drivers/s390/block/dcssblk.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * dcssblk.c -- the S/390 block driver for dcss memory
   4  *
   5  * Authors: Carsten Otte, Stefan Weinhuber, Gerald Schaefer
   6  */
   7
   8 #define KMSG_COMPONENT "dcssblk"
   9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  10
  11 #include <linux/module.h>
  12 #include <linux/moduleparam.h>
  13 #include <linux/ctype.h>
  14 #include <linux/errno.h>
  15 #include <linux/init.h>
  16 #include <linux/slab.h>
  17 #include <linux/blkdev.h>
  18 #include <linux/completion.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/pfn_t.h>
  22 #include <linux/uio.h>
  23 #include <linux/dax.h>
  24 #include <asm/extmem.h>
  25 #include <asm/io.h>
  26
  27 #define DCSSBLK_NAME "dcssblk"
  28 #define DCSSBLK_MINORS_PER_DISK 1
  29 #define DCSSBLK_PARM_LEN 400
  30 #define DCSS_BUS_ID_SIZE 20
  31
  32 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
  33 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
  34 static blk_qc_t dcssblk_make_request(struct request_queue *q,
  35                                                 struct bio *bio);
  36 static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
  37                 long nr_pages, void **kaddr, pfn_t *pfn);
  38
  39 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  40
  41 static int dcssblk_major;
  42 static const struct block_device_operations dcssblk_devops = {
  43         .owner          = THIS_MODULE,
  44         .open           = dcssblk_open,
  45         .release        = dcssblk_release,
  46 };
  47
  48 static size_t dcssblk_dax_copy_from_iter(struct dax_device *dax_dev,
  49                 pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
  50 {
  51         return copy_from_iter(addr, bytes, i);
  52 }
  53
  54 static const struct dax_operations dcssblk_dax_ops = {
  55         .direct_access = dcssblk_dax_direct_access,
  56         .copy_from_iter = dcssblk_dax_copy_from_iter,
  57 };
  58
  59 struct dcssblk_dev_info {
  60         struct list_head lh;
  61         struct device dev;
  62         char segment_name[DCSS_BUS_ID_SIZE];
  63         atomic_t use_count;
  64         struct gendisk *gd;
  65         unsigned long start;
  66         unsigned long end;
  67         int segment_type;
  68         unsigned char save_pending;
  69         unsigned char is_shared;
  70         struct request_queue *dcssblk_queue;
  71         int num_of_segments;
  72         struct list_head seg_list;
  73         struct dax_device *dax_dev;
  74 };
  75
  76 struct segment_info {
  77         struct list_head lh;
  78         char segment_name[DCSS_BUS_ID_SIZE];
  79         unsigned long start;
  80         unsigned long end;
  81         int segment_type;
  82 };
  83
  84 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  85                                   size_t count);
  86 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  87                                   size_t count);
  88
  89 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  90 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  91
  92 static struct device *dcssblk_root_dev;
  93
  94 static LIST_HEAD(dcssblk_devices);
  95 static struct rw_semaphore dcssblk_devices_sem;
  96
  97 /*
  98  * release function for segment device.
  99  */
 100 static void
 101 dcssblk_release_segment(struct device *dev)
 102 {
 103         struct dcssblk_dev_info *dev_info;
 104         struct segment_info *entry, *temp;
 105
 106         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 107         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 108                 list_del(&entry->lh);
 109                 kfree(entry);
 110         }
 111         kfree(dev_info);
 112         module_put(THIS_MODULE);
 113 }
 114
 115 /*
 116  * get a minor number. needs to be called with
 117  * down_write(&dcssblk_devices_sem) and the
 118  * device needs to be enqueued before the semaphore is
 119  * freed.
 120  */
 121 static int
 122 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 123 {
 124         int minor, found;
 125         struct dcssblk_dev_info *entry;
 126
 127         if (dev_info == NULL)
 128                 return -EINVAL;
 129         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 130                 found = 0;
 131                 // test if minor available
 132                 list_for_each_entry(entry, &dcssblk_devices, lh)
 133                         if (minor == entry->gd->first_minor)
 134                                 found++;
 135                 if (!found) break; // got unused minor
 136         }
 137         if (found)
 138                 return -EBUSY;
 139         dev_info->gd->first_minor = minor;
 140         return 0;
 141 }
 142
 143 /*
 144  * get the struct dcssblk_dev_info from dcssblk_devices
 145  * for the given name.
