git.oblomov.eu Git - linux-2.6/blob - 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 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                 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         dev_info(&device->cdev->dev, "Determining the size of the recorded "
 316                 "area...\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         dev_info(&device->cdev->dev, "The size of the recorded area is %i "
 344                 "blocks\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                 dev_warn(&device->cdev->dev, "Opening the tape failed because"
 380                         " of missing 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                         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         return 0;
 477 }
 478
 479 /*
 480  * Deregister major for block device frontend
 481  */
 482 void
 483 tapeblock_exit(void)
 484 {
 485         unregister_blkdev(tapeblock_major, "tBLK");
 486 }