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/moduleparam.h>
   9 #include <linux/ctype.h>
  10 #include <linux/errno.h>
  11 #include <linux/init.h>
  12 #include <linux/slab.h>
  13 #include <linux/blkdev.h>
  14 #include <asm/extmem.h>
  15 #include <asm/io.h>
  16 #include <linux/completion.h>
  17 #include <linux/interrupt.h>
  18 #include <asm/s390_rdev.h>
  19
  20 //#define DCSSBLK_DEBUG         /* Debug messages on/off */
  21 #define DCSSBLK_NAME "dcssblk"
  22 #define DCSSBLK_MINORS_PER_DISK 1
  23 #define DCSSBLK_PARM_LEN 400
  24
  25 #ifdef DCSSBLK_DEBUG
  26 #define PRINT_DEBUG(x...) printk(KERN_DEBUG DCSSBLK_NAME " debug: " x)
  27 #else
  28 #define PRINT_DEBUG(x...) do {} while (0)
  29 #endif
  30 #define PRINT_INFO(x...)  printk(KERN_INFO DCSSBLK_NAME " info: " x)
  31 #define PRINT_WARN(x...)  printk(KERN_WARNING DCSSBLK_NAME " warning: " x)
  32 #define PRINT_ERR(x...)   printk(KERN_ERR DCSSBLK_NAME " error: " x)
  33
  34
  35 static int dcssblk_open(struct inode *inode, struct file *filp);
  36 static int dcssblk_release(struct inode *inode, struct file *filp);
  37 static int dcssblk_make_request(struct request_queue *q, struct bio *bio);
  38 static int dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
  39                                  unsigned long *data);
  40
  41 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  42
  43 static int dcssblk_major;
  44 static struct block_device_operations dcssblk_devops = {
  45         .owner          = THIS_MODULE,
  46         .open           = dcssblk_open,
  47         .release        = dcssblk_release,
  48         .direct_access  = dcssblk_direct_access,
  49 };
  50
  51 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  52                                   size_t count);
  53 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  54                                   size_t count);
  55 static ssize_t dcssblk_save_store(struct device * dev, struct device_attribute *attr, const char * buf,
  56                                   size_t count);
  57 static ssize_t dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf);
  58 static ssize_t dcssblk_shared_store(struct device * dev, struct device_attribute *attr, const char * buf,
  59                                   size_t count);
  60 static ssize_t dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf);
  61
  62 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  63 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  64 static DEVICE_ATTR(save, S_IWUSR | S_IRUGO, dcssblk_save_show,
  65                    dcssblk_save_store);
  66 static DEVICE_ATTR(shared, S_IWUSR | S_IRUGO, dcssblk_shared_show,
  67                    dcssblk_shared_store);
  68
  69 static struct device *dcssblk_root_dev;
  70
  71 struct dcssblk_dev_info {
  72         struct list_head lh;
  73         struct device dev;
  74         char segment_name[BUS_ID_SIZE];
  75         atomic_t use_count;
  76         struct gendisk *gd;
  77         unsigned long start;
  78         unsigned long end;
  79         int segment_type;
  80         unsigned char save_pending;
  81         unsigned char is_shared;
  82         struct request_queue *dcssblk_queue;
  83 };
  84
  85 static LIST_HEAD(dcssblk_devices);
  86 static struct rw_semaphore dcssblk_devices_sem;
  87
  88 /*
  89  * release function for segment device.
  90  */
  91 static void
  92 dcssblk_release_segment(struct device *dev)
  93 {
  94         PRINT_DEBUG("segment release fn called for %s\n", dev->bus_id);
  95         kfree(container_of(dev, struct dcssblk_dev_info, dev));
  96         module_put(THIS_MODULE);
  97 }
  98
  99 /*
 100  * get a minor number. needs to be called with
 101  * down_write(&dcssblk_devices_sem) and the
 102  * device needs to be enqueued before the semaphore is
 103  * freed.
