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 #define KMSG_COMPONENT "dcssblk"
   8 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/ctype.h>
  13 #include <linux/errno.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/blkdev.h>
  17 #include <asm/extmem.h>
  18 #include <asm/io.h>
  19 #include <linux/completion.h>
  20 #include <linux/interrupt.h>
  21
  22 #define DCSSBLK_NAME "dcssblk"
  23 #define DCSSBLK_MINORS_PER_DISK 1
  24 #define DCSSBLK_PARM_LEN 400
  25 #define DCSS_BUS_ID_SIZE 20
  26
  27 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
  28 static int dcssblk_release(struct gendisk *disk, fmode_t mode);
  29 static int dcssblk_make_request(struct request_queue *q, struct bio *bio);
  30 static int dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
  31                                  void **kaddr, unsigned long *pfn);
  32
  33 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  34
  35 static int dcssblk_major;
  36 static struct block_device_operations dcssblk_devops = {
  37         .owner          = THIS_MODULE,
  38         .open           = dcssblk_open,
  39         .release        = dcssblk_release,
  40         .direct_access  = dcssblk_direct_access,
  41 };
  42
  43 struct dcssblk_dev_info {
  44         struct list_head lh;
  45         struct device dev;
  46         char segment_name[DCSS_BUS_ID_SIZE];
  47         atomic_t use_count;
  48         struct gendisk *gd;
  49         unsigned long start;
  50         unsigned long end;
  51         int segment_type;
  52         unsigned char save_pending;
  53         unsigned char is_shared;
  54         struct request_queue *dcssblk_queue;
  55         int num_of_segments;
  56         struct list_head seg_list;
  57 };
  58
  59 struct segment_info {
  60         struct list_head lh;
  61         char segment_name[DCSS_BUS_ID_SIZE];
  62         unsigned long start;
  63         unsigned long end;
  64         int segment_type;
  65 };
  66
  67 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  68                                   size_t count);
  69 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  70                                   size_t count);
  71 static ssize_t dcssblk_save_store(struct device * dev, struct device_attribute *attr, const char * buf,
  72                                   size_t count);
  73 static ssize_t dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf);
  74 static ssize_t dcssblk_shared_store(struct device * dev, struct device_attribute *attr, const char * buf,
  75                                   size_t count);
  76 static ssize_t dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf);
  77 static ssize_t dcssblk_seglist_show(struct device *dev,
  78                                 struct device_attribute *attr,
  79                                 char *buf);
  80
  81 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  82 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  83 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
  84                    dcssblk_save_store);
  85 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
  86                    dcssblk_shared_store);
  87 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
  88
  89 static struct device *dcssblk_root_dev;
  90
  91 static LIST_HEAD(dcssblk_devices);
  92 static struct rw_semaphore dcssblk_devices_sem;
  93
  94 /*
  95  * release function for segment device.
  96  */
  97 static void
  98 dcssblk_release_segment(struct device *dev)
  99 {
 100         struct dcssblk_dev_info *dev_info;
 101         struct segment_info *entry, *temp;
 102
 103         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 104         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 105                 list_del(&entry->lh);
 106                 kfree(entry);
 107         }
 108         kfree(dev_info);
 109         module_put(THIS_MODULE);
 110 }
 111
 112 /*
 113  * get a minor number. needs to be called with
 114  * down_write(&dcssblk_devices_sem) and the
 115  * device needs to be enqueued before the semaphore is
 116  * freed.
 117  */
 118 static int
 119 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 120 {
 121         int minor, found;
 122         struct dcssblk_dev_info *entry;
 123
 124         if (dev_info == NULL)
 125                 return -EINVAL;
 126         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 127                 found = 0;
 128                 // test if minor available
 129                 list_for_each_entry(entry, &dcssblk_devices, lh)
 130                         if (minor == MINOR(disk_devt(entry->gd)))
 131                                 found++;
 132                 if (!found) break; // got unused minor
 133         }
 134         if (found)
 135                 return -EBUSY;
 136         dev_info->gd->first_minor = minor;
 137         return 0;
 138 }
 139
 140 /*
 141  * get the struct dcssblk_dev_info from dcssblk_devices
 142  * for the given name.
