BUG_ON() Conversion in drivers/s390/char/tape_block.c
[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 #include <linux/fs.h>
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>
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 inline void
77 tapeblock_end_request(struct request *req, int uptodate)
78 {
79         if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
80                 BUG();
81         end_that_request_last(req, uptodate);
82 }
83
84 static void
85 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
86 {
87         struct tape_device *device;
88         struct request *req;
89
90         DBF_LH(6, "__tapeblock_end_request()\n");
91
92         device = ccw_req->device;
93         req = (struct request *) data;
94         tapeblock_end_request(req, ccw_req->rc == 0);
95         if (ccw_req->rc == 0)
96                 /* Update position. */
97                 device->blk_data.block_position =
98                         (req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
99         else
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);
106 }
107
108 /*
109  * Feed the tape device CCW queue with requests supplied in a list.
110  */
111 static inline int
112 tapeblock_start_request(struct tape_device *device, struct request *req)
113 {
114         struct tape_request *   ccw_req;
115         int                     rc;
116
117         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
118
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);
124         }
125         ccw_req->callback = __tapeblock_end_request;
126         ccw_req->callback_data = (void *) req;
127         ccw_req->retries = TAPEBLOCK_RETRIES;
128
129         rc = tape_do_io_async(device, ccw_req);
130         if (rc) {
131                 /*
132                  * Start/enqueueing failed. No retries in
133                  * this case.
134                  */
135                 tapeblock_end_request(req, 0);
136                 device->discipline->free_bread(ccw_req);
137         }
138
139         return rc;
140 }
141
142 /*
143  * Move requests from the block device request queue to the tape device ccw
144  * queue.
145  */
146 static void
147 tapeblock_requeue(void *data) {
148         struct tape_device *    device;
149         request_queue_t *       queue;
150         int                     nr_queued;
151         struct request *        req;
152         struct list_head *      l;
153         int                     rc;
154
155         device = (struct tape_device *) data;
156         if (!device)
157                 return;
158
159         spin_lock_irq(get_ccwdev_lock(device->cdev));
160         queue  = device->blk_data.request_queue;
161
162         /* Count number of requests on ccw queue. */
163         nr_queued = 0;
164         list_for_each(l, &device->req_queue)
165                 nr_queued++;
166         spin_unlock(get_ccwdev_lock(device->cdev));
167
168         spin_lock(&device->blk_data.request_queue_lock);
169         while (
170                 !blk_queue_plugged(queue) &&
171                 elv_next_request(queue)   &&
172                 nr_queued < TAPEBLOCK_MIN_REQUEUE
173         ) {
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);
179                         continue;
180                 }
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);
185                 nr_queued++;
186         }
187         spin_unlock_irq(&device->blk_data.request_queue_lock);
188         atomic_set(&device->blk_data.requeue_scheduled, 0);
189 }
190
191 /*
192  * Tape request queue function. Called from ll_rw_blk.c
193  */
194 static void
195 tapeblock_request_fn(request_queue_t *queue)
196 {
197         struct tape_device *device;
198
199         device = (struct tape_device *) queue->queuedata;
200         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
201         BUG_ON(device == NULL);
202         tapeblock_trigger_requeue(device);
203 }
204
205 /*
206  * This function is called for every new tapedevice
207  */
208 int
209 tapeblock_setup_device(struct tape_device * device)
210 {
211         struct tape_blk_data *  blkdat;
212         struct gendisk *        disk;
213         int                     rc;
214
215         blkdat = &device->blk_data;
216         spin_lock_init(&blkdat->request_queue_lock);
217         atomic_set(&blkdat->requeue_scheduled, 0);
218
219         blkdat->request_queue = blk_init_queue(
220                 tapeblock_request_fn,
221                 &blkdat->request_queue_lock
222         );
223         if (!blkdat->request_queue)
224                 return -ENOMEM;
225
226         elevator_exit(blkdat->request_queue->elevator);
227         rc = elevator_init(blkdat->request_queue, "noop");
228         if (rc)
229                 goto cleanup_queue;
230
231         blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
232         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
233         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
234         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
235         blk_queue_max_segment_size(blkdat->request_queue, -1L);
236         blk_queue_segment_boundary(blkdat->request_queue, -1L);
237
238         disk = alloc_disk(1);
239         if (!disk) {
240                 rc = -ENOMEM;
241                 goto cleanup_queue;
242         }
243
244         disk->major = tapeblock_major;
245         disk->first_minor = device->first_minor;
246         disk->fops = &tapeblock_fops;
247         disk->private_data = tape_get_device_reference(device);
248         disk->queue = blkdat->request_queue;
249         set_capacity(disk, 0);
250         sprintf(disk->disk_name, "btibm%d",
251                 device->first_minor / TAPE_MINORS_PER_DEV);
252
253         blkdat->disk = disk;
254         blkdat->medium_changed = 1;
255         blkdat->request_queue->queuedata = tape_get_device_reference(device);
256
257         add_disk(disk);
258
259         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
260                 tape_get_device_reference(device));
261
262         return 0;
263
264 cleanup_queue:
265         blk_cleanup_queue(blkdat->request_queue);
266         blkdat->request_queue = NULL;
267
268         return rc;
269 }
270
271 void
272 tapeblock_cleanup_device(struct tape_device *device)
273 {
274         flush_scheduled_work();
275         device->blk_data.requeue_task.data = tape_put_device(device);
276
277         if (!device->blk_data.disk) {
278                 PRINT_ERR("(%s): No gendisk to clean up!\n",
279                         device->cdev->dev.bus_id);
280                 goto cleanup_queue;
281         }
282
283         del_gendisk(device->blk_data.disk);
284         device->blk_data.disk->private_data =
285                 tape_put_device(device->blk_data.disk->private_data);
286         put_disk(device->blk_data.disk);
287
288         device->blk_data.disk = NULL;
289 cleanup_queue:
290         device->blk_data.request_queue->queuedata = tape_put_device(device);
291
292         blk_cleanup_queue(device->blk_data.request_queue);
293         device->blk_data.request_queue = NULL;
294 }
295
296 /*
297  * Detect number of blocks of the tape.
