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/module.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/buffer_head.h>
  18
  19 #include <asm/debug.h>
  20
  21 #define TAPE_DBF_AREA   tape_core_dbf
  22
  23 #include "tape.h"
  24
  25 #define PRINTK_HEADER "TAPE_BLOCK: "
  26
  27 #define TAPEBLOCK_MAX_SEC       100
  28 #define TAPEBLOCK_MIN_REQUEUE   3
  29
  30 /*
  31  * 2003/11/25  Stefan Bader <shbader@de.ibm.com>
  32  *
  33  * In 2.5/2.6 the block device request function is very likely to be called
  34  * with disabled interrupts (e.g. generic_unplug_device). So the driver can't
  35  * just call any function that tries to allocate CCW requests from that con-
  36  * text since it might sleep. There are two choices to work around this:
  37  *      a) do not allocate with kmalloc but use its own memory pool
  38  *      b) take requests from the queue outside that context, knowing that
  39  *         allocation might sleep
  40  */
  41
  42 /*
  43  * file operation structure for tape block frontend
  44  */
  45 static int tapeblock_open(struct inode *, struct file *);
  46 static int tapeblock_release(struct inode *, struct file *);
  47 static int tapeblock_ioctl(struct inode *, struct file *, unsigned int,
  48                                 unsigned long);
  49 static int tapeblock_medium_changed(struct gendisk *);
  50 static int tapeblock_revalidate_disk(struct gendisk *);
  51
  52 static struct block_device_operations tapeblock_fops = {
  53         .owner           = THIS_MODULE,
  54         .open            = tapeblock_open,
  55         .release         = tapeblock_release,
  56         .ioctl           = tapeblock_ioctl,
  57         .media_changed   = tapeblock_medium_changed,
  58         .revalidate_disk = tapeblock_revalidate_disk,
  59 };
  60
  61 static int tapeblock_major = 0;
  62
  63 static void
  64 tapeblock_trigger_requeue(struct tape_device *device)
  65 {
  66         /* Protect against rescheduling. */
  67         if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
  68                 return;
  69         schedule_work(&device->blk_data.requeue_task);
  70 }
  71
  72 /*
  73  * Post finished request.
  74  */
  75 static inline void
  76 tapeblock_end_request(struct request *req, int uptodate)
  77 {
  78         if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
  79                 BUG();
  80         end_that_request_last(req, uptodate);
  81 }
  82
  83 static void
  84 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
  85 {
  86         struct tape_device *device;
  87         struct request *req;
  88
  89         DBF_LH(6, "__tapeblock_end_request()\n");
  90
  91         device = ccw_req->device;
  92         req = (struct request *) data;
  93         tapeblock_end_request(req, ccw_req->rc == 0);
  94         if (ccw_req->rc == 0)
  95                 /* Update position. */
  96                 device->blk_data.block_position =
  97                         (req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
  98         else
  99                 /* We lost the position information due to an error. */
 100                 device->blk_data.block_position = -1;
 101         device->discipline->free_bread(ccw_req);
 102         if (!list_empty(&device->req_queue) ||
 103             elv_next_request(device->blk_data.request_queue))
 104                 tapeblock_trigger_requeue(device);
 105 }
 106
 107 /*
 108  * Feed the tape device CCW queue with requests supplied in a list.
 109  */
 110 static inline int
 111 tapeblock_start_request(struct tape_device *device, struct request *req)
 112 {
 113         struct tape_request *   ccw_req;
 114         int                     rc;
 115
 116         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
 117
 118         ccw_req = device->discipline->bread(device, req);
 119         if (IS_ERR(ccw_req)) {
 120                 DBF_EVENT(1, "TBLOCK: bread failed\n");
 121                 tapeblock_end_request(req, 0);
 122                 return PTR_ERR(ccw_req);
 123         }
 124         ccw_req->callback = __tapeblock_end_request;
 125         ccw_req->callback_data = (void *) req;
 126         ccw_req->retries = TAPEBLOCK_RETRIES;
 127
 128         rc = tape_do_io_async(device, ccw_req);
 129         if (rc) {
 130                 /*
 131                  * Start/enqueueing failed. No retries in
 132                  * this case.
 133                  */
 134                 tapeblock_end_request(req, 0);
 135                 device->discipline->free_bread(ccw_req);
 136         }
 137
 138         return rc;
 139 }
 140
 141 /*
 142  * Move requests from the block device request queue to the tape device ccw
 143  * queue.
