Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
[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 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                 blkdev_dequeue_request(req);
183                 nr_queued++;
184                 spin_unlock_irq(&device->blk_data.request_queue_lock);
185                 rc = tapeblock_start_request(device, req);
186                 spin_lock_irq(&device->blk_data.request_queue_lock);
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 }