 143  * down_read(&dcssblk_devices_sem) must be held.
 144  */
 145 static struct dcssblk_dev_info *
 146 dcssblk_get_device_by_name(char *name)
 147 {
 148         struct dcssblk_dev_info *entry;
 149
 150         list_for_each_entry(entry, &dcssblk_devices, lh) {
 151                 if (!strcmp(name, entry->segment_name)) {
 152                         return entry;
 153                 }
 154         }
 155         return NULL;
 156 }
 157
 158 /*
 159  * get the struct segment_info from seg_list
 160  * for the given name.
 161  * down_read(&dcssblk_devices_sem) must be held.
 162  */
 163 static struct segment_info *
 164 dcssblk_get_segment_by_name(char *name)
 165 {
 166         struct dcssblk_dev_info *dev_info;
 167         struct segment_info *entry;
 168
 169         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 170                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 171                         if (!strcmp(name, entry->segment_name))
 172                                 return entry;
 173                 }
 174         }
 175         return NULL;
 176 }
 177
 178 /*
 179  * get the highest address of the multi-segment block.
 180  */
 181 static unsigned long
 182 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 183 {
 184         unsigned long highest_addr;
 185         struct segment_info *entry;
 186
 187         highest_addr = 0;
 188         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 189                 if (highest_addr < entry->end)
 190                         highest_addr = entry->end;
 191         }
 192         return highest_addr;
 193 }
 194
 195 /*
 196  * get the lowest address of the multi-segment block.
 197  */
 198 static unsigned long
 199 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 200 {
 201         int set_first;
 202         unsigned long lowest_addr;
 203         struct segment_info *entry;
 204
 205         set_first = 0;
 206         lowest_addr = 0;
 207         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 208                 if (set_first == 0) {
 209                         lowest_addr = entry->start;
 210                         set_first = 1;
 211                 } else {
 212                         if (lowest_addr > entry->start)
 213                                 lowest_addr = entry->start;
 214                 }
 215         }
 216         return lowest_addr;
 217 }
 218
 219 /*
 220  * Check continuity of segments.
 221  */
 222 static int
 223 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 224 {
 225         int i, j, rc;
 226         struct segment_info *sort_list, *entry, temp;
 227
 228         if (dev_info->num_of_segments <= 1)
 229                 return 0;
 230
 231         sort_list = kzalloc(
 232                         sizeof(struct segment_info) * dev_info->num_of_segments,
 233                         GFP_KERNEL);
 234         if (sort_list == NULL)
 235                 return -ENOMEM;
 236         i = 0;
 237         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 238                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 239                 i++;
 240         }
 241
 242         /* sort segments */
 243         for (i = 0; i < dev_info->num_of_segments; i++)
 244                 for (j = 0; j < dev_info->num_of_segments; j++)
 245                         if (sort_list[j].start > sort_list[i].start) {
 246                                 memcpy(&temp, &sort_list[i],
 247                                         sizeof(struct segment_info));
 248                                 memcpy(&sort_list[i], &sort_list[j],
 249                                         sizeof(struct segment_info));
 250                                 memcpy(&sort_list[j], &temp,
 251                                         sizeof(struct segment_info));
 252                         }
 253
 254         /* check continuity */
 255         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 256                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 257                         pr_err("Adjacent DCSSs %s and %s are not "
 258                                "contiguous\n", sort_list[i].segment_name,
 259                                sort_list[i+1].segment_name);
 260                         rc = -EINVAL;
 261                         goto out;
 262                 }
 263                 /* EN and EW are allowed in a block device */
 264                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 265                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 266                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 267                                 !(sort_list[i+1].segment_type &
 268                                 SEGMENT_EXCLUSIVE) ||
 269                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 270                                 pr_err("DCSS %s and DCSS %s have "
 271                                        "incompatible types\n",
 272                                        sort_list[i].segment_name,
 273                                        sort_list[i+1].segment_name);
 274                                 rc = -EINVAL;
 275                                 goto out;
 276                         }
 277                 }
 278         }
 279         rc = 0;
 280 out:
 281         kfree(sort_list);
