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 <linux/completion.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/pfn_t.h>
  21 #include <linux/uio.h>
  22 #include <linux/dax.h>
  23 #include <asm/extmem.h>
  24 #include <asm/io.h>
  25
  26 #define DCSSBLK_NAME "dcssblk"
  27 #define DCSSBLK_MINORS_PER_DISK 1
  28 #define DCSSBLK_PARM_LEN 400
  29 #define DCSS_BUS_ID_SIZE 20
  30
  31 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
  32 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
  33 static blk_qc_t dcssblk_make_request(struct request_queue *q,
  34                                                 struct bio *bio);
  35 static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
  36                 long nr_pages, void **kaddr, pfn_t *pfn);
  37
  38 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  39
  40 static int dcssblk_major;
  41 static const struct block_device_operations dcssblk_devops = {
  42         .owner          = THIS_MODULE,
  43         .open           = dcssblk_open,
  44         .release        = dcssblk_release,
  45 };
  46
  47 static size_t dcssblk_dax_copy_from_iter(struct dax_device *dax_dev,
  48                 pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
  49 {
  50         return copy_from_iter(addr, bytes, i);
  51 }
  52
  53 static const struct dax_operations dcssblk_dax_ops = {
  54         .direct_access = dcssblk_dax_direct_access,
  55         .copy_from_iter = dcssblk_dax_copy_from_iter,
  56 };
  57
  58 struct dcssblk_dev_info {
  59         struct list_head lh;
  60         struct device dev;
  61         char segment_name[DCSS_BUS_ID_SIZE];
  62         atomic_t use_count;
  63         struct gendisk *gd;
  64         unsigned long start;
  65         unsigned long end;
  66         int segment_type;
  67         unsigned char save_pending;
  68         unsigned char is_shared;
  69         struct request_queue *dcssblk_queue;
  70         int num_of_segments;
  71         struct list_head seg_list;
  72         struct dax_device *dax_dev;
  73 };
  74
  75 struct segment_info {
  76         struct list_head lh;
  77         char segment_name[DCSS_BUS_ID_SIZE];
  78         unsigned long start;
  79         unsigned long end;
  80         int segment_type;
  81 };
  82
  83 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  84                                   size_t count);
  85 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  86                                   size_t count);
  87
  88 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  89 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  90
  91 static struct device *dcssblk_root_dev;
  92
  93 static LIST_HEAD(dcssblk_devices);
  94 static struct rw_semaphore dcssblk_devices_sem;
  95
  96 /*
  97  * release function for segment device.
  98  */
  99 static void
 100 dcssblk_release_segment(struct device *dev)
 101 {
 102         struct dcssblk_dev_info *dev_info;
 103         struct segment_info *entry, *temp;
 104
 105         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 106         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 107                 list_del(&entry->lh);
 108                 kfree(entry);
 109         }
 110         kfree(dev_info);
 111         module_put(THIS_MODULE);
 112 }
 113
 114 /*
 115  * get a minor number. needs to be called with
 116  * down_write(&dcssblk_devices_sem) and the
 117  * device needs to be enqueued before the semaphore is
 118  * freed.
 119  */
 120 static int
 121 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 122 {
 123         int minor, found;
 124         struct dcssblk_dev_info *entry;
 125
 126         if (dev_info == NULL)
 127                 return -EINVAL;
 128         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 129                 found = 0;
 130                 // test if minor available
 131                 list_for_each_entry(entry, &dcssblk_devices, lh)
 132                         if (minor == entry->gd->first_minor)
 133                                 found++;
 134                 if (!found) break; // got unused minor
 135         }
 136         if (found)
 137                 return -EBUSY;
 138         dev_info->gd->first_minor = minor;
 139         return 0;
 140 }
 141
 142 /*
 143  * get the struct dcssblk_dev_info from dcssblk_devices
 144  * for the given name.
 145  * down_read(&dcssblk_devices_sem) must be held.
 146  */
 147 static struct dcssblk_dev_info *
 148 dcssblk_get_device_by_name(char *name)
 149 {
 150         struct dcssblk_dev_info *entry;
 151
 152         list_for_each_entry(entry, &dcssblk_devices, lh) {
 153                 if (!strcmp(name, entry->segment_name)) {
 154                         return entry;
 155                 }
 156         }
 157         return NULL;
 158 }
 159
 160 /*
 161  * get the struct segment_info from seg_list
 162  * for the given name.
