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 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  15
  16 #include <linux/fs.h>
  17 #include <linux/module.h>
  18 #include <linux/blkdev.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/buffer_head.h>
  21 #include <linux/kernel.h>
  22
  23 #include <asm/debug.h>
  24
  25 #define TAPE_DBF_AREA   tape_core_dbf
  26
  27 #include "tape.h"
  28
  29 #define TAPEBLOCK_MAX_SEC       100
  30 #define TAPEBLOCK_MIN_REQUEUE   3
  31
  32 /*
  33  * 2003/11/25  Stefan Bader <shbader@de.ibm.com>
  34  *
  35  * In 2.5/2.6 the block device request function is very likely to be called
  36  * with disabled interrupts (e.g. generic_unplug_device). So the driver can't
  37  * just call any function that tries to allocate CCW requests from that con-
  38  * text since it might sleep. There are two choices to work around this:
  39  *      a) do not allocate with kmalloc but use its own memory pool
  40  *      b) take requests from the queue outside that context, knowing that
  41  *         allocation might sleep
  42  */
  43
  44 /*
  45  * file operation structure for tape block frontend
  46  */
  47 static int tapeblock_open(struct block_device *, fmode_t);
  48 static int tapeblock_release(struct gendisk *, fmode_t);
  49 static int tapeblock_ioctl(struct block_device *, fmode_t, unsigned int,
  50                                 unsigned long);
  51 static int tapeblock_medium_changed(struct gendisk *);
  52 static int tapeblock_revalidate_disk(struct gendisk *);
  53
  54 static const struct block_device_operations tapeblock_fops = {
  55         .owner           = THIS_MODULE,
  56         .open            = tapeblock_open,
  57         .release         = tapeblock_release,
  58         .ioctl           = tapeblock_ioctl,
  59         .media_changed   = tapeblock_medium_changed,
  60         .revalidate_disk = tapeblock_revalidate_disk,
  61 };
  62
  63 static int tapeblock_major = 0;
  64
  65 static void
  66 tapeblock_trigger_requeue(struct tape_device *device)
  67 {
  68         /* Protect against rescheduling. */
  69         if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
  70                 return;
  71         schedule_work(&device->blk_data.requeue_task);
  72 }
  73
  74 /*
  75  * Post finished request.
  76  */
  77 static void
  78 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
  79 {
  80         struct tape_device *device;
  81         struct request *req;
  82
  83         DBF_LH(6, "__tapeblock_end_request()\n");
  84
  85         device = ccw_req->device;
  86         req = (struct request *) data;
  87         blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
  88         if (ccw_req->rc == 0)
  89                 /* Update position. */
  90                 device->blk_data.block_position =
  91                   (blk_rq_pos(req) + blk_rq_sectors(req)) >> TAPEBLOCK_HSEC_S2B;
  92         else
  93                 /* We lost the position information due to an error. */
  94                 device->blk_data.block_position = -1;
  95         device->discipline->free_bread(ccw_req);
  96         if (!list_empty(&device->req_queue) ||
  97             blk_peek_request(device->blk_data.request_queue))
  98                 tapeblock_trigger_requeue(device);
  99 }
 100
 101 /*
 102  * Feed the tape device CCW queue with requests supplied in a list.
 103  */
 104 static int
 105 tapeblock_start_request(struct tape_device *device, struct request *req)
 106 {
 107         struct tape_request *   ccw_req;
 108         int                     rc;
 109
 110         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
 111
 112         ccw_req = device->discipline->bread(device, req);
 113         if (IS_ERR(ccw_req)) {
 114                 DBF_EVENT(1, "TBLOCK: bread failed\n");
 115                 blk_end_request_all(req, -EIO);
 116                 return PTR_ERR(ccw_req);
 117         }
 118         ccw_req->callback = __tapeblock_end_request;
 119         ccw_req->callback_data = (void *) req;
 120         ccw_req->retries = TAPEBLOCK_RETRIES;
 121
 122         rc = tape_do_io_async(device, ccw_req);
 123         if (rc) {
 124                 /*
 125                  * Start/enqueueing failed. No retries in
 126                  * this case.
 127                  */
 128                 blk_end_request_all(req, -EIO);
 129                 device->discipline->free_bread(ccw_req);
 130         }
 131
 132         return rc;
 133 }
 134
 135 /*
 136  * Move requests from the block device request queue to the tape device ccw
 137  * queue.
