block: Do away with the notion of hardsect_size
[linux-2.6.git] / drivers / s390 / char / tape_block.c
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 #define KMSG_COMPONENT "tape"
14
15 #include <linux/fs.h>
16 #include <linux/module.h>
17 #include <linux/blkdev.h>
18 #include <linux/interrupt.h>
19 #include <linux/buffer_head.h>
20 #include <linux/kernel.h>
21
22 #include <asm/debug.h>
23
24 #define TAPE_DBF_AREA   tape_core_dbf
25
26 #include "tape.h"
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
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 tape_request *ccw_req, void *data)
78 {
79         struct tape_device *device;
80         struct request *req;
81
82         DBF_LH(6, "__tapeblock_end_request()\n");
83
84         device = ccw_req->device;
85         req = (struct request *) data;
86         blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
87         if (ccw_req->rc == 0)
88                 /* Update position. */
89                 device->blk_data.block_position =
90                   (blk_rq_pos(req) + blk_rq_sectors(req)) >> TAPEBLOCK_HSEC_S2B;
91         else
92                 /* We lost the position information due to an error. */
93                 device->blk_data.block_position = -1;
94         device->discipline->free_bread(ccw_req);
95         if (!list_empty(&device->req_queue) ||
96             blk_peek_request(device->blk_data.request_queue))
97                 tapeblock_trigger_requeue(device);
98 }
99
100 /*
101  * Feed the tape device CCW queue with requests supplied in a list.
102  */
103 static int
104 tapeblock_start_request(struct tape_device *device, struct request *req)
105 {
106         struct tape_request *   ccw_req;
107         int                     rc;
108
109         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
110
111         ccw_req = device->discipline->bread(device, req);
112         if (IS_ERR(ccw_req)) {
113                 DBF_EVENT(1, "TBLOCK: bread failed\n");
114                 blk_end_request_all(req, -EIO);
115                 return PTR_ERR(ccw_req);
116         }
117         ccw_req->callback = __tapeblock_end_request;
118         ccw_req->callback_data = (void *) req;
119         ccw_req->retries = TAPEBLOCK_RETRIES;
120
121         rc = tape_do_io_async(device, ccw_req);
122         if (rc) {
123                 /*
124                  * Start/enqueueing failed. No retries in
125                  * this case.
126                  */
127                 blk_end_request_all(req, -EIO);
128                 device->discipline->free_bread(ccw_req);
129         }
130
131         return rc;
132 }
133
134 /*
135  * Move requests from the block device request queue to the tape device ccw
136  * queue.
137  */
138 static void
139 tapeblock_requeue(struct work_struct *work) {
140         struct tape_blk_data *  blkdat;
141         struct tape_device *    device;
142         struct request_queue *  queue;
143         int                     nr_queued;
144         struct request *        req;
145         struct list_head *      l;
146         int                     rc;
147
148         blkdat = container_of(work, struct tape_blk_data, requeue_task);
149         device = blkdat->device;
150         if (!device)
151                 return;
152
153         spin_lock_irq(get_ccwdev_lock(device->cdev));
154         queue  = device->blk_data.request_queue;
155
156         /* Count number of requests on ccw queue. */
157         nr_queued = 0;
158         list_for_each(l, &device->req_queue)
159                 nr_queued++;
160         spin_unlock(get_ccwdev_lock(device->cdev));
161
162         spin_lock_irq(&device->blk_data.request_queue_lock);
163         while (
164                 !blk_queue_plugged(queue) &&
165                 (req = blk_fetch_request(queue)) &&
166                 nr_queued < TAPEBLOCK_MIN_REQUEUE
167         ) {
168                 if (rq_data_dir(req) == WRITE) {
169                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
170                         spin_unlock_irq(&device->blk_data.request_queue_lock);
171                         blk_end_request_all(req, -EIO);
172                         spin_lock_irq(&device->blk_data.request_queue_lock);
173                         continue;
174                 }
175                 nr_queued++;
176                 spin_unlock_irq(&device->blk_data.request_queue_lock);
177                 rc = tapeblock_start_request(device, req);
178                 spin_lock_irq(&device->blk_data.request_queue_lock);
179         }
180         spin_unlock_irq(&device->blk_data.request_queue_lock);
181         atomic_set(&device->blk_data.requeue_scheduled, 0);
182 }
183
184 /*
185  * Tape request queue function. Called from ll_rw_blk.c
186  */
187 static void
188 tapeblock_request_fn(struct request_queue *queue)
189 {
190         struct tape_device *device;
191
192         device = (struct tape_device *) queue->queuedata;
193         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
194         BUG_ON(device == NULL);
195         tapeblock_trigger_requeue(device);
196 }
197
198 /*
199  * This function is called for every new tapedevice
200  */
201 int
202 tapeblock_setup_device(struct tape_device * device)
203 {
204         struct tape_blk_data *  blkdat;
205         struct gendisk *        disk;
206         int                     rc;
207
208         blkdat = &device->blk_data;
209         blkdat->device = device;
210         spin_lock_init(&blkdat->request_queue_lock);
211         atomic_set(&blkdat->requeue_scheduled, 0);
212
213         blkdat->request_queue = blk_init_queue(