 163  * down_read(&dcssblk_devices_sem) must be held.
 164  */
 165 static struct segment_info *
 166 dcssblk_get_segment_by_name(char *name)
 167 {
 168         struct dcssblk_dev_info *dev_info;
 169         struct segment_info *entry;
 170
 171         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 172                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 173                         if (!strcmp(name, entry->segment_name))
 174                                 return entry;
 175                 }
 176         }
 177         return NULL;
 178 }
 179
 180 /*
 181  * get the highest address of the multi-segment block.
 182  */
 183 static unsigned long
 184 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 185 {
 186         unsigned long highest_addr;
 187         struct segment_info *entry;
 188
 189         highest_addr = 0;
 190         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 191                 if (highest_addr < entry->end)
 192                         highest_addr = entry->end;
 193         }
 194         return highest_addr;
 195 }
 196
 197 /*
 198  * get the lowest address of the multi-segment block.
 199  */
 200 static unsigned long
 201 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 202 {
 203         int set_first;
 204         unsigned long lowest_addr;
 205         struct segment_info *entry;
 206
 207         set_first = 0;
 208         lowest_addr = 0;
 209         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 210                 if (set_first == 0) {
 211                         lowest_addr = entry->start;
 212                         set_first = 1;
 213                 } else {
 214                         if (lowest_addr > entry->start)
 215                                 lowest_addr = entry->start;
 216                 }
 217         }
 218         return lowest_addr;
 219 }
 220
 221 /*
 222  * Check continuity of segments.
 223  */
 224 static int
 225 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 226 {
 227         int i, j, rc;
 228         struct segment_info *sort_list, *entry, temp;
 229
 230         if (dev_info->num_of_segments <= 1)
 231                 return 0;
 232
 233         sort_list = kzalloc(
 234                         sizeof(struct segment_info) * dev_info->num_of_segments,
 235                         GFP_KERNEL);
 236         if (sort_list == NULL)
 237                 return -ENOMEM;
 238         i = 0;
 239         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 240                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 241                 i++;
 242         }
 243
 244         /* sort segments */
 245         for (i = 0; i < dev_info->num_of_segments; i++)
 246                 for (j = 0; j < dev_info->num_of_segments; j++)
 247                         if (sort_list[j].start > sort_list[i].start) {
 248                                 memcpy(&temp, &sort_list[i],
 249                                         sizeof(struct segment_info));
 250                                 memcpy(&sort_list[i], &sort_list[j],
 251                                         sizeof(struct segment_info));
 252                                 memcpy(&sort_list[j], &temp,
 253                                         sizeof(struct segment_info));
 254                         }
 255
 256         /* check continuity */
 257         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 258                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 259                         pr_err("Adjacent DCSSs %s and %s are not "
 260                                "contiguous\n", sort_list[i].segment_name,
 261                                sort_list[i+1].segment_name);
 262                         rc = -EINVAL;
 263                         goto out;
 264                 }
 265                 /* EN and EW are allowed in a block device */
 266                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 267                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 268                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 269                                 !(sort_list[i+1].segment_type &
 270                                 SEGMENT_EXCLUSIVE) ||
 271                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 272                                 pr_err("DCSS %s and DCSS %s have "
 273                                        "incompatible types\n",
 274                                        sort_list[i].segment_name,
 275                                        sort_list[i+1].segment_name);
 276                                 rc = -EINVAL;
 277                                 goto out;
 278                         }
 279                 }
 280         }
 281         rc = 0;
 282 out:
 283         kfree(sort_list);
 284         return rc;
 285 }
 286
 287 /*
 288  * Load a segment
 289  */
 290 static int
 291 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 292 {
 293         int rc;
 294
 295         /* already loaded? */
 296         down_read(&dcssblk_devices_sem);
 297         *seg_info = dcssblk_get_segment_by_name(name);
 298         up_read(&dcssblk_devices_sem);