 104  */
 105 static int
 106 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 107 {
 108         int minor, found;
 109         struct dcssblk_dev_info *entry;
 110
 111         if (dev_info == NULL)
 112                 return -EINVAL;
 113         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 114                 found = 0;
 115                 // test if minor available
 116                 list_for_each_entry(entry, &dcssblk_devices, lh)
 117                         if (minor == entry->gd->first_minor)
 118                                 found++;
 119                 if (!found) break; // got unused minor
 120         }
 121         if (found)
 122                 return -EBUSY;
 123         dev_info->gd->first_minor = minor;
 124         return 0;
 125 }
 126
 127 /*
 128  * get the struct dcssblk_dev_info from dcssblk_devices
 129  * for the given name.
 130  * down_read(&dcssblk_devices_sem) must be held.
 131  */
 132 static struct dcssblk_dev_info *
 133 dcssblk_get_device_by_name(char *name)
 134 {
 135         struct dcssblk_dev_info *entry;
 136
 137         list_for_each_entry(entry, &dcssblk_devices, lh) {
 138                 if (!strcmp(name, entry->segment_name)) {
 139                         return entry;
 140                 }
 141         }
 142         return NULL;
 143 }
 144
 145 /*
 146  * print appropriate error message for segment_load()/segment_type()
 147  * return code
 148  */
 149 static void
 150 dcssblk_segment_warn(int rc, char* seg_name)
 151 {
 152         switch (rc) {
 153         case -ENOENT:
 154                 PRINT_WARN("cannot load/query segment %s, does not exist\n",
 155                            seg_name);
 156                 break;
 157         case -ENOSYS:
 158                 PRINT_WARN("cannot load/query segment %s, not running on VM\n",
 159                            seg_name);
 160                 break;
 161         case -EIO:
 162                 PRINT_WARN("cannot load/query segment %s, hardware error\n",
 163                            seg_name);
 164                 break;
 165         case -ENOTSUPP:
 166                 PRINT_WARN("cannot load/query segment %s, is a multi-part "
 167                            "segment\n", seg_name);
 168                 break;
 169         case -ENOSPC:
 170                 PRINT_WARN("cannot load/query segment %s, overlaps with "
 171                            "storage\n", seg_name);
 172                 break;
 173         case -EBUSY:
 174                 PRINT_WARN("cannot load/query segment %s, overlaps with "
 175                            "already loaded dcss\n", seg_name);
 176                 break;
 177         case -EPERM:
 178                 PRINT_WARN("cannot load/query segment %s, already loaded in "
 179                            "incompatible mode\n", seg_name);
 180                 break;
 181         case -ENOMEM:
 182                 PRINT_WARN("cannot load/query segment %s, out of memory\n",
 183                            seg_name);
 184                 break;
 185         case -ERANGE:
 186                 PRINT_WARN("cannot load/query segment %s, exceeds kernel "
 187                            "mapping range\n", seg_name);
 188                 break;
 189         default:
 190                 PRINT_WARN("cannot load/query segment %s, return value %i\n",
 191                            seg_name, rc);
 192                 break;
 193         }
 194 }
 195
 196 static void dcssblk_unregister_callback(struct device *dev)
 197 {
 198         device_unregister(dev);
 199         put_device(dev);
 200 }
 201
 202 /*
 203  * device attribute for switching shared/nonshared (exclusive)
 204  * operation (show + store)
 205  */
 206 static ssize_t
 207 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 208 {
 209         struct dcssblk_dev_info *dev_info;
 210
 211         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 212         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 213 }
 214
 215 static ssize_t
 216 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 217 {
 218         struct dcssblk_dev_info *dev_info;
 219         int rc;
 220
 221         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0')) {
 222                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 223                 return -EINVAL;
 224         }
 225         down_write(&dcssblk_devices_sem);
 226         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 227         if (atomic_read(&dev_info->use_count)) {
 228                 PRINT_ERR("share: segment %s is busy!\n",
 229                           dev_info->segment_name);
 230                 rc = -EBUSY;
 231                 goto out;
 232         }
 233         if (inbuf[0] == '1') {
 234                 // reload segment in shared mode
 235                 rc = segment_modify_shared(dev_info->segment_name,
 236                                            SEGMENT_SHARED);
 237                 if (rc < 0) {
 238                         BUG_ON(rc == -EINVAL);
 239                         if (rc != -EAGAIN)
 240                                 goto removeseg;
 241                 } else {
 242                         dev_info->is_shared = 1;
 243                         switch (dev_info->segment_type) {
 244                                 case SEG_TYPE_SR:
 245                                 case SEG_TYPE_ER:
 246                                 case SEG_TYPE_SC:
