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/ccwdev.h>         // for s390_root_dev_(un)register()
  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
  39 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  40
  41 static int dcssblk_major;
  42 static struct block_device_operations dcssblk_devops = {
  43         .owner   = THIS_MODULE,
  44         .open    = dcssblk_open,
  45         .release = dcssblk_release,
  46 };
  47
  48 static ssize_t dcssblk_add_store(struct device * dev, const char * buf,
  49                                   size_t count);
  50 static ssize_t dcssblk_remove_store(struct device * dev, const char * buf,
  51                                   size_t count);
  52 static ssize_t dcssblk_save_store(struct device * dev, const char * buf,
  53                                   size_t count);
  54 static ssize_t dcssblk_save_show(struct device *dev, char *buf);
  55 static ssize_t dcssblk_shared_store(struct device * dev, const char * buf,
  56                                   size_t count);
  57 static ssize_t dcssblk_shared_show(struct device *dev, char *buf);
  58
  59 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  60 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  61 static DEVICE_ATTR(save, S_IWUSR | S_IRUGO, dcssblk_save_show,
  62                    dcssblk_save_store);
  63 static DEVICE_ATTR(shared, S_IWUSR | S_IRUGO, dcssblk_shared_show,
  64                    dcssblk_shared_store);
  65
  66 static struct device *dcssblk_root_dev;
  67
  68 struct dcssblk_dev_info {
  69         struct list_head lh;
  70         struct device dev;
  71         char segment_name[BUS_ID_SIZE];
  72         atomic_t use_count;
  73         struct gendisk *gd;
  74         unsigned long start;
  75         unsigned long end;
  76         int segment_type;
  77         unsigned char save_pending;
  78         unsigned char is_shared;
  79         struct request_queue *dcssblk_queue;
  80 };
  81
  82 static struct list_head dcssblk_devices = LIST_HEAD_INIT(dcssblk_devices);
  83 static struct rw_semaphore dcssblk_devices_sem;
  84
  85 /*
  86  * release function for segment device.
  87  */
  88 static void
  89 dcssblk_release_segment(struct device *dev)
  90 {
  91         PRINT_DEBUG("segment release fn called for %s\n", dev->bus_id);
  92         kfree(container_of(dev, struct dcssblk_dev_info, dev));
  93         module_put(THIS_MODULE);
  94 }
  95
  96 /*
  97  * get a minor number. needs to be called with
  98  * down_write(&dcssblk_devices_sem) and the
  99  * device needs to be enqueued before the semaphore is
 100  * freed.
 101  */
 102 static inline int
 103 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 104 {
 105         int minor, found;
 106         struct dcssblk_dev_info *entry;
 107
 108         if (dev_info == NULL)
 109                 return -EINVAL;
 110         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 111                 found = 0;
 112                 // test if minor available
 113                 list_for_each_entry(entry, &dcssblk_devices, lh)
 114                         if (minor == entry->gd->first_minor)
 115                                 found++;
 116                 if (!found) break; // got unused minor
 117         }
 118         if (found)
 119                 return -EBUSY;
 120         dev_info->gd->first_minor = minor;
 121         return 0;
 122 }
 123
 124 /*
 125  * get the struct dcssblk_dev_info from dcssblk_devices
 126  * for the given name.
 127  * down_read(&dcssblk_devices_sem) must be held.
