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             elv_next_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                 elv_next_request(queue)   &&
 166                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 167         ) {
 168                 req = elv_next_request(queue);
 169                 if (rq_data_dir(req) == WRITE) {
 170                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 171                         blkdev_dequeue_request(req);
 172                         spin_unlock_irq(&device->blk_data.request_queue_lock);
 173                         blk_end_request_all(req, -EIO);
 174                         spin_lock_irq(&device->blk_data.request_queue_lock);
 175                         continue;
 176                 }
 177                 blkdev_dequeue_request(req);
 178                 nr_queued++;
 179                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 180                 rc = tapeblock_start_request(device, req);
 181                 spin_lock_irq(&device->blk_data.request_queue_lock);
 182         }
 183         spin_unlock_irq(&device->blk_data.request_queue_lock);
 184         atomic_set(&device->blk_data.requeue_scheduled, 0);
 185 }
 186
 187 /*
 188  * Tape request queue function. Called from ll_rw_blk.c
 189  */
 190 static void
 191 tapeblock_request_fn(struct request_queue *queue)
 192 {
 193         struct tape_device *device;
 194
 195         device = (struct tape_device *) queue->queuedata;
 196         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 197         BUG_ON(device == NULL);
 198         tapeblock_trigger_requeue(device);
 199 }
 200
 201 /*
 202  * This function is called for every new tapedevice
 203  */
 204 int
 205 tapeblock_setup_device(struct tape_device * device)
 206 {
 207         struct tape_blk_data *  blkdat;
 208         struct gendisk *        disk;
 209         int                     rc;
 210
 211         blkdat = &device->blk_data;
 212         blkdat->device = device;
 213         spin_lock_init(&blkdat->request_queue_lock);
 214         atomic_set(&blkdat->requeue_scheduled, 0);
 215
 216         blkdat->request_queue = blk_init_queue(
 217                 tapeblock_request_fn,
 218                 &blkdat->request_queue_lock
 219         );
 220         if (!blkdat->request_queue)
 221                 return -ENOMEM;
 222
 223         elevator_exit(blkdat->request_queue->elevator);
 224         rc = elevator_init(blkdat->request_queue, "noop");
 225         if (rc)
 226                 goto cleanup_queue;
 227
 228         blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 229         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 230         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
 231         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
 232         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 233         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 234
 235         disk = alloc_disk(1);
 236         if (!disk) {
 237                 rc = -ENOMEM;
 238                 goto cleanup_queue;
 239         }
 240
 241         disk->major = tapeblock_major;
 242         disk->first_minor = device->first_minor;
 243         disk->fops = &tapeblock_fops;
 244         disk->private_data = tape_get_device_reference(device);
 245         disk->queue = blkdat->request_queue;
 246         set_capacity(disk, 0);
 247         sprintf(disk->disk_name, "btibm%d",
 248                 device->first_minor / TAPE_MINORS_PER_DEV);
 249
 250         blkdat->disk = disk;
 251         blkdat->medium_changed = 1;
 252         blkdat->request_queue->queuedata = tape_get_device_reference(device);
 253
 254         add_disk(disk);
 255
 256         tape_get_device_reference(device);
 257         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 258
 259         return 0;
 260
 261 cleanup_queue:
 262         blk_cleanup_queue(blkdat->request_queue);
 263         blkdat->request_queue = NULL;
 264
 265         return rc;
 266 }
 267
 268 void
 269 tapeblock_cleanup_device(struct tape_device *device)
 270 {
 271         flush_scheduled_work();
 272         tape_put_device(device);
 273
 274         if (!device->blk_data.disk) {
 275                 goto cleanup_queue;
 276         }
 277
 278         del_gendisk(device->blk_data.disk);
 279         device->blk_data.disk->private_data =
 280                 tape_put_device(device->blk_data.disk->private_data);
 281         put_disk(device->blk_data.disk);
 282
 283         device->blk_data.disk = NULL;
 284 cleanup_queue:
 285         device->blk_data.request_queue->queuedata = tape_put_device(device);
 286
 287         blk_cleanup_queue(device->blk_data.request_queue);
 288         device->blk_data.request_queue = NULL;
 289 }
 290
 291 /*
 292  * Detect number of blocks of the tape.
 293  * FIXME: can we extent this to detect the blocks size as well ?
