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 #include <linux/fs.h>
  14 #include <linux/config.h>
  15 #include <linux/module.h>
  16 #include <linux/blkdev.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/buffer_head.h>
  19
  20 #include <asm/debug.h>
  21
  22 #include "tape.h"
  23
  24 #define PRINTK_HEADER "TAPE_BLOCK: "
  25
  26 #define TAPEBLOCK_MAX_SEC       100
  27 #define TAPEBLOCK_MIN_REQUEUE   3
  28
  29 /*
  30  * 2003/11/25  Stefan Bader <shbader@de.ibm.com>
  31  *
  32  * In 2.5/2.6 the block device request function is very likely to be called
  33  * with disabled interrupts (e.g. generic_unplug_device). So the driver can't
  34  * just call any function that tries to allocate CCW requests from that con-
  35  * text since it might sleep. There are two choices to work around this:
  36  *      a) do not allocate with kmalloc but use its own memory pool
  37  *      b) take requests from the queue outside that context, knowing that
  38  *         allocation might sleep
  39  */
  40
  41 /*
  42  * file operation structure for tape block frontend
  43  */
  44 static int tapeblock_open(struct inode *, struct file *);
  45 static int tapeblock_release(struct inode *, struct file *);
  46 static int tapeblock_ioctl(struct inode *, struct file *, unsigned int,
  47                                 unsigned long);
  48 static int tapeblock_medium_changed(struct gendisk *);
  49 static int tapeblock_revalidate_disk(struct gendisk *);
  50
  51 static struct block_device_operations tapeblock_fops = {
  52         .owner           = THIS_MODULE,
  53         .open            = tapeblock_open,
  54         .release         = tapeblock_release,
  55         .ioctl           = tapeblock_ioctl,
  56         .media_changed   = tapeblock_medium_changed,
  57         .revalidate_disk = tapeblock_revalidate_disk,
  58 };
  59
  60 static int tapeblock_major = 0;
  61
  62 static void
  63 tapeblock_trigger_requeue(struct tape_device *device)
  64 {
  65         /* Protect against rescheduling. */
  66         if (atomic_compare_and_swap(0, 1, &device->blk_data.requeue_scheduled))
  67                 return;
  68         schedule_work(&device->blk_data.requeue_task);
  69 }
  70
  71 /*
  72  * Post finished request.
  73  */
  74 static inline void
  75 tapeblock_end_request(struct request *req, int uptodate)
  76 {
  77         if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
  78                 BUG();
  79         end_that_request_last(req);
  80 }
  81
  82 static void
  83 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
  84 {
  85         struct tape_device *device;
  86         struct request *req;
  87
  88         DBF_LH(6, "__tapeblock_end_request()\n");
  89
  90         device = ccw_req->device;
  91         req = (struct request *) data;
  92         tapeblock_end_request(req, ccw_req->rc == 0);
  93         if (ccw_req->rc == 0)
  94                 /* Update position. */
  95                 device->blk_data.block_position =
  96                         (req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
  97         else
  98                 /* We lost the position information due to an error. */
  99                 device->blk_data.block_position = -1;
 100         device->discipline->free_bread(ccw_req);
 101         if (!list_empty(&device->req_queue) ||
 102             elv_next_request(device->blk_data.request_queue))
 103                 tapeblock_trigger_requeue(device);
 104 }
 105
 106 /*
 107  * Feed the tape device CCW queue with requests supplied in a list.
 108  */
 109 static inline int
 110 tapeblock_start_request(struct tape_device *device, struct request *req)
 111 {
 112         struct tape_request *   ccw_req;
 113         int                     rc;
 114
 115         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
 116
 117         ccw_req = device->discipline->bread(device, req);
 118         if (IS_ERR(ccw_req)) {
 119                 DBF_EVENT(1, "TBLOCK: bread failed\n");
 120                 tapeblock_end_request(req, 0);
 121                 return PTR_ERR(ccw_req);
 122         }
 123         ccw_req->callback = __tapeblock_end_request;
 124         ccw_req->callback_data = (void *) req;
 125         ccw_req->retries = TAPEBLOCK_RETRIES;
 126
 127         rc = tape_do_io_async(device, ccw_req);
 128         if (rc) {
 129                 /*
 130                  * Start/enqueueing failed. No retries in
 131                  * this case.
 132                  */
 133                 tapeblock_end_request(req, 0);
 134                 device->discipline->free_bread(ccw_req);
 135         }
 136
 137         return rc;
 138 }
 139
 140 /*
 141  * Move requests from the block device request queue to the tape device ccw
 142  * queue.