 299         if (*seg_info != NULL)
 300                 return -EEXIST;
 301
 302         /* get a struct segment_info */
 303         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 304         if (*seg_info == NULL)
 305                 return -ENOMEM;
 306
 307         strcpy((*seg_info)->segment_name, name);
 308
 309         /* load the segment */
 310         rc = segment_load(name, SEGMENT_SHARED,
 311                         &(*seg_info)->start, &(*seg_info)->end);
 312         if (rc < 0) {
 313                 segment_warning(rc, (*seg_info)->segment_name);
 314                 kfree(*seg_info);
 315         } else {
 316                 INIT_LIST_HEAD(&(*seg_info)->lh);
 317                 (*seg_info)->segment_type = rc;
 318         }
 319         return rc;
 320 }
 321
 322 /*
 323  * device attribute for switching shared/nonshared (exclusive)
 324  * operation (show + store)
 325  */
 326 static ssize_t
 327 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 328 {
 329         struct dcssblk_dev_info *dev_info;
 330
 331         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 332         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 333 }
 334
 335 static ssize_t
 336 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 337 {
 338         struct dcssblk_dev_info *dev_info;
 339         struct segment_info *entry, *temp;
 340         int rc;
 341
 342         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 343                 return -EINVAL;
 344         down_write(&dcssblk_devices_sem);
 345         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 346         if (atomic_read(&dev_info->use_count)) {
 347                 rc = -EBUSY;
 348                 goto out;
 349         }
 350         if (inbuf[0] == '1') {
 351                 /* reload segments in shared mode */
 352                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 353                         rc = segment_modify_shared(entry->segment_name,
 354                                                 SEGMENT_SHARED);
 355                         if (rc < 0) {
 356                                 BUG_ON(rc == -EINVAL);
 357                                 if (rc != -EAGAIN)
 358                                         goto removeseg;
 359                         }
 360                 }
 361                 dev_info->is_shared = 1;
 362                 switch (dev_info->segment_type) {
 363                 case SEG_TYPE_SR:
 364                 case SEG_TYPE_ER:
 365                 case SEG_TYPE_SC:
 366                         set_disk_ro(dev_info->gd, 1);
 367                 }
 368         } else if (inbuf[0] == '0') {
 369                 /* reload segments in exclusive mode */
 370                 if (dev_info->segment_type == SEG_TYPE_SC) {
 371                         pr_err("DCSS %s is of type SC and cannot be "
 372                                "loaded as exclusive-writable\n",
 373                                dev_info->segment_name);
 374                         rc = -EINVAL;
 375                         goto out;
 376                 }
 377                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 378                         rc = segment_modify_shared(entry->segment_name,
 379                                                    SEGMENT_EXCLUSIVE);
 380                         if (rc < 0) {
 381                                 BUG_ON(rc == -EINVAL);
 382                                 if (rc != -EAGAIN)
 383                                         goto removeseg;
 384                         }
 385                 }
 386                 dev_info->is_shared = 0;
 387                 set_disk_ro(dev_info->gd, 0);
 388         } else {
 389                 rc = -EINVAL;
 390                 goto out;
 391         }
 392         rc = count;
 393         goto out;
 394
 395 removeseg:
 396         pr_err("DCSS device %s is removed after a failed access mode "
 397                "change\n", dev_info->segment_name);
 398         temp = entry;
 399         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 400                 if (entry != temp)
 401                         segment_unload(entry->segment_name);
 402         }
 403         list_del(&dev_info->lh);
 404
 405         kill_dax(dev_info->dax_dev);
 406         put_dax(dev_info->dax_dev);
 407         del_gendisk(dev_info->gd);
 408         blk_cleanup_queue(dev_info->dcssblk_queue);
 409         dev_info->gd->queue = NULL;
 410         put_disk(dev_info->gd);
 411         up_write(&dcssblk_devices_sem);
 412
 413         if (device_remove_file_self(dev, attr)) {
 414                 device_unregister(dev);
 415                 put_device(dev);
 416         }
 417         return rc;
 418 out:
 419         up_write(&dcssblk_devices_sem);
 420         return rc;
 421 }
 422 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 423                    dcssblk_shared_store);
 424
 425 /*
 426  * device attribute for save operation on current copy
 427  * of the segment. If the segment is busy, saving will
 428  * become pending until it gets released, which can be
 429  * undone by storing a non-true value to this entry.