 146  * down_read(&dcssblk_devices_sem) must be held.
 147  */
 148 static struct dcssblk_dev_info *
 149 dcssblk_get_device_by_name(char *name)
 150 {
 151         struct dcssblk_dev_info *entry;
 152
 153         list_for_each_entry(entry, &dcssblk_devices, lh) {
 154                 if (!strcmp(name, entry->segment_name)) {
 155                         return entry;
 156                 }
 157         }
 158         return NULL;
 159 }
 160
 161 /*
 162  * get the struct segment_info from seg_list
 163  * for the given name.
 164  * down_read(&dcssblk_devices_sem) must be held.
 165  */
 166 static struct segment_info *
 167 dcssblk_get_segment_by_name(char *name)
 168 {
 169         struct dcssblk_dev_info *dev_info;
 170         struct segment_info *entry;
 171
 172         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 173                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 174                         if (!strcmp(name, entry->segment_name))
 175                                 return entry;
 176                 }
 177         }
 178         return NULL;
 179 }
 180
 181 /*
 182  * get the highest address of the multi-segment block.
 183  */
 184 static unsigned long
 185 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 186 {
 187         unsigned long highest_addr;
 188         struct segment_info *entry;
 189
 190         highest_addr = 0;
 191         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 192                 if (highest_addr < entry->end)
 193                         highest_addr = entry->end;
 194         }
 195         return highest_addr;
 196 }
 197
 198 /*
 199  * get the lowest address of the multi-segment block.
 200  */
 201 static unsigned long
 202 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 203 {
 204         int set_first;
 205         unsigned long lowest_addr;
 206         struct segment_info *entry;
 207
 208         set_first = 0;
 209         lowest_addr = 0;
 210         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 211                 if (set_first == 0) {
 212                         lowest_addr = entry->start;
 213                         set_first = 1;
 214                 } else {
 215                         if (lowest_addr > entry->start)
 216                                 lowest_addr = entry->start;
 217                 }
 218         }
 219         return lowest_addr;
 220 }
 221
 222 /*
 223  * Check continuity of segments.
 224  */
 225 static int
 226 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 227 {
 228         int i, j, rc;
 229         struct segment_info *sort_list, *entry, temp;
 230
 231         if (dev_info->num_of_segments <= 1)
 232                 return 0;
 233
 234         sort_list = kzalloc(
 235                         sizeof(struct segment_info) * dev_info->num_of_segments,
 236                         GFP_KERNEL);
 237         if (sort_list == NULL)
 238                 return -ENOMEM;
 239         i = 0;
 240         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 241                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 242                 i++;
 243         }
 244
 245         /* sort segments */
 246         for (i = 0; i < dev_info->num_of_segments; i++)
 247                 for (j = 0; j < dev_info->num_of_segments; j++)
 248                         if (sort_list[j].start > sort_list[i].start) {
 249                                 memcpy(&temp, &sort_list[i],
 250                                         sizeof(struct segment_info));
 251                                 memcpy(&sort_list[i], &sort_list[j],
 252                                         sizeof(struct segment_info));
 253                                 memcpy(&sort_list[j], &temp,
 254                                         sizeof(struct segment_info));
 255                         }
 256
 257         /* check continuity */
 258         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 259                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 260                         pr_err("Adjacent DCSSs %s and %s are not "
 261                                "contiguous\n", sort_list[i].segment_name,
 262                                sort_list[i+1].segment_name);
 263                         rc = -EINVAL;
 264                         goto out;
 265                 }
 266                 /* EN and EW are allowed in a block device */
 267                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 268                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 269                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 270                                 !(sort_list[i+1].segment_type &
 271                                 SEGMENT_EXCLUSIVE) ||
 272                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 273                                 pr_err("DCSS %s and DCSS %s have "
 274                                        "incompatible types\n",
 275                                        sort_list[i].segment_name,
 276                                        sort_list[i+1].segment_name);
 277                                 rc = -EINVAL;
 278                                 goto out;
 279                         }
 280                 }
 281         }
 282         rc = 0;
 283 out:
 284         kfree(sort_list);
 285         return rc;
 286 }
 287
 288 /*
 289  * Load a segment
 290  */
 291 static int