 143  */
 144 static void
 145 tapeblock_requeue(void *data) {
 146         struct tape_device *    device;
 147         request_queue_t *       queue;
 148         int                     nr_queued;
 149         struct request *        req;
 150         struct list_head *      l;
 151         int                     rc;
 152
 153         device = (struct tape_device *) data;
 154         if (!device)
 155                 return;
 156
 157         spin_lock_irq(get_ccwdev_lock(device->cdev));
 158         queue  = device->blk_data.request_queue;
 159
 160         /* Count number of requests on ccw queue. */
 161         nr_queued = 0;
 162         list_for_each(l, &device->req_queue)
 163                 nr_queued++;
 164         spin_unlock(get_ccwdev_lock(device->cdev));
 165
 166         spin_lock(&device->blk_data.request_queue_lock);
 167         while (
 168                 !blk_queue_plugged(queue) &&
 169                 elv_next_request(queue)   &&
 170                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 171         ) {
 172                 req = elv_next_request(queue);
 173                 if (rq_data_dir(req) == WRITE) {
 174                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 175                         blkdev_dequeue_request(req);
 176                         tapeblock_end_request(req, 0);
 177                         continue;
 178                 }
 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                 blkdev_dequeue_request(req);
 183                 nr_queued++;
 184         }
 185         spin_unlock_irq(&device->blk_data.request_queue_lock);
 186         atomic_set(&device->blk_data.requeue_scheduled, 0);
 187 }
 188
 189 /*
 190  * Tape request queue function. Called from ll_rw_blk.c
 191  */
 192 static void
 193 tapeblock_request_fn(request_queue_t *queue)
 194 {
 195         struct tape_device *device;
 196
 197         device = (struct tape_device *) queue->queuedata;
 198         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 199         if (device == NULL)
 200                 BUG();
 201
 202         tapeblock_trigger_requeue(device);
 203 }
 204
 205 /*
 206  * This function is called for every new tapedevice
 207  */
 208 int
 209 tapeblock_setup_device(struct tape_device * device)
 210 {
 211         struct tape_blk_data *  blkdat;
 212         struct gendisk *        disk;
 213         int                     rc;
 214
 215         blkdat = &device->blk_data;
 216         spin_lock_init(&blkdat->request_queue_lock);
 217         atomic_set(&blkdat->requeue_scheduled, 0);
 218
 219         blkdat->request_queue = blk_init_queue(
 220                 tapeblock_request_fn,
 221                 &blkdat->request_queue_lock
 222         );
 223         if (!blkdat->request_queue)
 224                 return -ENOMEM;
 225
 226         elevator_exit(blkdat->request_queue);
 227         rc = elevator_init(blkdat->request_queue, &elevator_noop);
 228         if (rc)
 229                 goto cleanup_queue;
 230
 231         blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 232         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 233         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
 234         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
 235         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 236         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 237
 238         disk = alloc_disk(1);
 239         if (!disk) {
 240                 rc = -ENOMEM;
 241                 goto cleanup_queue;
 242         }
 243
 244         disk->major = tapeblock_major;
 245         disk->first_minor = device->first_minor;
 246         disk->fops = &tapeblock_fops;
 247         disk->private_data = tape_get_device_reference(device);
 248         disk->queue = blkdat->request_queue;
 249         set_capacity(disk, 0);
 250         sprintf(disk->disk_name, "btibm%d",
 251                 device->first_minor / TAPE_MINORS_PER_DEV);
 252
 253         blkdat->disk = disk;
 254         blkdat->medium_changed = 1;
 255         blkdat->request_queue->queuedata = tape_get_device_reference(device);
 256
 257         add_disk(disk);
 258
 259         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
 260                 tape_get_device_reference(device));
 261
 262         return 0;
 263
 264 cleanup_queue:
 265         blk_cleanup_queue(blkdat->request_queue);
 266         blkdat->request_queue = NULL;
 267
 268         return rc;
 269 }
 270
 271 void
 272 tapeblock_cleanup_device(struct tape_device *device)
 273 {
 274         flush_scheduled_work();
 275         device->blk_data.requeue_task.data = tape_put_device(device);
 276
 277         if (!device->blk_data.disk) {
 278                 PRINT_ERR("(%s): No gendisk to clean up!\n",
 279                         device->cdev->dev.bus_id);
 280                 goto cleanup_queue;
 281         }
 282
 283         del_gendisk(device->blk_data.disk);
 284         device->blk_data.disk->private_data =
 285                 tape_put_device(device->blk_data.disk->private_data);
 286         put_disk(device->blk_data.disk);
 287
 288         device->blk_data.disk = NULL;
 289 cleanup_queue:
 290         device->blk_data.request_queue->queuedata = tape_put_device(device);
 291
 292         blk_cleanup_queue(device->blk_data.request_queue);
 293         device->blk_data.request_queue = NULL;
 294 }
 295
 296 /*
 297  * Detect number of blocks of the tape.
 298  * FIXME: can we extent this to detect the blocks size as well ?