 247                                         set_disk_ro(dev_info->gd,1);
 248                         }
 249                 }
 250         } else if (inbuf[0] == '0') {
 251                 // reload segment in exclusive mode
 252                 if (dev_info->segment_type == SEG_TYPE_SC) {
 253                         PRINT_ERR("Segment type SC (%s) cannot be loaded in "
 254                                   "non-shared mode\n", dev_info->segment_name);
 255                         rc = -EINVAL;
 256                         goto out;
 257                 }
 258                 rc = segment_modify_shared(dev_info->segment_name,
 259                                            SEGMENT_EXCLUSIVE);
 260                 if (rc < 0) {
 261                         BUG_ON(rc == -EINVAL);
 262                         if (rc != -EAGAIN)
 263                                 goto removeseg;
 264                 } else {
 265                         dev_info->is_shared = 0;
 266                         set_disk_ro(dev_info->gd, 0);
 267                 }
 268         } else {
 269                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 270                 rc = -EINVAL;
 271                 goto out;
 272         }
 273         rc = count;
 274         goto out;
 275
 276 removeseg:
 277         PRINT_ERR("Could not reload segment %s, removing it now!\n",
 278                         dev_info->segment_name);
 279         list_del(&dev_info->lh);
 280
 281         del_gendisk(dev_info->gd);
 282         blk_cleanup_queue(dev_info->dcssblk_queue);
 283         dev_info->gd->queue = NULL;
 284         put_disk(dev_info->gd);
 285         rc = device_schedule_callback(dev, dcssblk_unregister_callback);
 286 out:
 287         up_write(&dcssblk_devices_sem);
 288         return rc;
 289 }
 290
 291 /*
 292  * device attribute for save operation on current copy
 293  * of the segment. If the segment is busy, saving will
 294  * become pending until it gets released, which can be
 295  * undone by storing a non-true value to this entry.
 296  * (show + store)
 297  */
 298 static ssize_t
 299 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 300 {
 301         struct dcssblk_dev_info *dev_info;
 302
 303         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 304         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 305 }
 306
 307 static ssize_t
 308 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 309 {
 310         struct dcssblk_dev_info *dev_info;
 311
 312         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0')) {
 313                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 314                 return -EINVAL;
 315         }
 316         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 317
 318         down_write(&dcssblk_devices_sem);
 319         if (inbuf[0] == '1') {
 320                 if (atomic_read(&dev_info->use_count) == 0) {
 321                         // device is idle => we save immediately
 322                         PRINT_INFO("Saving segment %s\n",
 323                                    dev_info->segment_name);
 324                         segment_save(dev_info->segment_name);
 325                 }  else {
 326                         // device is busy => we save it when it becomes
 327                         // idle in dcssblk_release
 328                         PRINT_INFO("Segment %s is currently busy, it will "
 329                                    "be saved when it becomes idle...\n",
 330                                    dev_info->segment_name);
 331                         dev_info->save_pending = 1;
 332                 }
 333         } else if (inbuf[0] == '0') {
 334                 if (dev_info->save_pending) {
 335                         // device is busy & the user wants to undo his save
 336                         // request
 337                         dev_info->save_pending = 0;
 338                         PRINT_INFO("Pending save for segment %s deactivated\n",
 339                                         dev_info->segment_name);
 340                 }
 341         } else {
 342                 up_write(&dcssblk_devices_sem);
 343                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 344                 return -EINVAL;
 345         }
 346         up_write(&dcssblk_devices_sem);
 347         return count;
 348 }
 349
 350 /*
 351  * device attribute for adding devices
 352  */
 353 static ssize_t
 354 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 355 {
 356         int rc, i;
 357         struct dcssblk_dev_info *dev_info;
 358         char *local_buf;
 359         unsigned long seg_byte_size;
 360
 361         dev_info = NULL;
 362         if (dev != dcssblk_root_dev) {
 363                 rc = -EINVAL;
 364                 goto out_nobuf;
 365         }
 366         local_buf = kmalloc(count + 1, GFP_KERNEL);
 367         if (local_buf == NULL) {
 368                 rc = -ENOMEM;
 369                 goto out_nobuf;
 370         }
 371         /*
 372          * parse input
 373          */
 374         for (i = 0; ((buf[i] != '\0') && (buf[i] != '\n') && i < count); i++) {
 375                 local_buf[i] = toupper(buf[i]);
 376         }
 377         local_buf[i] = '\0';
 378         if ((i == 0) || (i > 8)) {
 379                 rc = -ENAMETOOLONG;
 380                 goto out;
 381         }
 382         /*
 383          * already loaded?