 128  */
 129 static struct dcssblk_dev_info *
 130 dcssblk_get_device_by_name(char *name)
 131 {
 132         struct dcssblk_dev_info *entry;
 133
 134         list_for_each_entry(entry, &dcssblk_devices, lh) {
 135                 if (!strcmp(name, entry->segment_name)) {
 136                         return entry;
 137                 }
 138         }
 139         return NULL;
 140 }
 141
 142 /*
 143  * print appropriate error message for segment_load()/segment_type()
 144  * return code
 145  */
 146 static void
 147 dcssblk_segment_warn(int rc, char* seg_name)
 148 {
 149         switch (rc) {
 150         case -ENOENT:
 151                 PRINT_WARN("cannot load/query segment %s, does not exist\n",
 152                            seg_name);
 153                 break;
 154         case -ENOSYS:
 155                 PRINT_WARN("cannot load/query segment %s, not running on VM\n",
 156                            seg_name);
 157                 break;
 158         case -EIO:
 159                 PRINT_WARN("cannot load/query segment %s, hardware error\n",
 160                            seg_name);
 161                 break;
 162         case -ENOTSUPP:
 163                 PRINT_WARN("cannot load/query segment %s, is a multi-part "
 164                            "segment\n", seg_name);
 165                 break;
 166         case -ENOSPC:
 167                 PRINT_WARN("cannot load/query segment %s, overlaps with "
 168                            "storage\n", seg_name);
 169                 break;
 170         case -EBUSY:
 171                 PRINT_WARN("cannot load/query segment %s, overlaps with "
 172                            "already loaded dcss\n", seg_name);
 173                 break;
 174         case -EPERM:
 175                 PRINT_WARN("cannot load/query segment %s, already loaded in "
 176                            "incompatible mode\n", seg_name);
 177                 break;
 178         case -ENOMEM:
 179                 PRINT_WARN("cannot load/query segment %s, out of memory\n",
 180                            seg_name);
 181                 break;
 182         case -ERANGE:
 183                 PRINT_WARN("cannot load/query segment %s, exceeds kernel "
 184                            "mapping range\n", seg_name);
 185                 break;
 186         default:
 187                 PRINT_WARN("cannot load/query segment %s, return value %i\n",
 188                            seg_name, rc);
 189                 break;
 190         }
 191 }
 192
 193 /*
 194  * device attribute for switching shared/nonshared (exclusive)
 195  * operation (show + store)
 196  */
 197 static ssize_t
 198 dcssblk_shared_show(struct device *dev, char *buf)
 199 {
 200         struct dcssblk_dev_info *dev_info;
 201
 202         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 203         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 204 }
 205
 206 static ssize_t
 207 dcssblk_shared_store(struct device *dev, const char *inbuf, size_t count)
 208 {
 209         struct dcssblk_dev_info *dev_info;
 210         int rc;
 211
 212         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0')) {
 213                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 214                 return -EINVAL;
 215         }
 216         down_write(&dcssblk_devices_sem);
 217         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 218         if (atomic_read(&dev_info->use_count)) {
 219                 PRINT_ERR("share: segment %s is busy!\n",
 220                           dev_info->segment_name);
 221                 rc = -EBUSY;
 222                 goto out;
 223         }
 224         if (inbuf[0] == '1') {
 225                 // reload segment in shared mode
 226                 rc = segment_modify_shared(dev_info->segment_name,
 227                                            SEGMENT_SHARED);
 228                 if (rc < 0) {
 229                         BUG_ON(rc == -EINVAL);
 230                         if (rc == -EIO || rc == -ENOENT)
 231                                 goto removeseg;
 232                 } else {
 233                         dev_info->is_shared = 1;
 234                         switch (dev_info->segment_type) {
 235                                 case SEG_TYPE_SR:
 236                                 case SEG_TYPE_ER:
 237                                 case SEG_TYPE_SC:
 238                                         set_disk_ro(dev_info->gd,1);
 239                         }
 240                 }
 241         } else if (inbuf[0] == '0') {
 242                 // reload segment in exclusive mode
 243                 if (dev_info->segment_type == SEG_TYPE_SC) {
 244                         PRINT_ERR("Segment type SC (%s) cannot be loaded in "
 245                                   "non-shared mode\n", dev_info->segment_name);
 246                         rc = -EINVAL;
 247                         goto out;
