struct request *req, int uptodate)
78	{
79	if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
80	BUG();
81	end_that_request_last(req);
82	}
83
84	static void
85	__tapeblock_end_request(struct tape_request ccw_req, void data)
86	{
87	struct tape_device *device;
88	struct request *req;
89
90	DBF_LH(6, "__tapeblock_end_request()\n");
91
92	device = ccw_req->device;
93	req = (struct request *) data;
94	tapeblock_end_request(req, ccw_req->rc == 0);
95	if (ccw_req->rc == 0)
96	/* Update position. */
97	device->blk_data.block_position =
98	(req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
99	else
100	/* We lost the position information due to an error. */
101	device->blk_data.block_position = -1;
102	device->discipline->free_bread(ccw_req);
103	if (!list_empty(&device->req_queue) \|\|
104	elv_next_request(device->blk_data.request_queue))
105	tapeblock_trigger_requeue(device);
106	}
107
108	/*
109	* Feed the tape device CCW queue with requests supplied in a list.
110	*/
111	static inline int
112	tapeblock_start_request(struct tape_device device, struct request req)
113	{
114	struct tape_request * ccw_req;
115	int rc;
116
117	DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
118
119	ccw_req = device->discipline->bread(device, req);
120	if (IS_ERR(ccw_req)) {
121	DBF_EVENT(1, "TBLOCK: bread failed\n");
122	tapeblock_end_request(req, 0);
123	return PTR_ERR(ccw_req);
124	}
125	ccw_req->callback = __tapeblock_end_request;
126	ccw_req->callback_data = (void *) req;
127	ccw_req->retries = TAPEBLOCK_RETRIES;
128
129	rc = tape_do_io_async(device, ccw_req);
130	if (rc) {
131	/*
132	* Start/enqueueing failed. No retries in
133	* this case.
134	*/
135	tapeblock_end_request(req, 0);
136	device->discipline->free_bread(ccw_req);
137	}
138
139	return rc;
140	}
141
142	/*
143	* Move requests from the block device request queue to the tape device ccw
144	* queue.
145	*/
146	static void
147	tapeblock_requeue(void *data) {
148	struct tape_device * device;
149	request_queue_t * queue;
150	int nr_queued;
151	struct request * req;
152	struct list_head * l;
153	int rc;
154
155	device = (struct tape_device *) data;
156	if (!device)
157	return;
158
159	spin_lock_irq(get_ccwdev_lock(device->cdev));
160	queue = device->blk_data.request_queue;
161
162	/* Count number of requests on ccw queue. */
163	nr_queued = 0;
164	list_for_each(l, &device->req_queue)
165	nr_queued++;
166	spin_unlock(get_ccwdev_lock(device->cdev));
167
168	spin_lock(&device->blk_data.request_queue_lock);
169	while (
170	!blk_queue_plugged(queue) &&
171	elv_next_request(queue) &&
172	nr_queued < TAPEBLOCK_MIN_REQUEUE
173	) {
174	req = elv_next_request(queue);
175	if (rq_data_dir(req) == WRITE) {
176	DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
177	blkdev_dequeue_request(req);
178	tapeblock_end_request(req, 0);
179	continue;
180	}
181	spin_unlock_irq(&device->blk_data.request_queue_lock);
182	rc = tapeblock_start_request(device, req);
183	spin_lock_irq(&device->blk_data.request_queue_lock);
184	blkdev_dequeue_request(req);
185	nr_queued++;
186	}
187	spin_unlock_irq(&device->blk_data.request_queue_lock);
188	atomic_set(&device->blk_data.requeue_scheduled, 0);
189	}
190
191	/*
192	* Tape request queue function. Called from ll_rw_blk.c
193	*/
194	static void
195	tapeblock_request_fn(request_queue_t *queue)
196	{
197	struct tape_device *device;
198
199	device = (struct tape_device *) queue->queuedata;
200	DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
201	if (device == NULL)
202	BUG();
203
204	tapeblock_trigger_requeue(device);
205	}
206
207	/*
208	* This function is called for every new tapedevice
209	*/
210	int
211	tapeblock_setup_device(struct tape_device * device)
212	{
213	struct tape_blk_data * blkdat;
214	struct gendisk * disk;
215	int rc;
216
217	blkdat = &device->blk_data;
218	spin_lock_init(&blkdat->request_queue_lock);
219	atomic_set(&blkdat->requeue_scheduled, 0);
220