 282         return rc;
 283 }
 284
 285 /*
 286  * Load a segment
 287  */
 288 static int
 289 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 290 {
 291         int rc;
 292
 293         /* already loaded? */
 294         down_read(&dcssblk_devices_sem);
 295         *seg_info = dcssblk_get_segment_by_name(name);
 296         up_read(&dcssblk_devices_sem);
 297         if (*seg_info != NULL)
 298                 return -EEXIST;
 299
 300         /* get a struct segment_info */
 301         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 302         if (*seg_info == NULL)
 303                 return -ENOMEM;
 304
 305         strcpy((*seg_info)->segment_name, name);
 306
 307         /* load the segment */
 308         rc = segment_load(name, SEGMENT_SHARED,
 309                         &(*seg_info)->start, &(*seg_info)->end);
 310         if (rc < 0) {
 311                 segment_warning(rc, (*seg_info)->segment_name);
 312                 kfree(*seg_info);
 313         } else {
 314                 INIT_LIST_HEAD(&(*seg_info)->lh);
 315                 (*seg_info)->segment_type = rc;
 316         }
 317         return rc;
 318 }
 319
 320 static void dcssblk_unregister_callback(struct device *dev)
 321 {
 322         device_unregister(dev);
 323         put_device(dev);
 324 }
 325
 326 /*
 327  * device attribute for switching shared/nonshared (exclusive)
 328  * operation (show + store)
 329  */
 330 static ssize_t
 331 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 332 {
 333         struct dcssblk_dev_info *dev_info;
 334
 335         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 336         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 337 }
 338
 339 static ssize_t
 340 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 341 {
 342         struct dcssblk_dev_info *dev_info;
 343         struct segment_info *entry, *temp;
 344         int rc;
 345
 346         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 347                 return -EINVAL;
 348         down_write(&dcssblk_devices_sem);
 349         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 350         if (atomic_read(&dev_info->use_count)) {
 351                 rc = -EBUSY;
 352                 goto out;
 353         }
 354         if (inbuf[0] == '1') {
 355                 /* reload segments in shared mode */
 356                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 357                         rc = segment_modify_shared(entry->segment_name,
 358                                                 SEGMENT_SHARED);
 359                         if (rc < 0) {
 360                                 BUG_ON(rc == -EINVAL);
 361                                 if (rc != -EAGAIN)
 362                                         goto removeseg;
 363                         }
 364                 }
 365                 dev_info->is_shared = 1;
 366                 switch (dev_info->segment_type) {
 367                 case SEG_TYPE_SR:
 368                 case SEG_TYPE_ER:
 369                 case SEG_TYPE_SC:
 370                         set_disk_ro(dev_info->gd, 1);
 371                 }
 372         } else if (inbuf[0] == '0') {
 373                 /* reload segments in exclusive mode */
 374                 if (dev_info->segment_type == SEG_TYPE_SC) {
 375                         pr_err("DCSS %s is of type SC and cannot be "
 376                                "loaded as exclusive-writable\n",
 377                                dev_info->segment_name);
 378                         rc = -EINVAL;
 379                         goto out;
 380                 }
 381                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 382                         rc = segment_modify_shared(entry->segment_name,
 383                                                    SEGMENT_EXCLUSIVE);
 384                         if (rc < 0) {
 385                                 BUG_ON(rc == -EINVAL);
 386                                 if (rc != -EAGAIN)
 387                                         goto removeseg;
 388                         }
 389                 }
 390                 dev_info->is_shared = 0;
 391                 set_disk_ro(dev_info->gd, 0);
 392         } else {
 393                 rc = -EINVAL;
 394                 goto out;
 395         }
 396         rc = count;
 397         goto out;
 398
 399 removeseg:
 400         pr_err("DCSS device %s is removed after a failed access mode "
 401                "change\n", dev_info->segment_name);
 402         temp = entry;
 403         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 404                 if (entry != temp)
 405                         segment_unload(entry->segment_name);
 406         }
 407         list_del(&dev_info->lh);
 408
 409         del_gendisk(dev_info->gd);
 410         blk_cleanup_queue(dev_info->dcssblk_queue);
 411         dev_info->gd->queue = NULL;
 412         put_disk(dev_info->gd);
 413         rc = device_schedule_callback(dev, dcssblk_unregister_callback);
 414 out:
 415         up_write(&dcssblk_devices_sem);
 416         return rc;
 417 }
 418
 419 /*
 420  * device attribute for save operation on current copy
 421  * of the segment. If the segment is busy, saving will
 422  * become pending until it gets released, which can be
 423  * undone by storing a non-true value to this entry.