 384          */
 385         down_read(&dcssblk_devices_sem);
 386         dev_info = dcssblk_get_device_by_name(local_buf);
 387         up_read(&dcssblk_devices_sem);
 388         if (dev_info != NULL) {
 389                 PRINT_WARN("Segment %s already loaded!\n", local_buf);
 390                 rc = -EEXIST;
 391                 goto out;
 392         }
 393         /*
 394          * get a struct dcssblk_dev_info
 395          */
 396         dev_info = kzalloc(sizeof(struct dcssblk_dev_info), GFP_KERNEL);
 397         if (dev_info == NULL) {
 398                 rc = -ENOMEM;
 399                 goto out;
 400         }
 401
 402         strcpy(dev_info->segment_name, local_buf);
 403         strlcpy(dev_info->dev.bus_id, local_buf, BUS_ID_SIZE);
 404         dev_info->dev.release = dcssblk_release_segment;
 405         INIT_LIST_HEAD(&dev_info->lh);
 406
 407         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 408         if (dev_info->gd == NULL) {
 409                 rc = -ENOMEM;
 410                 goto free_dev_info;
 411         }
 412         dev_info->gd->major = dcssblk_major;
 413         dev_info->gd->fops = &dcssblk_devops;
 414         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 415         dev_info->gd->queue = dev_info->dcssblk_queue;
 416         dev_info->gd->private_data = dev_info;
 417         dev_info->gd->driverfs_dev = &dev_info->dev;
 418         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 419         blk_queue_hardsect_size(dev_info->dcssblk_queue, 4096);
 420         /*
 421          * load the segment
 422          */
 423         rc = segment_load(local_buf, SEGMENT_SHARED,
 424                                 &dev_info->start, &dev_info->end);
 425         if (rc < 0) {
 426                 dcssblk_segment_warn(rc, dev_info->segment_name);
 427                 goto dealloc_gendisk;
 428         }
 429         seg_byte_size = (dev_info->end - dev_info->start + 1);
 430         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 431         PRINT_INFO("Loaded segment %s, size = %lu Byte, "
 432                    "capacity = %lu (512 Byte) sectors\n", local_buf,
 433                    seg_byte_size, seg_byte_size >> 9);
 434
 435         dev_info->segment_type = rc;
 436         dev_info->save_pending = 0;
 437         dev_info->is_shared = 1;
 438         dev_info->dev.parent = dcssblk_root_dev;
 439
 440         /*
 441          * get minor, add to list
 442          */
 443         down_write(&dcssblk_devices_sem);
 444         rc = dcssblk_assign_free_minor(dev_info);
 445         if (rc) {
 446                 up_write(&dcssblk_devices_sem);
 447                 PRINT_ERR("No free minor number available! "
 448                           "Unloading segment...\n");
 449                 goto unload_seg;
 450         }
 451         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 452                 dev_info->gd->first_minor);
 453         list_add_tail(&dev_info->lh, &dcssblk_devices);
 454
 455         if (!try_module_get(THIS_MODULE)) {
 456                 rc = -ENODEV;
 457                 goto list_del;
 458         }
 459         /*
 460          * register the device
 461          */
 462         rc = device_register(&dev_info->dev);
 463         if (rc) {
 464                 PRINT_ERR("Segment %s could not be registered RC=%d\n",
 465                                 local_buf, rc);
 466                 module_put(THIS_MODULE);
 467                 goto list_del;
 468         }
 469         get_device(&dev_info->dev);
 470         rc = device_create_file(&dev_info->dev, &dev_attr_shared);