 430  * (show + store)
 431  */
 432 static ssize_t
 433 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 434 {
 435         struct dcssblk_dev_info *dev_info;
 436
 437         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 438         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 439 }
 440
 441 static ssize_t
 442 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 443 {
 444         struct dcssblk_dev_info *dev_info;
 445         struct segment_info *entry;
 446
 447         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 448                 return -EINVAL;
 449         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 450
 451         down_write(&dcssblk_devices_sem);
 452         if (inbuf[0] == '1') {
 453                 if (atomic_read(&dev_info->use_count) == 0) {
 454                         // device is idle => we save immediately
 455                         pr_info("All DCSSs that map to device %s are "
 456                                 "saved\n", dev_info->segment_name);
 457                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 458                                 if (entry->segment_type == SEG_TYPE_EN ||
 459                                     entry->segment_type == SEG_TYPE_SN)
 460                                         pr_warn("DCSS %s is of type SN or EN"
 461                                                 " and cannot be saved\n",
 462                                                 entry->segment_name);
 463                                 else
 464                                         segment_save(entry->segment_name);
 465                         }
 466                 }  else {
 467                         // device is busy => we save it when it becomes
 468                         // idle in dcssblk_release
 469                         pr_info("Device %s is in use, its DCSSs will be "
 470                                 "saved when it becomes idle\n",
 471                                 dev_info->segment_name);
 472                         dev_info->save_pending = 1;
 473                 }
 474         } else if (inbuf[0] == '0') {
 475                 if (dev_info->save_pending) {
 476                         // device is busy & the user wants to undo his save
 477                         // request
 478                         dev_info->save_pending = 0;
 479                         pr_info("A pending save request for device %s "
 480                                 "has been canceled\n",
 481                                 dev_info->segment_name);
 482                 }
 483         } else {
 484                 up_write(&dcssblk_devices_sem);
 485                 return -EINVAL;
 486         }
 487         up_write(&dcssblk_devices_sem);
 488         return count;
 489 }
 490 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 491                    dcssblk_save_store);
 492
 493 /*
 494  * device attribute for showing all segments in a device
 495  */
 496 static ssize_t
 497 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 498                 char *buf)
 499 {
 500         int i;
 501
 502         struct dcssblk_dev_info *dev_info;
 503         struct segment_info *entry;
 504
 505         down_read(&dcssblk_devices_sem);
 506         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 507         i = 0;
 508         buf[0] = '\0';
 509         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 510                 strcpy(&buf[i], entry->segment_name);
 511                 i += strlen(entry->segment_name);
 512                 buf[i] = '\n';
 513                 i++;
 514         }
 515         up_read(&dcssblk_devices_sem);
 516         return i;
 517 }
 518 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 519
 520 static struct attribute *dcssblk_dev_attrs[] = {
 521         &dev_attr_shared.attr,
 522         &dev_attr_save.attr,
 523         &dev_attr_seglist.attr,
 524         NULL,
 525 };
 526 static struct attribute_group dcssblk_dev_attr_group = {
 527         .attrs = dcssblk_dev_attrs,
 528 };
 529 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 530         &dcssblk_dev_attr_group,
 531         NULL,
 532 };
 533
 534 /*
 535  * device attribute for adding devices
 536  */
 537 static ssize_t
 538 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 539 {
 540         int rc, i, j, num_of_segments;
 541         struct dcssblk_dev_info *dev_info;
 542         struct segment_info *seg_info, *temp;
 543         char *local_buf;
 544         unsigned long seg_byte_size;
 545
 546         dev_info = NULL;
 547         seg_info = NULL;
 548         if (dev != dcssblk_root_dev) {
 549                 rc = -EINVAL;
 550                 goto out_nobuf;
 551         }
 552         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 553                 rc = -ENAMETOOLONG;
 554                 goto out_nobuf;
 555         }
 556
 557         local_buf = kmalloc(count + 1, GFP_KERNEL);
 558         if (local_buf == NULL) {
 559                 rc = -ENOMEM;
 560                 goto out_nobuf;
 561         }
 562
 563         /*
 564          * parse input
 565          */
 566         num_of_segments = 0;
 567         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 568                 for (j = i; j < count &&
 569                         (buf[j] != ':') &&
 570                         (buf[j] != '\0') &&
 571                         (buf[j] != '\n'); j++) {
 572                         local_buf[j-i] = toupper(buf[j]);
 573                 }
 574                 local_buf[j-i] = '\0';
 575                 if (((j - i) == 0) || ((j - i) > 8)) {
 576                         rc = -ENAMETOOLONG;