 424  * (show + store)
 425  */
 426 static ssize_t
 427 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 428 {
 429         struct dcssblk_dev_info *dev_info;
 430
 431         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 432         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 433 }
 434
 435 static ssize_t
 436 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 437 {
 438         struct dcssblk_dev_info *dev_info;
 439         struct segment_info *entry;
 440
 441         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 442                 return -EINVAL;
 443         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 444
 445         down_write(&dcssblk_devices_sem);
 446         if (inbuf[0] == '1') {
 447                 if (atomic_read(&dev_info->use_count) == 0) {
 448                         // device is idle => we save immediately
 449                         pr_info("All DCSSs that map to device %s are "
 450                                 "saved\n", dev_info->segment_name);
 451                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 452                                 segment_save(entry->segment_name);
 453                         }
 454                 }  else {
 455                         // device is busy => we save it when it becomes
 456                         // idle in dcssblk_release
 457                         pr_info("Device %s is in use, its DCSSs will be "
 458                                 "saved when it becomes idle\n",
 459                                 dev_info->segment_name);
 460                         dev_info->save_pending = 1;
 461                 }
 462         } else if (inbuf[0] == '0') {
 463                 if (dev_info->save_pending) {
 464                         // device is busy & the user wants to undo his save
 465                         // request
 466                         dev_info->save_pending = 0;
 467                         pr_info("A pending save request for device %s "
 468                                 "has been canceled\n",
 469                                 dev_info->segment_name);
 470                 }
 471         } else {
 472                 up_write(&dcssblk_devices_sem);
 473                 return -EINVAL;
 474         }
 475         up_write(&dcssblk_devices_sem);
 476         return count;
 477 }
 478
 479 /*
 480  * device attribute for showing all segments in a device
 481  */
 482 static ssize_t
 483 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 484                 char *buf)
 485 {
 486         int i;
 487
 488         struct dcssblk_dev_info *dev_info;
 489         struct segment_info *entry;
 490
 491         down_read(&dcssblk_devices_sem);
 492         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 493         i = 0;
 494         buf[0] = '\0';
 495         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 496                 strcpy(&buf[i], entry->segment_name);
 497                 i += strlen(entry->segment_name);
 498                 buf[i] = '\n';
 499                 i++;
 500         }
 501         up_read(&dcssblk_devices_sem);
 502         return i;
 503 }
 504
 505 /*
 506  * device attribute for adding devices
 507  */
 508 static ssize_t
 509 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 510 {
 511         int rc, i, j, num_of_segments;
 512         struct dcssblk_dev_info *dev_info;
 513         struct segment_info *seg_info, *temp;
 514         char *local_buf;
 515         unsigned long seg_byte_size;
 516
 517         dev_info = NULL;
 518         seg_info = NULL;
 519         if (dev != dcssblk_root_dev) {
 520                 rc = -EINVAL;
 521                 goto out_nobuf;
 522         }
 523         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 524                 rc = -ENAMETOOLONG;
 525                 goto out_nobuf;
 526         }
 527
 528         local_buf = kmalloc(count + 1, GFP_KERNEL);
 529         if (local_buf == NULL) {
 530                 rc = -ENOMEM;
 531                 goto out_nobuf;
 532         }
 533
 534         /*
 535          * parse input
 536          */
 537         num_of_segments = 0;
