[linux-2.6-block.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>
 */

#define KMSG_COMPONENT "tape"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

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

#include <asm/debug.h>

#define TAPE_DBF_AREA	tape_core_dbf

#include "tape.h"

#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 block_device *, fmode_t);
static int tapeblock_release(struct gendisk *, fmode_t);
static int tapeblock_medium_changed(struct gendisk *);
static int tapeblock_revalidate_disk(struct gendisk *);

static const struct block_device_operations tapeblock_fops = {
	.owner		 = THIS_MODULE,
	.open		 = tapeblock_open,
	.release	 = tapeblock_release,
	.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_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
		return;
	schedule_work(&device->blk_data.requeue_task);
}

/*
 * Post finished request.
 */
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;
	blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
	if (ccw_req->rc == 0)
		/* Update position. */
		device->blk_data.block_position =
		  (blk_rq_pos(req) + blk_rq_sectors(req)) >> 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) ||
	    blk_peek_request(device->blk_data.request_queue))
		tapeblock_trigger_requeue(device);
}

/*
 * Feed the tape device CCW queue with requests supplied in a list.
 */
static 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");
		blk_end_request_all(req, -EIO);
		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.
		 */
		blk_end_request_all(req, -EIO);
		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(struct work_struct *work) {
	struct tape_blk_data *	blkdat;
	struct tape_device *	device;
	struct request_queue *	queue;
	int			nr_queued;
	struct request *	req;
	struct list_head *	l;
	int			rc;

	blkdat = container_of(work, struct tape_blk_data, requeue_task);
	device = blkdat->device;
	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_irq(&device->blk_data.request_queue_lock);
	while (
		!blk_queue_plugged(queue) &&
		blk_peek_request(queue) &&
		nr_queued < TAPEBLOCK_MIN_REQUEUE
	) {
		req = blk_fetch_request(queue);
		if (rq_data_dir(req) == WRITE) {
			DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
			spin_unlock_irq(&device->blk_data.request_queue_lock);
			blk_end_request_all(req, -EIO);
			spin_lock_irq(&device->blk_data.request_queue_lock);
			continue;
		}
		nr_queued++;
		spin_unlock_irq(&device->blk_data.request_queue_lock);
		rc = tapeblock_start_request(device, req);
		spin_lock_irq(&device->blk_data.request_queue_lock);
	}
	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(struct request_queue *queue)
{
	struct tape_device *device;

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

	add_disk(disk);

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

	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();
	tape_put_device(device);

	if (!device->blk_data.disk) {
		goto cleanup_queue;
	}

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

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

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

	rc = tape_mtop(device, MTFSFM, 1);
	if (rc)
		return rc;

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

	pr_info("%s: Determining the size of the recorded area...\n",
		dev_name(&device->cdev->dev));
	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;

	pr_info("%s: The size of the recorded area is %i blocks\n",
		dev_name(&device->cdev->dev), 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 block_device *bdev, fmode_t mode)
{
	struct gendisk *	disk = bdev->bd_disk;
	struct tape_device *	device;
	int			rc;

	device = tape_get_device(disk->private_data);

	if (device->required_tapemarks) {
		DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
		pr_warning("%s: Opening the tape failed because of missing "
			   "end-of-file marks\n", dev_name(&device->cdev->dev));
		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 gendisk *disk, fmode_t mode)
{
	struct tape_device *device = disk->private_data;

