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 #define TAPE_DBF_AREA   tape_core_dbf
  23
  24 #include "tape.h"
  25
  26 #define PRINTK_HEADER "TAPE_BLOCK: "
  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 inode *, struct file *);
  47 static int tapeblock_release(struct inode *, struct file *);
  48 static int tapeblock_ioctl(struct inode *, struct file *, 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         .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 inline void
  77 tapeblock_end_request(struct request *req, int uptodate)
  78 {
  79         if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
  80                 BUG();
  81         end_that_request_last(req, uptodate);
  82 }
  83
  84 static void
  85 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
  86 {
  87         struct tape_device *device;
  88         struct request *req;
  89
  90         DBF_LH(6, "__tapeblock_end_request()\n");
  91
  92         device = ccw_req->device;
  93         req = (struct request *) data;
  94         tapeblock_end_request(req, ccw_req->rc == 0);
  95         if (ccw_req->rc == 0)
  96                 /* Update position. */
  97                 device->blk_data.block_position =
  98                         (req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
  99         else
 100                 /* We lost the position information due to an error. */
 101                 device->blk_data.block_position = -1;
 102         device->discipline->free_bread(ccw_req);
 103         if (!list_empty(&device->req_queue) ||
 104             elv_next_request(device->blk_data.request_queue))
 105                 tapeblock_trigger_requeue(device);
 106 }
 107
 108 /*
 109  * Feed the tape device CCW queue with requests supplied in a list.
 110  */
 111 static inline int
 112 tapeblock_start_request(struct tape_device *device, struct request *req)
 113 {
 114         struct tape_request *   ccw_req;
 115         int                     rc;
 116
 117         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
 118
 119         ccw_req = device->discipline->bread(device, req);
 120         if (IS_ERR(ccw_req)) {
 121                 DBF_EVENT(1, "TBLOCK: bread failed\n");
 122                 tapeblock_end_request(req, 0);
 123                 return PTR_ERR(ccw_req);
 124         }
 125         ccw_req->callback = __tapeblock_end_request;
 126         ccw_req->callback_data = (void *) req;
 127         ccw_req->retries = TAPEBLOCK_RETRIES;
 128
 129         rc = tape_do_io_async(device, ccw_req);
 130         if (rc) {
 131                 /*
 132                  * Start/enqueueing failed. No retries in
 133                  * this case.
 134                  */
 135                 tapeblock_end_request(req, 0);
 136                 device->discipline->free_bread(ccw_req);
 137         }
 138
 139         return rc;
 140 }
 141
 142 /*
 143  * Move requests from the block device request queue to the tape device ccw
 144  * queue.
 145  */
 146 static void
 147 tapeblock_requeue(void *data) {
 148         struct tape_device *    device;
 149         request_queue_t *       queue;
 150         int                     nr_queued;
 151         struct request *        req;
 152         struct list_head *      l;
 153         int                     rc;
 154
 155         device = (struct tape_device *) data;
 156         if (!device)
 157                 return;
 158
 159         spin_lock_irq(get_ccwdev_lock(device->cdev));
 160         queue  = device->blk_data.request_queue;
 161
 162         /* Count number of requests on ccw queue. */
 163         nr_queued = 0;
 164         list_for_each(l, &device->req_queue)
 165                 nr_queued++;
 166         spin_unlock(get_ccwdev_lock(device->cdev));
 167
 168         spin_lock(&device->blk_data.request_queue_lock);
 169         while (
 170                 !blk_queue_plugged(queue) &&
 171                 elv_next_request(queue)   &&
 172                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 173         ) {
 174                 req = elv_next_request(queue);
 175                 if (rq_data_dir(req) == WRITE) {
 176                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 177                         blkdev_dequeue_request(req);
 178                         tapeblock_end_request(req, 0);
 179                         continue;
 180                 }
 181                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 182                 rc = tapeblock_start_request(device, req);
 183                 spin_lock_irq(&device->blk_data.request_queue_lock);
 184                 blkdev_dequeue_request(req);
 185                 nr_queued++;
 186         }
 187         spin_unlock_irq(&device->blk_data.request_queue_lock);
 188         atomic_set(&device->blk_data.requeue_scheduled, 0);
 189 }
 190
 191 /*
 192  * Tape request queue function. Called from ll_rw_blk.c
 193  */
 194 static void
 195 tapeblock_request_fn(request_queue_t *queue)
 196 {
 197         struct tape_device *device;
 198
 199         device = (struct tape_device *) queue->queuedata;
 200         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 201         if (device == NULL)
 202                 BUG();
 203
 204         tapeblock_trigger_requeue(device);
 205 }
 206
 207 /*
 208  * This function is called for every new tapedevice