 538         for (i = 0; ((buf[i] != '\0') && (buf[i] != '\n') && i < count); i++) {
 539                 for (j = i; (buf[j] != ':') &&
 540                         (buf[j] != '\0') &&
 541                         (buf[j] != '\n') &&
 542                         j < count; j++) {
 543                         local_buf[j-i] = toupper(buf[j]);
 544                 }
 545                 local_buf[j-i] = '\0';
 546                 if (((j - i) == 0) || ((j - i) > 8)) {
 547                         rc = -ENAMETOOLONG;
 548                         goto seg_list_del;
 549                 }
 550
 551                 rc = dcssblk_load_segment(local_buf, &seg_info);
 552                 if (rc < 0)
 553                         goto seg_list_del;
 554                 /*
 555                  * get a struct dcssblk_dev_info
 556                  */
 557                 if (num_of_segments == 0) {
 558                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 559                                         GFP_KERNEL);
 560                         if (dev_info == NULL) {
 561                                 rc = -ENOMEM;
 562                                 goto out;
 563                         }
 564                         strcpy(dev_info->segment_name, local_buf);
 565                         dev_info->segment_type = seg_info->segment_type;
 566                         INIT_LIST_HEAD(&dev_info->seg_list);
 567                 }
 568                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 569                 num_of_segments++;
 570                 i = j;
 571
 572                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 573                         break;
 574         }
 575
 576         /* no trailing colon at the end of the input */
 577         if ((i > 0) && (buf[i-1] == ':')) {
 578                 rc = -ENAMETOOLONG;
 579                 goto seg_list_del;
 580         }
 581         strlcpy(local_buf, buf, i + 1);
 582         dev_info->num_of_segments = num_of_segments;
 583         rc = dcssblk_is_continuous(dev_info);
 584         if (rc < 0)
 585                 goto seg_list_del;
 586
 587         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 588         dev_info->end = dcssblk_find_highest_addr(dev_info);
 589
 590         dev_set_name(&dev_info->dev, dev_info->segment_name);
 591         dev_info->dev.release = dcssblk_release_segment;
 592         INIT_LIST_HEAD(&dev_info->lh);
 593         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 594         if (dev_info->gd == NULL) {
 595                 rc = -ENOMEM;
 596                 goto seg_list_del;
 597         }
 598         dev_info->gd->major = dcssblk_major;
 599         dev_info->gd->fops = &dcssblk_devops;
 600         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 601         dev_info->gd->queue = dev_info->dcssblk_queue;
 602         dev_info->gd->private_data = dev_info;
 603         dev_info->gd->driverfs_dev = &dev_info->dev;
 604         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 605         blk_queue_hardsect_size(dev_info->dcssblk_queue, 4096);
 606
 607         seg_byte_size = (dev_info->end - dev_info->start + 1);
 608         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 609         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 610                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 611
 612         dev_info->save_pending = 0;
 613         dev_info->is_shared = 1;
 614         dev_info->dev.parent = dcssblk_root_dev;
 615
 616         /*
 617          *get minor, add to list
 618          */
 619         down_write(&dcssblk_devices_sem);
 620         if (dcssblk_get_segment_by_name(local_buf)) {
 621                 rc = -EEXIST;
 622                 goto release_gd;
 623         }
 624         rc = dcssblk_assign_free_minor(dev_info);
 625         if (rc)
 626                 goto release_gd;
 627         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 628                 MINOR(disk_devt(dev_info->gd)));
 629         list_add_tail(&dev_info->lh, &dcssblk_devices);
 630
 631         if (!try_module_get(THIS_MODULE)) {