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

	return 0;
}

/*
 * 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;
	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
ab640db0	13	#define KMSG_COMPONENT "tape"
bb509912	14	#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
ab640db0	15
1da177e4	16	#include <linux/fs.h>
1da177e4 LT	17	#include <linux/module.h>
	18	#include <linux/blkdev.h>
	19	#include <linux/interrupt.h>
	20	#include <linux/buffer_head.h>
c1637532	21	#include <linux/kernel.h>
1da177e4 LT	22
	23	#include <asm/debug.h>
	24
	25	#define TAPE_DBF_AREA tape_core_dbf
	26
	27	#include "tape.h"
	28
1da177e4 LT	29	#define TAPEBLOCK_MAX_SEC 100
	30	#define TAPEBLOCK_MIN_REQUEUE 3
	31
	32	/*
	33	* 2003/11/25 Stefan Bader <shbader@de.ibm.com>
	34	*
	35	* In 2.5/2.6 the block device request function is very likely to be called
	36	* with disabled interrupts (e.g. generic_unplug_device). So the driver can't
	37	* just call any function that tries to allocate CCW requests from that con-
	38	* text since it might sleep. There are two choices to work around this:
	39	* a) do not allocate with kmalloc but use its own memory pool
	40	* b) take requests from the queue outside that context, knowing that
	41	* allocation might sleep
	42	*/
	43
	44	/*
	45	* file operation structure for tape block frontend
	46	*/
4e999af9 AV	47	static int tapeblock_open(struct block_device *, fmode_t);
4e999af9 AV	48	static int tapeblock_release(struct gendisk *, fmode_t);
1da177e4 LT	49	static int tapeblock_medium_changed(struct gendisk *);
	50	static int tapeblock_revalidate_disk(struct gendisk *);
	51
83d5cde4	52	static const struct block_device_operations tapeblock_fops = {
1da177e4	53	.owner = THIS_MODULE,
4e999af9 AV	54	.open = tapeblock_open,
4e999af9 AV	55	.release = tapeblock_release,
1da177e4 LT	56	.media_changed = tapeblock_medium_changed,
	57	.revalidate_disk = tapeblock_revalidate_disk,
	58	};
	59
	60	static int tapeblock_major = 0;
	61
	62	static void
	63	tapeblock_trigger_requeue(struct tape_device *device)
	64	{
	65	/* Protect against rescheduling. */
973bd993	66	if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
1da177e4 LT	67	return;
	68	schedule_work(&device->blk_data.requeue_task);
	69	}
	70
	71	/*
	72	* Post finished request.
	73	*/
1da177e4 LT	74	static void
	75	__tapeblock_end_request(struct tape_request ccw_req, void data)
	76	{
	77	struct tape_device *device;
	78	struct request *req;
	79
	80	DBF_LH(6, "__tapeblock_end_request()\n");
	81
	82	device = ccw_req->device;
	83	req = (struct request *) data;
40cbbb78	84	blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
1da177e4 LT	85	if (ccw_req->rc == 0)
	86	/* Update position. */
	87	device->blk_data.block_position =
83096ebf	88	(blk_rq_pos(req) + blk_rq_sectors(req)) >> TAPEBLOCK_HSEC_S2B;
1da177e4 LT	89	else
	90	/* We lost the position information due to an error. */
	91	device->blk_data.block_position = -1;
	92	device->discipline->free_bread(ccw_req);
	93	if (!list_empty(&device->req_queue) \|\|
9934c8c0	94	blk_peek_request(device->blk_data.request_queue))
1da177e4 LT	95	tapeblock_trigger_requeue(device);
	96	}
	97
	98	/*
	99	* Feed the tape device CCW queue with requests supplied in a list.
	100	*/
4d284cac	101	static int
1da177e4 LT	102	tapeblock_start_request(struct tape_device device, struct request req)