 138  */
 139 static void
 140 tapeblock_requeue(struct work_struct *work) {
 141         struct tape_blk_data *  blkdat;
 142         struct tape_device *    device;
 143         struct request_queue *  queue;
 144         int                     nr_queued;
 145         struct request *        req;
 146         struct list_head *      l;
 147         int                     rc;
 148
 149         blkdat = container_of(work, struct tape_blk_data, requeue_task);
 150         device = blkdat->device;
 151         if (!device)
 152                 return;
 153
 154         spin_lock_irq(get_ccwdev_lock(device->cdev));
 155         queue  = device->blk_data.request_queue;
 156
 157         /* Count number of requests on ccw queue. */
 158         nr_queued = 0;
 159         list_for_each(l, &device->req_queue)
 160                 nr_queued++;
 161         spin_unlock(get_ccwdev_lock(device->cdev));
 162
 163         spin_lock_irq(&device->blk_data.request_queue_lock);
 164         while (
 165                 !blk_queue_plugged(queue) &&
 166                 blk_peek_request(queue) &&
 167                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 168         ) {
 169                 req = blk_fetch_request(queue);
 170                 if (rq_data_dir(req) == WRITE) {
 171                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 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                 nr_queued++;
 178                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 179                 rc = tapeblock_start_request(device, req);
 180                 spin_lock_irq(&device->blk_data.request_queue_lock);
 181         }
 182         spin_unlock_irq(&device->blk_data.request_queue_lock);
 183         atomic_set(&device->blk_data.requeue_scheduled, 0);
 184 }
 185
 186 /*
 187  * Tape request queue function. Called from ll_rw_blk.c
 188  */
 189 static void
 190 tapeblock_request_fn(struct request_queue *queue)
 191 {
 192         struct tape_device *device;
 193
 194         device = (struct tape_device *) queue->queuedata;
 195         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 196         BUG_ON(device == NULL);
 197         tapeblock_trigger_requeue(device);
 198 }
 199
 200 /*
 201  * This function is called for every new tapedevice
 202  */
 203 int
 204 tapeblock_setup_device(struct tape_device * device)
 205 {
 206         struct tape_blk_data *  blkdat;
 207         struct gendisk *        disk;
 208         int                     rc;
 209
 210         blkdat = &device->blk_data;
 211         blkdat->device = device;
 212         spin_lock_init(&blkdat->request_queue_lock);
 213         atomic_set(&blkdat->requeue_scheduled, 0);
 214
 215         blkdat->request_queue = blk_init_queue(
 216                 tapeblock_request_fn,
 217                 &blkdat->request_queue_lock
 218         );
 219         if (!blkdat->request_queue)
 220                 return -ENOMEM;
 221
 222         elevator_exit(blkdat->request_queue->elevator);
 223         rc = elevator_init(blkdat->request_queue, "noop");
 224         if (rc)
 225                 goto cleanup_queue;
 226
 227         blk_queue_logical_block_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 228         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 229         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
 230         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
 231         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 232         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 233
 234         disk = alloc_disk(1);
 235         if (!disk) {
 236                 rc = -ENOMEM;
 237                 goto cleanup_queue;
 238         }
 239
 240         disk->major = tapeblock_major;
 241         disk->first_minor = device->first_minor;
 242         disk->fops = &tapeblock_fops;
 243         disk->private_data = tape_get_device(device);
 244         disk->queue = blkdat->request_queue;
 245         set_capacity(disk, 0);
 246         sprintf(disk->disk_name, "btibm%d",
 247                 device->first_minor / TAPE_MINORS_PER_DEV);
 248
 249         blkdat->disk = disk;
 250         blkdat->medium_changed = 1;
 251         blkdat->request_queue->queuedata = tape_get_device(device);
 252
 253         add_disk(disk);
 254
 255         tape_get_device(device);
 256         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 257
 258         return 0;
 259
 260 cleanup_queue:
 261         blk_cleanup_queue(blkdat->request_queue);
 262         blkdat->request_queue = NULL;
 263
 264         return rc;
 265 }
 266
 267 void
 268 tapeblock_cleanup_device(struct tape_device *device)
 269 {
 270         flush_scheduled_work();
 271         tape_put_device(device);
 272
 273         if (!device->blk_data.disk) {
 274                 goto cleanup_queue;
 275         }
 276
 277         del_gendisk(device->blk_data.disk);
 278         device->blk_data.disk->private_data = NULL;
 279         tape_put_device(device);
 280         put_disk(device->blk_data.disk);
 281
 282         device->blk_data.disk = NULL;
 283 cleanup_queue:
 284         device->blk_data.request_queue->queuedata = NULL;
 285         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         rc = tape_mtop(device, MTFSFM, 1);
 309         if (rc)
 310                 return rc;
 311
 312         rc = tape_mtop(device, MTTELL, 1);
 313         if (rc < 0)
 314                 return rc;
 315
 316         pr_info("%s: Determining the size of the recorded area...\n",
 317                 dev_name(&device->cdev->dev));
 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         pr_info("%s: The size of the recorded area is %i blocks\n",
 337                 dev_name(&device->cdev->dev), 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(disk->private_data);
 369
 370         if (device->required_tapemarks) {
 371                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 372                 pr_warning("%s: Opening the tape failed because of missing "
 373                            "end-of-file marks\n", dev_name(&device->cdev->dev));
 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 }