2 * drivers/s390/char/tape_block.c
3 * block device frontend for tape device driver
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>
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>
20 #include <asm/debug.h>
22 #define TAPE_DBF_AREA tape_core_dbf
26 #define PRINTK_HEADER "TAPE_BLOCK: "
28 #define TAPEBLOCK_MAX_SEC 100
29 #define TAPEBLOCK_MIN_REQUEUE 3
32 * 2003/11/25 Stefan Bader <shbader@de.ibm.com>
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
44 * file operation structure for tape block frontend
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,
50 static int tapeblock_medium_changed(struct gendisk *);
51 static int tapeblock_revalidate_disk(struct gendisk *);
53 static struct block_device_operations tapeblock_fops = {
55 .open = tapeblock_open,
56 .release = tapeblock_release,
57 .ioctl = tapeblock_ioctl,
58 .media_changed = tapeblock_medium_changed,
59 .revalidate_disk = tapeblock_revalidate_disk,
62 static int tapeblock_major = 0;
65 tapeblock_trigger_requeue(struct tape_device *device)
67 /* Protect against rescheduling. */
68 if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
70 schedule_work(&device->blk_data.requeue_task);
74 * Post finished request.
77 tapeblock_end_request(struct request *req, int uptodate)
79 if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
81 end_that_request_last(req, uptodate);
85 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
87 struct tape_device *device;
90 DBF_LH(6, "__tapeblock_end_request()\n");
92 device = ccw_req->device;
93 req = (struct request *) data;
94 tapeblock_end_request(req, ccw_req->rc == 0);
96 /* Update position. */
97 device->blk_data.block_position =
98 (req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
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);
109 * Feed the tape device CCW queue with requests supplied in a list.
112 tapeblock_start_request(struct tape_device *device, struct request *req)
114 struct tape_request * ccw_req;
117 DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
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);
125 ccw_req->callback = __tapeblock_end_request;
126 ccw_req->callback_data = (void *) req;
127 ccw_req->retries = TAPEBLOCK_RETRIES;
129 rc = tape_do_io_async(device, ccw_req);
132 * Start/enqueueing failed. No retries in
135 tapeblock_end_request(req, 0);
136 device->discipline->free_bread(ccw_req);
143 * Move requests from the block device request queue to the tape device ccw
147 tapeblock_requeue(void *data) {
148 struct tape_device * device;
149 request_queue_t * queue;
151 struct request * req;
152 struct list_head * l;
155 device = (struct tape_device *) data;
159 spin_lock_irq(get_ccwdev_lock(device->cdev));
160 queue = device->blk_data.request_queue;
162 /* Count number of requests on ccw queue. */
164 list_for_each(l, &device->req_queue)
166 spin_unlock(get_ccwdev_lock(device->cdev));
168 spin_lock(&device->blk_data.request_queue_lock);
170 !blk_queue_plugged(queue) &&
171 elv_next_request(queue) &&
172 nr_queued < TAPEBLOCK_MIN_REQUEUE
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);
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);
187 spin_unlock_irq(&device->blk_data.request_queue_lock);
188 atomic_set(&device->blk_data.requeue_scheduled, 0);
192 * Tape request queue function. Called from ll_rw_blk.c
195 tapeblock_request_fn(request_queue_t *queue)
197 struct tape_device *device;
199 device = (struct tape_device *) queue->queuedata;
200 DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
204 tapeblock_trigger_requeue(device);
208 * This function is called for every new tapedevice
211 tapeblock_setup_device(struct tape_device * device)
213 struct tape_blk_data * blkdat;
214 struct gendisk * disk;
217 blkdat = &device->blk_data;
218 spin_lock_init(&blkdat->request_queue_lock);
219 atomic_set(&blkdat->requeue_scheduled, 0);
221 blkdat->request_queue = blk_init_queue(
222 tapeblock_request_fn,
223 &blkdat->request_queue_lock
225 if (!blkdat->request_queue)
228 elevator_exit(blkdat->request_queue->elevator);
229 rc = elevator_init(blkdat->request_queue, "noop");
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);
240 disk = alloc_disk(1);
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);
256 blkdat->medium_changed = 1;
257 blkdat->request_queue->queuedata = tape_get_device_reference(device);
261 INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
262 tape_get_device_reference(device));
267 blk_cleanup_queue(blkdat->request_queue);
268 blkdat->request_queue = NULL;
274 tapeblock_cleanup_device(struct tape_device *device)
276 flush_scheduled_work();
277 device->blk_data.requeue_task.data = tape_put_device(device);
279 if (!device->blk_data.disk) {
280 PRINT_ERR("(%s): No gendisk to clean up!\n",
281 device->cdev->dev.bus_id);
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);
290 device->blk_data.disk = NULL;
292 device->blk_data.request_queue->queuedata = tape_put_device(device);
294 blk_cleanup_queue(device->blk_data.request_queue);
295 device->blk_data.request_queue = NULL;
299 * Detect number of blocks of the tape.
