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   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 #include <linux/kernel.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 void
  77 tapeblock_end_request(struct request *req, int error)
  78 {
  79         if (__blk_end_request(req, error, blk_rq_bytes(req)))
  80                 BUG();
  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) ? 0 : -EIO);
  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 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, -EIO);
 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, -EIO);
 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(struct work_struct *work) {
 147         struct tape_blk_data *  blkdat;
 148         struct tape_device *    device;
 149         struct request_queue *  queue;
 150         int                     nr_queued;
 151         struct request *        req;
 152         struct list_head *      l;
 153         int                     rc;
 154
 155         blkdat = container_of(work, struct tape_blk_data, requeue_task);
 156         device = blkdat->device;
 157         if (!device)
 158                 return;
 159
 160         spin_lock_irq(get_ccwdev_lock(device->cdev));
 161         queue  = device->blk_data.request_queue;
 162
 163         /* Count number of requests on ccw queue. */
 164         nr_queued = 0;
 165         list_for_each(l, &device->req_queue)
 166                 nr_queued++;
 167         spin_unlock(get_ccwdev_lock(device->cdev));
 168
 169         spin_lock(&device->blk_data.request_queue_lock);
 170         while (
 171                 !blk_queue_plugged(queue) &&
 172                 elv_next_request(queue)   &&
 173                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 174         ) {
 175                 req = elv_next_request(queue);
 176                 if (rq_data_dir(req) == WRITE) {
 177                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 178                         blkdev_dequeue_request(req);
 179                         tapeblock_end_request(req, -EIO);
 180                         continue;
 181                 }
 182                 blkdev_dequeue_request(req);
 183                 nr_queued++;
 184                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 185                 rc = tapeblock_start_request(device, req);
 186                 spin_lock_irq(&device->blk_data.request_queue_lock);
 187         }
 188         spin_unlock_irq(&device->blk_data.request_queue_lock);
 189         atomic_set(&device->blk_data.requeue_scheduled, 0);
 190 }
 191
 192 /*
 193  * Tape request queue function. Called from ll_rw_blk.c
 194  */
 195 static void
 196 tapeblock_request_fn(struct request_queue *queue)
 197 {
 198         struct tape_device *device;
 199
 200         device = (struct tape_device *) queue->queuedata;
 201         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 202         BUG_ON(device == NULL);
 203         tapeblock_trigger_requeue(device);
 204 }
 205
 206 /*
 207  * This function is called for every new tapedevice
 208  */
 209 int
 210 tapeblock_setup_device(struct tape_device * device)
 211 {
 212         struct tape_blk_data *  blkdat;
 213         struct gendisk *        disk;
 214         int                     rc;
 215
 216         blkdat = &device->blk_data;
 217         blkdat->device = device;
 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         tape_get_device_reference(device);
 262         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 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         tape_put_device(device);
 278
 279         if (!device->blk_data.disk) {
 280                 PRINT_ERR("(%s): No gendisk to clean up!\n",
 281                         dev_name(&device->cdev->dev));
 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         BUG_ON(!device);
 311
 312         if (!device->blk_data.medium_changed)
 313                 return 0;
 314
 315         PRINT_INFO("Detecting media size...\n");
 316         rc = tape_mtop(device, MTFSFM, 1);
 317         if (rc)
 318                 return rc;
 319
 320         rc = tape_mtop(device, MTTELL, 1);
 321         if (rc < 0)
 322                 return rc;
 323
 324         DBF_LH(3, "Image file ends at %d\n", rc);
 325         nr_of_blks = rc;
 326
 327         /* This will fail for the first file. Catch the error by checking the
 328          * position. */
 329         tape_mtop(device, MTBSF, 1);
 330
 331         rc = tape_mtop(device, MTTELL, 1);
 332         if (rc < 0)
 333                 return rc;
 334
 335         if (rc > nr_of_blks)
 336                 return -EINVAL;
 337
 338         DBF_LH(3, "Image file starts at %d\n", rc);
 339         device->bof = rc;
 340         nr_of_blks -= rc;
 341
 342         PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
 343         set_capacity(device->blk_data.disk,
 344                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 345
 346         device->blk_data.block_position = 0;
 347         device->blk_data.medium_changed = 0;
 348         return 0;
 349 }
 350
 351 static int
 352 tapeblock_medium_changed(struct gendisk *disk)
 353 {
 354         struct tape_device *device;
 355
 356         device = (struct tape_device *) disk->private_data;
 357         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 358                 device, device->blk_data.medium_changed);
 359
 360         return device->blk_data.medium_changed;
 361 }
 362
 363 /*
 364  * Block frontend tape device open function.
