drivers/s390/block/dcssblk.c

   1 /*
   2  * dcssblk.c -- the S/390 block driver for dcss memory
   3  *
   4  * Authors: Carsten Otte, Stefan Weinhuber, Gerald Schaefer
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/ctype.h>
   9 #include <linux/errno.h>
  10 #include <linux/init.h>
  11 #include <linux/slab.h>
  12 #include <linux/blkdev.h>
  13 #include <asm/extmem.h>
  14 #include <asm/io.h>
  15 #include <linux/completion.h>
  16 #include <linux/interrupt.h>
  17 #include <asm/ccwdev.h>         // for s390_root_dev_(un)register()
  18
  19 //#define DCSSBLK_DEBUG         /* Debug messages on/off */
  20 #define DCSSBLK_NAME "dcssblk"
  21 #define DCSSBLK_MINORS_PER_DISK 1
  22
  23 #ifdef DCSSBLK_DEBUG
  24 #define PRINT_DEBUG(x...) printk(KERN_DEBUG DCSSBLK_NAME " debug: " x)
  25 #else
  26 #define PRINT_DEBUG(x...) do {} while (0)
  27 #endif
  28 #define PRINT_INFO(x...)  printk(KERN_INFO DCSSBLK_NAME " info: " x)
  29 #define PRINT_WARN(x...)  printk(KERN_WARNING DCSSBLK_NAME " warning: " x)
  30 #define PRINT_ERR(x...)   printk(KERN_ERR DCSSBLK_NAME " error: " x)
  31
  32
  33 static int dcssblk_open(struct inode *inode, struct file *filp);
  34 static int dcssblk_release(struct inode *inode, struct file *filp);
  35 static int dcssblk_make_request(struct request_queue *q, struct bio *bio);
  36
  37 static int dcssblk_major;
  38 static struct block_device_operations dcssblk_devops = {
  39         .owner   = THIS_MODULE,
  40         .open    = dcssblk_open,
  41         .release = dcssblk_release,
  42 };
  43
  44 static ssize_t dcssblk_add_store(struct device * dev, const char * buf,
  45                                   size_t count);
  46 static ssize_t dcssblk_remove_store(struct device * dev, const char * buf,
  47                                   size_t count);
  48 static ssize_t dcssblk_save_store(struct device * dev, const char * buf,
  49                                   size_t count);
  50 static ssize_t dcssblk_save_show(struct device *dev, char *buf);
  51 static ssize_t dcssblk_shared_store(struct device * dev, const char * buf,
  52                                   size_t count);
  53 static ssize_t dcssblk_shared_show(struct device *dev, char *buf);
  54
  55 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  56 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  57 static DEVICE_ATTR(save, S_IWUSR | S_IRUGO, dcssblk_save_show,
  58                    dcssblk_save_store);
  59 static DEVICE_ATTR(shared, S_IWUSR | S_IRUGO, dcssblk_shared_show,
  60                    dcssblk_shared_store);
  61
  62 static struct device *dcssblk_root_dev;
  63
  64 struct dcssblk_dev_info {
  65         struct list_head lh;
  66         struct device dev;
  67         char segment_name[BUS_ID_SIZE];
  68         atomic_t use_count;
  69         struct gendisk *gd;
  70         unsigned long start;
  71         unsigned long end;
  72         int segment_type;
  73         unsigned char save_pending;
  74         unsigned char is_shared;
  75         struct request_queue *dcssblk_queue;
  76 };
  77
  78 static struct list_head dcssblk_devices = LIST_HEAD_INIT(dcssblk_devices);
  79 static struct rw_semaphore dcssblk_devices_sem;
  80
  81 /*
  82  * release function for segment device.
  83  */
  84 static void
  85 dcssblk_release_segment(struct device *dev)
  86 {
  87         PRINT_DEBUG("segment release fn called for %s\n", dev->bus_id);
  88         kfree(container_of(dev, struct dcssblk_dev_info, dev));
  89         module_put(THIS_MODULE);
  90 }
  91
  92 /*
  93  * get a minor number. needs to be called with
  94  * down_write(&dcssblk_devices_sem) and the
  95  * device needs to be enqueued before the semaphore is
  96  * freed.