 144  */
 145 static void
 146 tapeblock_requeue(void *data) {
 147         struct tape_device *    device;
 148         request_queue_t *       queue;
 149         int                     nr_queued;
 150         struct request *        req;
 151         struct list_head *      l;
 152         int                     rc;
 153
 154         device = (struct tape_device *) data;
 155         if (!device)
 156                 return;
 157
 158         spin_lock_irq(get_ccwdev_lock(device->cdev));
 159         queue  = device->blk_data.request_queue;
 160
 161         /* Count number of requests on ccw queue. */
 162         nr_queued = 0;
 163         list_for_each(l, &device->req_queue)
 164                 nr_queued++;
 165         spin_unlock(get_ccwdev_lock(device->cdev));
 166
 167         spin_lock(&device->blk_data.request_queue_lock);
 168         while (
 169                 !blk_queue_plugged(queue) &&
 170                 elv_next_request(queue)   &&
 171                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 172         ) {
 173                 req = elv_next_request(queue);
 174                 if (rq_data_dir(req) == WRITE) {
 175                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 176                         blkdev_dequeue_request(req);
 177                         tapeblock_end_request(req, 0);
 178                         continue;
 179                 }
 180                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 181                 rc = tapeblock_start_request(device, req);
 182                 spin_lock_irq(&device->blk_data.request_queue_lock);
 183                 blkdev_dequeue_request(req);
 184                 nr_queued++;
 185         }
 186         spin_unlock_irq(&device->blk_data.request_queue_lock);
 187         atomic_set(&device->blk_data.requeue_scheduled, 0);
 188 }
 189
 190 /*
 191  * Tape request queue function. Called from ll_rw_blk.c
 192  */
 193 static void
 194 tapeblock_request_fn(request_queue_t *queue)
 195 {
 196         struct tape_device *device;
 197
 198         device = (struct tape_device *) queue->queuedata;
 199         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 200         BUG_ON(device == NULL);
 201         tapeblock_trigger_requeue(device);
 202 }
 203
 204 /*
 205  * This function is called for every new tapedevice
 206  */
 207 int
 208 tapeblock_setup_device(struct tape_device * device)
 209 {
 210         struct tape_blk_data *  blkdat;
 211         struct gendisk *        disk;
 212         int                     rc;
 213
 214         blkdat = &device->blk_data;
 215         spin_lock_init(&blkdat->request_queue_lock);
 216         atomic_set(&blkdat->requeue_scheduled, 0);
 217
 218         blkdat->request_queue = blk_init_queue(
 219                 tapeblock_request_fn,
 220                 &blkdat->request_queue_lock
 221         );
 222         if (!blkdat->request_queue)
 223                 return -ENOMEM;
 224
 225         elevator_exit(blkdat->request_queue->elevator);
 226         rc = elevator_init(blkdat->request_queue, "noop");
 227         if (rc)
 228                 goto cleanup_queue;
 229
 230         blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 231         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 232         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
 233         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
 234         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 235         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 236
 237         disk = alloc_disk(1);
 238         if (!disk) {
 239                 rc = -ENOMEM;
 240                 goto cleanup_queue;
 241         }
 242
 243         disk->major = tapeblock_major;
 244         disk->first_minor = device->first_minor;
 245         disk->fops = &tapeblock_fops;
 246         disk->private_data = tape_get_device_reference(device);
 247         disk->queue = blkdat->request_queue;
 248         set_capacity(disk, 0);
 249         sprintf(disk->disk_name, "btibm%d",
 250                 device->first_minor / TAPE_MINORS_PER_DEV);
 251
 252         blkdat->disk = disk;
 253         blkdat->medium_changed = 1;
 254         blkdat->request_queue->queuedata = tape_get_device_reference(device);
 255
 256         add_disk(disk);
 257
 258         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
 259                 tape_get_device_reference(device));
 260
 261         return 0;
 262
 263 cleanup_queue:
 264         blk_cleanup_queue(blkdat->request_queue);
 265         blkdat->request_queue = NULL;
 266
 267         return rc;
 268 }
 269
 270 void
 271 tapeblock_cleanup_device(struct tape_device *device)
 272 {
 273         flush_scheduled_work();
 274         device->blk_data.requeue_task.data = tape_put_device(device);
 275
 276         if (!device->blk_data.disk) {
 277                 PRINT_ERR("(%s): No gendisk to clean up!\n",
 278                         device->cdev->dev.bus_id);
 279                 goto cleanup_queue;
 280         }
 281
 282         del_gendisk(device->blk_data.disk);
 283         device->blk_data.disk->private_data =
 284                 tape_put_device(device->blk_data.disk->private_data);
 285         put_disk(device->blk_data.disk);
 286
 287         device->blk_data.disk = NULL;
 288 cleanup_queue:
 289         device->blk_data.request_queue->queuedata = tape_put_device(device);
 290
 291         blk_cleanup_queue(device->blk_data.request_queue);
 292         device->blk_data.request_queue = NULL;
 293 }
 294
 295 /*
 296  * Detect number of blocks of the tape.
 297  * FIXME: can we extent this to detect the blocks size as well ?