 209  */
 210 int
 211 tapeblock_setup_device(struct tape_device * device)
 212 {
 213         struct tape_blk_data *  blkdat;
 214         struct gendisk *        disk;
 215         int                     rc;
 216
 217         blkdat = &device->blk_data;
 218         spin_lock_init(&blkdat->request_queue_lock);
 219         atomic_set(&blkdat->requeue_scheduled, 0);
 220
 221         blkdat->request_queue = blk_init_queue(
 222                 tapeblock_request_fn,
 223                 &blkdat->request_queue_lock
 224         );
 225         if (!blkdat->request_queue)
 226                 return -ENOMEM;
 227
 228         elevator_exit(blkdat->request_queue->elevator);
 229         rc = elevator_init(blkdat->request_queue, "noop");
 230         if (rc)
 231                 goto cleanup_queue;
 232
 233         blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 234         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 235         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
 236         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
 237         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 238         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 239
 240         disk = alloc_disk(1);
 241         if (!disk) {
 242                 rc = -ENOMEM;
 243                 goto cleanup_queue;
 244         }
 245
 246         disk->major = tapeblock_major;
 247         disk->first_minor = device->first_minor;
 248         disk->fops = &tapeblock_fops;
 249         disk->private_data = tape_get_device_reference(device);
 250         disk->queue = blkdat->request_queue;
 251         set_capacity(disk, 0);
 252         sprintf(disk->disk_name, "btibm%d",
 253                 device->first_minor / TAPE_MINORS_PER_DEV);
 254
 255         blkdat->disk = disk;
 256         blkdat->medium_changed = 1;
 257         blkdat->request_queue->queuedata = tape_get_device_reference(device);
 258
 259         add_disk(disk);
 260
 261         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
 262                 tape_get_device_reference(device));
 263
 264         return 0;
 265
 266 cleanup_queue:
 267         blk_cleanup_queue(blkdat->request_queue);
 268         blkdat->request_queue = NULL;
 269
 270         return rc;
 271 }
 272
 273 void
 274 tapeblock_cleanup_device(struct tape_device *device)
 275 {
 276         flush_scheduled_work();
 277         device->blk_data.requeue_task.data = tape_put_device(device);
 278
 279         if (!device->blk_data.disk) {
 280                 PRINT_ERR("(%s): No gendisk to clean up!\n",
 281                         device->cdev->dev.bus_id);
 282                 goto cleanup_queue;
 283         }
 284
 285         del_gendisk(device->blk_data.disk);
 286         device->blk_data.disk->private_data =
 287                 tape_put_device(device->blk_data.disk->private_data);
 288         put_disk(device->blk_data.disk);
 289
 290         device->blk_data.disk = NULL;
 291 cleanup_queue:
 292         device->blk_data.request_queue->queuedata = tape_put_device(device);
 293
 294         blk_cleanup_queue(device->blk_data.request_queue);
 295         device->blk_data.request_queue = NULL;
 296 }
 297
 298 /*
 299  * Detect number of blocks of the tape.
 300  * FIXME: can we extent this to detect the blocks size as well ?
 301  */
 302 static int
 303 tapeblock_revalidate_disk(struct gendisk *disk)
 304 {
 305         struct tape_device *    device;
 306         unsigned int            nr_of_blks;
 307         int                     rc;
 308
 309         device = (struct tape_device *) disk->private_data;
 310         if (!device)
 311                 BUG();
 312
 313         if (!device->blk_data.medium_changed)
 314                 return 0;
 315
 316         PRINT_INFO("Detecting media size...\n");
 317         rc = tape_mtop(device, MTFSFM, 1);
 318         if (rc)
 319                 return rc;
 320
 321         rc = tape_mtop(device, MTTELL, 1);
 322         if (rc < 0)
 323                 return rc;
 324
 325         DBF_LH(3, "Image file ends at %d\n", rc);
 326         nr_of_blks = rc;
 327
 328         /* This will fail for the first file. Catch the error by checking the
 329          * position. */
 330         tape_mtop(device, MTBSF, 1);
 331
 332         rc = tape_mtop(device, MTTELL, 1);
 333         if (rc < 0)
 334                 return rc;
 335
 336         if (rc > nr_of_blks)
 337                 return -EINVAL;
 338
 339         DBF_LH(3, "Image file starts at %d\n", rc);
 340         device->bof = rc;
 341         nr_of_blks -= rc;
 342
 343         PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
 344         set_capacity(device->blk_data.disk,
 345                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 346
 347         device->blk_data.block_position = 0;
 348         device->blk_data.medium_changed = 0;
 349         return 0;
 350 }
 351
 352 static int
 353 tapeblock_medium_changed(struct gendisk *disk)
 354 {
 355         struct tape_device *device;
 356
 357         device = (struct tape_device *) disk->private_data;
 358         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 359                 device, device->blk_data.medium_changed);
 360
 361         return device->blk_data.medium_changed;
 362 }
 363
 364 /*
 365  * Block frontend tape device open function.