  97  */
  98 static inline int
  99 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 100 {
 101         int minor, found;
 102         struct dcssblk_dev_info *entry;
 103
 104         if (dev_info == NULL)
 105                 return -EINVAL;
 106         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 107                 found = 0;
 108                 // test if minor available
 109                 list_for_each_entry(entry, &dcssblk_devices, lh)
 110                         if (minor == entry->gd->first_minor)
 111                                 found++;
 112                 if (!found) break; // got unused minor
 113         }
 114         if (found)
 115                 return -EBUSY;
 116         dev_info->gd->first_minor = minor;
 117         return 0;
 118 }
 119
 120 /*
 121  * get the struct dcssblk_dev_info from dcssblk_devices
 122  * for the given name.
 123  * down_read(&dcssblk_devices_sem) must be held.
 124  */
 125 static struct dcssblk_dev_info *
 126 dcssblk_get_device_by_name(char *name)
 127 {
 128         struct dcssblk_dev_info *entry;
 129
 130         list_for_each_entry(entry, &dcssblk_devices, lh) {
 131                 if (!strcmp(name, entry->segment_name)) {
 132                         return entry;
 133                 }
 134         }
 135         return NULL;
 136 }
 137
 138 /*
 139  * device attribute for switching shared/nonshared (exclusive)
 140  * operation (show + store)
 141  */
 142 static ssize_t
 143 dcssblk_shared_show(struct device *dev, char *buf)
 144 {
 145         struct dcssblk_dev_info *dev_info;
 146
 147         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 148         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 149 }
 150
 151 static ssize_t
 152 dcssblk_shared_store(struct device *dev, const char *inbuf, size_t count)
 153 {
 154         struct dcssblk_dev_info *dev_info;
 155         int rc;
 156
 157         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0')) {
 158                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 159                 return -EINVAL;
 160         }
 161         down_write(&dcssblk_devices_sem);
 162         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 163         if (atomic_read(&dev_info->use_count)) {
 164                 PRINT_ERR("share: segment %s is busy!\n",
 165                           dev_info->segment_name);
 166                 up_write(&dcssblk_devices_sem);
 167                 return -EBUSY;
 168         }
 169         if ((inbuf[0] == '1') && (dev_info->is_shared == 1)) {
 170                 PRINT_WARN("Segment %s already loaded in shared mode!\n",
 171                            dev_info->segment_name);
 172                 up_write(&dcssblk_devices_sem);
 173                 return count;
 174         }
 175         if ((inbuf[0] == '0') && (dev_info->is_shared == 0)) {
 176                 PRINT_WARN("Segment %s already loaded in exclusive mode!\n",
 177                            dev_info->segment_name);
 178                 up_write(&dcssblk_devices_sem);
 179                 return count;
 180         }
 181         if (inbuf[0] == '1') {
 182                 // reload segment in shared mode
 183                 segment_unload(dev_info->segment_name);
 184                 rc = segment_load(dev_info->segment_name, SEGMENT_SHARED_RO,
 185                                         &dev_info->start, &dev_info->end);
 186                 if (rc < 0) {
 187                         PRINT_ERR("Segment %s not reloaded, rc=%d\n",
 188                                         dev_info->segment_name, rc);
 189                         goto removeseg;
 190                 }
 191                 dev_info->is_shared = 1;
 192                 PRINT_INFO("Segment %s reloaded, shared mode.\n",
 193                            dev_info->segment_name);
 194         } else if (inbuf[0] == '0') {
 195                 // reload segment in exclusive mode
 196                 segment_unload(dev_info->segment_name);
 197                 rc = segment_load(dev_info->segment_name, SEGMENT_EXCLUSIVE_RW,
 198                                         &dev_info->start, &dev_info->end);
 199                 if (rc < 0) {
 200                         PRINT_ERR("Segment %s not reloaded, rc=%d\n",
 201                                         dev_info->segment_name, rc);
 202                         goto removeseg;
 203                 }
 204                 dev_info->is_shared = 0;
 205                 PRINT_INFO("Segment %s reloaded, exclusive (read-write) mode.\n",
 206                            dev_info->segment_name);
 207         } else {
 208                 up_write(&dcssblk_devices_sem);
 209                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 210                 return -EINVAL;
 211         }
 212         dev_info->segment_type = rc;
 213         rc = count;
 214
 215         switch (dev_info->segment_type) {
 216                 case SEGMENT_SHARED_RO:
 217                 case SEGMENT_EXCLUSIVE_RO:
 218                         set_disk_ro(dev_info->gd, 1);
 219                         break;
 220                 case SEGMENT_SHARED_RW:
 221                 case SEGMENT_EXCLUSIVE_RW:
 222                         set_disk_ro(dev_info->gd, 0);
 223                         break;
 224         }
 225         if ((inbuf[0] == '1') &&
 226            ((dev_info->segment_type == SEGMENT_EXCLUSIVE_RO) ||
 227             (dev_info->segment_type == SEGMENT_EXCLUSIVE_RW))) {
 228                 PRINT_WARN("Could not get shared copy of segment %s\n",
 229                                 dev_info->segment_name);
 230                 rc = -EPERM;
 231         }
 232         if ((inbuf[0] == '0') &&
 233            ((dev_info->segment_type == SEGMENT_SHARED_RO) ||
 234             (dev_info->segment_type == SEGMENT_SHARED_RW))) {
 235                 PRINT_WARN("Could not get exclusive copy of segment %s\n",
 236                                 dev_info->segment_name);
 237                 rc = -EPERM;
 238         }
 239         up_write(&dcssblk_devices_sem);
 240         goto out;
 241
 242 removeseg:
 243         PRINT_ERR("Could not reload segment %s, removing it now!\n",
 244                         dev_info->segment_name);
 245         list_del(&dev_info->lh);
 246
 247         del_gendisk(dev_info->gd);
 248         blk_put_queue(dev_info->dcssblk_queue);
 249         dev_info->gd->queue = NULL;
 250         put_disk(dev_info->gd);
 251         device_unregister(dev);
 252         put_device(dev);
 253         up_write(&dcssblk_devices_sem);
 254 out:
 255         return rc;
 256 }
 257
 258 /*
 259  * device attribute for save operation on current copy
 260  * of the segment. If the segment is busy, saving will
 261  * become pending until it gets released, which can be
 262  * undone by storing a non-true value to this entry.
 263  * (show + store)
 264  */
 265 static ssize_t
 266 dcssblk_save_show(struct device *dev, char *buf)
 267 {
 268         struct dcssblk_dev_info *dev_info;
 269
 270         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 271         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 272 }
 273
 274 static ssize_t
 275 dcssblk_save_store(struct device *dev, const char *inbuf, size_t count)
 276 {
 277         struct dcssblk_dev_info *dev_info;
 278
 279         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0')) {
 280                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 281                 return -EINVAL;
 282         }
 283         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 284
 285         down_write(&dcssblk_devices_sem);
 286         if (inbuf[0] == '1') {
 287                 if (atomic_read(&dev_info->use_count) == 0) {
 288                         // device is idle => we save immediately
 289                         PRINT_INFO("Saving segment %s\n",
 290                                    dev_info->segment_name);
 291                         segment_replace(dev_info->segment_name);
 292                 }  else {
 293                         // device is busy => we save it when it becomes
 294                         // idle in dcssblk_release
 295                         PRINT_INFO("Segment %s is currently busy, it will "
 296                                    "be saved when it becomes idle...\n",
 297                                    dev_info->segment_name);
 298                         dev_info->save_pending = 1;
 299                 }
 300         } else if (inbuf[0] == '0') {
 301                 if (dev_info->save_pending) {
 302                         // device is busy & the user wants to undo his save
 303                         // request
 304                         dev_info->save_pending = 0;
 305                         PRINT_INFO("Pending save for segment %s deactivated\n",
 306                                         dev_info->segment_name);
 307                 }
 308         } else {
 309                 up_write(&dcssblk_devices_sem);
 310                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 311                 return -EINVAL;
 312         }
 313         up_write(&dcssblk_devices_sem);
 314         return count;
 315 }
 316
 317 /*
 318  * device attribute for adding devices
 319  */
 320 static ssize_t
 321 dcssblk_add_store(struct device *dev, const char *buf, size_t count)
 322 {
 323         int rc, i;
 324         struct dcssblk_dev_info *dev_info;
 325         char *local_buf;
 326         unsigned long seg_byte_size;
 327
 328         dev_info = NULL;
 329         if (dev != dcssblk_root_dev) {
 330                 rc = -EINVAL;
 331                 goto out_nobuf;
 332         }
 333         local_buf = kmalloc(count + 1, GFP_KERNEL);
 334         if (local_buf == NULL) {
 335                 rc = -ENOMEM;
 336                 goto out_nobuf;
 337         }
 338         /*
 339          * parse input
 340          */
 341         for (i = 0; ((buf[i] != '\0') && (buf[i] != '\n') && i < count); i++) {
 342                 local_buf[i] = toupper(buf[i]);
 343         }
 344         local_buf[i] = '\0';
 345         if ((i == 0) || (i > 8)) {
 346                 rc = -ENAMETOOLONG;
 347                 goto out;
 348         }
 349         /*
 350          * already loaded?
