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 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_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
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
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
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
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(&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 tapeblock_end_request(req, -EIO);
180 continue;
181 }
182 spin_unlock_irq(&device->blk_data.request_queue_lock);
183 rc = tapeblock_start_request(device, req);
184 spin_lock_irq(&device->blk_data.request_queue_lock);
185 blkdev_dequeue_request(req);
186 nr_queued++;
187 }
188 spin_unlock_irq(&device->blk_data.request_queue_lock);
189 atomic_set(&device->blk_data.requeue_scheduled, 0);
190 }
191
192 /*
193 * Tape request queue function. Called from ll_rw_blk.c
194 */
195 static void
196 tapeblock_request_fn(struct request_queue *queue)
197 {
198 struct tape_device *device;
199
200 device = (struct tape_device *) queue->queuedata;
201 DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
202 BUG_ON(device == NULL);
203 tapeblock_trigger_requeue(device);
204 }
205
206 /*
207 * This function is called for every new tapedevice
208 */
209 int
210 tapeblock_setup_device(struct tape_device * device)
211 {
212 struct tape_blk_data * blkdat;
213 struct gendisk * disk;
214 int rc;
215
216 blkdat = &device->blk_data;
217 blkdat->device = device;
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 tape_get_device_reference(device);
262 INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
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 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 BUG_ON(!device);
311
312 if (!device->blk_data.medium_changed)
313 return 0;
314
315 PRINT_INFO("Detecting media size...\n");
316 rc = tape_mtop(device, MTFSFM, 1);
317 if (rc)
318 return rc;
319
320 rc = tape_mtop(device, MTTELL, 1);
321 if (rc < 0)
322 return rc;
323
324 DBF_LH(3, "Image file ends at %d\n", rc);
325 nr_of_blks = rc;
326
327 /* This will fail for the first file. Catch the error by checking the
328 * position. */
329 tape_mtop(device, MTBSF, 1);
330
331 rc = tape_mtop(device, MTTELL, 1);
332 if (rc < 0)
333 return rc;
334
335 if (rc > nr_of_blks)
336 return -EINVAL;
337
338 DBF_LH(3, "Image file starts at %d\n", rc);
339 device->bof = rc;
340 nr_of_blks -= rc;
341
342 PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
343 set_capacity(device->blk_data.disk,
344 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
345
346 device->blk_data.block_position = 0;
347 device->blk_data.medium_changed = 0;
348 return 0;
349 }
350
351 static int
352 tapeblock_medium_changed(struct gendisk *disk)
353 {
354 struct tape_device *device;
355
356 device = (struct tape_device *) disk->private_data;
357 DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
358 device, device->blk_data.medium_changed);
359
360 return device->blk_data.medium_changed;
361 }
362
363 /*
364 * Block frontend tape device open function.
365 */
366 static int
367 tapeblock_open(struct inode *inode, struct file *filp)
368 {
369 struct gendisk * disk;
370 struct tape_device * device;
371 int rc;
372
373 disk = inode->i_bdev->bd_disk;
374 device = tape_get_device_reference(disk->private_data);
375
376 if (device->required_tapemarks) {
377 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
378 PRINT_ERR("TBLOCK: Refusing to open tape with missing"
379 " end of file marks.\n");
380 rc = -EPERM;
381 goto put_device;
382 }
383
384 rc = tape_open(device);
385 if (rc)
386 goto put_device;
387
388 rc = tapeblock_revalidate_disk(disk);
389 if (rc)
390 goto release;
391
392 /*
393 * Note: The reference to <device> is hold until the release function
394 * is called.
395 */
396 tape_state_set(device, TS_BLKUSE);
397 return 0;
398
399 release:
400 tape_release(device);
401 put_device:
402 tape_put_device(device);
403 return rc;
404 }
405
406 /*
407 * Block frontend tape device release function.
408 *
409 * Note: One reference to the tape device was made by the open function. So
410 * we just get the pointer here and release the reference.
411 */
412 static int
413 tapeblock_release(struct inode *inode, struct file *filp)
414 {
415 struct gendisk *disk = inode->i_bdev->bd_disk;
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
429 tapeblock_ioctl(
430 struct inode * inode,
431 struct file * file,
432 unsigned int command,
433 unsigned long arg
434 ) {
435 int rc;
436 int minor;
437 struct gendisk *disk;
438 struct tape_device *device;
439
440 rc = 0;
441 disk = inode->i_bdev->bd_disk;
442 BUG_ON(!disk);
443 device = disk->private_data;
444 BUG_ON(!device);
445 minor = iminor(inode);
446
447 DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
448 DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
449
450 switch (command) {
451 /* Refuse some IOCTL calls without complaining (mount). */
452 case 0x5310: /* CDROMMULTISESSION */
453 rc = -EINVAL;
454 break;
455 default:
456 PRINT_WARN("invalid ioctl 0x%x\n", command);
457 rc = -EINVAL;
458 }
459
460 return rc;
461 }
462
463 /*
464 * Initialize block device frontend.
465 */
466 int
467 tapeblock_init(void)
468 {
469 int rc;
470
471 /* Register the tape major number to the kernel */
472 rc = register_blkdev(tapeblock_major, "tBLK");
473 if (rc < 0)
474 return rc;
475
476 if (tapeblock_major == 0)
477 tapeblock_major = rc;
478 PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
479 return 0;
480 }
481
482 /*
483 * Deregister major for block device frontend
484 */
485 void
486 tapeblock_exit(void)
487 {
488 unregister_blkdev(tapeblock_major, "tBLK");
489 }
490
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