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 struct list_head dcssblk_devices = LIST_HEAD_INIT(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 /*
 197  * device attribute for switching shared/nonshared (exclusive)
 198  * operation (show + store)
 199  */
 200 static ssize_t
 201 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 202 {
 203         struct dcssblk_dev_info *dev_info;
 204
 205         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 206         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 207 }
 208
 209 static ssize_t
 210 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 211 {
 212         struct dcssblk_dev_info *dev_info;
 213         int rc;
 214
 215         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0')) {
 216                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 217                 return -EINVAL;
 218         }
 219         down_write(&dcssblk_devices_sem);
 220         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 221         if (atomic_read(&dev_info->use_count)) {
 222                 PRINT_ERR("share: segment %s is busy!\n",
 223                           dev_info->segment_name);
 224                 rc = -EBUSY;
 225                 goto out;
 226         }
 227         if (inbuf[0] == '1') {
 228                 // reload segment in shared mode
 229                 rc = segment_modify_shared(dev_info->segment_name,
 230                                            SEGMENT_SHARED);
 231                 if (rc < 0) {
 232                         BUG_ON(rc == -EINVAL);
 233                         if (rc != -EAGAIN)
 234                                 goto removeseg;
 235                 } else {
 236                         dev_info->is_shared = 1;
 237                         switch (dev_info->segment_type) {
 238                                 case SEG_TYPE_SR:
 239                                 case SEG_TYPE_ER:
 240                                 case SEG_TYPE_SC:
 241                                         set_disk_ro(dev_info->gd,1);
 242                         }
 243                 }
 244         } else if (inbuf[0] == '0') {
 245                 // reload segment in exclusive mode
 246                 if (dev_info->segment_type == SEG_TYPE_SC) {
 247                         PRINT_ERR("Segment type SC (%s) cannot be loaded in "
 248                                   "non-shared mode\n", dev_info->segment_name);
 249                         rc = -EINVAL;
 250                         goto out;
 251                 }
 252                 rc = segment_modify_shared(dev_info->segment_name,
 253                                            SEGMENT_EXCLUSIVE);
 254                 if (rc < 0) {
 255                         BUG_ON(rc == -EINVAL);
 256                         if (rc != -EAGAIN)
 257                                 goto removeseg;
 258                 } else {
 259                         dev_info->is_shared = 0;
 260                         set_disk_ro(dev_info->gd, 0);
 261                 }
 262         } else {
 263                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 264                 rc = -EINVAL;
 265                 goto out;
 266         }
 267         rc = count;
 268         goto out;
 269
 270 removeseg:
 271         PRINT_ERR("Could not reload segment %s, removing it now!\n",
 272                         dev_info->segment_name);
 273         list_del(&dev_info->lh);
 274
 275         del_gendisk(dev_info->gd);
 276         blk_cleanup_queue(dev_info->dcssblk_queue);
 277         dev_info->gd->queue = NULL;
 278         put_disk(dev_info->gd);
 279         device_unregister(dev);
 280         put_device(dev);
 281 out:
 282         up_write(&dcssblk_devices_sem);
 283         return rc;
 284 }
 285
 286 /*
 287  * device attribute for save operation on current copy
 288  * of the segment. If the segment is busy, saving will
 289  * become pending until it gets released, which can be
 290  * undone by storing a non-true value to this entry.