 351          */
 352         down_read(&dcssblk_devices_sem);
 353         dev_info = dcssblk_get_device_by_name(local_buf);
 354         up_read(&dcssblk_devices_sem);
 355         if (dev_info != NULL) {
 356                 PRINT_WARN("Segment %s already loaded!\n", local_buf);
 357                 rc = -EEXIST;
 358                 goto out;
 359         }
 360         /*
 361          * get a struct dcssblk_dev_info
 362          */
 363         dev_info = kmalloc(sizeof(struct dcssblk_dev_info), GFP_KERNEL);
 364         if (dev_info == NULL) {
 365                 rc = -ENOMEM;
 366                 goto out;
 367         }
 368         memset(dev_info, 0, sizeof(struct dcssblk_dev_info));
 369
 370         strcpy(dev_info->segment_name, local_buf);
 371         strlcpy(dev_info->dev.bus_id, local_buf, BUS_ID_SIZE);
 372         dev_info->dev.release = dcssblk_release_segment;
 373         INIT_LIST_HEAD(&dev_info->lh);
 374
 375         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 376         if (dev_info->gd == NULL) {
 377                 rc = -ENOMEM;
 378                 goto free_dev_info;
 379         }
 380         dev_info->gd->major = dcssblk_major;
 381         dev_info->gd->fops = &dcssblk_devops;
 382         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 383         dev_info->gd->queue = dev_info->dcssblk_queue;
 384         dev_info->gd->private_data = dev_info;
 385         dev_info->gd->driverfs_dev = &dev_info->dev;
 386         /*
 387          * load the segment
 388          */
 389         rc = segment_load(local_buf, SEGMENT_SHARED_RO,
 390                                 &dev_info->start, &dev_info->end);
 391         if (rc < 0) {
 392                 PRINT_ERR("Segment %s not loaded, rc=%d\n", local_buf, rc);
 393                 goto dealloc_gendisk;
 394         }
 395         seg_byte_size = (dev_info->end - dev_info->start + 1);
 396         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 397         PRINT_INFO("Loaded segment %s from %p to %p, size = %lu Byte, "
 398                    "capacity = %lu sectors (512 Byte)\n", local_buf,
 399                         (void *) dev_info->start, (void *) dev_info->end,
 400                         seg_byte_size, seg_byte_size >> 9);
 401
 402         dev_info->segment_type = rc;
 403         dev_info->save_pending = 0;
 404         dev_info->is_shared = 1;
 405         dev_info->dev.parent = dcssblk_root_dev;
 406
 407         /*
 408          * get minor, add to list
 409          */
 410         down_write(&dcssblk_devices_sem);
 411         rc = dcssblk_assign_free_minor(dev_info);
 412         if (rc) {
 413                 up_write(&dcssblk_devices_sem);
 414                 PRINT_ERR("No free minor number available! "
 415                           "Unloading segment...\n");
 416                 goto unload_seg;
 417         }
 418         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 419                 dev_info->gd->first_minor);
 420         list_add_tail(&dev_info->lh, &dcssblk_devices);
 421
 422         if (!try_module_get(THIS_MODULE)) {
 423                 rc = -ENODEV;
 424                 goto list_del;
 425         }
 426         /*
 427          * register the device
 428          */
 429         rc = device_register(&dev_info->dev);
 430         if (rc) {
 431                 PRINT_ERR("Segment %s could not be registered RC=%d\n",
 432                                 local_buf, rc);
 433                 module_put(THIS_MODULE);
 434                 goto list_del;
 435         }
 436         get_device(&dev_info->dev);
 437         rc = device_create_file(&dev_info->dev, &dev_attr_shared);
 438         if (rc)
 439                 goto unregister_dev;
 440         rc = device_create_file(&dev_info->dev, &dev_attr_save);
 441         if (rc)
 442                 goto unregister_dev;
 443
 444         add_disk(dev_info->gd);
 445
 446         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 447         blk_queue_hardsect_size(dev_info->dcssblk_queue, 4096);
 448
 449         switch (dev_info->segment_type) {
 450                 case SEGMENT_SHARED_RO:
 451                 case SEGMENT_EXCLUSIVE_RO:
 452                         set_disk_ro(dev_info->gd,1);
 453                         break;