 292 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 293 {
 294         int rc;
 295
 296         /* already loaded? */
 297         down_read(&dcssblk_devices_sem);
 298         *seg_info = dcssblk_get_segment_by_name(name);
 299         up_read(&dcssblk_devices_sem);
 300         if (*seg_info != NULL)
 301                 return -EEXIST;
 302
 303         /* get a struct segment_info */
 304         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 305         if (*seg_info == NULL)
 306                 return -ENOMEM;
 307
 308         strcpy((*seg_info)->segment_name, name);
 309
 310         /* load the segment */
 311         rc = segment_load(name, SEGMENT_SHARED,
 312                         &(*seg_info)->start, &(*seg_info)->end);
 313         if (rc < 0) {
 314                 segment_warning(rc, (*seg_info)->segment_name);
 315                 kfree(*seg_info);
 316         } else {
 317                 INIT_LIST_HEAD(&(*seg_info)->lh);
 318                 (*seg_info)->segment_type = rc;
 319         }
 320         return rc;
 321 }
 322
 323 /*
 324  * device attribute for switching shared/nonshared (exclusive)
 325  * operation (show + store)
 326  */
 327 static ssize_t
 328 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 329 {
 330         struct dcssblk_dev_info *dev_info;
 331
 332         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 333         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 334 }
 335
 336 static ssize_t
 337 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 338 {
 339         struct dcssblk_dev_info *dev_info;
 340         struct segment_info *entry, *temp;
 341         int rc;
 342
 343         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 344                 return -EINVAL;
 345         down_write(&dcssblk_devices_sem);
 346         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 347         if (atomic_read(&dev_info->use_count)) {
 348                 rc = -EBUSY;
 349                 goto out;
 350         }
 351         if (inbuf[0] == '1') {
 352                 /* reload segments in shared mode */
 353                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 354                         rc = segment_modify_shared(entry->segment_name,
 355                                                 SEGMENT_SHARED);
 356                         if (rc < 0) {
 357                                 BUG_ON(rc == -EINVAL);
 358                                 if (rc != -EAGAIN)
 359                                         goto removeseg;
 360                         }
 361                 }
 362                 dev_info->is_shared = 1;
 363                 switch (dev_info->segment_type) {
 364                 case SEG_TYPE_SR:
 365                 case SEG_TYPE_ER:
 366                 case SEG_TYPE_SC:
 367                         set_disk_ro(dev_info->gd, 1);
 368                 }
 369         } else if (inbuf[0] == '0') {
 370                 /* reload segments in exclusive mode */
 371                 if (dev_info->segment_type == SEG_TYPE_SC) {
 372                         pr_err("DCSS %s is of type SC and cannot be "
 373                                "loaded as exclusive-writable\n",
 374                                dev_info->segment_name);
 375                         rc = -EINVAL;
 376                         goto out;
 377                 }
 378                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 379                         rc = segment_modify_shared(entry->segment_name,
 380                                                    SEGMENT_EXCLUSIVE);
 381                         if (rc < 0) {
 382                                 BUG_ON(rc == -EINVAL);
 383                                 if (rc != -EAGAIN)
 384                                         goto removeseg;
 385                         }
 386                 }
 387                 dev_info->is_shared = 0;
 388                 set_disk_ro(dev_info->gd, 0);
 389         } else {
 390                 rc = -EINVAL;
 391                 goto out;
 392         }
 393         rc = count;
 394         goto out;
 395
 396 removeseg:
 397         pr_err("DCSS device %s is removed after a failed access mode "
 398                "change\n", dev_info->segment_name);
 399         temp = entry;
 400         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 401                 if (entry != temp)
 402                         segment_unload(entry->segment_name);
 403         }
 404         list_del(&dev_info->lh);
 405
 406         kill_dax(dev_info->dax_dev);
 407         put_dax(dev_info->dax_dev);
 408         del_gendisk(dev_info->gd);
 409         blk_cleanup_queue(dev_info->dcssblk_queue);
 410         dev_info->gd->queue = NULL;
 411         put_disk(dev_info->gd);
 412         up_write(&dcssblk_devices_sem);
 413
 414         if (device_remove_file_self(dev, attr)) {
 415                 device_unregister(dev);
 416                 put_device(dev);
 417         }
 418         return rc;
 419 out:
 420         up_write(&dcssblk_devices_sem);
 421         return rc;
 422 }
 423 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 424                    dcssblk_shared_store);
 425
 426 /*
 427  * device attribute for save operation on current copy
 428  * of the segment. If the segment is busy, saving will
 429  * become pending until it gets released, which can be
 430  * undone by storing a non-true value to this entry.