 294  */
 295 static int
 296 tapeblock_revalidate_disk(struct gendisk *disk)
 297 {
 298         struct tape_device *    device;
 299         unsigned int            nr_of_blks;
 300         int                     rc;
 301
 302         device = (struct tape_device *) disk->private_data;
 303         BUG_ON(!device);
 304
 305         if (!device->blk_data.medium_changed)
 306                 return 0;
 307
 308         dev_info(&device->cdev->dev, "Determining the size of the recorded "
 309                 "area...\n");
 310         rc = tape_mtop(device, MTFSFM, 1);
 311         if (rc)
 312                 return rc;
 313
 314         rc = tape_mtop(device, MTTELL, 1);
 315         if (rc < 0)
 316                 return rc;
 317
 318         DBF_LH(3, "Image file ends at %d\n", rc);
 319         nr_of_blks = rc;
 320
 321         /* This will fail for the first file. Catch the error by checking the
 322          * position. */
 323         tape_mtop(device, MTBSF, 1);
 324
 325         rc = tape_mtop(device, MTTELL, 1);
 326         if (rc < 0)
 327                 return rc;
 328
 329         if (rc > nr_of_blks)
 330                 return -EINVAL;
 331
 332         DBF_LH(3, "Image file starts at %d\n", rc);
 333         device->bof = rc;
 334         nr_of_blks -= rc;
 335
 336         dev_info(&device->cdev->dev, "The size of the recorded area is %i "
 337                 "blocks\n", nr_of_blks);
 338         set_capacity(device->blk_data.disk,
 339                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 340
 341         device->blk_data.block_position = 0;
 342         device->blk_data.medium_changed = 0;
 343         return 0;
 344 }
 345
 346 static int
 347 tapeblock_medium_changed(struct gendisk *disk)
 348 {
 349         struct tape_device *device;
 350
 351         device = (struct tape_device *) disk->private_data;
 352         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 353                 device, device->blk_data.medium_changed);
 354
 355         return device->blk_data.medium_changed;
 356 }
 357
 358 /*
 359  * Block frontend tape device open function.
 360  */
 361 static int
 362 tapeblock_open(struct block_device *bdev, fmode_t mode)
 363 {
 364         struct gendisk *        disk = bdev->bd_disk;
 365         struct tape_device *    device;
 366         int                     rc;
 367
 368         device = tape_get_device_reference(disk->private_data);
 369
 370         if (device->required_tapemarks) {
 371                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 372                 dev_warn(&device->cdev->dev, "Opening the tape failed because"
 373                         " of missing end-of-file marks\n");
 374                 rc = -EPERM;
 375                 goto put_device;
 376         }
 377
 378         rc = tape_open(device);
 379         if (rc)
 380                 goto put_device;
 381
 382         rc = tapeblock_revalidate_disk(disk);
 383         if (rc)
 384                 goto release;
 385
 386         /*
 387          * Note: The reference to <device> is hold until the release function
 388          *       is called.
 389          */
 390         tape_state_set(device, TS_BLKUSE);
 391         return 0;
 392
 393 release:
 394         tape_release(device);
 395  put_device:
 396         tape_put_device(device);
 397         return rc;
 398 }
 399
 400 /*
 401  * Block frontend tape device release function.
 402  *
 403  * Note: One reference to the tape device was made by the open function. So
 404  *       we just get the pointer here and release the reference.
 405  */
 406 static int
 407 tapeblock_release(struct gendisk *disk, fmode_t mode)
 408 {
 409         struct tape_device *device = disk->private_data;
 410
 411         tape_state_set(device, TS_IN_USE);
 412         tape_release(device);
 413         tape_put_device(device);
 414
 415         return 0;
 416 }
 417
 418 /*
 419  * Support of some generic block device IOCTLs.
 420  */
 421 static int
 422 tapeblock_ioctl(
 423         struct block_device *   bdev,
 424         fmode_t                 mode,
 425         unsigned int            command,
 426         unsigned long           arg
 427 ) {
 428         int rc;
 429         int minor;
 430         struct gendisk *disk = bdev->bd_disk;
 431         struct tape_device *device;
 432
 433         rc     = 0;
 434         BUG_ON(!disk);
 435         device = disk->private_data;
 436         BUG_ON(!device);
 437         minor  = MINOR(bdev->bd_dev);
 438
 439         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
 440         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
 441
 442         switch (command) {
 443                 /* Refuse some IOCTL calls without complaining (mount). */
 444                 case 0x5310:            /* CDROMMULTISESSION */
 445                         rc = -EINVAL;
 446                         break;
 447                 default:
 448                         rc = -EINVAL;
 449         }
 450
 451         return rc;
 452 }
 453
 454 /*
 455  * Initialize block device frontend.
 456  */
 457 int
 458 tapeblock_init(void)
 459 {
 460         int rc;
 461
 462         /* Register the tape major number to the kernel */
 463         rc = register_blkdev(tapeblock_major, "tBLK");
 464         if (rc < 0)
 465                 return rc;
 466
 467         if (tapeblock_major == 0)
 468                 tapeblock_major = rc;
 469         return 0;
 470 }
 471
 472 /*
 473  * Deregister major for block device frontend
 474  */
 475 void
 476 tapeblock_exit(void)
 477 {
 478         unregister_blkdev(tapeblock_major, "tBLK");
 479 }