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 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                 (req = blk_fetch_request(queue)) &&
 166                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 167         ) {
 168                 if (rq_data_dir(req) == WRITE) {
 169                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 170                         spin_unlock_irq(&device->blk_data.request_queue_lock);
 171                         blk_end_request_all(req, -EIO);
 172                         spin_lock_irq(&device->blk_data.request_queue_lock);
 173                         continue;
 174                 }
 175                 nr_queued++;
 176                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 177                 rc = tapeblock_start_request(device, req);
 178                 spin_lock_irq(&device->blk_data.request_queue_lock);
 179         }
 180         spin_unlock_irq(&device->blk_data.request_queue_lock);
 181         atomic_set(&device->blk_data.requeue_scheduled, 0);
 182 }
 183
 184 /*
 185  * Tape request queue function. Called from ll_rw_blk.c
 186  */
 187 static void
 188 tapeblock_request_fn(struct request_queue *queue)
 189 {
 190         struct tape_device *device;
 191
 192         device = (struct tape_device *) queue->queuedata;
 193         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 194         BUG_ON(device == NULL);
 195         tapeblock_trigger_requeue(device);
 196 }
 197
 198 /*
 199  * This function is called for every new tapedevice
 200  */
 201 int
 202 tapeblock_setup_device(struct tape_device * device)
 203 {
 204         struct tape_blk_data *  blkdat;
 205         struct gendisk *        disk;
 206         int                     rc;
 207
 208         blkdat = &device->blk_data;
 209         blkdat->device = device;
 210         spin_lock_init(&blkdat->request_queue_lock);
 211         atomic_set(&blkdat->requeue_scheduled, 0);
 212
 213         blkdat->request_queue = blk_init_queue(
 214                 tapeblock_request_fn,
 215                 &blkdat->request_queue_lock
 216         );
 217         if (!blkdat->request_queue)
 218                 return -ENOMEM;
 219
 220         elevator_exit(blkdat->request_queue->elevator);
 221         rc = elevator_init(blkdat->request_queue, "noop");
 222         if (rc)
 223                 goto cleanup_queue;
 224
 225         blk_queue_logical_block_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 226         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 227         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
 228         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
 229         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 230         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 231
 232         disk = alloc_disk(1);
 233         if (!disk) {
 234                 rc = -ENOMEM;
 235                 goto cleanup_queue;
 236         }
 237
 238         disk->major = tapeblock_major;
 239         disk->first_minor = device->first_minor;
 240         disk->fops = &tapeblock_fops;
 241         disk->private_data = tape_get_device_reference(device);
 242         disk->queue = blkdat->request_queue;
 243         set_capacity(disk, 0);
 244         sprintf(disk->disk_name, "btibm%d",
 245                 device->first_minor / TAPE_MINORS_PER_DEV);
 246
 247         blkdat->disk = disk;
 248         blkdat->medium_changed = 1;
 249         blkdat->request_queue->queuedata = tape_get_device_reference(device);
 250
 251         add_disk(disk);
 252
 253         tape_get_device_reference(device);
 254         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 255
 256         return 0;
 257
 258 cleanup_queue:
 259         blk_cleanup_queue(blkdat->request_queue);
 260         blkdat->request_queue = NULL;
 261
 262         return rc;
 263 }
 264
 265 void
 266 tapeblock_cleanup_device(struct tape_device *device)
 267 {
 268         flush_scheduled_work();
 269         tape_put_device(device);
 270
 271         if (!device->blk_data.disk) {
 272                 goto cleanup_queue;
 273         }
 274
 275         del_gendisk(device->blk_data.disk);
 276         device->blk_data.disk->private_data =
 277                 tape_put_device(device->blk_data.disk->private_data);
 278         put_disk(device->blk_data.disk);
 279
 280         device->blk_data.disk = NULL;
 281 cleanup_queue:
 282         device->blk_data.request_queue->queuedata = tape_put_device(device);
 283
 284         blk_cleanup_queue(device->blk_data.request_queue);
 285         device->blk_data.request_queue = NULL;
 286 }
 287
 288 /*
 289  * Detect number of blocks of the tape.
 290  * FIXME: can we extent this to detect the blocks size as well ?