 431  * (show + store)
 432  */
 433 static ssize_t
 434 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 435 {
 436         struct dcssblk_dev_info *dev_info;
 437
 438         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 439         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 440 }
 441
 442 static ssize_t
 443 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 444 {
 445         struct dcssblk_dev_info *dev_info;
 446         struct segment_info *entry;
 447
 448         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 449                 return -EINVAL;
 450         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 451
 452         down_write(&dcssblk_devices_sem);
 453         if (inbuf[0] == '1') {
 454                 if (atomic_read(&dev_info->use_count) == 0) {
 455                         // device is idle => we save immediately
 456                         pr_info("All DCSSs that map to device %s are "
 457                                 "saved\n", dev_info->segment_name);
 458                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 459                                 if (entry->segment_type == SEG_TYPE_EN ||
 460                                     entry->segment_type == SEG_TYPE_SN)
 461                                         pr_warn("DCSS %s is of type SN or EN"
 462                                                 " and cannot be saved\n",
 463                                                 entry->segment_name);
 464                                 else
 465                                         segment_save(entry->segment_name);
 466                         }
 467                 }  else {
 468                         // device is busy => we save it when it becomes
 469                         // idle in dcssblk_release
 470                         pr_info("Device %s is in use, its DCSSs will be "
 471                                 "saved when it becomes idle\n",
 472                                 dev_info->segment_name);
 473                         dev_info->save_pending = 1;
 474                 }
 475         } else if (inbuf[0] == '0') {
 476                 if (dev_info->save_pending) {
 477                         // device is busy & the user wants to undo his save
 478                         // request
 479                         dev_info->save_pending = 0;
 480                         pr_info("A pending save request for device %s "
 481                                 "has been canceled\n",
 482                                 dev_info->segment_name);
 483                 }
 484         } else {
 485                 up_write(&dcssblk_devices_sem);
 486                 return -EINVAL;
 487         }
 488         up_write(&dcssblk_devices_sem);
 489         return count;
 490 }
 491 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 492                    dcssblk_save_store);
 493
 494 /*
 495  * device attribute for showing all segments in a device
 496  */
 497 static ssize_t
 498 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 499                 char *buf)
 500 {
 501         int i;
 502
 503         struct dcssblk_dev_info *dev_info;
 504         struct segment_info *entry;
 505
 506         down_read(&dcssblk_devices_sem);
 507         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 508         i = 0;
 509         buf[0] = '\0';
 510         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 511                 strcpy(&buf[i], entry->segment_name);
 512                 i += strlen(entry->segment_name);
 513                 buf[i] = '\n';
 514                 i++;
 515         }
 516         up_read(&dcssblk_devices_sem);
 517         return i;
 518 }
 519 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 520
 521 static struct attribute *dcssblk_dev_attrs[] = {
 522         &dev_attr_shared.attr,
 523         &dev_attr_save.attr,
 524         &dev_attr_seglist.attr,
 525         NULL,
 526 };
 527 static struct attribute_group dcssblk_dev_attr_group = {
 528         .attrs = dcssblk_dev_attrs,
 529 };
 530 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 531         &dcssblk_dev_attr_group,
 532         NULL,
 533 };
 534
 535 /*
 536  * device attribute for adding devices
 537  */
 538 static ssize_t
 539 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 540 {
 541         int rc, i, j, num_of_segments;
 542         struct dcssblk_dev_info *dev_info;
 543         struct segment_info *seg_info, *temp;
 544         char *local_buf;
 545         unsigned long seg_byte_size;
 546
 547         dev_info = NULL;
 548         seg_info = NULL;
 549         if (dev != dcssblk_root_dev) {
 550                 rc = -EINVAL;
 551                 goto out_nobuf;
 552         }
 553         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 554                 rc = -ENAMETOOLONG;
 555                 goto out_nobuf;
 556         }
 557
 558         local_buf = kmalloc(count + 1, GFP_KERNEL);
 559         if (local_buf == NULL) {
 560                 rc = -ENOMEM;
 561                 goto out_nobuf;
 562         }
 563
 564         /*
 565          * parse input
 566          */
 567         num_of_segments = 0;
 568         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 569                 for (j = i; j < count &&