221	blkdat->request_queue = blk_init_queue(
222	tapeblock_request_fn,
223	&blkdat->request_queue_lock
224	);
225	if (!blkdat->request_queue)
226	return -ENOMEM;
227
228	elevator_exit(blkdat->request_queue->elevator);
229	rc = elevator_init(blkdat->request_queue, "noop");
230	if (rc)
231	goto cleanup_queue;
232
233	blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
234	blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
235	blk_queue_max_phys_segments(blkdat->request_queue, -1L);
236	blk_queue_max_hw_segments(blkdat->request_queue, -1L);
237	blk_queue_max_segment_size(blkdat->request_queue, -1L);
238	blk_queue_segment_boundary(blkdat->request_queue, -1L);
239
240	disk = alloc_disk(1);
241	if (!disk) {
242	rc = -ENOMEM;
243	goto cleanup_queue;
244	}
245
246	disk->major = tapeblock_major;
247	disk->first_minor = device->first_minor;
248	disk->fops = &tapeblock_fops;
249	disk->private_data = tape_get_device_reference(device);
250	disk->queue = blkdat->request_queue;
251	set_capacity(disk, 0);
252	sprintf(disk->disk_name, "btibm%d",
253	device->first_minor / TAPE_MINORS_PER_DEV);
254
255	blkdat->disk = disk;
256	blkdat->medium_changed = 1;
257	blkdat->request_queue->queuedata = tape_get_device_reference(device);
258
259	add_disk(disk);
260
261	INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
262	tape_get_device_reference(device));
263
264	return 0;
265
266	cleanup_queue:
267	blk_cleanup_queue(blkdat->request_queue);
268	blkdat->request_queue = NULL;
269
270	return rc;
271	}
272
273	void
274	tapeblock_cleanup_device(struct tape_device *device)
275	{
276	flush_scheduled_work();
277	device->blk_data.requeue_task.data = tape_put_device(device);
278
279	if (!device->blk_data.disk) {
280	PRINT_ERR("(%s): No gendisk to clean up!\n",
281	device->cdev->dev.bus_id);
282	goto cleanup_queue;
283	}
284
285	del_gendisk(device->blk_data.disk);
286	device->blk_data.disk->private_data =
287	tape_put_device(device->blk_data.disk->private_data);
288	put_disk(device->blk_data.disk);
289
290	device->blk_data.disk = NULL;
291	cleanup_queue:
292	device->blk_data.request_queue->queuedata = tape_put_device(device);
293
294	blk_cleanup_queue(device->blk_data.request_queue);
295	device->blk_data.request_queue = NULL;
296	}
297
298	/*
299	* Detect number of blocks of the tape.
300	* FIXME: can we extent this to detect the blocks size as well ?
301	*/
302	static int
303	tapeblock_revalidate_disk(struct gendisk *disk)
304	{
305	struct tape_device * device;
306	unsigned int nr_of_blks;
307	int rc;
308
309	device = (struct tape_device *) disk->private_data;
310	if (!device)
311	BUG();
312
313	if (!device->blk_data.medium_changed)
314	return 0;
315
316	PRINT_INFO("Detecting media size...\n");
317	rc = tape_mtop(device, MTFSFM, 1);
318	if (rc)
319	return rc;
320
321	rc = tape_mtop(device, MTTELL, 1);
322	if (rc < 0)
323	return rc;
324
325	DBF_LH(3, "Image file ends at %d\n", rc);
326	nr_of_blks = rc;
327
328	/* This will fail for the first file. Catch the error by checking the
329	* position. */
330	tape_mtop(device, MTBSF, 1);
331
332	rc = tape_mtop(device, MTTELL, 1);
333	if (rc < 0)
334	return rc;
335
336	if (rc > nr_of_blks)
337	return -EINVAL;
338
339	DBF_LH(3, "Image file starts at %d\n", rc);
340	device->bof = rc;
341	nr_of_blks -= rc;
342
343	PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
344	set_capacity(device->blk_data.disk,
345	nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
346
347	device->blk_data.block_position = 0;
348	device->blk_data.medium_changed = 0;
349	return 0;
350	}
351
352	static int
353	tapeblock_medium_changed(struct gendisk *disk)
354	{
355	struct tape_device *device;
356
357	device = (struct tape_device *) disk->private_data;
358	DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
359	device, device->blk_data.medium_changed);
360
361	return device->blk_data.medium_changed;
362	}
363
364	/*
365	* Block frontend tape device open function.