	103	{
	104	struct tape_request * ccw_req;
	105	int rc;
	106
	107	DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
	108
	109	ccw_req = device->discipline->bread(device, req);
	110	if (IS_ERR(ccw_req)) {
	111	DBF_EVENT(1, "TBLOCK: bread failed\n");
40cbbb78	112	blk_end_request_all(req, -EIO);
1da177e4 LT	113	return PTR_ERR(ccw_req);
	114	}
	115	ccw_req->callback = __tapeblock_end_request;
	116	ccw_req->callback_data = (void *) req;
	117	ccw_req->retries = TAPEBLOCK_RETRIES;
	118
	119	rc = tape_do_io_async(device, ccw_req);
	120	if (rc) {
	121	/*
	122	* Start/enqueueing failed. No retries in
	123	* this case.
	124	*/
40cbbb78	125	blk_end_request_all(req, -EIO);
1da177e4 LT	126	device->discipline->free_bread(ccw_req);
	127	}
	128
	129	return rc;
	130	}
	131
	132	/*
	133	* Move requests from the block device request queue to the tape device ccw
	134	* queue.
	135	*/
	136	static void
c1637532 MS	137	tapeblock_requeue(struct work_struct *work) {
c1637532 MS	138	struct tape_blk_data * blkdat;
1da177e4	139	struct tape_device * device;
165125e1	140	struct request_queue * queue;
1da177e4 LT	141	int nr_queued;
	142	struct request * req;
	143	struct list_head * l;
	144	int rc;
	145
c1637532 MS	146	blkdat = container_of(work, struct tape_blk_data, requeue_task);
c1637532 MS	147	device = blkdat->device;
1da177e4 LT	148	if (!device)
	149	return;
	150
	151	spin_lock_irq(get_ccwdev_lock(device->cdev));
	152	queue = device->blk_data.request_queue;
	153
	154	/* Count number of requests on ccw queue. */
	155	nr_queued = 0;
	156	list_for_each(l, &device->req_queue)
	157	nr_queued++;
	158	spin_unlock(get_ccwdev_lock(device->cdev));
	159
7a4a1ccd	160	spin_lock_irq(&device->blk_data.request_queue_lock);
1da177e4 LT	161	while (
1da177e4 LT	162	!blk_queue_plugged(queue) &&
03cadd36	163	blk_peek_request(queue) &&
1da177e4 LT	164	nr_queued < TAPEBLOCK_MIN_REQUEUE
1da177e4 LT	165	) {
03cadd36	166	req = blk_fetch_request(queue);
1da177e4 LT	167	if (rq_data_dir(req) == WRITE) {
1da177e4 LT	168	DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
7a4a1ccd	169	spin_unlock_irq(&device->blk_data.request_queue_lock);
40cbbb78	170	blk_end_request_all(req, -EIO);
7a4a1ccd	171	spin_lock_irq(&device->blk_data.request_queue_lock);
1da177e4 LT	172	continue;
1da177e4 LT	173	}
f71ad62a	174	nr_queued++;
1da177e4 LT	175	spin_unlock_irq(&device->blk_data.request_queue_lock);
	176	rc = tapeblock_start_request(device, req);
	177	spin_lock_irq(&device->blk_data.request_queue_lock);
1da177e4 LT	178	}
	179	spin_unlock_irq(&device->blk_data.request_queue_lock);
	180	atomic_set(&device->blk_data.requeue_scheduled, 0);
	181	}
	182
	183	/*
	184	* Tape request queue function. Called from ll_rw_blk.c
	185	*/
	186	static void
165125e1	187	tapeblock_request_fn(struct request_queue *queue)
1da177e4 LT	188	{
	189	struct tape_device *device;
	190
	191	device = (struct tape_device *) queue->queuedata;
	192	DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
3a8dc893	193	BUG_ON(device == NULL);
1da177e4 LT	194	tapeblock_trigger_requeue(device);
	195	}
	196
	197	/*
	198	* This function is called for every new tapedevice
	199	*/
	200	int
	201	tapeblock_setup_device(struct tape_device * device)
	202	{
	203	struct tape_blk_data * blkdat;
	204	struct gendisk * disk;