 248                 }
 249                 rc = segment_modify_shared(dev_info->segment_name,
 250                                            SEGMENT_EXCLUSIVE);
 251                 if (rc < 0) {
 252                         BUG_ON(rc == -EINVAL);
 253                         if (rc == -EIO || rc == -ENOENT)
 254                                 goto removeseg;
 255                 } else {
 256                         dev_info->is_shared = 0;
 257                         set_disk_ro(dev_info->gd, 0);
 258                 }
 259         } else {
 260                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 261                 rc = -EINVAL;
 262                 goto out;
 263         }
 264         rc = count;
 265         goto out;
 266
 267 removeseg:
 268         PRINT_ERR("Could not reload segment %s, removing it now!\n",
 269                         dev_info->segment_name);
 270         list_del(&dev_info->lh);
 271
 272         del_gendisk(dev_info->gd);
 273         blk_put_queue(dev_info->dcssblk_queue);
 274         dev_info->gd->queue = NULL;
 275         put_disk(dev_info->gd);
 276         device_unregister(dev);
 277         put_device(dev);
 278 out:
 279         up_write(&dcssblk_devices_sem);
 280         return rc;
 281 }
 282
 283 /*
 284  * device attribute for save operation on current copy
 285  * of the segment. If the segment is busy, saving will
 286  * become pending until it gets released, which can be
 287  * undone by storing a non-true value to this entry.
 288  * (show + store)
 289  */
 290 static ssize_t
 291 dcssblk_save_show(struct device *dev, char *buf)
 292 {
 293         struct dcssblk_dev_info *dev_info;
 294
 295         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 296         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 297 }
 298
 299 static ssize_t
 300 dcssblk_save_store(struct device *dev, const char *inbuf, size_t count)
 301 {
 302         struct dcssblk_dev_info *dev_info;
 303
 304         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0')) {
 305                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 306                 return -EINVAL;
 307         }
 308         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 309
 310         down_write(&dcssblk_devices_sem);
 311         if (inbuf[0] == '1') {
 312                 if (atomic_read(&dev_info->use_count) == 0) {
 313                         // device is idle => we save immediately
 314                         PRINT_INFO("Saving segment %s\n",
 315                                    dev_info->segment_name);
 316                         segment_save(dev_info->segment_name);
 317                 }  else {
 318                         // device is busy => we save it when it becomes
 319                         // idle in dcssblk_release
 320                         PRINT_INFO("Segment %s is currently busy, it will "
 321                                    "be saved when it becomes idle...\n",
 322                                    dev_info->segment_name);
 323                         dev_info->save_pending = 1;
 324                 }
 325         } else if (inbuf[0] == '0') {
 326                 if (dev_info->save_pending) {
 327                         // device is busy & the user wants to undo his save
 328                         // request
 329                         dev_info->save_pending = 0;
 330                         PRINT_INFO("Pending save for segment %s deactivated\n",
 331                                         dev_info->segment_name);
 332                 }
 333         } else {
 334                 up_write(&dcssblk_devices_sem);
 335                 PRINT_WARN("Invalid value, must be 0 or 1\n");
 336                 return -EINVAL;
 337         }
 338         up_write(&dcssblk_devices_sem);
 339         return count;
 340 }
 341
 342 /*
 343  * device attribute for adding devices
 344  */
 345 static ssize_t
 346 dcssblk_add_store(struct device *dev, const char *buf, size_t count)
 347 {
 348         int rc, i;
 349         struct dcssblk_dev_info *dev_info;
 350         char *local_buf;
 351         unsigned long seg_byte_size;
 352
 353         dev_info = NULL;
 354         if (dev != dcssblk_root_dev) {
 355                 rc = -EINVAL;
 356                 goto out_nobuf;
 357         }
 358         local_buf = kmalloc(count + 1, GFP_KERNEL);
 359         if (local_buf == NULL) {
 360                 rc = -ENOMEM;
 361                 goto out_nobuf;
 362         }
 363         /*
 364          * parse input
 365          */
 366         for (i = 0; ((buf[i] != '\0') && (buf[i] != '\n') && i < count); i++) {
 367                 local_buf[i] = toupper(buf[i]);
 368         }
 369         local_buf[i] = '\0';
 370         if ((i == 0) || (i > 8)) {
 371                 rc = -ENAMETOOLONG;
 372                 goto out;
 373         }
 374         /*
 375          * already loaded?