 298  */
 299 static int
 300 tapeblock_revalidate_disk(struct gendisk *disk)
 301 {
 302         struct tape_device *    device;
 303         unsigned int            nr_of_blks;
 304         int                     rc;
 305
 306         device = (struct tape_device *) disk->private_data;
 307         BUG_ON(!device);
 308
 309         if (!device->blk_data.medium_changed)
 310                 return 0;
 311
 312         PRINT_INFO("Detecting media size...\n");
 313         rc = tape_mtop(device, MTFSFM, 1);
 314         if (rc)
 315                 return rc;
 316
 317         rc = tape_mtop(device, MTTELL, 1);
 318         if (rc < 0)
 319                 return rc;
 320
 321         DBF_LH(3, "Image file ends at %d\n", rc);
 322         nr_of_blks = rc;
 323
 324         /* This will fail for the first file. Catch the error by checking the
 325          * position. */
 326         tape_mtop(device, MTBSF, 1);
 327
 328         rc = tape_mtop(device, MTTELL, 1);
 329         if (rc < 0)
 330                 return rc;
 331
 332         if (rc > nr_of_blks)
 333                 return -EINVAL;
 334
 335         DBF_LH(3, "Image file starts at %d\n", rc);
 336         device->bof = rc;
 337         nr_of_blks -= rc;
 338
 339         PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
 340         set_capacity(device->blk_data.disk,
 341                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 342
 343         device->blk_data.block_position = 0;
 344         device->blk_data.medium_changed = 0;
 345         return 0;
 346 }
 347
 348 static int
 349 tapeblock_medium_changed(struct gendisk *disk)
 350 {
 351         struct tape_device *device;
 352
 353         device = (struct tape_device *) disk->private_data;
 354         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 355                 device, device->blk_data.medium_changed);
 356
 357         return device->blk_data.medium_changed;
 358 }
 359
 360 /*
 361  * Block frontend tape device open function.
 362  */
 363 static int
 364 tapeblock_open(struct inode *inode, struct file *filp)
 365 {
 366         struct gendisk *        disk;
 367         struct tape_device *    device;
 368         int                     rc;
 369
 370         disk   = inode->i_bdev->bd_disk;
 371         device = tape_get_device_reference(disk->private_data);
 372
 373         if (device->required_tapemarks) {
 374                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 375                 PRINT_ERR("TBLOCK: Refusing to open tape with missing"
 376                         " end of file marks.\n");
 377                 rc = -EPERM;
 378                 goto put_device;
 379         }
 380
 381         rc = tape_open(device);
 382         if (rc)
 383                 goto put_device;
 384
 385         rc = tapeblock_revalidate_disk(disk);
 386         if (rc)
 387                 goto release;
 388
 389         /*
 390          * Note: The reference to <device> is hold until the release function
 391          *       is called.
 392          */
 393         tape_state_set(device, TS_BLKUSE);
 394         return 0;
 395
 396 release:
 397         tape_release(device);
 398  put_device:
 399         tape_put_device(device);
 400         return rc;
 401 }
 402
 403 /*
 404  * Block frontend tape device release function.
 405  *
 406  * Note: One reference to the tape device was made by the open function. So
 407  *       we just get the pointer here and release the reference.
 408  */
 409 static int
 410 tapeblock_release(struct inode *inode, struct file *filp)
 411 {
 412         struct gendisk *disk = inode->i_bdev->bd_disk;
 413         struct tape_device *device = disk->private_data;
 414
 415         tape_state_set(device, TS_IN_USE);
 416         tape_release(device);
 417         tape_put_device(device);
 418
 419         return 0;
 420 }
 421
 422 /*
 423  * Support of some generic block device IOCTLs.
 424  */
 425 static int
 426 tapeblock_ioctl(
 427         struct inode *          inode,
 428         struct file *           file,
 429         unsigned int            command,
 430         unsigned long           arg
 431 ) {
 432         int rc;
 433         int minor;
 434         struct gendisk *disk;
 435         struct tape_device *device;
 436
 437         rc     = 0;
 438         disk   = inode->i_bdev->bd_disk;
 439         BUG_ON(!disk);
 440         device = disk->private_data;
 441         BUG_ON(!device);
 442         minor  = iminor(inode);
 443
 444         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
 445         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
 446
 447         switch (command) {
 448                 /* Refuse some IOCTL calls without complaining (mount). */
 449                 case 0x5310:            /* CDROMMULTISESSION */
 450                         rc = -EINVAL;
 451                         break;
 452                 default:
 453                         PRINT_WARN("invalid ioctl 0x%x\n", command);
 454                         rc = -EINVAL;
 455         }
 456
 457         return rc;
 458 }
 459
 460 /*
 461  * Initialize block device frontend.
 462  */
 463 int
 464 tapeblock_init(void)
 465 {
 466         int rc;
 467
 468         /* Register the tape major number to the kernel */
 469         rc = register_blkdev(tapeblock_major, "tBLK");
 470         if (rc < 0)
 471                 return rc;
 472
 473         if (tapeblock_major == 0)
 474                 tapeblock_major = rc;
 475         PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
 476         return 0;
 477 }
 478
 479 /*
 480  * Deregister major for block device frontend
 481  */
 482 void
 483 tapeblock_exit(void)
 484 {
 485         unregister_blkdev(tapeblock_major, "tBLK");
 486 }