 471         if (rc)
 472                 goto unregister_dev;
 473         rc = device_create_file(&dev_info->dev, &dev_attr_save);
 474         if (rc)
 475                 goto unregister_dev;
 476
 477         add_disk(dev_info->gd);
 478
 479         switch (dev_info->segment_type) {
 480                 case SEG_TYPE_SR:
 481                 case SEG_TYPE_ER:
 482                 case SEG_TYPE_SC:
 483                         set_disk_ro(dev_info->gd,1);
 484                         break;
 485                 default:
 486                         set_disk_ro(dev_info->gd,0);
 487                         break;
 488         }
 489         PRINT_DEBUG("Segment %s loaded successfully\n", local_buf);
 490         up_write(&dcssblk_devices_sem);
 491         rc = count;
 492         goto out;
 493
 494 unregister_dev:
 495         PRINT_ERR("device_create_file() failed!\n");
 496         list_del(&dev_info->lh);
 497         blk_cleanup_queue(dev_info->dcssblk_queue);
 498         dev_info->gd->queue = NULL;
 499         put_disk(dev_info->gd);
 500         device_unregister(&dev_info->dev);
 501         segment_unload(dev_info->segment_name);
 502         put_device(&dev_info->dev);
 503         up_write(&dcssblk_devices_sem);
 504         goto out;
 505 list_del:
 506         list_del(&dev_info->lh);
 507         up_write(&dcssblk_devices_sem);
 508 unload_seg:
 509         segment_unload(local_buf);
 510 dealloc_gendisk:
 511         blk_cleanup_queue(dev_info->dcssblk_queue);
 512         dev_info->gd->queue = NULL;
 513         put_disk(dev_info->gd);
 514 free_dev_info:
 515         kfree(dev_info);
 516 out:
 517         kfree(local_buf);
 518 out_nobuf:
 519         return rc;
 520 }
 521
 522 /*
 523  * device attribute for removing devices
 524  */
 525 static ssize_t
 526 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 527 {
 528         struct dcssblk_dev_info *dev_info;
 529         int rc, i;
 530         char *local_buf;
 531
 532         if (dev != dcssblk_root_dev) {
 533                 return -EINVAL;
 534         }
 535         local_buf = kmalloc(count + 1, GFP_KERNEL);
 536         if (local_buf == NULL) {
 537                 return -ENOMEM;
 538         }
 539         /*
 540          * parse input
 541          */
 542         for (i = 0; ((*(buf+i)!='\0') && (*(buf+i)!='\n') && i < count); i++) {
 543                 local_buf[i] = toupper(buf[i]);
 544         }
 545         local_buf[i] = '\0';
 546         if ((i == 0) || (i > 8)) {
 547                 rc = -ENAMETOOLONG;
 548                 goto out_buf;
 549         }
 550
 551         down_write(&dcssblk_devices_sem);
 552         dev_info = dcssblk_get_device_by_name(local_buf);
 553         if (dev_info == NULL) {
 554                 up_write(&dcssblk_devices_sem);
 555                 PRINT_WARN("Segment %s is not loaded!\n", local_buf);
 556                 rc = -ENODEV;
 557                 goto out_buf;
 558         }
 559         if (atomic_read(&dev_info->use_count) != 0) {
 560                 up_write(&dcssblk_devices_sem);
 561                 PRINT_WARN("Segment %s is in use!\n", local_buf);
 562                 rc = -EBUSY;
 563                 goto out_buf;
 564         }
 565         list_del(&dev_info->lh);
 566
 567         del_gendisk(dev_info->gd);
 568         blk_cleanup_queue(dev_info->dcssblk_queue);
 569         dev_info->gd->queue = NULL;
 570         put_disk(dev_info->gd);
 571         device_unregister(&dev_info->dev);
 572         segment_unload(dev_info->segment_name);