 577                         goto seg_list_del;
 578                 }
 579
 580                 rc = dcssblk_load_segment(local_buf, &seg_info);
 581                 if (rc < 0)
 582                         goto seg_list_del;
 583                 /*
 584                  * get a struct dcssblk_dev_info
 585                  */
 586                 if (num_of_segments == 0) {
 587                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 588                                         GFP_KERNEL);
 589                         if (dev_info == NULL) {
 590                                 rc = -ENOMEM;
 591                                 goto out;
 592                         }
 593                         strcpy(dev_info->segment_name, local_buf);
 594                         dev_info->segment_type = seg_info->segment_type;
 595                         INIT_LIST_HEAD(&dev_info->seg_list);
 596                 }
 597                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 598                 num_of_segments++;
 599                 i = j;
 600
 601                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 602                         break;
 603         }
 604
 605         /* no trailing colon at the end of the input */
 606         if ((i > 0) && (buf[i-1] == ':')) {
 607                 rc = -ENAMETOOLONG;
 608                 goto seg_list_del;
 609         }
 610         strlcpy(local_buf, buf, i + 1);
 611         dev_info->num_of_segments = num_of_segments;
 612         rc = dcssblk_is_continuous(dev_info);
 613         if (rc < 0)
 614                 goto seg_list_del;
 615
 616         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 617         dev_info->end = dcssblk_find_highest_addr(dev_info);
 618
 619         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 620         dev_info->dev.release = dcssblk_release_segment;
 621         dev_info->dev.groups = dcssblk_dev_attr_groups;
 622         INIT_LIST_HEAD(&dev_info->lh);
 623         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 624         if (dev_info->gd == NULL) {
 625                 rc = -ENOMEM;
 626                 goto seg_list_del;
 627         }
 628         dev_info->gd->major = dcssblk_major;
 629         dev_info->gd->fops = &dcssblk_devops;
 630         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 631         dev_info->gd->queue = dev_info->dcssblk_queue;
 632         dev_info->gd->private_data = dev_info;
 633         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 634         blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 635         queue_flag_set_unlocked(QUEUE_FLAG_DAX, dev_info->dcssblk_queue);
 636
 637         seg_byte_size = (dev_info->end - dev_info->start + 1);
 638         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 639         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 640                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 641
 642         dev_info->save_pending = 0;
 643         dev_info->is_shared = 1;
 644         dev_info->dev.parent = dcssblk_root_dev;
 645
 646         /*
 647          *get minor, add to list
 648          */
 649         down_write(&dcssblk_devices_sem);
 650         if (dcssblk_get_segment_by_name(local_buf)) {
 651                 rc = -EEXIST;
 652                 goto release_gd;
 653         }
 654         rc = dcssblk_assign_free_minor(dev_info);
 655         if (rc)
 656                 goto release_gd;
 657         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 658                 dev_info->gd->first_minor);
 659         list_add_tail(&dev_info->lh, &dcssblk_devices);
 660
 661         if (!try_module_get(THIS_MODULE)) {
 662                 rc = -ENODEV;
 663                 goto dev_list_del;
 664         }
 665         /*
 666          * register the device
 667          */
 668         rc = device_register(&dev_info->dev);
 669         if (rc)
 670                 goto put_dev;
 671
 672         dev_info->dax_dev = alloc_dax(dev_info, dev_info->gd->disk_name,
 673                         &dcssblk_dax_ops);
 674         if (!dev_info->dax_dev) {
 675                 rc = -ENOMEM;
 676                 goto put_dev;
 677         }
 678
 679         get_device(&dev_info->dev);
 680         device_add_disk(&dev_info->dev, dev_info->gd);
 681
 682         switch (dev_info->segment_type) {
 683                 case SEG_TYPE_SR:
 684                 case SEG_TYPE_ER:
 685                 case SEG_TYPE_SC:
 686                         set_disk_ro(dev_info->gd,1);
 687                         break;
 688                 default:
 689                         set_disk_ro(dev_info->gd,0);
 690                         break;
 691         }
 692         up_write(&dcssblk_devices_sem);
 693         rc = count;
 694         goto out;
 695
 696 put_dev:
 697         list_del(&dev_info->lh);
 698         blk_cleanup_queue(dev_info->dcssblk_queue);
 699         dev_info->gd->queue = NULL;
 700         put_disk(dev_info->gd);
 701         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 702                 segment_unload(seg_info->segment_name);
 703         }
 704         put_device(&dev_info->dev);
 705         up_write(&dcssblk_devices_sem);
 706         goto out;
 707 dev_list_del:
 708         list_del(&dev_info->lh);
 709 release_gd:
 710         blk_cleanup_queue(dev_info->dcssblk_queue);
 711         dev_info->gd->queue = NULL;
 712         put_disk(dev_info->gd);
 713         up_write(&dcssblk_devices_sem);
 714 seg_list_del:
 715         if (dev_info == NULL)
 716                 goto out;
 717         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 718                 list_del(&seg_info->lh);
