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/module.h>
15 #include <linux/blkdev.h>
16 #include <linux/interrupt.h>
17 #include <linux/buffer_head.h>
18 #include <linux/kernel.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 block_device *, fmode_t);
47 static int tapeblock_release(struct gendisk *, fmode_t);
48 static int tapeblock_ioctl(struct block_device *, fmode_t, 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 .locked_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
tapeblock_trigger_requeue(struct tape_device * device)65 tapeblock_trigger_requeue(struct tape_device *device)
66 {
67 /* Protect against rescheduling. */
68 if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
69 return;
70 schedule_work(&device->blk_data.requeue_task);
71 }
72
73 /*
74 * Post finished request.
75 */
76 static void
tapeblock_end_request(struct request * req,int error)77 tapeblock_end_request(struct request *req, int error)
78 {
79 if (blk_end_request(req, error, blk_rq_bytes(req)))
80 BUG();
81 }
82
83 static void
__tapeblock_end_request(struct tape_request * ccw_req,void * data)84 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
85 {
86 struct tape_device *device;
87 struct request *req;
88
89 DBF_LH(6, "__tapeblock_end_request()\n");
90
91 device = ccw_req->device;
92 req = (struct request *) data;
93 tapeblock_end_request(req, (ccw_req->rc == 0) ? 0 : -EIO);
94 if (ccw_req->rc == 0)
95 /* Update position. */
96 device->blk_data.block_position =
97 (req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
98 else
99 /* We lost the position information due to an error. */
100 device->blk_data.block_position = -1;
101 device->discipline->free_bread(ccw_req);
102 if (!list_empty(&device->req_queue) ||
103 elv_next_request(device->blk_data.request_queue))
104 tapeblock_trigger_requeue(device);
105 }
106
107 /*
108 * Feed the tape device CCW queue with requests supplied in a list.
109 */
110 static int
tapeblock_start_request(struct tape_device * device,struct request * req)111 tapeblock_start_request(struct tape_device *device, struct request *req)
112 {
113 struct tape_request * ccw_req;
114 int rc;
115
116 DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
117
118 ccw_req = device->discipline->bread(device, req);
119 if (IS_ERR(ccw_req)) {
120 DBF_EVENT(1, "TBLOCK: bread failed\n");
121 tapeblock_end_request(req, -EIO);
122 return PTR_ERR(ccw_req);
123 }
124 ccw_req->callback = __tapeblock_end_request;
125 ccw_req->callback_data = (void *) req;
126 ccw_req->retries = TAPEBLOCK_RETRIES;
127
128 rc = tape_do_io_async(device, ccw_req);
129 if (rc) {
130 /*
131 * Start/enqueueing failed. No retries in
132 * this case.
133 */
134 tapeblock_end_request(req, -EIO);
135 device->discipline->free_bread(ccw_req);
136 }
137
138 return rc;
139 }
140
141 /*
142 * Move requests from the block device request queue to the tape device ccw
143 * queue.
144 */
145 static void
tapeblock_requeue(struct work_struct * work)146 tapeblock_requeue(struct work_struct *work) {
147 struct tape_blk_data * blkdat;
148 struct tape_device * device;
149 struct request_queue * queue;
150 int nr_queued;
151 struct request * req;
152 struct list_head * l;
153 int rc;
154
155 blkdat = container_of(work, struct tape_blk_data, requeue_task);
156 device = blkdat->device;
157 if (!device)
158 return;
159
160 spin_lock_irq(get_ccwdev_lock(device->cdev));
161 queue = device->blk_data.request_queue;
162
163 /* Count number of requests on ccw queue. */
164 nr_queued = 0;
165 list_for_each(l, &device->req_queue)
166 nr_queued++;
167 spin_unlock(get_ccwdev_lock(device->cdev));
168
169 spin_lock_irq(&device->blk_data.request_queue_lock);
170 while (
171 !blk_queue_plugged(queue) &&
172 elv_next_request(queue) &&
173 nr_queued < TAPEBLOCK_MIN_REQUEUE
174 ) {
175 req = elv_next_request(queue);