 632                 rc = -ENODEV;
 633                 goto dev_list_del;
 634         }
 635         /*
 636          * register the device
 637          */
 638         rc = device_register(&dev_info->dev);
 639         if (rc) {
 640                 module_put(THIS_MODULE);
 641                 goto dev_list_del;
 642         }
 643         get_device(&dev_info->dev);
 644         rc = device_create_file(&dev_info->dev, &dev_attr_shared);
 645         if (rc)
 646                 goto unregister_dev;
 647         rc = device_create_file(&dev_info->dev, &dev_attr_save);
 648         if (rc)
 649                 goto unregister_dev;
 650         rc = device_create_file(&dev_info->dev, &dev_attr_seglist);
 651         if (rc)
 652                 goto unregister_dev;
 653
 654         add_disk(dev_info->gd);
 655
 656         switch (dev_info->segment_type) {
 657                 case SEG_TYPE_SR:
 658                 case SEG_TYPE_ER:
 659                 case SEG_TYPE_SC:
 660                         set_disk_ro(dev_info->gd,1);
 661                         break;
 662                 default:
 663                         set_disk_ro(dev_info->gd,0);
 664                         break;
 665         }
 666         up_write(&dcssblk_devices_sem);
 667         rc = count;
 668         goto out;
 669
 670 unregister_dev:
 671         list_del(&dev_info->lh);
 672         blk_cleanup_queue(dev_info->dcssblk_queue);
 673         dev_info->gd->queue = NULL;
 674         put_disk(dev_info->gd);
 675         device_unregister(&dev_info->dev);
 676         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 677                 segment_unload(seg_info->segment_name);
 678         }
 679         put_device(&dev_info->dev);
 680         up_write(&dcssblk_devices_sem);
 681         goto out;
 682 dev_list_del:
 683         list_del(&dev_info->lh);
 684 release_gd:
 685         blk_cleanup_queue(dev_info->dcssblk_queue);
 686         dev_info->gd->queue = NULL;
 687         put_disk(dev_info->gd);
 688         up_write(&dcssblk_devices_sem);
 689 seg_list_del:
 690         if (dev_info == NULL)
 691                 goto out;
 692         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 693                 list_del(&seg_info->lh);
 694                 segment_unload(seg_info->segment_name);
 695                 kfree(seg_info);
 696         }
 697         kfree(dev_info);
 698 out:
 699         kfree(local_buf);
 700 out_nobuf:
 701         return rc;
 702 }
 703
 704 /*
 705  * device attribute for removing devices
 706  */
 707 static ssize_t
 708 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 709 {
 710         struct dcssblk_dev_info *dev_info;
 711         struct segment_info *entry;
 712         int rc, i;
 713         char *local_buf;
 714
 715         if (dev != dcssblk_root_dev) {
 716                 return -EINVAL;
 717         }
 718         local_buf = kmalloc(count + 1, GFP_KERNEL);
 719         if (local_buf == NULL) {
 720                 return -ENOMEM;
 721         }
 722         /*
 723          * parse input
 724          */
 725         for (i = 0; ((*(buf+i)!='\0') && (*(buf+i)!='\n') && i < count); i++) {
 726                 local_buf[i] = toupper(buf[i]);
 727         }
 728         local_buf[i] = '\0';
 729         if ((i == 0) || (i > 8)) {
 730                 rc = -ENAMETOOLONG;
 731                 goto out_buf;
 732         }
 733
 734         down_write(&dcssblk_devices_sem);
 735         dev_info = dcssblk_get_device_by_name(local_buf);
 736         if (dev_info == NULL) {
 737                 up_write(&dcssblk_devices_sem);
 738                 pr_warning("Device %s cannot be removed because it is not a "
 739                            "known device\n", local_buf);
 740                 rc = -ENODEV;
 741                 goto out_buf;
 742         }
 743         if (atomic_read(&dev_info->use_count) != 0) {
 744                 up_write(&dcssblk_devices_sem);
 745                 pr_warning("Device %s cannot be removed while it is in "
 746                            "use\n", local_buf);
 747                 rc = -EBUSY;
 748                 goto out_buf;