 719                 segment_unload(seg_info->segment_name);
 720                 kfree(seg_info);
 721         }
 722         kfree(dev_info);
 723 out:
 724         kfree(local_buf);
 725 out_nobuf:
 726         return rc;
 727 }
 728
 729 /*
 730  * device attribute for removing devices
 731  */
 732 static ssize_t
 733 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 734 {
 735         struct dcssblk_dev_info *dev_info;
 736         struct segment_info *entry;
 737         int rc, i;
 738         char *local_buf;
 739
 740         if (dev != dcssblk_root_dev) {
 741                 return -EINVAL;
 742         }
 743         local_buf = kmalloc(count + 1, GFP_KERNEL);
 744         if (local_buf == NULL) {
 745                 return -ENOMEM;
 746         }
 747         /*
 748          * parse input
 749          */
 750         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 751                 local_buf[i] = toupper(buf[i]);
 752         }
 753         local_buf[i] = '\0';
 754         if ((i == 0) || (i > 8)) {
 755                 rc = -ENAMETOOLONG;
 756                 goto out_buf;
 757         }
 758
 759         down_write(&dcssblk_devices_sem);
 760         dev_info = dcssblk_get_device_by_name(local_buf);
 761         if (dev_info == NULL) {
 762                 up_write(&dcssblk_devices_sem);
 763                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 764                         local_buf);
 765                 rc = -ENODEV;
 766                 goto out_buf;
 767         }
 768         if (atomic_read(&dev_info->use_count) != 0) {
 769                 up_write(&dcssblk_devices_sem);
 770                 pr_warn("Device %s cannot be removed while it is in use\n",
 771                         local_buf);
 772                 rc = -EBUSY;
 773                 goto out_buf;
 774         }
 775
 776         list_del(&dev_info->lh);
 777         kill_dax(dev_info->dax_dev);
 778         put_dax(dev_info->dax_dev);
 779         del_gendisk(dev_info->gd);
 780         blk_cleanup_queue(dev_info->dcssblk_queue);
 781         dev_info->gd->queue = NULL;
 782         put_disk(dev_info->gd);
 783
 784         /* unload all related segments */
 785         list_for_each_entry(entry, &dev_info->seg_list, lh)
 786                 segment_unload(entry->segment_name);
 787
 788         up_write(&dcssblk_devices_sem);
 789
 790         device_unregister(&dev_info->dev);
 791         put_device(&dev_info->dev);
 792
 793         rc = count;
 794 out_buf:
 795         kfree(local_buf);
 796         return rc;
 797 }
 798
 799 static int
 800 dcssblk_open(struct block_device *bdev, fmode_t mode)
 801 {
 802         struct dcssblk_dev_info *dev_info;
 803         int rc;
 804
 805         dev_info = bdev->bd_disk->private_data;
 806         if (NULL == dev_info) {
 807                 rc = -ENODEV;
 808                 goto out;
 809         }
 810         atomic_inc(&dev_info->use_count);
 811         bdev->bd_block_size = 4096;
 812         rc = 0;
 813 out:
 814         return rc;
 815 }
 816
 817 static void
 818 dcssblk_release(struct gendisk *disk, fmode_t mode)
 819 {
 820         struct dcssblk_dev_info *dev_info = disk->private_data;
 821         struct segment_info *entry;
 822
 823         if (!dev_info) {
 824                 WARN_ON(1);
 825                 return;
 826         }
 827         down_write(&dcssblk_devices_sem);
 828         if (atomic_dec_and_test(&dev_info->use_count)
 829             && (dev_info->save_pending)) {
 830                 pr_info("Device %s has become idle and is being saved "
 831                         "now\n", dev_info->segment_name);
 832                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 833                         if (entry->segment_type == SEG_TYPE_EN ||
 834                             entry->segment_type == SEG_TYPE_SN)
 835                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 836                                         " be saved\n", entry->segment_name);
 837                         else
 838                                 segment_save(entry->segment_name);
 839                 }
 840                 dev_info->save_pending = 0;
 841         }
 842         up_write(&dcssblk_devices_sem);
 843 }
 844
 845 static blk_qc_t
 846 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 847 {
 848         struct dcssblk_dev_info *dev_info;
 849         struct bio_vec bvec;
 850         struct bvec_iter iter;
 851         unsigned long index;
 852         unsigned long page_addr;
 853         unsigned long source_addr;
 854         unsigned long bytes_done;
 855
 856         blk_queue_split(q, &bio);
 857
 858         bytes_done = 0;
 859         dev_info = bio->bi_disk->private_data;
 860         if (dev_info == NULL)
 861                 goto fail;
 862         if ((bio->bi_iter.bi_sector & 7) != 0 ||
 863             (bio->bi_iter.bi_size & 4095) != 0)
 864                 /* Request is not page-aligned. */
 865                 goto fail;
 866         if (bio_end_sector(bio) > get_capacity(bio->bi_disk)) {
 867                 /* Request beyond end of DCSS segment. */
 868                 goto fail;
 869         }
 870         /* verify data transfer direction */
 871         if (dev_info->is_shared) {
 872                 switch (dev_info->segment_type) {
 873                 case SEG_TYPE_SR:
 874                 case SEG_TYPE_ER:
 875                 case SEG_TYPE_SC:
 876                         /* cannot write to these segments */
 877                         if (bio_data_dir(bio) == WRITE) {
 878                                 pr_warn("Writing to %s failed because it is a read-only device\n",
