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