214                 tapeblock_request_fn,
215                 &blkdat->request_queue_lock
216         );
217         if (!blkdat->request_queue)
218                 return -ENOMEM;
219
220         elevator_exit(blkdat->request_queue->elevator);
221         rc = elevator_init(blkdat->request_queue, "noop");
222         if (rc)
223                 goto cleanup_queue;
224
225         blk_queue_logical_block_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
226         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
227         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
228         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
229         blk_queue_max_segment_size(blkdat->request_queue, -1L);
230         blk_queue_segment_boundary(blkdat->request_queue, -1L);
231
232         disk = alloc_disk(1);
233         if (!disk) {
234                 rc = -ENOMEM;
235                 goto cleanup_queue;
236         }
237
238         disk->major = tapeblock_major;
239         disk->first_minor = device->first_minor;
240         disk->fops = &tapeblock_fops;
241         disk->private_data = tape_get_device_reference(device);
242         disk->queue = blkdat->request_queue;
243         set_capacity(disk, 0);
244         sprintf(disk->disk_name, "btibm%d",
245                 device->first_minor / TAPE_MINORS_PER_DEV);
246
247         blkdat->disk = disk;
248         blkdat->medium_changed = 1;
249         blkdat->request_queue->queuedata = tape_get_device_reference(device);
250
251         add_disk(disk);
252
253         tape_get_device_reference(device);
254         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
255
256         return 0;
257
258 cleanup_queue:
259         blk_cleanup_queue(blkdat->request_queue);
260         blkdat->request_queue = NULL;
261
262         return rc;
263 }
264
265 void
266 tapeblock_cleanup_device(struct tape_device *device)
267 {
268         flush_scheduled_work();
269         tape_put_device(device);
270
271         if (!device->blk_data.disk) {
272                 goto cleanup_queue;
273         }
274
275         del_gendisk(device->blk_data.disk);
276         device->blk_data.disk->private_data =
277                 tape_put_device(device->blk_data.disk->private_data);
278         put_disk(device->blk_data.disk);
279
280         device->blk_data.disk = NULL;
281 cleanup_queue:
282         device->blk_data.request_queue->queuedata = tape_put_device(device);
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;
300         BUG_ON(!device);
301
302         if (!device->blk_data.medium_changed)
303                 return 0;
304
305         dev_info(&device->cdev->dev, "Determining the size of the recorded "
306                 "area...\n");
307         rc = tape_mtop(device, MTFSFM, 1);
308         if (rc)
309                 return rc;
310
311         rc = tape_mtop(device, MTTELL, 1);
312         if (rc < 0)
313                 return rc;
314
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
333         dev_info(&device->cdev->dev, "The size of the recorded area is %i "
334                 "blocks\n", nr_of_blks);
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
359 tapeblock_open(struct block_device *bdev, fmode_t mode)
360 {
361         struct gendisk *        disk = bdev->bd_disk;
362         struct tape_device *    device;
363         int                     rc;
364
365         device = tape_get_device_reference(disk->private_data);
366
367         if (device->required_tapemarks) {
368                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
369                 dev_warn(&device->cdev->dev, "Opening the tape failed because"
370                         " of missing end-of-file marks\n");
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
404 tapeblock_release(struct gendisk *disk, fmode_t mode)
405 {
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
415 /*
416  * Support of some generic block device IOCTLs.
417  */
418 static int
419 tapeblock_ioctl(
420         struct block_device *   bdev,
421         fmode_t                 mode,
422         unsigned int            command,
423         unsigned long           arg
424 ) {
425         int rc;
426         int minor;
427         struct gendisk *disk = bdev->bd_disk;
428         struct tape_device *device;
429
430         rc     = 0;
431         BUG_ON(!disk);
432         device = disk->private_data;
433         BUG_ON(!device);
434         minor  = MINOR(bdev->bd_dev);
435
436         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
437         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
438
439         switch (command) {
440                 /* Refuse some IOCTL calls without complaining (mount). */
441                 case 0x5310:            /* CDROMMULTISESSION */
442                         rc = -EINVAL;
443                         break;
444                 default:
445                         rc = -EINVAL;
446         }
447
448         return rc;
449 }
450
451 /*
452  * Initialize block device frontend.
453  */
454 int
455 tapeblock_init(void)
456 {
457         int rc;
458
459         /* Register the tape major number to the kernel */
460         rc = register_blkdev(tapeblock_major, "tBLK");
461         if (rc < 0)
462                 return rc;
463
464         if (tapeblock_major == 0)
465                 tapeblock_major = rc;
466         return 0;
467 }
468
469 /*
470  * Deregister major for block device frontend
471  */
472 void
473 tapeblock_exit(void)
474 {
475         unregister_blkdev(tapeblock_major, "tBLK");
476 }