 299  */
 300 static int
 301 tapeblock_revalidate_disk(struct gendisk *disk)
 302 {
 303         struct tape_device *    device;
 304         unsigned int            nr_of_blks;
 305         int                     rc;
 306
 307         device = (struct tape_device *) disk->private_data;
 308         if (!device)
 309                 BUG();
 310
 311         if (!device->blk_data.medium_changed)
 312                 return 0;
 313
 314         PRINT_INFO("Detecting media size...\n");
 315         rc = tape_mtop(device, MTFSFM, 1);
 316         if (rc)
 317                 return rc;
 318
 319         rc = tape_mtop(device, MTTELL, 1);
 320         if (rc < 0)
 321                 return rc;
 322
 323         DBF_LH(3, "Image file ends at %d\n", rc);
 324         nr_of_blks = rc;
 325
 326         /* This will fail for the first file. Catch the error by checking the
 327          * position. */
 328         tape_mtop(device, MTBSF, 1);
 329
 330         rc = tape_mtop(device, MTTELL, 1);
 331         if (rc < 0)
 332                 return rc;
 333
 334         if (rc > nr_of_blks)
 335                 return -EINVAL;
 336
 337         DBF_LH(3, "Image file starts at %d\n", rc);
 338         device->bof = rc;
 339         nr_of_blks -= rc;
 340
 341         PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
 342         set_capacity(device->blk_data.disk,
 343                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 344
 345         device->blk_data.block_position = 0;
 346         device->blk_data.medium_changed = 0;
 347         return 0;
 348 }
 349
 350 static int
 351 tapeblock_medium_changed(struct gendisk *disk)
 352 {
 353         struct tape_device *device;
 354
 355         device = (struct tape_device *) disk->private_data;
 356         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 357                 device, device->blk_data.medium_changed);
 358
 359         return device->blk_data.medium_changed;
 360 }
 361
 362 /*
 363  * Block frontend tape device open function.
 364  */
 365 static int
 366 tapeblock_open(struct inode *inode, struct file *filp)
 367 {
 368         struct gendisk *        disk;
 369         struct tape_device *    device;
 370         int                     rc;
 371
 372         disk   = inode->i_bdev->bd_disk;
 373         device = tape_get_device_reference(disk->private_data);
 374
 375         if (device->required_tapemarks) {
 376                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 377                 PRINT_ERR("TBLOCK: Refusing to open tape with missing"
 378                         " end of file marks.\n");
 379                 rc = -EPERM;
 380                 goto put_device;
 381         }
 382
 383         rc = tape_open(device);
 384         if (rc)
 385                 goto put_device;
 386
 387         rc = tapeblock_revalidate_disk(disk);
 388         if (rc)
 389                 goto release;
 390
 391         /*
 392          * Note: The reference to <device> is hold until the release function
 393          *       is called.
 394          */
 395         tape_state_set(device, TS_BLKUSE);
 396         return 0;
 397
 398 release:
 399         tape_release(device);
 400  put_device:
 401         tape_put_device(device);
 402         return rc;
 403 }
 404
 405 /*
 406  * Block frontend tape device release function.
 407  *
 408  * Note: One reference to the tape device was made by the open function. So
 409  *       we just get the pointer here and release the reference.
 410  */
 411 static int
 412 tapeblock_release(struct inode *inode, struct file *filp)
 413 {
 414         struct gendisk *disk = inode->i_bdev->bd_disk;
 415         struct tape_device *device = disk->private_data;
 416
 417         tape_state_set(device, TS_IN_USE);
 418         tape_release(device);
 419         tape_put_device(device);
 420
 421         return 0;
 422 }
 423
 424 /*
 425  * Support of some generic block device IOCTLs.
 426  */
 427 static int
 428 tapeblock_ioctl(
 429         struct inode *          inode,
 430         struct file *           file,
 431         unsigned int            command,
 432         unsigned long           arg
 433 ) {
 434         int rc;
 435         int minor;
 436         struct gendisk *disk = inode->i_bdev->bd_disk;
 437         struct tape_device *device = disk->private_data;
 438
 439         rc     = 0;
 440         disk   = inode->i_bdev->bd_disk;
 441         if (!disk)
 442                 BUG();
 443         device = disk->private_data;
 444         if (!device)
 445                 BUG();
 446         minor  = iminor(inode);
 447
 448         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
 449         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
 450
 451         switch (command) {
 452                 /* Refuse some IOCTL calls without complaining (mount). */
 453                 case 0x5310:            /* CDROMMULTISESSION */
 454                         rc = -EINVAL;
 455                         break;
 456                 default:
 457                         PRINT_WARN("invalid ioctl 0x%x\n", command);
 458                         rc = -EINVAL;
 459         }
 460
 461         return rc;
 462 }
 463
 464 /*
 465  * Initialize block device frontend.
 466  */
 467 int
 468 tapeblock_init(void)
 469 {
 470         int rc;
 471
 472         /* Register the tape major number to the kernel */
 473         rc = register_blkdev(tapeblock_major, "tBLK");
 474         if (rc < 0)
 475                 return rc;
 476
 477         if (tapeblock_major == 0)
 478                 tapeblock_major = rc;
 479         PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
 480         return 0;
 481 }
 482
 483 /*
 484  * Deregister major for block device frontend
 485  */
 486 void
 487 tapeblock_exit(void)
 488 {
 489         unregister_blkdev(tapeblock_major, "tBLK");
 490 }