 749         }
 750
 751         list_del(&dev_info->lh);
 752         del_gendisk(dev_info->gd);
 753         blk_cleanup_queue(dev_info->dcssblk_queue);
 754         dev_info->gd->queue = NULL;
 755         put_disk(dev_info->gd);
 756         device_unregister(&dev_info->dev);
 757
 758         /* unload all related segments */
 759         list_for_each_entry(entry, &dev_info->seg_list, lh)
 760                 segment_unload(entry->segment_name);
 761
 762         put_device(&dev_info->dev);
 763         up_write(&dcssblk_devices_sem);
 764
 765         rc = count;
 766 out_buf:
 767         kfree(local_buf);
 768         return rc;
 769 }
 770
 771 static int
 772 dcssblk_open(struct block_device *bdev, fmode_t mode)
 773 {
 774         struct dcssblk_dev_info *dev_info;
 775         int rc;
 776
 777         dev_info = bdev->bd_disk->private_data;
 778         if (NULL == dev_info) {
 779                 rc = -ENODEV;
 780                 goto out;
 781         }
 782         atomic_inc(&dev_info->use_count);
 783         bdev->bd_block_size = 4096;
 784         rc = 0;
 785 out:
 786         return rc;
 787 }
 788
 789 static int
 790 dcssblk_release(struct gendisk *disk, fmode_t mode)
 791 {
 792         struct dcssblk_dev_info *dev_info = disk->private_data;
 793         struct segment_info *entry;
 794         int rc;
 795
 796         if (!dev_info) {
 797                 rc = -ENODEV;
 798                 goto out;
 799         }
 800         down_write(&dcssblk_devices_sem);
 801         if (atomic_dec_and_test(&dev_info->use_count)
 802             && (dev_info->save_pending)) {
 803                 pr_info("Device %s has become idle and is being saved "
 804                         "now\n", dev_info->segment_name);
 805                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 806                         segment_save(entry->segment_name);
 807                 }
 808                 dev_info->save_pending = 0;
 809         }
 810         up_write(&dcssblk_devices_sem);
 811         rc = 0;
 812 out:
 813         return rc;
 814 }
 815
 816 static int
 817 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 818 {
 819         struct dcssblk_dev_info *dev_info;
 820         struct bio_vec *bvec;
 821         unsigned long index;
 822         unsigned long page_addr;
 823         unsigned long source_addr;
 824         unsigned long bytes_done;
 825         int i;
 826
 827         bytes_done = 0;
 828         dev_info = bio->bi_bdev->bd_disk->private_data;
 829         if (dev_info == NULL)
 830                 goto fail;
 831         if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
 832                 /* Request is not page-aligned. */
 833                 goto fail;
 834         if (((bio->bi_size >> 9) + bio->bi_sector)
 835                         > get_capacity(bio->bi_bdev->bd_disk)) {
 836                 /* Request beyond end of DCSS segment. */
 837                 goto fail;
 838         }
 839         /* verify data transfer direction */
 840         if (dev_info->is_shared) {
 841                 switch (dev_info->segment_type) {
 842                 case SEG_TYPE_SR:
 843                 case SEG_TYPE_ER:
 844                 case SEG_TYPE_SC:
 845                         /* cannot write to these segments */
 846                         if (bio_data_dir(bio) == WRITE) {
 847                                 pr_warning("Writing to %s failed because it "
 848                                            "is a read-only device\n",
 849                                            dev_name(&dev_info->dev));
 850                                 goto fail;
 851                         }
 852                 }
 853         }
 854
 855         index = (bio->bi_sector >> 3);
 856         bio_for_each_segment(bvec, bio, i) {
 857                 page_addr = (unsigned long)
 858                         page_address(bvec->bv_page) + bvec->bv_offset;
 859                 source_addr = dev_info->start + (index<<12) + bytes_done;
 860                 if (unlikely((page_addr & 4095) != 0) || (bvec->bv_len & 4095) != 0)
 861                         // More paranoia.