 376          */
 377         down_read(&dcssblk_devices_sem);
 378         dev_info = dcssblk_get_device_by_name(local_buf);
 379         up_read(&dcssblk_devices_sem);
 380         if (dev_info != NULL) {
 381                 PRINT_WARN("Segment %s already loaded!\n", local_buf);
 382                 rc = -EEXIST;
 383                 goto out;
 384         }
 385         /*
 386          * get a struct dcssblk_dev_info
 387          */
 388         dev_info = kmalloc(sizeof(struct dcssblk_dev_info), GFP_KERNEL);
 389         if (dev_info == NULL) {
 390                 rc = -ENOMEM;
 391                 goto out;
 392         }
 393         memset(dev_info, 0, sizeof(struct dcssblk_dev_info));
 394
 395         strcpy(dev_info->segment_name, local_buf);
 396         strlcpy(dev_info->dev.bus_id, local_buf, BUS_ID_SIZE);
 397         dev_info->dev.release = dcssblk_release_segment;
 398         INIT_LIST_HEAD(&dev_info->lh);
 399
 400         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 401         if (dev_info->gd == NULL) {
 402                 rc = -ENOMEM;
 403                 goto free_dev_info;
 404         }
 405         dev_info->gd->major = dcssblk_major;
 406         dev_info->gd->fops = &dcssblk_devops;
 407         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 408         dev_info->gd->queue = dev_info->dcssblk_queue;
 409         dev_info->gd->private_data = dev_info;
 410         dev_info->gd->driverfs_dev = &dev_info->dev;
 411         /*
 412          * load the segment
 413          */
 414         rc = segment_load(local_buf, SEGMENT_SHARED,
 415                                 &dev_info->start, &dev_info->end);
 416         if (rc < 0) {
 417                 dcssblk_segment_warn(rc, dev_info->segment_name);
 418                 goto dealloc_gendisk;
 419         }
 420         seg_byte_size = (dev_info->end - dev_info->start + 1);
 421         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 422         PRINT_INFO("Loaded segment %s, size = %lu Byte, "
 423                    "capacity = %lu (512 Byte) sectors\n", local_buf,
 424                    seg_byte_size, seg_byte_size >> 9);
 425
 426         dev_info->segment_type = rc;
 427         dev_info->save_pending = 0;
 428         dev_info->is_shared = 1;
 429         dev_info->dev.parent = dcssblk_root_dev;
 430
 431         /*
 432          * get minor, add to list
 433          */
 434         down_write(&dcssblk_devices_sem);
 435         rc = dcssblk_assign_free_minor(dev_info);
 436         if (rc) {
 437                 up_write(&dcssblk_devices_sem);
 438                 PRINT_ERR("No free minor number available! "
 439                           "Unloading segment...\n");
 440                 goto unload_seg;
 441         }
 442         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 443                 dev_info->gd->first_minor);
 444         list_add_tail(&dev_info->lh, &dcssblk_devices);
 445
 446         if (!try_module_get(THIS_MODULE)) {
 447                 rc = -ENODEV;
 448                 goto list_del;
 449         }
 450         /*
 451          * register the device
 452          */
 453         rc = device_register(&dev_info->dev);
 454         if (rc) {
 455                 PRINT_ERR("Segment %s could not be registered RC=%d\n",
 456                                 local_buf, rc);
 457                 module_put(THIS_MODULE);