 291  */
 292 static int
 293 tapeblock_revalidate_disk(struct gendisk *disk)
 294 {
 295         struct tape_device *    device;
 296         unsigned int            nr_of_blks;
 297         int                     rc;
 298
 299         device = (struct tape_device *) disk->private_data;
 300         BUG_ON(!device);
 301
 302         if (!device->blk_data.medium_changed)
 303                 return 0;
 304
 305         rc = tape_mtop(device, MTFSFM, 1);
 306         if (rc)
 307                 return rc;
 308
 309         rc = tape_mtop(device, MTTELL, 1);
 310         if (rc < 0)
 311                 return rc;
 312
 313         pr_info("%s: Determining the size of the recorded area...\n",
 314                 dev_name(&device->cdev->dev));
 315         DBF_LH(3, "Image file ends at %d\n", rc);
 316         nr_of_blks = rc;
 317
 318         /* This will fail for the first file. Catch the error by checking the
 319          * position. */
 320         tape_mtop(device, MTBSF, 1);
 321
 322         rc = tape_mtop(device, MTTELL, 1);
 323         if (rc < 0)
 324                 return rc;
 325
 326         if (rc > nr_of_blks)
 327                 return -EINVAL;
 328
 329         DBF_LH(3, "Image file starts at %d\n", rc);
 330         device->bof = rc;
 331         nr_of_blks -= rc;
 332
 333         pr_info("%s: The size of the recorded area is %i blocks\n",
 334                 dev_name(&device->cdev->dev), nr_of_blks);
 335         set_capacity(device->blk_data.disk,
 336                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 337
 338         device->blk_data.block_position = 0;
 339         device->blk_data.medium_changed = 0;
 340         return 0;
 341 }
 342
 343 static int
 344 tapeblock_medium_changed(struct gendisk *disk)
 345 {
 346         struct tape_device *device;
 347
 348         device = (struct tape_device *) disk->private_data;
 349         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 350                 device, device->blk_data.medium_changed);
 351
 352         return device->blk_data.medium_changed;
 353 }
 354
 355 /*
 356  * Block frontend tape device open function.
 357  */
 358 static int
 359 tapeblock_open(struct block_device *bdev, fmode_t mode)
 360 {
 361         struct gendisk *        disk = bdev->bd_disk;
 362         struct tape_device *    device;
 363         int                     rc;
 364
 365         device = tape_get_device_reference(disk->private_data);
 366
 367         if (device->required_tapemarks) {
 368                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 369                 pr_warning("%s: Opening the tape failed because of missing "
 370                            "end-of-file marks\n", dev_name(&device->cdev->dev));
 371                 rc = -EPERM;
 372                 goto put_device;
 373         }
 374
 375         rc = tape_open(device);
 376         if (rc)
 377                 goto put_device;
 378
 379         rc = tapeblock_revalidate_disk(disk);
 380         if (rc)
 381                 goto release;
 382
 383         /*
 384          * Note: The reference to <device> is hold until the release function
 385          *       is called.
 386          */
 387         tape_state_set(device, TS_BLKUSE);
 388         return 0;
 389
 390 release:
 391         tape_release(device);
 392  put_device:
 393         tape_put_device(device);
 394         return rc;
 395 }
 396
 397 /*
 398  * Block frontend tape device release function.
 399  *
 400  * Note: One reference to the tape device was made by the open function. So
 401  *       we just get the pointer here and release the reference.
 402  */
 403 static int
 404 tapeblock_release(struct gendisk *disk, fmode_t mode)
 405 {
 406         struct tape_device *device = disk->private_data;
 407
 408         tape_state_set(device, TS_IN_USE);
 409         tape_release(device);
 410         tape_put_device(device);
 411
 412         return 0;
 413 }
 414
 415 /*
 416  * Support of some generic block device IOCTLs.
 417  */
 418 static int
 419 tapeblock_ioctl(
 420         struct block_device *   bdev,
 421         fmode_t                 mode,
 422         unsigned int            command,
 423         unsigned long           arg
 424 ) {
 425         int rc;
 426         int minor;
 427         struct gendisk *disk = bdev->bd_disk;
 428         struct tape_device *device;
 429
 430         rc     = 0;
 431         BUG_ON(!disk);
 432         device = disk->private_data;
 433         BUG_ON(!device);
 434         minor  = MINOR(bdev->bd_dev);
 435
 436         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
 437         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
 438
 439         switch (command) {
 440                 /* Refuse some IOCTL calls without complaining (mount). */
 441                 case 0x5310:            /* CDROMMULTISESSION */
 442                         rc = -EINVAL;
 443                         break;
 444                 default:
 445                         rc = -EINVAL;
 446         }
 447
 448         return rc;
 449 }
 450
 451 /*
 452  * Initialize block device frontend.
 453  */
 454 int
 455 tapeblock_init(void)
 456 {
 457         int rc;
 458
 459         /* Register the tape major number to the kernel */
 460         rc = register_blkdev(tapeblock_major, "tBLK");
 461         if (rc < 0)
 462                 return rc;
 463
 464         if (tapeblock_major == 0)
 465                 tapeblock_major = rc;
 466         return 0;
 467 }
 468
 469 /*
 470  * Deregister major for block device frontend
 471  */
 472 void
 473 tapeblock_exit(void)
 474 {
 475         unregister_blkdev(tapeblock_major, "tBLK");
 476 }