 291  * (show + store)
 292  */
 293 static ssize_t
 294 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 295 {
 296         struct dcssblk_dev_info *dev_info;
 297
 298         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 299         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 300 }
 301
 302 static ssize_t
 303 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 304 {
 305         struct dcssblk_dev_info *dev_info;
 306
 307         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0')) {
 308                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 309                 return -EINVAL;
 310         }
 311         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 312
 313         down_write(&dcssblk_devices_sem);
 314         if (inbuf[0] == '1') {
 315                 if (atomic_read(&dev_info->use_count) == 0) {
 316                         // device is idle => we save immediately
 317                         PRINT_INFO("Saving segment %s\n",
 318                                    dev_info->segment_name);
 319                         segment_save(dev_info->segment_name);
 320                 }  else {
 321                         // device is busy => we save it when it becomes
 322                         // idle in dcssblk_release
 323                         PRINT_INFO("Segment %s is currently busy, it will "
 324                                    "be saved when it becomes idle...\n",
 325                                    dev_info->segment_name);
 326                         dev_info->save_pending = 1;
 327                 }
 328         } else if (inbuf[0] == '0') {
 329                 if (dev_info->save_pending) {
 330                         // device is busy & the user wants to undo his save
 331                         // request
 332                         dev_info->save_pending = 0;
 333                         PRINT_INFO("Pending save for segment %s deactivated\n",
 334                                         dev_info->segment_name);
 335                 }
 336         } else {
 337                 up_write(&dcssblk_devices_sem);
 338                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 339                 return -EINVAL;
 340         }
 341         up_write(&dcssblk_devices_sem);
 342         return count;
 343 }
 344
 345 /*
 346  * device attribute for adding devices
 347  */
 348 static ssize_t
 349 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 350 {
 351         int rc, i;
 352         struct dcssblk_dev_info *dev_info;
 353         char *local_buf;
 354         unsigned long seg_byte_size;
 355
 356         dev_info = NULL;
 357         if (dev != dcssblk_root_dev) {
 358                 rc = -EINVAL;
 359                 goto out_nobuf;
 360         }
 361         local_buf = kmalloc(count + 1, GFP_KERNEL);
 362         if (local_buf == NULL) {
 363                 rc = -ENOMEM;
 364                 goto out_nobuf;
 365         }
 366         /*
 367          * parse input
 368          */
 369         for (i = 0; ((buf[i] != '\0') && (buf[i] != '\n') && i < count); i++) {
 370                 local_buf[i] = toupper(buf[i]);
 371         }
 372         local_buf[i] = '\0';
 373         if ((i == 0) || (i > 8)) {
 374                 rc = -ENAMETOOLONG;
 375                 goto out;
 376         }
 377         /*
 378          * already loaded?
 379          */
 380         down_read(&dcssblk_devices_sem);
 381         dev_info = dcssblk_get_device_by_name(local_buf);
 382         up_read(&dcssblk_devices_sem);
 383         if (dev_info != NULL) {
 384                 PRINT_WARN("Segment %s already loaded!\n", local_buf);
 385                 rc = -EEXIST;
 386                 goto out;
 387         }
 388         /*
 389          * get a struct dcssblk_dev_info
 390          */
 391         dev_info = kzalloc(sizeof(struct dcssblk_dev_info), GFP_KERNEL);
 392         if (dev_info == NULL) {
 393                 rc = -ENOMEM;
 394                 goto out;
 395         }
 396
 397         strcpy(dev_info->segment_name, local_buf);
 398         strlcpy(dev_info->dev.bus_id, local_buf, BUS_ID_SIZE);
 399         dev_info->dev.release = dcssblk_release_segment;
 400         INIT_LIST_HEAD(&dev_info->lh);
 401
 402         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 403         if (dev_info->gd == NULL) {
 404                 rc = -ENOMEM;
 405                 goto free_dev_info;
 406         }
 407         dev_info->gd->major = dcssblk_major;
 408         dev_info->gd->fops = &dcssblk_devops;
 409         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 410         dev_info->gd->queue = dev_info->dcssblk_queue;
 411         dev_info->gd->private_data = dev_info;