 458                 goto list_del;
 459         }
 460         get_device(&dev_info->dev);
 461         rc = device_create_file(&dev_info->dev, &dev_attr_shared);
 462         if (rc)
 463                 goto unregister_dev;
 464         rc = device_create_file(&dev_info->dev, &dev_attr_save);
 465         if (rc)
 466                 goto unregister_dev;
 467
 468         add_disk(dev_info->gd);
 469
 470         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 471         blk_queue_hardsect_size(dev_info->dcssblk_queue, 4096);
 472
 473         switch (dev_info->segment_type) {
 474                 case SEG_TYPE_SR:
 475                 case SEG_TYPE_ER:
 476                 case SEG_TYPE_SC:
 477                         set_disk_ro(dev_info->gd,1);
 478                         break;
 479                 default:
 480                         set_disk_ro(dev_info->gd,0);
 481                         break;
 482         }
 483         PRINT_DEBUG("Segment %s loaded successfully\n", local_buf);
 484         up_write(&dcssblk_devices_sem);
 485         rc = count;
 486         goto out;
 487
 488 unregister_dev:
 489         PRINT_ERR("device_create_file() failed!\n");
 490         list_del(&dev_info->lh);
 491         blk_put_queue(dev_info->dcssblk_queue);
 492         dev_info->gd->queue = NULL;
 493         put_disk(dev_info->gd);
 494         device_unregister(&dev_info->dev);
 495         segment_unload(dev_info->segment_name);
 496         put_device(&dev_info->dev);
 497         up_write(&dcssblk_devices_sem);
 498         goto out;
 499 list_del:
 500         list_del(&dev_info->lh);
 501         up_write(&dcssblk_devices_sem);
 502 unload_seg:
 503         segment_unload(local_buf);
 504 dealloc_gendisk:
 505         blk_put_queue(dev_info->dcssblk_queue);
 506         dev_info->gd->queue = NULL;
 507         put_disk(dev_info->gd);
 508 free_dev_info:
 509         kfree(dev_info);
 510 out:
 511         kfree(local_buf);
 512 out_nobuf:
 513         return rc;
 514 }
 515
 516 /*
 517  * device attribute for removing devices
 518  */
 519 static ssize_t
 520 dcssblk_remove_store(struct device *dev, const char *buf, size_t count)
 521 {
 522         struct dcssblk_dev_info *dev_info;
 523         int rc, i;
 524         char *local_buf;
 525
 526         if (dev != dcssblk_root_dev) {
 527                 return -EINVAL;
 528         }
 529         local_buf = kmalloc(count + 1, GFP_KERNEL);
 530         if (local_buf == NULL) {
 531                 return -ENOMEM;
 532         }
 533         /*
 534          * parse input
 535          */
 536         for (i = 0; ((*(buf+i)!='\0') && (*(buf+i)!='\n') && i < count); i++) {
 537                 local_buf[i] = toupper(buf[i]);
 538         }
 539         local_buf[i] = '\0';
 540         if ((i == 0) || (i > 8)) {
 541                 rc = -ENAMETOOLONG;
 542                 goto out_buf;
 543         }
 544
 545         down_write(&dcssblk_devices_sem);
 546         dev_info = dcssblk_get_device_by_name(local_buf);
 547         if (dev_info == NULL) {
 548                 up_write(&dcssblk_devices_sem);
 549                 PRINT_WARN("Segment %s is not loaded!\n", local_buf);
 550                 rc = -ENODEV;
 551                 goto out_buf;
 552         }
 553         if (atomic_read(&dev_info->use_count) != 0) {
 554                 up_write(&dcssblk_devices_sem);
 555                 PRINT_WARN("Segment %s is in use!\n", local_buf);
