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 const 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 tape_request *ccw_req, void *data)
  78 {
  79         struct tape_device *device;
  80         struct request *req;
  81
  82         DBF_LH(6, "__tapeblock_end_request()\n");
  83
  84         device = ccw_req->device;
  85         req = (struct request *) data;
  86         blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
  87         if (ccw_req->rc == 0)
  88                 /* Update position. */
  89                 device->blk_data.block_position =
  90                   (blk_rq_pos(req) + blk_rq_sectors(req)) >> TAPEBLOCK_HSEC_S2B;
  91         else
  92                 /* We lost the position information due to an error. */
  93                 device->blk_data.block_position = -1;
  94         device->discipline->free_bread(ccw_req);
  95         if (!list_empty(&device->req_queue) ||
  96             blk_peek_request(device->blk_data.request_queue))
  97                 tapeblock_trigger_requeue(device);
  98 }
  99
 100 /*
 101  * Feed the tape device CCW queue with requests supplied in a list.
 102  */
 103 static int
 104 tapeblock_start_request(struct tape_device *device, struct request *req)
 105 {
 106         struct tape_request *   ccw_req;
 107         int                     rc;
 108
 109         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
 110
 111         ccw_req = device->discipline->bread(device, req);
 112         if (IS_ERR(ccw_req)) {
 113                 DBF_EVENT(1, "TBLOCK: bread failed\n");
 114                 blk_end_request_all(req, -EIO);
 115                 return PTR_ERR(ccw_req);
 116         }
 117         ccw_req->callback = __tapeblock_end_request;
 118         ccw_req->callback_data = (void *) req;
 119         ccw_req->retries = TAPEBLOCK_RETRIES;
 120
 121         rc = tape_do_io_async(device, ccw_req);
 122         if (rc) {
 123                 /*
 124                  * Start/enqueueing failed. No retries in
 125                  * this case.
 126                  */
 127                 blk_end_request_all(req, -EIO);
 128                 device->discipline->free_bread(ccw_req);
 129         }
 130
 131         return rc;
 132 }
 133
 134 /*
 135  * Move requests from the block device request queue to the tape device ccw
 136  * queue.
 137  */
 138 static void
 139 tapeblock_requeue(struct work_struct *work) {
 140         struct tape_blk_data *  blkdat;
 141         struct tape_device *    device;
 142         struct request_queue *  queue;
 143         int                     nr_queued;
 144         struct request *        req;
 145         struct list_head *      l;
 146         int                     rc;
 147
 148         blkdat = container_of(work, struct tape_blk_data, requeue_task);
 149         device = blkdat->device;
 150         if (!device)
 151                 return;
 152
 153         spin_lock_irq(get_ccwdev_lock(device->cdev));
 154         queue  = device->blk_data.request_queue;
 155
 156         /* Count number of requests on ccw queue. */
 157         nr_queued = 0;
 158         list_for_each(l, &device->req_queue)
 159                 nr_queued++;
 160         spin_unlock(get_ccwdev_lock(device->cdev));
 161
 162         spin_lock_irq(&device->blk_data.request_queue_lock);
 163         while (
 164                 !blk_queue_plugged(queue) &&
 165                 blk_peek_request(queue) &&
 166                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 167         ) {
 168                 req = blk_fetch_request(queue);
 169                 if (rq_data_dir(req) == WRITE) {
 170                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 171                         spin_unlock_irq(&device->blk_data.request_queue_lock);
 172                         blk_end_request_all(req, -EIO);
 173                         spin_lock_irq(&device->blk_data.request_queue_lock);
 174                         continue;
 175                 }
 176                 nr_queued++;
 177                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 178                 rc = tapeblock_start_request(device, req);
 179                 spin_lock_irq(&device->blk_data.request_queue_lock);
 180         }
 181         spin_unlock_irq(&device->blk_data.request_queue_lock);
 182         atomic_set(&device->blk_data.requeue_scheduled, 0);
 183 }
 184
 185 /*
 186  * Tape request queue function. Called from ll_rw_blk.c
 187  */
 188 static void
 189 tapeblock_request_fn(struct request_queue *queue)
 190 {
 191         struct tape_device *device;
 192
 193         device = (struct tape_device *) queue->queuedata;
 194         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 195         BUG_ON(device == NULL);
 196         tapeblock_trigger_requeue(device);
 197 }
 198
 199 /*
 200  * This function is called for every new tapedevice
 201  */
 202 int
 203 tapeblock_setup_device(struct tape_device * device)
 204 {
 205         struct tape_blk_data *  blkdat;
 206         struct gendisk *        disk;
 207         int                     rc;
 208