	205	int rc;
	206
	207	blkdat = &device->blk_data;
c1637532	208	blkdat->device = device;
1da177e4 LT	209	spin_lock_init(&blkdat->request_queue_lock);
	210	atomic_set(&blkdat->requeue_scheduled, 0);
	211
	212	blkdat->request_queue = blk_init_queue(
	213	tapeblock_request_fn,
	214	&blkdat->request_queue_lock
	215	);
	216	if (!blkdat->request_queue)
	217	return -ENOMEM;
	218
	219	elevator_exit(blkdat->request_queue->elevator);
	220	rc = elevator_init(blkdat->request_queue, "noop");
	221	if (rc)
	222	goto cleanup_queue;
	223
e1defc4f	224	blk_queue_logical_block_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
1da177e4 LT	225	blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
	226	blk_queue_max_phys_segments(blkdat->request_queue, -1L);
	227	blk_queue_max_hw_segments(blkdat->request_queue, -1L);
	228	blk_queue_max_segment_size(blkdat->request_queue, -1L);
	229	blk_queue_segment_boundary(blkdat->request_queue, -1L);
	230
	231	disk = alloc_disk(1);
	232	if (!disk) {
	233	rc = -ENOMEM;
	234	goto cleanup_queue;
	235	}
	236
	237	disk->major = tapeblock_major;
	238	disk->first_minor = device->first_minor;
	239	disk->fops = &tapeblock_fops;
8fd138c3	240	disk->private_data = tape_get_device(device);
1da177e4 LT	241	disk->queue = blkdat->request_queue;
	242	set_capacity(disk, 0);
	243	sprintf(disk->disk_name, "btibm%d",
	244	device->first_minor / TAPE_MINORS_PER_DEV);
	245
	246	blkdat->disk = disk;
	247	blkdat->medium_changed = 1;
8fd138c3	248	blkdat->request_queue->queuedata = tape_get_device(device);
1da177e4 LT	249
	250	add_disk(disk);
	251
8fd138c3	252	tape_get_device(device);
c1637532	253	INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
1da177e4 LT	254
	255	return 0;
	256
	257	cleanup_queue:
	258	blk_cleanup_queue(blkdat->request_queue);
	259	blkdat->request_queue = NULL;
	260
	261	return rc;
	262	}
	263
	264	void
	265	tapeblock_cleanup_device(struct tape_device *device)
	266	{
	267	flush_scheduled_work();
c1637532	268	tape_put_device(device);
1da177e4 LT	269
1da177e4 LT	270	if (!device->blk_data.disk) {
1da177e4 LT	271	goto cleanup_queue;
	272	}
	273
	274	del_gendisk(device->blk_data.disk);
8fd138c3 MS	275	device->blk_data.disk->private_data = NULL;
8fd138c3 MS	276	tape_put_device(device);
1da177e4 LT	277	put_disk(device->blk_data.disk);
	278
	279	device->blk_data.disk = NULL;
	280	cleanup_queue:
8fd138c3 MS	281	device->blk_data.request_queue->queuedata = NULL;
8fd138c3 MS	282	tape_put_device(device);
1da177e4 LT	283
	284	blk_cleanup_queue(device->blk_data.request_queue);
	285	device->blk_data.request_queue = NULL;
	286	}
	287
	288	/*
	289	* Detect number of blocks of the tape.
	290	* FIXME: can we extent this to detect the blocks size as well ?
	291	*/
	292	static int
	293	tapeblock_revalidate_disk(struct gendisk *disk)
	294	{
	295	struct tape_device * device;
	296	unsigned int nr_of_blks;
	297	int rc;
	298
	299	device = (struct tape_device *) disk->private_data;
3a8dc893	300	BUG_ON(!device);
1da177e4 LT	301
	302	if (!device->blk_data.medium_changed)
	303	return 0;
	304
1da177e4 LT	305	rc = tape_mtop(device, MTFSFM, 1);
	306	if (rc)
	307	return rc;
	308
	309	rc = tape_mtop(device, MTTELL, 1);
	310	if (rc < 0)
	311	return rc;
	312
59e36927 MH	313	pr_info("%s: Determining the size of the recorded area...\n",
59e36927 MH	314	dev_name(&device->cdev->dev));