 412         dev_info->gd->driverfs_dev = &dev_info->dev;
 413         /*
 414          * load the segment
 415          */
 416         rc = segment_load(local_buf, SEGMENT_SHARED,
 417                                 &dev_info->start, &dev_info->end);
 418         if (rc < 0) {
 419                 dcssblk_segment_warn(rc, dev_info->segment_name);
 420                 goto dealloc_gendisk;
 421         }
 422         seg_byte_size = (dev_info->end - dev_info->start + 1);
 423         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 424         PRINT_INFO("Loaded segment %s, size = %lu Byte, "
 425                    "capacity = %lu (512 Byte) sectors\n", local_buf,
 426                    seg_byte_size, seg_byte_size >> 9);
 427
 428         dev_info->segment_type = rc;
 429         dev_info->save_pending = 0;
 430         dev_info->is_shared = 1;
 431         dev_info->dev.parent = dcssblk_root_dev;
 432
 433         /*
 434          * get minor, add to list
 435          */
 436         down_write(&dcssblk_devices_sem);
 437         rc = dcssblk_assign_free_minor(dev_info);
 438         if (rc) {
 439                 up_write(&dcssblk_devices_sem);
 440                 PRINT_ERR("No free minor number available! "
 441                           "Unloading segment...\n");
 442                 goto unload_seg;
 443         }
 444         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 445                 dev_info->gd->first_minor);
 446         list_add_tail(&dev_info->lh, &dcssblk_devices);
 447
 448         if (!try_module_get(THIS_MODULE)) {
 449                 rc = -ENODEV;
 450                 goto list_del;
 451         }
 452         /*
 453          * register the device
 454          */
 455         rc = device_register(&dev_info->dev);
 456         if (rc) {
 457                 PRINT_ERR("Segment %s could not be registered RC=%d\n",
 458                                 local_buf, rc);
 459                 module_put(THIS_MODULE);
 460                 goto list_del;
 461         }
 462         get_device(&dev_info->dev);
 463         rc = device_create_file(&dev_info->dev, &dev_attr_shared);
 464         if (rc)
 465                 goto unregister_dev;
 466         rc = device_create_file(&dev_info->dev, &dev_attr_save);
 467         if (rc)
 468                 goto unregister_dev;
 469
 470         add_disk(dev_info->gd);
 471
 472         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 473         blk_queue_hardsect_size(dev_info->dcssblk_queue, 4096);
 474
 475         switch (dev_info->segment_type) {
 476                 case SEG_TYPE_SR:
 477                 case SEG_TYPE_ER:
 478                 case SEG_TYPE_SC:
 479                         set_disk_ro(dev_info->gd,1);
 480                         break;
 481                 default:
 482                         set_disk_ro(dev_info->gd,0);
 483                         break;
 484         }
 485         PRINT_DEBUG("Segment %s loaded successfully\n", local_buf);
 486         up_write(&dcssblk_devices_sem);
 487         rc = count;
 488         goto out;
 489
 490 unregister_dev:
 491         PRINT_ERR("device_create_file() failed!\n");
 492         list_del(&dev_info->lh);
 493         blk_cleanup_queue(dev_info->dcssblk_queue);
 494         dev_info->gd->queue = NULL;
 495         put_disk(dev_info->gd);
 496         device_unregister(&dev_info->dev);
 497         segment_unload(dev_info->segment_name);
 498         put_device(&dev_info->dev);
 499         up_write(&dcssblk_devices_sem);
 500         goto out;
 501 list_del:
 502         list_del(&dev_info->lh);
 503         up_write(&dcssblk_devices_sem);
 504 unload_seg:
 505         segment_unload(local_buf);
 506 dealloc_gendisk:
 507         blk_cleanup_queue(dev_info->dcssblk_queue);
 508         dev_info->gd->queue = NULL;
 509         put_disk(dev_info->gd);
 510 free_dev_info:
 511         kfree(dev_info);
 512 out:
 513         kfree(local_buf);
 514 out_nobuf:
 515         return rc;
 516 }
 517
 518 /*
 519  * device attribute for removing devices
 520  */
 521 static ssize_t
 522 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 523 {
 524         struct dcssblk_dev_info *dev_info;
 525         int rc, i;
 526         char *local_buf;
 527
 528         if (dev != dcssblk_root_dev) {
 529                 return -EINVAL;
 530         }
 531         local_buf = kmalloc(count + 1, GFP_KERNEL);
 532         if (local_buf == NULL) {
 533                 return -ENOMEM;
 534         }
 535         /*
 536          * parse input
 537          */
 538         for (i = 0; ((*(buf+i)!='\0') && (*(buf+i)!='\n') && i < count); i++) {
 539                 local_buf[i] = toupper(buf[i]);
 540         }