 454                 case SEGMENT_SHARED_RW:
 455                 case SEGMENT_EXCLUSIVE_RW:
 456                         set_disk_ro(dev_info->gd,0);
 457                         break;
 458         }
 459         PRINT_DEBUG("Segment %s loaded successfully\n", local_buf);
 460         up_write(&dcssblk_devices_sem);
 461         rc = count;
 462         goto out;
 463
 464 unregister_dev:
 465         PRINT_ERR("device_create_file() failed!\n");
 466         list_del(&dev_info->lh);
 467         blk_put_queue(dev_info->dcssblk_queue);
 468         dev_info->gd->queue = NULL;
 469         put_disk(dev_info->gd);
 470         device_unregister(&dev_info->dev);
 471         segment_unload(dev_info->segment_name);
 472         put_device(&dev_info->dev);
 473         up_write(&dcssblk_devices_sem);
 474         goto out;
 475 list_del:
 476         list_del(&dev_info->lh);
 477         up_write(&dcssblk_devices_sem);
 478 unload_seg:
 479         segment_unload(local_buf);
 480 dealloc_gendisk:
 481         blk_put_queue(dev_info->dcssblk_queue);
 482         dev_info->gd->queue = NULL;
 483         put_disk(dev_info->gd);
 484 free_dev_info:
 485         kfree(dev_info);
 486 out:
 487         kfree(local_buf);
 488 out_nobuf:
 489         return rc;
 490 }
 491
 492 /*
 493  * device attribute for removing devices
 494  */
 495 static ssize_t
 496 dcssblk_remove_store(struct device *dev, const char *buf, size_t count)
 497 {
 498         struct dcssblk_dev_info *dev_info;
 499         int rc, i;
 500         char *local_buf;
 501
 502         if (dev != dcssblk_root_dev) {
 503                 return -EINVAL;
 504         }
 505         local_buf = kmalloc(count + 1, GFP_KERNEL);
 506         if (local_buf == NULL) {
 507                 return -ENOMEM;
 508         }
 509         /*
 510          * parse input
 511          */
 512         for (i = 0; ((*(buf+i)!='\0') && (*(buf+i)!='\n') && i < count); i++) {
 513                 local_buf[i] = toupper(buf[i]);
 514         }
 515         local_buf[i] = '\0';
 516         if ((i == 0) || (i > 8)) {
 517                 rc = -ENAMETOOLONG;
 518                 goto out_buf;
 519         }
 520
 521         down_write(&dcssblk_devices_sem);
 522         dev_info = dcssblk_get_device_by_name(local_buf);
 523         if (dev_info == NULL) {
 524                 up_write(&dcssblk_devices_sem);
 525                 PRINT_WARN("Segment %s is not loaded!\n", local_buf);
 526                 rc = -ENODEV;
 527                 goto out_buf;
 528         }
 529         if (atomic_read(&dev_info->use_count) != 0) {
 530                 up_write(&dcssblk_devices_sem);
 531                 PRINT_WARN("Segment %s is in use!\n", local_buf);
 532                 rc = -EBUSY;
 533                 goto out_buf;
 534         }
 535         list_del(&dev_info->lh);
 536
 537         del_gendisk(dev_info->gd);
 538         blk_put_queue(dev_info->dcssblk_queue);
 539         dev_info->gd->queue = NULL;
 540         put_disk(dev_info->gd);
 541         device_unregister(&dev_info->dev);
 542         segment_unload(dev_info->segment_name);
 543         PRINT_DEBUG("Segment %s unloaded successfully\n",
 544                         dev_info->segment_name);
 545         put_device(&dev_info->dev);
 546         up_write(&dcssblk_devices_sem);
 547
 548         rc = count;
 549 out_buf:
 550         kfree(local_buf);
 551         return rc;
 552 }
 553
 554 static int
 555 dcssblk_open(struct inode *inode, struct file *filp)
 556 {
 557         struct dcssblk_dev_info *dev_info;
 558         int rc;
 559
 560         dev_info = inode->i_bdev->bd_disk->private_data;
 561         if (NULL == dev_info) {
 562                 rc = -ENODEV;
 563                 goto out;
 564         }
 565         atomic_inc(&dev_info->use_count);
 566         inode->i_bdev->bd_block_size = 4096;
 567         rc = 0;
 568 out:
 569         return rc;
 570 }
 571
 572 static int
 573 dcssblk_release(struct inode *inode, struct file *filp)
 574 {
 575         struct dcssblk_dev_info *dev_info;
 576         int rc;
 577
 578         dev_info = inode->i_bdev->bd_disk->private_data;
 579         if (NULL == dev_info) {
 580                 rc = -ENODEV;
 581                 goto out;
 582         }
 583         down_write(&dcssblk_devices_sem);