 862                         goto fail;
 863                 if (bio_data_dir(bio) == READ) {
 864                         memcpy((void*)page_addr, (void*)source_addr,
 865                                 bvec->bv_len);
 866                 } else {
 867                         memcpy((void*)source_addr, (void*)page_addr,
 868                                 bvec->bv_len);
 869                 }
 870                 bytes_done += bvec->bv_len;
 871         }
 872         bio_endio(bio, 0);
 873         return 0;
 874 fail:
 875         bio_io_error(bio);
 876         return 0;
 877 }
 878
 879 static int
 880 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
 881                         void **kaddr, unsigned long *pfn)
 882 {
 883         struct dcssblk_dev_info *dev_info;
 884         unsigned long pgoff;
 885
 886         dev_info = bdev->bd_disk->private_data;
 887         if (!dev_info)
 888                 return -ENODEV;
 889         if (secnum % (PAGE_SIZE/512))
 890                 return -EINVAL;
 891         pgoff = secnum / (PAGE_SIZE / 512);
 892         if ((pgoff+1)*PAGE_SIZE-1 > dev_info->end - dev_info->start)
 893                 return -ERANGE;
 894         *kaddr = (void *) (dev_info->start+pgoff*PAGE_SIZE);
 895         *pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
 896
 897         return 0;
 898 }
 899
 900 static void
 901 dcssblk_check_params(void)
 902 {
 903         int rc, i, j, k;
 904         char buf[DCSSBLK_PARM_LEN + 1];
 905         struct dcssblk_dev_info *dev_info;
 906
 907         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 908              i++) {
 909                 for (j = i; (dcssblk_segments[j] != ',')  &&
 910                             (dcssblk_segments[j] != '\0') &&
 911                             (dcssblk_segments[j] != '(')  &&
 912                             (j < DCSSBLK_PARM_LEN); j++)
 913                 {
 914                         buf[j-i] = dcssblk_segments[j];
 915                 }
 916                 buf[j-i] = '\0';
 917                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 918                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 919                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 920                                 buf[k] = toupper(buf[k]);
 921                         buf[k] = '\0';
 922                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 923                                 down_read(&dcssblk_devices_sem);
 924                                 dev_info = dcssblk_get_device_by_name(buf);
 925                                 up_read(&dcssblk_devices_sem);
 926                                 if (dev_info)
 927                                         dcssblk_shared_store(&dev_info->dev,
 928                                                              NULL, "0\n", 2);
 929                         }
 930                 }
 931                 while ((dcssblk_segments[j] != ',') &&
 932                        (dcssblk_segments[j] != '\0'))
 933                 {
 934                         j++;
 935                 }
 936                 if (dcssblk_segments[j] == '\0')
 937                         break;
 938                 i = j;
 939         }
 940 }
 941
 942 /*
 943  * The init/exit functions.
 944  */
 945 static void __exit
 946 dcssblk_exit(void)
 947 {
 948         root_device_unregister(dcssblk_root_dev);
 949         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 950 }
 951
 952 static int __init
 953 dcssblk_init(void)
 954 {
 955         int rc;
 956
 957         dcssblk_root_dev = root_device_register("dcssblk");
 958         if (IS_ERR(dcssblk_root_dev))
 959                 return PTR_ERR(dcssblk_root_dev);
 960         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
 961         if (rc) {
 962                 root_device_unregister(dcssblk_root_dev);
 963                 return rc;
 964         }
 965         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
 966         if (rc) {
 967                 root_device_unregister(dcssblk_root_dev);
 968                 return rc;
 969         }
 970         rc = register_blkdev(0, DCSSBLK_NAME);
 971         if (rc < 0) {
 972                 root_device_unregister(dcssblk_root_dev);
 973                 return rc;
 974         }
 975         dcssblk_major = rc;
 976         init_rwsem(&dcssblk_devices_sem);
 977
 978         dcssblk_check_params();
 979
 980         return 0;
 981 }
 982
 983 module_init(dcssblk_init);
 984 module_exit(dcssblk_exit);
 985
 986 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
 987 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
 988                  "comma-separated list, names in each set separated "
 989                  "by commas are separated by colons, each set contains "
 990                  "names of contiguous segments and each name max. 8 chars.\n"
 991                  "Adding \"(local)\" to the end of each set equals echoing 0 "
 992                  "to /sys/devices/dcssblk/<device name>/shared after loading "
 993                  "the contiguous segments - \n"
 994                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
 995
 996 MODULE_LICENSE("GPL");