Merge branch 'proc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/adobriyan...
[linux-2.6] / 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/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
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_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
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
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
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
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
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
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
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
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
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
485 tapeblock_exit(void)
486 {
487         unregister_blkdev(tapeblock_major, "tBLK");
488 }