 541         local_buf[i] = '\0';
 542         if ((i == 0) || (i > 8)) {
 543                 rc = -ENAMETOOLONG;
 544                 goto out_buf;
 545         }
 546
 547         down_write(&dcssblk_devices_sem);
 548         dev_info = dcssblk_get_device_by_name(local_buf);
 549         if (dev_info == NULL) {
 550                 up_write(&dcssblk_devices_sem);
 551                 PRINT_WARN("Segment %s is not loaded!\n", local_buf);
 552                 rc = -ENODEV;
 553                 goto out_buf;
 554         }
 555         if (atomic_read(&dev_info->use_count) != 0) {
 556                 up_write(&dcssblk_devices_sem);
 557                 PRINT_WARN("Segment %s is in use!\n", local_buf);
 558                 rc = -EBUSY;
 559                 goto out_buf;
 560         }
 561         list_del(&dev_info->lh);
 562
 563         del_gendisk(dev_info->gd);
 564         blk_cleanup_queue(dev_info->dcssblk_queue);
 565         dev_info->gd->queue = NULL;
 566         put_disk(dev_info->gd);
 567         device_unregister(&dev_info->dev);
 568         segment_unload(dev_info->segment_name);
 569         PRINT_DEBUG("Segment %s unloaded successfully\n",
 570                         dev_info->segment_name);
 571         put_device(&dev_info->dev);
 572         up_write(&dcssblk_devices_sem);
 573
 574         rc = count;
 575 out_buf:
 576         kfree(local_buf);
 577         return rc;
 578 }
 579
 580 static int
 581 dcssblk_open(struct inode *inode, struct file *filp)
 582 {
 583         struct dcssblk_dev_info *dev_info;
 584         int rc;
 585
 586         dev_info = inode->i_bdev->bd_disk->private_data;
 587         if (NULL == dev_info) {
 588                 rc = -ENODEV;
 589                 goto out;
 590         }
 591         atomic_inc(&dev_info->use_count);
 592         inode->i_bdev->bd_block_size = 4096;
 593         rc = 0;
 594 out:
 595         return rc;
 596 }
 597
 598 static int
 599 dcssblk_release(struct inode *inode, struct file *filp)
 600 {
 601         struct dcssblk_dev_info *dev_info;
 602         int rc;
 603
 604         dev_info = inode->i_bdev->bd_disk->private_data;
 605         if (NULL == dev_info) {
 606                 rc = -ENODEV;
 607                 goto out;
 608         }
 609         down_write(&dcssblk_devices_sem);
 610         if (atomic_dec_and_test(&dev_info->use_count)
 611             && (dev_info->save_pending)) {
 612                 PRINT_INFO("Segment %s became idle and is being saved now\n",
 613                             dev_info->segment_name);
 614                 segment_save(dev_info->segment_name);
 615                 dev_info->save_pending = 0;
 616         }
 617         up_write(&dcssblk_devices_sem);
 618         rc = 0;
 619 out:
 620         return rc;
 621 }
 622
 623 static int
 624 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 625 {
 626         struct dcssblk_dev_info *dev_info;
 627         struct bio_vec *bvec;
 628         unsigned long index;
 629         unsigned long page_addr;
 630         unsigned long source_addr;
 631         unsigned long bytes_done;
 632         int i;
 633
 634         bytes_done = 0;
 635         dev_info = bio->bi_bdev->bd_disk->private_data;
 636         if (dev_info == NULL)
 637                 goto fail;
 638         if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
 639                 /* Request is not page-aligned. */
 640                 goto fail;
 641         if (((bio->bi_size >> 9) + bio->bi_sector)
 642                         > get_capacity(bio->bi_bdev->bd_disk)) {
 643                 /* Request beyond end of DCSS segment. */
 644                 goto fail;
 645         }
 646         /* verify data transfer direction */
 647         if (dev_info->is_shared) {
 648                 switch (dev_info->segment_type) {
 649                 case SEG_TYPE_SR:
 650                 case SEG_TYPE_ER:
 651                 case SEG_TYPE_SC:
 652                         /* cannot write to these segments */
 653                         if (bio_data_dir(bio) == WRITE) {
 654                                 PRINT_WARN("rejecting write to ro segment %s\n", dev_info->dev.bus_id);
 655                                 goto fail;
 656                         }
 657                 }
 658         }
 659
 660         index = (bio->bi_sector >> 3);
 661         bio_for_each_segment(bvec, bio, i) {
 662                 page_addr = (unsigned long)
 663                         page_address(bvec->bv_page) + bvec->bv_offset;
 664                 source_addr = dev_info->start + (index<<12) + bytes_done;
 665                 if (unlikely(page_addr & 4095) != 0 || (bvec->bv_len & 4095) != 0)
 666                         // More paranoia.