 584         if (atomic_dec_and_test(&dev_info->use_count)
 585             && (dev_info->save_pending)) {
 586                 PRINT_INFO("Segment %s became idle and is being saved now\n",
 587                             dev_info->segment_name);
 588                 segment_replace(dev_info->segment_name);
 589                 dev_info->save_pending = 0;
 590         }
 591         up_write(&dcssblk_devices_sem);
 592         rc = 0;
 593 out:
 594         return rc;
 595 }
 596
 597 static int
 598 dcssblk_make_request(request_queue_t *q, struct bio *bio)
 599 {
 600         struct dcssblk_dev_info *dev_info;
 601         struct bio_vec *bvec;
 602         unsigned long index;
 603         unsigned long page_addr;
 604         unsigned long source_addr;
 605         unsigned long bytes_done;
 606         int i;
 607
 608         bytes_done = 0;
 609         dev_info = bio->bi_bdev->bd_disk->private_data;
 610         if (dev_info == NULL)
 611                 goto fail;
 612         if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
 613                 /* Request is not page-aligned. */
 614                 goto fail;
 615         if (((bio->bi_size >> 9) + bio->bi_sector)
 616                         > get_capacity(bio->bi_bdev->bd_disk)) {
 617                 /* Request beyond end of DCSS segment. */
 618                 goto fail;
 619         }
 620         index = (bio->bi_sector >> 3);
 621         bio_for_each_segment(bvec, bio, i) {
 622                 page_addr = (unsigned long)
 623                         page_address(bvec->bv_page) + bvec->bv_offset;
 624                 source_addr = dev_info->start + (index<<12) + bytes_done;
 625                 if (unlikely(page_addr & 4095) != 0 || (bvec->bv_len & 4095) != 0)
 626                         // More paranoia.
 627                         goto fail;
 628                 if (bio_data_dir(bio) == READ) {
 629                         memcpy((void*)page_addr, (void*)source_addr,
 630                                 bvec->bv_len);
 631                 } else {
 632                         memcpy((void*)source_addr, (void*)page_addr,
 633                                 bvec->bv_len);
 634                 }
 635                 bytes_done += bvec->bv_len;
 636         }
 637         bio_endio(bio, bytes_done, 0);
 638         return 0;
 639 fail:
 640         bio_io_error(bio, bytes_done);
 641         return 0;
 642 }
 643
 644 /*
 645  * The init/exit functions.
 646  */
 647 static void __exit
 648 dcssblk_exit(void)
 649 {
 650         int rc;
 651
 652         PRINT_DEBUG("DCSSBLOCK EXIT...\n");
 653         s390_root_dev_unregister(dcssblk_root_dev);
 654         rc = unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 655         if (rc) {
 656                 PRINT_ERR("unregister_blkdev() failed!\n");
 657         }
 658         PRINT_DEBUG("...finished!\n");
 659 }
 660
 661 static int __init
 662 dcssblk_init(void)
 663 {
 664         int rc;
 665
 666         PRINT_DEBUG("DCSSBLOCK INIT...\n");
 667         dcssblk_root_dev = s390_root_dev_register("dcssblk");
 668         if (IS_ERR(dcssblk_root_dev)) {
 669                 PRINT_ERR("device_register() failed!\n");
 670                 return PTR_ERR(dcssblk_root_dev);
 671         }
 672         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
 673         if (rc) {
 674                 PRINT_ERR("device_create_file(add) failed!\n");
 675                 s390_root_dev_unregister(dcssblk_root_dev);
 676                 return rc;
 677         }
 678         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
 679         if (rc) {
 680                 PRINT_ERR("device_create_file(remove) failed!\n");
 681                 s390_root_dev_unregister(dcssblk_root_dev);
 682                 return rc;
 683         }
 684         rc = register_blkdev(0, DCSSBLK_NAME);
 685         if (rc < 0) {
 686                 PRINT_ERR("Can't get dynamic major!\n");
 687                 s390_root_dev_unregister(dcssblk_root_dev);
 688                 return rc;
 689         }
 690         dcssblk_major = rc;
 691         init_rwsem(&dcssblk_devices_sem);
 692         PRINT_DEBUG("...finished!\n");
 693         return 0;
 694 }
 695
 696 module_init(dcssblk_init);
 697 module_exit(dcssblk_exit);
 698
 699 MODULE_LICENSE("GPL");