 209         blkdat = &device->blk_data;
 210         blkdat->device = device;
 211         spin_lock_init(&blkdat->request_queue_lock);
 212         atomic_set(&blkdat->requeue_scheduled, 0);
 213
 214         blkdat->request_queue = blk_init_queue(
 215                 tapeblock_request_fn,
 216                 &blkdat->request_queue_lock
 217         );
 218         if (!blkdat->request_queue)
 219                 return -ENOMEM;
 220
 221         elevator_exit(blkdat->request_queue->elevator);
 222         rc = elevator_init(blkdat->request_queue, "noop");
 223         if (rc)
 224                 goto cleanup_queue;
 225
 226         blk_queue_logical_block_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 227         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 228         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
 229         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
 230         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 231         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 232
 233         disk = alloc_disk(1);
 234         if (!disk) {
 235                 rc = -ENOMEM;
 236                 goto cleanup_queue;
 237         }
 238
 239         disk->major = tapeblock_major;
 240         disk->first_minor = device->first_minor;
 241         disk->fops = &tapeblock_fops;
 242         disk->private_data = tape_get_device(device);
 243         disk->queue = blkdat->request_queue;
 244         set_capacity(disk, 0);
 245         sprintf(disk->disk_name, "btibm%d",
 246                 device->first_minor / TAPE_MINORS_PER_DEV);
 247
 248         blkdat->disk = disk;
 249         blkdat->medium_changed = 1;
 250         blkdat->request_queue->queuedata = tape_get_device(device);
 251
 252         add_disk(disk);
 253
 254         tape_get_device(device);
 255         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 256
 257         return 0;
 258
 259 cleanup_queue:
 260         blk_cleanup_queue(blkdat->request_queue);
 261         blkdat->request_queue = NULL;
 262
 263         return rc;
 264 }
 265
 266 void
 267 tapeblock_cleanup_device(struct tape_device *device)
 268 {
 269         flush_scheduled_work();
 270         tape_put_device(device);
 271
 272         if (!device->blk_data.disk) {
 273                 goto cleanup_queue;
 274         }
 275
 276         del_gendisk(device->blk_data.disk);
 277         device->blk_data.disk->private_data = NULL;
 278         tape_put_device(device);
 279         put_disk(device->blk_data.disk);
 280
 281         device->blk_data.disk = NULL;
 282 cleanup_queue:
 283         device->blk_data.request_queue->queuedata = NULL;
 284         tape_put_device(device);
 285
 286         blk_cleanup_queue(device->blk_data.request_queue);
 287         device->blk_data.request_queue = NULL;
 288 }
 289
 290 /*
 291  * Detect number of blocks of the tape.
 292  * FIXME: can we extent this to detect the blocks size as well ?
 293  */
 294 static int
 295 tapeblock_revalidate_disk(struct gendisk *disk)
 296 {
 297         struct tape_device *    device;
 298         unsigned int            nr_of_blks;
 299         int                     rc;
 300
 301         device = (struct tape_device *) disk->private_data;
 302         BUG_ON(!device);
 303
 304         if (!device->blk_data.medium_changed)
 305                 return 0;
 306
 307         rc = tape_mtop(device, MTFSFM, 1);
 308         if (rc)
 309                 return rc;
 310
 311         rc = tape_mtop(device, MTTELL, 1);
 312         if (rc < 0)
 313                 return rc;
 314
 315         pr_info("%s: Determining the size of the recorded area...\n",
 316                 dev_name(&device->cdev->dev));
 317         DBF_LH(3, "Image file ends at %d\n", rc);
 318         nr_of_blks = rc;
 319
 320         /* This will fail for the first file. Catch the error by checking the
 321          * position. */
 322         tape_mtop(device, MTBSF, 1);
 323
 324         rc = tape_mtop(device, MTTELL, 1);
 325         if (rc < 0)
 326                 return rc;
 327
 328         if (rc > nr_of_blks)
 329                 return -EINVAL;
 330
 331         DBF_LH(3, "Image file starts at %d\n", rc);
 332         device->bof = rc;
 333         nr_of_blks -= rc;
 334
 335         pr_info("%s: The size of the recorded area is %i blocks\n",
 336                 dev_name(&device->cdev->dev), nr_of_blks);
 337         set_capacity(device->blk_data.disk,
 338                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 339
 340         device->blk_data.block_position = 0;
 341         device->blk_data.medium_changed = 0;
 342         return 0;
 343 }
 344
 345 static int
 346 tapeblock_medium_changed(struct gendisk *disk)
 347 {
 348         struct tape_device *device;
 349
 350         device = (struct tape_device *) disk->private_data;
 351         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 352                 device, device->blk_data.medium_changed);
 353
 354         return device->blk_data.medium_changed;
 355 }
 356
 357 /*
 358  * Block frontend tape device open function.