 879                                         dev_name(&dev_info->dev));
 880                                 goto fail;
 881                         }
 882                 }
 883         }
 884
 885         index = (bio->bi_iter.bi_sector >> 3);
 886         bio_for_each_segment(bvec, bio, iter) {
 887                 page_addr = (unsigned long)
 888                         page_address(bvec.bv_page) + bvec.bv_offset;
 889                 source_addr = dev_info->start + (index<<12) + bytes_done;
 890                 if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 891                         // More paranoia.
 892                         goto fail;
 893                 if (bio_data_dir(bio) == READ) {
 894                         memcpy((void*)page_addr, (void*)source_addr,
 895                                 bvec.bv_len);
 896                 } else {
 897                         memcpy((void*)source_addr, (void*)page_addr,
 898                                 bvec.bv_len);
 899                 }
 900                 bytes_done += bvec.bv_len;
 901         }
 902         bio_endio(bio);
 903         return BLK_QC_T_NONE;
 904 fail:
 905         bio_io_error(bio);
 906         return BLK_QC_T_NONE;
 907 }
 908
 909 static long
 910 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 911                 long nr_pages, void **kaddr, pfn_t *pfn)
 912 {
 913         resource_size_t offset = pgoff * PAGE_SIZE;
 914         unsigned long dev_sz;
 915
 916         dev_sz = dev_info->end - dev_info->start + 1;
 917         *kaddr = (void *) dev_info->start + offset;
 918         *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), PFN_DEV);
 919
 920         return (dev_sz - offset) / PAGE_SIZE;
 921 }
 922
 923 static long
 924 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 925                 long nr_pages, void **kaddr, pfn_t *pfn)
 926 {
 927         struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 928
 929         return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 930 }
 931
 932 static void
 933 dcssblk_check_params(void)
 934 {
 935         int rc, i, j, k;
 936         char buf[DCSSBLK_PARM_LEN + 1];
 937         struct dcssblk_dev_info *dev_info;
 938
 939         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 940              i++) {
 941                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 942                             (dcssblk_segments[j] != ',')  &&
 943                             (dcssblk_segments[j] != '\0') &&
 944                             (dcssblk_segments[j] != '('); j++)
 945                 {
 946                         buf[j-i] = dcssblk_segments[j];
 947                 }
 948                 buf[j-i] = '\0';
 949                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 950                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 951                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 952                                 buf[k] = toupper(buf[k]);
 953                         buf[k] = '\0';
 954                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 955                                 down_read(&dcssblk_devices_sem);
 956                                 dev_info = dcssblk_get_device_by_name(buf);
 957                                 up_read(&dcssblk_devices_sem);
 958                                 if (dev_info)
 959                                         dcssblk_shared_store(&dev_info->dev,
 960                                                              NULL, "0\n", 2);
 961                         }
 962                 }
 963                 while ((dcssblk_segments[j] != ',') &&
 964                        (dcssblk_segments[j] != '\0'))
 965                 {
 966                         j++;
 967                 }
 968                 if (dcssblk_segments[j] == '\0')
 969                         break;
 970                 i = j;
 971         }
 972 }
 973
 974 /*
 975  * Suspend / Resume
 976  */
 977 static int dcssblk_freeze(struct device *dev)
 978 {
 979         struct dcssblk_dev_info *dev_info;
 980         int rc = 0;
 981
 982         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 983                 switch (dev_info->segment_type) {
 984                         case SEG_TYPE_SR:
 985                         case SEG_TYPE_ER:
 986                         case SEG_TYPE_SC:
 987                                 if (!dev_info->is_shared)
 988                                         rc = -EINVAL;
 989                                 break;
 990                         default:
 991                                 rc = -EINVAL;
 992                                 break;
 993                 }
 994                 if (rc)
 995                         break;
 996         }
 997         if (rc)
 998                 pr_err("Suspending the system failed because DCSS device %s "
 999                        "is writable\n",
1000                        dev_info->segment_name);
1001         return rc;
1002 }
1003
1004 static int dcssblk_restore(struct device *dev)
1005 {
1006         struct dcssblk_dev_info *dev_info;
1007         struct segment_info *entry;
1008         unsigned long start, end;
1009         int rc = 0;
1010
1011         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
1012                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
1013                         segment_unload(entry->segment_name);
1014                         rc = segment_load(entry->segment_name, SEGMENT_SHARED,
1015                                           &start, &end);
1016                         if (rc < 0) {
1017 // TODO in_use check ?