366	*/
367	static int
368	tapeblock_open(struct inode inode, struct file filp)
369	{
370	struct gendisk * disk;
371	struct tape_device * device;
372	int rc;
373
374	disk = inode->i_bdev->bd_disk;
375	device = tape_get_device_reference(disk->private_data);
376
377	if (device->required_tapemarks) {
378	DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
379	PRINT_ERR("TBLOCK: Refusing to open tape with missing"
380	" end of file marks.\n");
381	rc = -EPERM;
382	goto put_device;
383	}
384
385	rc = tape_open(device);
386	if (rc)
387	goto put_device;
388
389	rc = tapeblock_revalidate_disk(disk);
390	if (rc)
391	goto release;
392
393	/*
394	* Note: The reference to <device> is hold until the release function
395	* is called.
396	*/
397	tape_state_set(device, TS_BLKUSE);
398	return 0;
399
400	release:
401	tape_release(device);
402	put_device:
403	tape_put_device(device);
404	return rc;
405	}
406
407	/*
408	* Block frontend tape device release function.
409	*
410	* Note: One reference to the tape device was made by the open function. So
411	* we just get the pointer here and release the reference.
412	*/
413	static int
414	tapeblock_release(struct inode inode, struct file filp)
415	{
416	struct gendisk *disk = inode->i_bdev->bd_disk;
417	struct tape_device *device = disk->private_data;
418
419	tape_state_set(device, TS_IN_USE);
420	tape_release(device);
421	tape_put_device(device);
422
423	return 0;
424	}
425
426	/*
427	* Support of some generic block device IOCTLs.
428	*/
429	static int
430	tapeblock_ioctl(
431	struct inode * inode,
432	struct file * file,
433	unsigned int command,
434	unsigned long arg
435	) {
436	int rc;
437	int minor;
438	struct gendisk *disk = inode->i_bdev->bd_disk;
439	struct tape_device *device = disk->private_data;
440
441	rc = 0;
442	disk = inode->i_bdev->bd_disk;
443	if (!disk)
444	BUG();
445	device = disk->private_data;
446	if (!device)
447	BUG();
448	minor = iminor(inode);
449
450	DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
451	DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
452
453	switch (command) {
454	/* Refuse some IOCTL calls without complaining (mount). */
455	case 0x5310: /* CDROMMULTISESSION */
456	rc = -EINVAL;
457	break;
458	default:
459	PRINT_WARN("invalid ioctl 0x%x\n", command);
460	rc = -EINVAL;
461	}
462
463	return rc;
464	}
465
466	/*
467	* Initialize block device frontend.
468	*/
469	int
470	tapeblock_init(void)
471	{
472	int rc;
473
474	/* Register the tape major number to the kernel */
475	rc = register_blkdev(tapeblock_major, "tBLK");
476	if (rc < 0)
477	return rc;
478
479	if (tapeblock_major == 0)
480	tapeblock_major = rc;
481	PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
482	return 0;
483	}
484
485	/*
486	* Deregister major for block device frontend
487	*/
488	void
489	tapeblock_exit(void)
490	{
491	unregister_blkdev(tapeblock_major, "tBLK");
492	}