300 * FIXME: can we extent this to detect the blocks size as well ?
303 tapeblock_revalidate_disk(struct gendisk *disk)
305 struct tape_device * device;
306 unsigned int nr_of_blks;
309 device = (struct tape_device *) disk->private_data;
313 if (!device->blk_data.medium_changed)
316 PRINT_INFO("Detecting media size...\n");
317 rc = tape_mtop(device, MTFSFM, 1);
321 rc = tape_mtop(device, MTTELL, 1);
325 DBF_LH(3, "Image file ends at %d\n", rc);
328 /* This will fail for the first file. Catch the error by checking the
330 tape_mtop(device, MTBSF, 1);
332 rc = tape_mtop(device, MTTELL, 1);
339 DBF_LH(3, "Image file starts at %d\n", rc);
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));
347 device->blk_data.block_position = 0;
348 device->blk_data.medium_changed = 0;
353 tapeblock_medium_changed(struct gendisk *disk)
355 struct tape_device *device;
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);
361 return device->blk_data.medium_changed;
365 * Block frontend tape device open function.
368 tapeblock_open(struct inode *inode, struct file *filp)
370 struct gendisk * disk;
371 struct tape_device * device;
374 disk = inode->i_bdev->bd_disk;
375 device = tape_get_device_reference(disk->private_data);
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");
385 rc = tape_open(device);
389 rc = tapeblock_revalidate_disk(disk);
394 * Note: The reference to <device> is hold until the release function
397 tape_state_set(device, TS_BLKUSE);
401 tape_release(device);
403 tape_put_device(device);
408 * Block frontend tape device release function.
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.
414 tapeblock_release(struct inode *inode, struct file *filp)
416 struct gendisk *disk = inode->i_bdev->bd_disk;
417 struct tape_device *device = disk->private_data;
419 tape_state_set(device, TS_IN_USE);
420 tape_release(device);
421 tape_put_device(device);
427 * Support of some generic block device IOCTLs.
431 struct inode * inode,
433 unsigned int command,
438 struct gendisk *disk = inode->i_bdev->bd_disk;
439 struct tape_device *device = disk->private_data;
442 disk = inode->i_bdev->bd_disk;
445 device = disk->private_data;
448 minor = iminor(inode);
450 DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
451 DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
454 /* Refuse some IOCTL calls without complaining (mount). */
455 case 0x5310: /* CDROMMULTISESSION */
459 PRINT_WARN("invalid ioctl 0x%x\n", command);
467 * Initialize block device frontend.
474 /* Register the tape major number to the kernel */
475 rc = register_blkdev(tapeblock_major, "tBLK");
479 if (tapeblock_major == 0)
480 tapeblock_major = rc;
481 PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
486 * Deregister major for block device frontend
491 unregister_blkdev(tapeblock_major, "tBLK");