1018                                 segment_warning(rc, entry->segment_name);
1019                                 goto out_panic;
1020                         }
1021                         if (start != entry->start || end != entry->end) {
1022                                 pr_err("The address range of DCSS %s changed "
1023                                        "while the system was suspended\n",
1024                                        entry->segment_name);
1025                                 goto out_panic;
1026                         }
1027                 }
1028         }
1029         return 0;
1030 out_panic:
1031         panic("fatal dcssblk resume error\n");
1032 }
1033
1034 static int dcssblk_thaw(struct device *dev)
1035 {
1036         return 0;
1037 }
1038
1039 static const struct dev_pm_ops dcssblk_pm_ops = {
1040         .freeze         = dcssblk_freeze,
1041         .thaw           = dcssblk_thaw,
1042         .restore        = dcssblk_restore,
1043 };
1044
1045 static struct platform_driver dcssblk_pdrv = {
1046         .driver = {
1047                 .name   = "dcssblk",
1048                 .pm     = &dcssblk_pm_ops,
1049         },
1050 };
1051
1052 static struct platform_device *dcssblk_pdev;
1053
1054
1055 /*
1056  * The init/exit functions.
1057  */
1058 static void __exit
1059 dcssblk_exit(void)
1060 {
1061         platform_device_unregister(dcssblk_pdev);
1062         platform_driver_unregister(&dcssblk_pdrv);
1063         root_device_unregister(dcssblk_root_dev);
1064         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1065 }
1066
1067 static int __init
1068 dcssblk_init(void)
1069 {
1070         int rc;
1071
1072         rc = platform_driver_register(&dcssblk_pdrv);
1073         if (rc)
1074                 return rc;
1075
1076         dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1077                                                         0);
1078         if (IS_ERR(dcssblk_pdev)) {
1079                 rc = PTR_ERR(dcssblk_pdev);
1080                 goto out_pdrv;
1081         }
1082
1083         dcssblk_root_dev = root_device_register("dcssblk");
1084         if (IS_ERR(dcssblk_root_dev)) {
1085                 rc = PTR_ERR(dcssblk_root_dev);
1086                 goto out_pdev;
1087         }
1088         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1089         if (rc)
1090                 goto out_root;
1091         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1092         if (rc)
1093                 goto out_root;
1094         rc = register_blkdev(0, DCSSBLK_NAME);
1095         if (rc < 0)
1096                 goto out_root;
1097         dcssblk_major = rc;
1098         init_rwsem(&dcssblk_devices_sem);
1099
1100         dcssblk_check_params();
1101         return 0;
1102
1103 out_root:
1104         root_device_unregister(dcssblk_root_dev);
1105 out_pdev:
1106         platform_device_unregister(dcssblk_pdev);
1107 out_pdrv:
1108         platform_driver_unregister(&dcssblk_pdrv);
1109         return rc;
1110 }
1111
1112 module_init(dcssblk_init);
1113 module_exit(dcssblk_exit);
1114
1115 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1116 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1117                  "comma-separated list, names in each set separated "
1118                  "by commas are separated by colons, each set contains "
1119                  "names of contiguous segments and each name max. 8 chars.\n"
1120                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1121                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1122                  "the contiguous segments - \n"
1123                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1124
1125 MODULE_LICENSE("GPL");