 365  */
 366 static int
 367 tapeblock_open(struct inode *inode, struct file *filp)
 368 {
 369         struct gendisk *        disk;
 370         struct tape_device *    device;
 371         int                     rc;
 372
 373         disk   = inode->i_bdev->bd_disk;
 374         device = tape_get_device_reference(disk->private_data);
 375
 376         if (device->required_tapemarks) {
 377                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 378                 PRINT_ERR("TBLOCK: Refusing to open tape with missing"
 379                         " end of file marks.\n");
 380                 rc = -EPERM;
 381                 goto put_device;
 382         }
 383
 384         rc = tape_open(device);
 385         if (rc)
 386                 goto put_device;
 387
 388         rc = tapeblock_revalidate_disk(disk);
 389         if (rc)
 390                 goto release;
 391
 392         /*
 393          * Note: The reference to <device> is hold until the release function
 394          *       is called.
 395          */
 396         tape_state_set(device, TS_BLKUSE);
 397         return 0;
 398
 399 release:
 400         tape_release(device);
 401  put_device:
 402         tape_put_device(device);
 403         return rc;
 404 }
 405
 406 /*
 407  * Block frontend tape device release function.
 408  *
 409  * Note: One reference to the tape device was made by the open function. So
 410  *       we just get the pointer here and release the reference.
 411  */
 412 static int
 413 tapeblock_release(struct inode *inode, struct file *filp)
 414 {
 415         struct gendisk *disk = inode->i_bdev->bd_disk;
 416         struct tape_device *device = disk->private_data;
 417
 418         tape_state_set(device, TS_IN_USE);
 419         tape_release(device);
 420         tape_put_device(device);
 421
 422         return 0;
 423 }
 424
 425 /*
 426  * Support of some generic block device IOCTLs.
 427  */
 428 static int
 429 tapeblock_ioctl(
 430         struct inode *          inode,
 431         struct file *           file,
 432         unsigned int            command,
 433         unsigned long           arg
 434 ) {
 435         int rc;
 436         int minor;
 437         struct gendisk *disk;
 438         struct tape_device *device;
 439
 440         rc     = 0;
 441         disk   = inode->i_bdev->bd_disk;
 442         BUG_ON(!disk);
 443         device = disk->private_data;
 444         BUG_ON(!device);
 445         minor  = iminor(inode);
 446
 447         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
 448         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
 449
 450         switch (command) {
 451                 /* Refuse some IOCTL calls without complaining (mount). */
 452                 case 0x5310:            /* CDROMMULTISESSION */
 453                         rc = -EINVAL;
 454                         break;
 455                 default:
 456                         PRINT_WARN("invalid ioctl 0x%x\n", command);
 457                         rc = -EINVAL;
 458         }
 459
 460         return rc;
 461 }
 462
 463 /*
 464  * Initialize block device frontend.
 465  */
 466 int
 467 tapeblock_init(void)
 468 {
 469         int rc;
 470
 471         /* Register the tape major number to the kernel */
 472         rc = register_blkdev(tapeblock_major, "tBLK");
 473         if (rc < 0)
 474                 return rc;
 475
 476         if (tapeblock_major == 0)
 477                 tapeblock_major = rc;
 478         PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
 479         return 0;
 480 }
 481
 482 /*
 483  * Deregister major for block device frontend
 484  */
 485 void
 486 tapeblock_exit(void)
 487 {
 488         unregister_blkdev(tapeblock_major, "tBLK");
 489 }