 573         PRINT_DEBUG("Segment %s unloaded successfully\n",
 574                         dev_info->segment_name);
 575         put_device(&dev_info->dev);
 576         up_write(&dcssblk_devices_sem);
 577
 578         rc = count;
 579 out_buf:
 580         kfree(local_buf);
 581         return rc;
 582 }
 583
 584 static int
 585 dcssblk_open(struct inode *inode, struct file *filp)
 586 {
 587         struct dcssblk_dev_info *dev_info;
 588         int rc;
 589
 590         dev_info = inode->i_bdev->bd_disk->private_data;
 591         if (NULL == dev_info) {
 592                 rc = -ENODEV;
 593                 goto out;
 594         }
 595         atomic_inc(&dev_info->use_count);
 596         inode->i_bdev->bd_block_size = 4096;
 597         rc = 0;
 598 out:
 599         return rc;
 600 }
 601
 602 static int
 603 dcssblk_release(struct inode *inode, struct file *filp)
 604 {
 605         struct dcssblk_dev_info *dev_info;
 606         int rc;
 607
 608         dev_info = inode->i_bdev->bd_disk->private_data;
 609         if (NULL == dev_info) {
 610                 rc = -ENODEV;
 611                 goto out;
 612         }
 613         down_write(&dcssblk_devices_sem);
 614         if (atomic_dec_and_test(&dev_info->use_count)
 615             && (dev_info->save_pending)) {
 616                 PRINT_INFO("Segment %s became idle and is being saved now\n",
 617                             dev_info->segment_name);
 618                 segment_save(dev_info->segment_name);
 619                 dev_info->save_pending = 0;
 620         }
 621         up_write(&dcssblk_devices_sem);
 622         rc = 0;
 623 out:
 624         return rc;
 625 }
 626
 627 static int
 628 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 629 {
 630         struct dcssblk_dev_info *dev_info;
 631         struct bio_vec *bvec;
 632         unsigned long index;
 633         unsigned long page_addr;
 634         unsigned long source_addr;
 635         unsigned long bytes_done;
 636         int i;
 637
 638         bytes_done = 0;
 639         dev_info = bio->bi_bdev->bd_disk->private_data;
 640         if (dev_info == NULL)
 641                 goto fail;
 642         if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
 643                 /* Request is not page-aligned. */
 644                 goto fail;
 645         if (((bio->bi_size >> 9) + bio->bi_sector)
 646                         > get_capacity(bio->bi_bdev->bd_disk)) {
 647                 /* Request beyond end of DCSS segment. */
 648                 goto fail;
 649         }
 650         /* verify data transfer direction */
 651         if (dev_info->is_shared) {
 652                 switch (dev_info->segment_type) {
 653                 case SEG_TYPE_SR:
 654                 case SEG_TYPE_ER:
 655                 case SEG_TYPE_SC:
 656                         /* cannot write to these segments */
 657                         if (bio_data_dir(bio) == WRITE) {
 658                                 PRINT_WARN("rejecting write to ro segment %s\n", dev_info->dev.bus_id);
 659                                 goto fail;
 660                         }
 661                 }
 662         }
 663
 664         index = (bio->bi_sector >> 3);
 665         bio_for_each_segment(bvec, bio, i) {
 666                 page_addr = (unsigned long)
 667                         page_address(bvec->bv_page) + bvec->bv_offset;
 668                 source_addr = dev_info->start + (index<<12) + bytes_done;
 669                 if (unlikely((page_addr & 4095) != 0) || (bvec->bv_len & 4095) != 0)
 670                         // More paranoia.