 556                 rc = -EBUSY;
 557                 goto out_buf;
 558         }
 559         list_del(&dev_info->lh);
 560
 561         del_gendisk(dev_info->gd);
 562         blk_put_queue(dev_info->dcssblk_queue);
 563         dev_info->gd->queue = NULL;
 564         put_disk(dev_info->gd);
 565         device_unregister(&dev_info->dev);
 566         segment_unload(dev_info->segment_name);
 567         PRINT_DEBUG("Segment %s unloaded successfully\n",
 568                         dev_info->segment_name);
 569         put_device(&dev_info->dev);
 570         up_write(&dcssblk_devices_sem);
 571
 572         rc = count;
 573 out_buf:
 574         kfree(local_buf);
 575         return rc;
 576 }
 577
 578 static int
 579 dcssblk_open(struct inode *inode, struct file *filp)
 580 {
 581         struct dcssblk_dev_info *dev_info;
 582         int rc;
 583
 584         dev_info = inode->i_bdev->bd_disk->private_data;
 585         if (NULL == dev_info) {
 586                 rc = -ENODEV;
 587                 goto out;
 588         }
 589         atomic_inc(&dev_info->use_count);
 590         inode->i_bdev->bd_block_size = 4096;
 591         rc = 0;
 592 out:
 593         return rc;
 594 }
 595
 596 static int
 597 dcssblk_release(struct inode *inode, struct file *filp)
 598 {
 599         struct dcssblk_dev_info *dev_info;
 600         int rc;
 601
 602         dev_info = inode->i_bdev->bd_disk->private_data;
 603         if (NULL == dev_info) {
 604                 rc = -ENODEV;
 605                 goto out;
 606         }
 607         down_write(&dcssblk_devices_sem);
 608         if (atomic_dec_and_test(&dev_info->use_count)
 609             && (dev_info->save_pending)) {
 610                 PRINT_INFO("Segment %s became idle and is being saved now\n",
 611                             dev_info->segment_name);
 612                 segment_save(dev_info->segment_name);
 613                 dev_info->save_pending = 0;
 614         }
 615         up_write(&dcssblk_devices_sem);
 616         rc = 0;
 617 out:
 618         return rc;
 619 }
 620
 621 static int
 622 dcssblk_make_request(request_queue_t *q, struct bio *bio)
 623 {
 624         struct dcssblk_dev_info *dev_info;
 625         struct bio_vec *bvec;
 626         unsigned long index;
 627         unsigned long page_addr;
 628         unsigned long source_addr;
 629         unsigned long bytes_done;
 630         int i;
 631
 632         bytes_done = 0;
 633         dev_info = bio->bi_bdev->bd_disk->private_data;
 634         if (dev_info == NULL)
 635                 goto fail;
 636         if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
 637                 /* Request is not page-aligned. */
 638                 goto fail;
 639         if (((bio->bi_size >> 9) + bio->bi_sector)
 640                         > get_capacity(bio->bi_bdev->bd_disk)) {
 641                 /* Request beyond end of DCSS segment. */
 642                 goto fail;
 643         }
 644         index = (bio->bi_sector >> 3);
 645         bio_for_each_segment(bvec, bio, i) {
 646                 page_addr = (unsigned long)
 647                         page_address(bvec->bv_page) + bvec->bv_offset;
 648                 source_addr = dev_info->start + (index<<12) + bytes_done;
 649                 if (unlikely(page_addr & 4095) != 0 || (bvec->bv_len & 4095) != 0)
 650                         // More paranoia.