1da177e4 LT	315	DBF_LH(3, "Image file ends at %d\n", rc);
	316	nr_of_blks = rc;
	317
	318	/* This will fail for the first file. Catch the error by checking the
	319	* position. */
	320	tape_mtop(device, MTBSF, 1);
	321
	322	rc = tape_mtop(device, MTTELL, 1);
	323	if (rc < 0)
	324	return rc;
	325
	326	if (rc > nr_of_blks)
	327	return -EINVAL;
	328
	329	DBF_LH(3, "Image file starts at %d\n", rc);
	330	device->bof = rc;
	331	nr_of_blks -= rc;
	332
59e36927 MH	333	pr_info("%s: The size of the recorded area is %i blocks\n",
59e36927 MH	334	dev_name(&device->cdev->dev), nr_of_blks);
1da177e4 LT	335	set_capacity(device->blk_data.disk,
	336	nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
	337
	338	device->blk_data.block_position = 0;
	339	device->blk_data.medium_changed = 0;
	340	return 0;
	341	}
	342
	343	static int
	344	tapeblock_medium_changed(struct gendisk *disk)
	345	{
	346	struct tape_device *device;
	347
	348	device = (struct tape_device *) disk->private_data;
	349	DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
	350	device, device->blk_data.medium_changed);
	351
	352	return device->blk_data.medium_changed;
	353	}
	354
	355	/*
	356	* Block frontend tape device open function.
	357	*/
	358	static int
4e999af9	359	tapeblock_open(struct block_device *bdev, fmode_t mode)
1da177e4	360	{
4e999af9	361	struct gendisk * disk = bdev->bd_disk;
1da177e4 LT	362	struct tape_device * device;
	363	int rc;
	364
8fd138c3	365	device = tape_get_device(disk->private_data);
1da177e4 LT	366
	367	if (device->required_tapemarks) {
	368	DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
59e36927 MH	369	pr_warning("%s: Opening the tape failed because of missing "
59e36927 MH	370	"end-of-file marks\n", dev_name(&device->cdev->dev));
1da177e4 LT	371	rc = -EPERM;
	372	goto put_device;
	373	}
	374
	375	rc = tape_open(device);
	376	if (rc)
	377	goto put_device;
	378
	379	rc = tapeblock_revalidate_disk(disk);
	380	if (rc)
	381	goto release;
	382
	383	/*
	384	* Note: The reference to <device> is hold until the release function
	385	* is called.
	386	*/
	387	tape_state_set(device, TS_BLKUSE);
	388	return 0;
	389
	390	release:
	391	tape_release(device);
	392	put_device:
	393	tape_put_device(device);
	394	return rc;
	395	}
	396
	397	/*
	398	* Block frontend tape device release function.
	399	*
	400	* Note: One reference to the tape device was made by the open function. So
	401	* we just get the pointer here and release the reference.
	402	*/
	403	static int
4e999af9	404	tapeblock_release(struct gendisk *disk, fmode_t mode)
1da177e4	405	{
1da177e4 LT	406	struct tape_device *device = disk->private_data;
	407
	408	tape_state_set(device, TS_IN_USE);
	409	tape_release(device);
	410	tape_put_device(device);
	411
	412	return 0;
	413	}
	414
1da177e4 LT	415	/*
	416	* Initialize block device frontend.
	417	*/
	418	int
	419	tapeblock_init(void)
	420	{
	421	int rc;
	422
	423	/* Register the tape major number to the kernel */
	424	rc = register_blkdev(tapeblock_major, "tBLK");
	425	if (rc < 0)
	426	return rc;
	427
	428	if (tapeblock_major == 0)
	429	tapeblock_major = rc;
1da177e4 LT	430	return 0;
	431	}
	432
	433	/*
	434	* Deregister major for block device frontend
	435	*/
	436	void
	437	tapeblock_exit(void)
	438	{
	439	unregister_blkdev(tapeblock_major, "tBLK");
	440	}