 366  */
 367 static int
 368 tapeblock_open(struct inode *inode, struct file *filp)
 369 {
 370         struct gendisk *        disk;
 371         struct tape_device *    device;
 372         int                     rc;
 373
 374         disk   = inode->i_bdev->bd_disk;
 375         device = tape_get_device_reference(disk->private_data);
 376
 377         if (device->required_tapemarks) {
 378                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 379                 PRINT_ERR("TBLOCK: Refusing to open tape with missing"
 380                         " end of file marks.\n");
 381                 rc = -EPERM;
 382                 goto put_device;
 383         }
 384
 385         rc = tape_open(device);
 386         if (rc)
 387                 goto put_device;
 388
 389         rc = tapeblock_revalidate_disk(disk);
 390         if (rc)
 391                 goto release;
 392
 393         /*
 394          * Note: The reference to <device> is hold until the release function
 395          *       is called.
 396          */
 397         tape_state_set(device, TS_BLKUSE);
 398         return 0;
 399
 400 release:
 401         tape_release(device);
 402  put_device:
 403         tape_put_device(device);
 404         return rc;
 405 }
 406
 407 /*
 408  * Block frontend tape device release function.
 409  *
 410  * Note: One reference to the tape device was made by the open function. So
 411  *       we just get the pointer here and release the reference.
 412  */
 413 static int
 414 tapeblock_release(struct inode *inode, struct file *filp)
 415 {
 416         struct gendisk *disk = inode->i_bdev->bd_disk;
 417         struct tape_device *device = disk->private_data;
 418
 419         tape_state_set(device, TS_IN_USE);
 420         tape_release(device);
 421         tape_put_device(device);
 422
 423         return 0;
 424 }
 425
 426 /*
 427  * Support of some generic block device IOCTLs.
 428  */
 429 static int
 430 tapeblock_ioctl(
 431         struct inode *          inode,
 432         struct file *           file,
 433         unsigned int            command,
 434         unsigned long           arg
 435 ) {
 436         int rc;
 437         int minor;
 438         struct gendisk *disk = inode->i_bdev->bd_disk;
 439         struct tape_device *device = disk->private_data;
 440
 441         rc     = 0;
 442         disk   = inode->i_bdev->bd_disk;
 443         if (!disk)
 444                 BUG();
 445         device = disk->private_data;
 446         if (!device)
 447                 BUG();
 448         minor  = iminor(inode);
 449
 450         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
 451         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
 452
 453         switch (command) {
 454                 /* Refuse some IOCTL calls without complaining (mount). */
 455                 case 0x5310:            /* CDROMMULTISESSION */
 456                         rc = -EINVAL;
 457                         break;
 458                 default:
 459                         PRINT_WARN("invalid ioctl 0x%x\n", command);
 460                         rc = -EINVAL;
 461         }
 462
 463         return rc;
 464 }
 465
 466 /*
 467  * Initialize block device frontend.
 468  */
 469 int
 470 tapeblock_init(void)
 471 {
 472         int rc;
 473
 474         /* Register the tape major number to the kernel */
 475         rc = register_blkdev(tapeblock_major, "tBLK");
 476         if (rc < 0)
 477                 return rc;
 478
 479         if (tapeblock_major == 0)
 480                 tapeblock_major = rc;
 481         PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
 482         return 0;
 483 }
 484
 485 /*
 486  * Deregister major for block device frontend
 487  */
 488 void
 489 tapeblock_exit(void)
 490 {
 491         unregister_blkdev(tapeblock_major, "tBLK");
 492 }