298  * FIXME: can we extent this to detect the blocks size as well ?
299  */
300 static int
301 tapeblock_revalidate_disk(struct gendisk *disk)
302 {
303         struct tape_device *    device;
304         unsigned int            nr_of_blks;
305         int                     rc;
306
307         device = (struct tape_device *) disk->private_data;
308         BUG_ON(!device);
309
310         if (!device->blk_data.medium_changed)
311                 return 0;
312
313         PRINT_INFO("Detecting media size...\n");
314         rc = tape_mtop(device, MTFSFM, 1);
315         if (rc)
316                 return rc;
317
318         rc = tape_mtop(device, MTTELL, 1);
319         if (rc < 0)
320                 return rc;
321
322         DBF_LH(3, "Image file ends at %d\n", rc);
323         nr_of_blks = rc;
324
325         /* This will fail for the first file. Catch the error by checking the
326          * position. */
327         tape_mtop(device, MTBSF, 1);
328
329         rc = tape_mtop(device, MTTELL, 1);
330         if (rc < 0)
331                 return rc;
332
333         if (rc > nr_of_blks)
334                 return -EINVAL;
335
336         DBF_LH(3, "Image file starts at %d\n", rc);
337         device->bof = rc;
338         nr_of_blks -= rc;
339
340         PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
341         set_capacity(device->blk_data.disk,
342                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
343
344         device->blk_data.block_position = 0;
345         device->blk_data.medium_changed = 0;
346         return 0;
347 }
348
349 static int
350 tapeblock_medium_changed(struct gendisk *disk)
351 {
352         struct tape_device *device;
353
354         device = (struct tape_device *) disk->private_data;
355         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
356                 device, device->blk_data.medium_changed);
357
358         return device->blk_data.medium_changed;
359 }
360
361 /*
362  * Block frontend tape device open function.
363  */
364 static int
365 tapeblock_open(struct inode *inode, struct file *filp)
366 {
367         struct gendisk *        disk;
368         struct tape_device *    device;
369         int                     rc;
370
371         disk   = inode->i_bdev->bd_disk;
372         device = tape_get_device_reference(disk->private_data);
373
374         if (device->required_tapemarks) {
375                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
376                 PRINT_ERR("TBLOCK: Refusing to open tape with missing"
377                         " end of file marks.\n");
378                 rc = -EPERM;
379                 goto put_device;
380         }
381
382         rc = tape_open(device);
383         if (rc)
384                 goto put_device;
385
386         rc = tapeblock_revalidate_disk(disk);
387         if (rc)
388                 goto release;
389
390         /*
391          * Note: The reference to <device> is hold until the release function
392          *       is called.
393          */
394         tape_state_set(device, TS_BLKUSE);
395         return 0;
396
397 release:
398         tape_release(device);
399  put_device:
400         tape_put_device(device);
401         return rc;
402 }
403
404 /*
405  * Block frontend tape device release function.
406  *
407  * Note: One reference to the tape device was made by the open function. So
408  *       we just get the pointer here and release the reference.
409  */
410 static int
411 tapeblock_release(struct inode *inode, struct file *filp)
412 {
413         struct gendisk *disk = inode->i_bdev->bd_disk;
414         struct tape_device *device = disk->private_data;
415
416         tape_state_set(device, TS_IN_USE);
417         tape_release(device);
418         tape_put_device(device);
419
420         return 0;
421 }
422
423 /*
424  * Support of some generic block device IOCTLs.
425  */
426 static int
427 tapeblock_ioctl(
428         struct inode *          inode,
429         struct file *           file,
430         unsigned int            command,
431         unsigned long           arg
432 ) {
433         int rc;
434         int minor;
435         struct gendisk *disk = inode->i_bdev->bd_disk;
436         struct tape_device *device = disk->private_data;
437
438         rc     = 0;
439         disk   = inode->i_bdev->bd_disk;
440         BUG_ON(!disk);
441         device = disk->private_data;
442         BUG_ON(!device);
443         minor  = iminor(inode);
444
445         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
446         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
447
448         switch (command) {
449                 /* Refuse some IOCTL calls without complaining (mount). */
450                 case 0x5310:            /* CDROMMULTISESSION */
451                         rc = -EINVAL;
452                         break;
453                 default:
454                         PRINT_WARN("invalid ioctl 0x%x\n", command);
455                         rc = -EINVAL;
456         }
457
458         return rc;
459 }
460
461 /*
462  * Initialize block device frontend.
463  */
464 int
465 tapeblock_init(void)
466 {
467         int rc;
468
469         /* Register the tape major number to the kernel */
470         rc = register_blkdev(tapeblock_major, "tBLK");
471         if (rc < 0)
472                 return rc;
473
474         if (tapeblock_major == 0)
475                 tapeblock_major = rc;
476         PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
477         return 0;
478 }
479
480 /*
481  * Deregister major for block device frontend
482  */
483 void
484 tapeblock_exit(void)
485 {
486         unregister_blkdev(tapeblock_major, "tBLK");
487 }