176 if (rq_data_dir(req) == WRITE) {
177 DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
178 blkdev_dequeue_request(req);
179 spin_unlock_irq(&device->blk_data.request_queue_lock);
180 tapeblock_end_request(req, -EIO);
181 spin_lock_irq(&device->blk_data.request_queue_lock);
182 continue;
183 }
184 blkdev_dequeue_request(req);
185 nr_queued++;
186 spin_unlock_irq(&device->blk_data.request_queue_lock);
187 rc = tapeblock_start_request(device, req);
188 spin_lock_irq(&device->blk_data.request_queue_lock);
189 }
190 spin_unlock_irq(&device->blk_data.request_queue_lock);
191 atomic_set(&device->blk_data.requeue_scheduled, 0);
192 }
193
194 /*
195 * Tape request queue function. Called from ll_rw_blk.c
196 */
197 static void
tapeblock_request_fn(struct request_queue * queue)198 tapeblock_request_fn(struct request_queue *queue)
199 {
200 struct tape_device *device;
201
202 device = (struct tape_device *) queue->queuedata;
203 DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
204 BUG_ON(device == NULL);
205 tapeblock_trigger_requeue(device);
206 }
207
208 /*
209 * This function is called for every new tapedevice
210 */
211 int
tapeblock_setup_device(struct tape_device * device)212 tapeblock_setup_device(struct tape_device * device)
213 {
214 struct tape_blk_data * blkdat;
215 struct gendisk * disk;
216 int rc;
217
218 blkdat = &device->blk_data;
219 blkdat->device = device;
220 spin_lock_init(&blkdat->request_queue_lock);
221 atomic_set(&blkdat->requeue_scheduled, 0);
222
223 blkdat->request_queue = blk_init_queue(
224 tapeblock_request_fn,
225 &blkdat->request_queue_lock
226 );
227 if (!blkdat->request_queue)
228 return -ENOMEM;
229
230 elevator_exit(blkdat->request_queue->elevator);
231 rc = elevator_init(blkdat->request_queue, "noop");
232 if (rc)
233 goto cleanup_queue;
234
235 blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
236 blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
237 blk_queue_max_phys_segments(blkdat->request_queue, -1L);
238 blk_queue_max_hw_segments(blkdat->request_queue, -1L);
239 blk_queue_max_segment_size(blkdat->request_queue, -1L);
240 blk_queue_segment_boundary(blkdat->request_queue, -1L);
241
242 disk = alloc_disk(1);
243 if (!disk) {
244 rc = -ENOMEM;
245 goto cleanup_queue;
246 }
247
248 disk->major = tapeblock_major;
249 disk->first_minor = device->first_minor;
250 disk->fops = &tapeblock_fops;
251 disk->private_data = tape_get_device_reference(device);
252 disk->queue = blkdat->request_queue;
253 set_capacity(disk, 0);
254 sprintf(disk->disk_name, "btibm%d",
255 device->first_minor / TAPE_MINORS_PER_DEV);
256
257 blkdat->disk = disk;
258 blkdat->medium_changed = 1;
259 blkdat->request_queue->queuedata = tape_get_device_reference(device);
260
261 add_disk(disk);
262
263 tape_get_device_reference(device);
264 INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
265
266 return 0;
267
268 cleanup_queue:
269 blk_cleanup_queue(blkdat->request_queue);
270 blkdat->request_queue = NULL;
271
272 return rc;
273 }
274
275 void
tapeblock_cleanup_device(struct tape_device * device)276 tapeblock_cleanup_device(struct tape_device *device)
277 {
278 flush_scheduled_work();
279 tape_put_device(device);
280
281 if (!device->blk_data.disk) {
282 PRINT_ERR("(%s): No gendisk to clean up!\n",
283 dev_name(&device->cdev->dev));
284 goto cleanup_queue;
285 }
286
287 del_gendisk(device->blk_data.disk);
288 device->blk_data.disk->private_data =
289 tape_put_device(device->blk_data.disk->private_data);
290 put_disk(device->blk_data.disk);
291
292 device->blk_data.disk = NULL;
293 cleanup_queue:
294 device->blk_data.request_queue->queuedata = tape_put_device(device);
295
296 blk_cleanup_queue(device->blk_data.request_queue);
297 device->blk_data.request_queue = NULL;
298 }
299
300 /*
301 * Detect number of blocks of the tape.