 359  */
 360 static int
 361 tapeblock_open(struct block_device *bdev, fmode_t mode)
 362 {
 363         struct gendisk *        disk = bdev->bd_disk;
 364         struct tape_device *    device;
 365         int                     rc;
 366
 367         device = tape_get_device(disk->private_data);
 368
 369         if (device->required_tapemarks) {
 370                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 371                 pr_warning("%s: Opening the tape failed because of missing "
 372                            "end-of-file marks\n", dev_name(&device->cdev->dev));
 373                 rc = -EPERM;
 374                 goto put_device;
 375         }
 376
 377         rc = tape_open(device);
 378         if (rc)
 379                 goto put_device;
 380
 381         rc = tapeblock_revalidate_disk(disk);
 382         if (rc)
 383                 goto release;
 384
 385         /*
 386          * Note: The reference to <device> is hold until the release function
 387          *       is called.
 388          */
 389         tape_state_set(device, TS_BLKUSE);
 390         return 0;
 391
 392 release:
 393         tape_release(device);
 394  put_device:
 395         tape_put_device(device);
 396         return rc;
 397 }
 398
 399 /*
 400  * Block frontend tape device release function.
 401  *
 402  * Note: One reference to the tape device was made by the open function. So
 403  *       we just get the pointer here and release the reference.
 404  */
 405 static int
 406 tapeblock_release(struct gendisk *disk, fmode_t mode)
 407 {
 408         struct tape_device *device = disk->private_data;
 409
 410         tape_state_set(device, TS_IN_USE);
 411         tape_release(device);
 412         tape_put_device(device);
 413
 414         return 0;
 415 }
 416
 417 /*
 418  * Support of some generic block device IOCTLs.
 419  */
 420 static int
 421 tapeblock_ioctl(
 422         struct block_device *   bdev,
 423         fmode_t                 mode,
 424         unsigned int            command,
 425         unsigned long           arg
 426 ) {
 427         int rc;
 428         int minor;
 429         struct gendisk *disk = bdev->bd_disk;
 430         struct tape_device *device;
 431
 432         rc     = 0;
 433         BUG_ON(!disk);
 434         device = disk->private_data;
 435         BUG_ON(!device);
 436         minor  = MINOR(bdev->bd_dev);
 437
 438         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
 439         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
 440
 441         switch (command) {
 442                 /* Refuse some IOCTL calls without complaining (mount). */
 443                 case 0x5310:            /* CDROMMULTISESSION */
 444                         rc = -EINVAL;
 445                         break;
 446                 default:
 447                         rc = -EINVAL;
 448         }
 449
 450         return rc;
 451 }
 452
 453 /*
 454  * Initialize block device frontend.
 455  */
 456 int
 457 tapeblock_init(void)
 458 {
 459         int rc;
 460
 461         /* Register the tape major number to the kernel */
 462         rc = register_blkdev(tapeblock_major, "tBLK");
 463         if (rc < 0)
 464                 return rc;
 465
 466         if (tapeblock_major == 0)
 467                 tapeblock_major = rc;
 468         return 0;
 469 }
 470
 471 /*
 472  * Deregister major for block device frontend
 473  */
 474 void
 475 tapeblock_exit(void)
 476 {
 477         unregister_blkdev(tapeblock_major, "tBLK");
 478 }