 651                         goto fail;
 652                 if (bio_data_dir(bio) == READ) {
 653                         memcpy((void*)page_addr, (void*)source_addr,
 654                                 bvec->bv_len);
 655                 } else {
 656                         memcpy((void*)source_addr, (void*)page_addr,
 657                                 bvec->bv_len);
 658                 }
 659                 bytes_done += bvec->bv_len;
 660         }
 661         bio_endio(bio, bytes_done, 0);
 662         return 0;
 663 fail:
 664         bio_io_error(bio, bytes_done);
 665         return 0;
 666 }
 667
 668 static void
 669 dcssblk_check_params(void)
 670 {
 671         int rc, i, j, k;
 672         char buf[9];
 673         struct dcssblk_dev_info *dev_info;
 674
 675         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 676              i++) {
 677                 for (j = i; (dcssblk_segments[j] != ',')  &&
 678                             (dcssblk_segments[j] != '\0') &&
 679                             (dcssblk_segments[j] != '(')  &&
 680                             (j - i) < 8; j++)
 681                 {
 682                         buf[j-i] = dcssblk_segments[j];
 683                 }
 684                 buf[j-i] = '\0';
 685                 rc = dcssblk_add_store(dcssblk_root_dev, buf, j-i);
 686                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 687                         for (k = 0; buf[k] != '\0'; k++)
 688                                 buf[k] = toupper(buf[k]);
 689                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 690                                 down_read(&dcssblk_devices_sem);
 691                                 dev_info = dcssblk_get_device_by_name(buf);
 692                                 up_read(&dcssblk_devices_sem);
 693                                 if (dev_info)
 694                                         dcssblk_shared_store(&dev_info->dev,
 695                                                              "0\n", 2);
 696                         }
 697                 }
 698                 while ((dcssblk_segments[j] != ',') &&
 699                        (dcssblk_segments[j] != '\0'))
 700                 {
 701                         j++;
 702                 }
 703                 if (dcssblk_segments[j] == '\0')
 704                         break;
 705                 i = j;
 706         }
 707 }
 708
 709 /*
 710  * The init/exit functions.
 711  */
 712 static void __exit
 713 dcssblk_exit(void)
 714 {
 715         int rc;
 716
 717         PRINT_DEBUG("DCSSBLOCK EXIT...\n");
 718         s390_root_dev_unregister(dcssblk_root_dev);
 719         rc = unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 720         if (rc) {
 721                 PRINT_ERR("unregister_blkdev() failed!\n");
 722         }
 723         PRINT_DEBUG("...finished!\n");
 724 }
 725
 726 static int __init
 727 dcssblk_init(void)
 728 {
 729         int rc;
 730
 731         PRINT_DEBUG("DCSSBLOCK INIT...\n");
 732         dcssblk_root_dev = s390_root_dev_register("dcssblk");
 733         if (IS_ERR(dcssblk_root_dev)) {
 734                 PRINT_ERR("device_register() failed!\n");
 735                 return PTR_ERR(dcssblk_root_dev);
 736         }
 737         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
 738         if (rc) {
 739                 PRINT_ERR("device_create_file(add) failed!\n");
 740                 s390_root_dev_unregister(dcssblk_root_dev);
 741                 return rc;
 742         }
 743         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
 744         if (rc) {
 745                 PRINT_ERR("device_create_file(remove) failed!\n");
 746                 s390_root_dev_unregister(dcssblk_root_dev);
 747                 return rc;
 748         }
 749         rc = register_blkdev(0, DCSSBLK_NAME);
 750         if (rc < 0) {
 751                 PRINT_ERR("Can't get dynamic major!\n");
 752                 s390_root_dev_unregister(dcssblk_root_dev);
 753                 return rc;
 754         }
 755         dcssblk_major = rc;
 756         init_rwsem(&dcssblk_devices_sem);
 757
 758         dcssblk_check_params();
 759
 760         PRINT_DEBUG("...finished!\n");
 761         return 0;
 762 }
 763
 764 module_init(dcssblk_init);
 765 module_exit(dcssblk_exit);
 766
 767 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
 768 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
 769                  "comma-separated list, each name max. 8 chars.\n"
 770                  "Adding \"(local)\" to segment name equals echoing 0 to "
 771                  "/sys/devices/dcssblk/<segment name>/shared after loading "
 772                  "the segment - \n"
 773                  "e.g. segments=\"mydcss1,mydcss2,mydcss3(local)\"");
 774
 775 MODULE_LICENSE("GPL");