 671                         goto fail;
 672                 if (bio_data_dir(bio) == READ) {
 673                         memcpy((void*)page_addr, (void*)source_addr,
 674                                 bvec->bv_len);
 675                 } else {
 676                         memcpy((void*)source_addr, (void*)page_addr,
 677                                 bvec->bv_len);
 678                 }
 679                 bytes_done += bvec->bv_len;
 680         }
 681         bio_endio(bio, 0);
 682         return 0;
 683 fail:
 684         bio_io_error(bio);
 685         return 0;
 686 }
 687
 688 static int
 689 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
 690                         unsigned long *data)
 691 {
 692         struct dcssblk_dev_info *dev_info;
 693         unsigned long pgoff;
 694
 695         dev_info = bdev->bd_disk->private_data;
 696         if (!dev_info)
 697                 return -ENODEV;
 698         if (secnum % (PAGE_SIZE/512))
 699                 return -EINVAL;
 700         pgoff = secnum / (PAGE_SIZE / 512);
 701         if ((pgoff+1)*PAGE_SIZE-1 > dev_info->end - dev_info->start)
 702                 return -ERANGE;
 703         *data = (unsigned long) (dev_info->start+pgoff*PAGE_SIZE);
 704         return 0;
 705 }
 706
 707 static void
 708 dcssblk_check_params(void)
 709 {
 710         int rc, i, j, k;
 711         char buf[9];
 712         struct dcssblk_dev_info *dev_info;
 713
 714         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 715              i++) {
 716                 for (j = i; (dcssblk_segments[j] != ',')  &&
 717                             (dcssblk_segments[j] != '\0') &&
 718                             (dcssblk_segments[j] != '(')  &&
 719                             (j - i) < 8; j++)
 720                 {
 721                         buf[j-i] = dcssblk_segments[j];
 722                 }
 723                 buf[j-i] = '\0';
 724                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 725                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 726                         for (k = 0; buf[k] != '\0'; k++)
 727                                 buf[k] = toupper(buf[k]);
 728                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 729                                 down_read(&dcssblk_devices_sem);
 730                                 dev_info = dcssblk_get_device_by_name(buf);
 731                                 up_read(&dcssblk_devices_sem);
 732                                 if (dev_info)
 733                                         dcssblk_shared_store(&dev_info->dev,
 734                                                              NULL, "0\n", 2);
 735                         }
 736                 }
 737                 while ((dcssblk_segments[j] != ',') &&
 738                        (dcssblk_segments[j] != '\0'))
 739                 {
 740                         j++;
 741                 }
 742                 if (dcssblk_segments[j] == '\0')
 743                         break;
 744                 i = j;
 745         }
 746 }
 747
 748 /*
 749  * The init/exit functions.
 750  */
 751 static void __exit
 752 dcssblk_exit(void)
 753 {
 754         PRINT_DEBUG("DCSSBLOCK EXIT...\n");
 755         s390_root_dev_unregister(dcssblk_root_dev);
 756         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 757         PRINT_DEBUG("...finished!\n");
 758 }
 759
 760 static int __init
 761 dcssblk_init(void)
 762 {
 763         int rc;
 764
 765         PRINT_DEBUG("DCSSBLOCK INIT...\n");
 766         dcssblk_root_dev = s390_root_dev_register("dcssblk");
 767         if (IS_ERR(dcssblk_root_dev)) {
 768                 PRINT_ERR("device_register() failed!\n");
 769                 return PTR_ERR(dcssblk_root_dev);
 770         }
 771         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
 772         if (rc) {
 773                 PRINT_ERR("device_create_file(add) failed!\n");
 774                 s390_root_dev_unregister(dcssblk_root_dev);
 775                 return rc;
 776         }
 777         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
 778         if (rc) {
 779                 PRINT_ERR("device_create_file(remove) failed!\n");
 780                 s390_root_dev_unregister(dcssblk_root_dev);
 781                 return rc;
 782         }
 783         rc = register_blkdev(0, DCSSBLK_NAME);
 784         if (rc < 0) {
 785                 PRINT_ERR("Can't get dynamic major!\n");
 786                 s390_root_dev_unregister(dcssblk_root_dev);
 787                 return rc;
 788         }
 789         dcssblk_major = rc;
 790         init_rwsem(&dcssblk_devices_sem);
 791
 792         dcssblk_check_params();
 793
 794         PRINT_DEBUG("...finished!\n");
 795         return 0;
 796 }
 797
 798 module_init(dcssblk_init);
 799 module_exit(dcssblk_exit);
 800
 801 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
 802 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
 803                  "comma-separated list, each name max. 8 chars.\n"
 804                  "Adding \"(local)\" to segment name equals echoing 0 to "
 805                  "/sys/devices/dcssblk/<segment name>/shared after loading "
 806                  "the segment - \n"
 807                  "e.g. segments=\"mydcss1,mydcss2,mydcss3(local)\"");
 808
 809 MODULE_LICENSE("GPL");