 667                         goto fail;
 668                 if (bio_data_dir(bio) == READ) {
 669                         memcpy((void*)page_addr, (void*)source_addr,
 670                                 bvec->bv_len);
 671                 } else {
 672                         memcpy((void*)source_addr, (void*)page_addr,
 673                                 bvec->bv_len);
 674                 }
 675                 bytes_done += bvec->bv_len;
 676         }
 677         bio_endio(bio, 0);
 678         return 0;
 679 fail:
 680         bio_io_error(bio);
 681         return 0;
 682 }
 683
 684 static int
 685 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
 686                         unsigned long *data)
 687 {
 688         struct dcssblk_dev_info *dev_info;
 689         unsigned long pgoff;
 690
 691         dev_info = bdev->bd_disk->private_data;
 692         if (!dev_info)
 693                 return -ENODEV;
 694         if (secnum % (PAGE_SIZE/512))
 695                 return -EINVAL;
 696         pgoff = secnum / (PAGE_SIZE / 512);
 697         if ((pgoff+1)*PAGE_SIZE-1 > dev_info->end - dev_info->start)
 698                 return -ERANGE;
 699         *data = (unsigned long) (dev_info->start+pgoff*PAGE_SIZE);
 700         return 0;
 701 }
 702
 703 static void
 704 dcssblk_check_params(void)
 705 {
 706         int rc, i, j, k;
 707         char buf[9];
 708         struct dcssblk_dev_info *dev_info;
 709
 710         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 711              i++) {
 712                 for (j = i; (dcssblk_segments[j] != ',')  &&
 713                             (dcssblk_segments[j] != '\0') &&
 714                             (dcssblk_segments[j] != '(')  &&
 715                             (j - i) < 8; j++)
 716                 {
 717                         buf[j-i] = dcssblk_segments[j];
 718                 }
 719                 buf[j-i] = '\0';
 720                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 721                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 722                         for (k = 0; buf[k] != '\0'; k++)
 723                                 buf[k] = toupper(buf[k]);
 724                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 725                                 down_read(&dcssblk_devices_sem);
 726                                 dev_info = dcssblk_get_device_by_name(buf);
 727                                 up_read(&dcssblk_devices_sem);
 728                                 if (dev_info)
 729                                         dcssblk_shared_store(&dev_info->dev,
 730                                                              NULL, "0\n", 2);
 731                         }
 732                 }
 733                 while ((dcssblk_segments[j] != ',') &&
 734                        (dcssblk_segments[j] != '\0'))
 735                 {
 736                         j++;
 737                 }
 738                 if (dcssblk_segments[j] == '\0')
 739                         break;
 740                 i = j;
 741         }
 742 }
 743
 744 /*
 745  * The init/exit functions.
 746  */
 747 static void __exit
 748 dcssblk_exit(void)
 749 {
 750         PRINT_DEBUG("DCSSBLOCK EXIT...\n");
 751         s390_root_dev_unregister(dcssblk_root_dev);
 752         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 753         PRINT_DEBUG("...finished!\n");
 754 }
 755
 756 static int __init
 757 dcssblk_init(void)
 758 {
 759         int rc;
 760
 761         PRINT_DEBUG("DCSSBLOCK INIT...\n");
 762         dcssblk_root_dev = s390_root_dev_register("dcssblk");
 763         if (IS_ERR(dcssblk_root_dev)) {
 764                 PRINT_ERR("device_register() failed!\n");
 765                 return PTR_ERR(dcssblk_root_dev);
 766         }
 767         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
 768         if (rc) {
 769                 PRINT_ERR("device_create_file(add) failed!\n");
 770                 s390_root_dev_unregister(dcssblk_root_dev);
 771                 return rc;
 772         }
 773         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
 774         if (rc) {
 775                 PRINT_ERR("device_create_file(remove) failed!\n");
 776                 s390_root_dev_unregister(dcssblk_root_dev);
 777                 return rc;
 778         }
 779         rc = register_blkdev(0, DCSSBLK_NAME);
 780         if (rc < 0) {
 781                 PRINT_ERR("Can't get dynamic major!\n");
 782                 s390_root_dev_unregister(dcssblk_root_dev);
 783                 return rc;
 784         }
 785         dcssblk_major = rc;
 786         init_rwsem(&dcssblk_devices_sem);
 787
 788         dcssblk_check_params();
 789
 790         PRINT_DEBUG("...finished!\n");
 791         return 0;
 792 }
 793
 794 module_init(dcssblk_init);
 795 module_exit(dcssblk_exit);
 796
 797 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
 798 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
 799                  "comma-separated list, each name max. 8 chars.\n"
 800                  "Adding \"(local)\" to segment name equals echoing 0 to "
 801                  "/sys/devices/dcssblk/<segment name>/shared after loading "
 802                  "the segment - \n"
 803                  "e.g. segments=\"mydcss1,mydcss2,mydcss3(local)\"");
 804
 805 MODULE_LICENSE("GPL");