302 * FIXME: can we extent this to detect the blocks size as well ?
303 */
304 static int
tapeblock_revalidate_disk(struct gendisk * disk)305 tapeblock_revalidate_disk(struct gendisk *disk)
306 {
307 struct tape_device * device;
308 unsigned int nr_of_blks;
309 int rc;
310
311 device = (struct tape_device *) disk->private_data;
312 BUG_ON(!device);
313
314 if (!device->blk_data.medium_changed)
315 return 0;
316
317 PRINT_INFO("Detecting media size...\n");
318 rc = tape_mtop(device, MTFSFM, 1);
319 if (rc)
320 return rc;
321
322 rc = tape_mtop(device, MTTELL, 1);
323 if (rc < 0)
324 return rc;
325
326 DBF_LH(3, "Image file ends at %d\n", rc);
327 nr_of_blks = rc;
328
329 /* This will fail for the first file. Catch the error by checking the
330 * position. */
331 tape_mtop(device, MTBSF, 1);
332
333 rc = tape_mtop(device, MTTELL, 1);
334 if (rc < 0)
335 return rc;
336
337 if (rc > nr_of_blks)
338 return -EINVAL;
339
340 DBF_LH(3, "Image file starts at %d\n", rc);
341 device->bof = rc;
342 nr_of_blks -= rc;
343
344 PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
345 set_capacity(device->blk_data.disk,
346 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
347
348 device->blk_data.block_position = 0;
349 device->blk_data.medium_changed = 0;
350 return 0;
351 }
352
353 static int
tapeblock_medium_changed(struct gendisk * disk)354 tapeblock_medium_changed(struct gendisk *disk)
355 {
356 struct tape_device *device;
357
358 device = (struct tape_device *) disk->private_data;
359 DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
360 device, device->blk_data.medium_changed);
361
362 return device->blk_data.medium_changed;
363 }
364
365 /*
366 * Block frontend tape device open function.
367 */
368 static int
tapeblock_open(struct block_device * bdev,fmode_t mode)369 tapeblock_open(struct block_device *bdev, fmode_t mode)
370 {
371 struct gendisk * disk = bdev->bd_disk;
372 struct tape_device * device;
373 int rc;
374
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
tapeblock_release(struct gendisk * disk,fmode_t mode)414 tapeblock_release(struct gendisk *disk, fmode_t mode)
415 {
416 struct tape_device *device = disk->private_data;
417
418 tape_state_set(device, TS_IN_USE);
419 tape_release(device);
420 tape_put_device(device);
421
422 return 0;
423 }
424
425 /*
426 * Support of some generic block device IOCTLs.
427 */
428 static int
tapeblock_ioctl(struct block_device * bdev,fmode_t mode,unsigned int command,unsigned long arg)429 tapeblock_ioctl(
430 struct block_device * bdev,
431 fmode_t mode,
432 unsigned int command,
433 unsigned long arg
434 ) {
435 int rc;
436 int minor;
437 struct gendisk *disk = bdev->bd_disk;
438 struct tape_device *device;
439
440 rc = 0;
441 BUG_ON(!disk);
442 device = disk->private_data;
443 BUG_ON(!device);
444 minor = MINOR(bdev->bd_dev);
445
446 DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
447 DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
448
449 switch (command) {
450 /* Refuse some IOCTL calls without complaining (mount). */
451 case 0x5310: /* CDROMMULTISESSION */
452 rc = -EINVAL;
453 break;
454 default:
455 PRINT_WARN("invalid ioctl 0x%x\n", command);
456 rc = -EINVAL;
457 }
458
459 return rc;
460 }
461
462 /*
463 * Initialize block device frontend.
464 */
465 int
tapeblock_init(void)466 tapeblock_init(void)
467 {
468 int rc;
469
470 /* Register the tape major number to the kernel */
471 rc = register_blkdev(tapeblock_major, "tBLK");
472 if (rc < 0)
473 return rc;
474
475 if (tapeblock_major == 0)
476 tapeblock_major = rc;
477 PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
478 return 0;
479 }
480
481 /*
482 * Deregister major for block device frontend
483 */
484 void
tapeblock_exit(void)485 tapeblock_exit(void)
486 {
487 unregister_blkdev(tapeblock_major, "tBLK");
488 }
489