Merge branch 'post-2.6.15' of git://brick.kernel.dk/data/git/linux-2.6-block
[sfrench/cifs-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         if (device == NULL)
202                 BUG();
203
204         tapeblock_trigger_requeue(device);
205 }
206
207 /*
208  * This function is called for every new tapedevice
209  */
210 int
211 tapeblock_setup_device(struct tape_device * device)
212 {
213         struct tape_blk_data *  blkdat;
214         struct gendisk *        disk;
215         int                     rc;
216
217         blkdat = &device->blk_data;
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         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
262                 tape_get_device_reference(device));
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         device->blk_data.requeue_task.data = 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         if (!device)
311                 BUG();
312
313         if (!device->blk_data.medium_changed)
314                 return 0;
315
316         PRINT_INFO("Detecting media size...\n");
317         rc = tape_mtop(device, MTFSFM, 1);
318         if (rc)
319                 return rc;
320
321         rc = tape_mtop(device, MTTELL, 1);
322         if (rc < 0)
323                 return rc;
324
325         DBF_LH(3, "Image file ends at %d\n", rc);
326         nr_of_blks = rc;
327
328         /* This will fail for the first file. Catch the error by checking the
329          * position. */
330         tape_mtop(device, MTBSF, 1);
331
332         rc = tape_mtop(device, MTTELL, 1);
333         if (rc < 0)
334                 return rc;
335
336         if (rc > nr_of_blks)
337                 return -EINVAL;
338
339         DBF_LH(3, "Image file starts at %d\n", rc);
340         device->bof = rc;
341         nr_of_blks -= rc;
342
343         PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
344         set_capacity(device->blk_data.disk,
345                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
346
347         device->blk_data.block_position = 0;
348         device->blk_data.medium_changed = 0;
349         return 0;
350 }
351
352 static int
353 tapeblock_medium_changed(struct gendisk *disk)
354 {
355         struct tape_device *device;
356
357         device = (struct tape_device *) disk->private_data;
358         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
359                 device, device->blk_data.medium_changed);
360
361         return device->blk_data.medium_changed;
362 }
363
364 /*
365  * Block frontend tape device open function.
366  */
367 static int
368 tapeblock_open(struct inode *inode, struct file *filp)
369 {
370         struct gendisk *        disk;
371         struct tape_device *    device;
372         int                     rc;
373
374         disk   = inode->i_bdev->bd_disk;
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 inode *inode, struct file *filp)
415 {
416         struct gendisk *disk = inode->i_bdev->bd_disk;
417         struct tape_device *device = disk->private_data;
418
419         tape_state_set(device, TS_IN_USE);
420         tape_release(device);
421         tape_put_device(device);
422
423         return 0;
424 }
425
426 /*
427  * Support of some generic block device IOCTLs.
428  */
429 static int
430 tapeblock_ioctl(
431         struct inode *          inode,
432         struct file *           file,
433         unsigned int            command,
434         unsigned long           arg
435 ) {
436         int rc;
437         int minor;
438         struct gendisk *disk = inode->i_bdev->bd_disk;
439         struct tape_device *device = disk->private_data;
440
441         rc     = 0;
442         disk   = inode->i_bdev->bd_disk;
443         if (!disk)
444                 BUG();
445         device = disk->private_data;
446         if (!device)
447                 BUG();
448         minor  = iminor(inode);
449
450         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
451         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
452
453         switch (command) {
454                 /* Refuse some IOCTL calls without complaining (mount). */
455                 case 0x5310:            /* CDROMMULTISESSION */
456                         rc = -EINVAL;
457                         break;
458                 default:
459                         PRINT_WARN("invalid ioctl 0x%x\n", command);
460                         rc = -EINVAL;
461         }
462
463         return rc;
464 }
465
466 /*
467  * Initialize block device frontend.
468  */
469 int
470 tapeblock_init(void)
471 {
472         int rc;
473
474         /* Register the tape major number to the kernel */
475         rc = register_blkdev(tapeblock_major, "tBLK");
476         if (rc < 0)
477                 return rc;
478
479         if (tapeblock_major == 0)
480                 tapeblock_major = rc;
481         PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
482         return 0;
483 }
484
485 /*
486  * Deregister major for block device frontend
487  */
488 void
489 tapeblock_exit(void)
490 {
491         unregister_blkdev(tapeblock_major, "tBLK");
492 }