 570                         (buf[j] != ':') &&
 571                         (buf[j] != '\0') &&
 572                         (buf[j] != '\n'); j++) {
 573                         local_buf[j-i] = toupper(buf[j]);
 574                 }
 575                 local_buf[j-i] = '\0';
 576                 if (((j - i) == 0) || ((j - i) > 8)) {
 577                         rc = -ENAMETOOLONG;
 578                         goto seg_list_del;
 579                 }
 580
 581                 rc = dcssblk_load_segment(local_buf, &seg_info);
 582                 if (rc < 0)
 583                         goto seg_list_del;
 584                 /*
 585                  * get a struct dcssblk_dev_info
 586                  */
 587                 if (num_of_segments == 0) {
 588                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 589                                         GFP_KERNEL);
 590                         if (dev_info == NULL) {
 591                                 rc = -ENOMEM;
 592                                 goto out;
 593                         }
 594                         strcpy(dev_info->segment_name, local_buf);
 595                         dev_info->segment_type = seg_info->segment_type;
 596                         INIT_LIST_HEAD(&dev_info->seg_list);
 597                 }
 598                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 599                 num_of_segments++;
 600                 i = j;
 601
 602                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 603                         break;
 604         }
 605
 606         /* no trailing colon at the end of the input */
 607         if ((i > 0) && (buf[i-1] == ':')) {
 608                 rc = -ENAMETOOLONG;
 609                 goto seg_list_del;
 610         }
 611         strlcpy(local_buf, buf, i + 1);
 612         dev_info->num_of_segments = num_of_segments;
 613         rc = dcssblk_is_continuous(dev_info);
 614         if (rc < 0)
 615                 goto seg_list_del;
 616
 617         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 618         dev_info->end = dcssblk_find_highest_addr(dev_info);
 619
 620         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 621         dev_info->dev.release = dcssblk_release_segment;
 622         dev_info->dev.groups = dcssblk_dev_attr_groups;
 623         INIT_LIST_HEAD(&dev_info->lh);
 624         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 625         if (dev_info->gd == NULL) {
 626                 rc = -ENOMEM;
 627                 goto seg_list_del;
 628         }
 629         dev_info->gd->major = dcssblk_major;
 630         dev_info->gd->fops = &dcssblk_devops;
 631         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 632         dev_info->gd->queue = dev_info->dcssblk_queue;
 633         dev_info->gd->private_data = dev_info;
 634         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 635         blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 636         queue_flag_set_unlocked(QUEUE_FLAG_DAX, dev_info->dcssblk_queue);
 637
 638         seg_byte_size = (dev_info->end - dev_info->start + 1);
 639         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 640         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 641                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 642
 643         dev_info->save_pending = 0;
 644         dev_info->is_shared = 1;
 645         dev_info->dev.parent = dcssblk_root_dev;
 646
 647         /*
 648          *get minor, add to list
 649          */
 650         down_write(&dcssblk_devices_sem);
 651         if (dcssblk_get_segment_by_name(local_buf)) {
 652                 rc = -EEXIST;
 653                 goto release_gd;
 654         }
 655         rc = dcssblk_assign_free_minor(dev_info);
 656         if (rc)
 657                 goto release_gd;
 658         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 659                 dev_info->gd->first_minor);
 660         list_add_tail(&dev_info->lh, &dcssblk_devices);
 661
 662         if (!try_module_get(THIS_MODULE)) {
 663                 rc = -ENODEV;
 664                 goto dev_list_del;
 665         }
 666         /*
 667          * register the device
 668          */
 669         rc = device_register(&dev_info->dev);
 670         if (rc)
 671                 goto put_dev;
 672
 673         dev_info->dax_dev = alloc_dax(dev_info, dev_info->gd->disk_name,
 674                         &dcssblk_dax_ops);
 675         if (!dev_info->dax_dev) {
 676                 rc = -ENOMEM;
 677                 goto put_dev;
 678         }
 679
 680         get_device(&dev_info->dev);
 681         device_add_disk(&dev_info->dev, dev_info->gd);
 682
 683         switch (dev_info->segment_type) {
 684                 case SEG_TYPE_SR:
 685                 case SEG_TYPE_ER:
 686                 case SEG_TYPE_SC:
 687                         set_disk_ro(dev_info->gd,1);
 688                         break;
 689                 default:
 690                         set_disk_ro(dev_info->gd,0);
 691                         break;
 692         }
 693         up_write(&dcssblk_devices_sem);
 694         rc = count;
 695         goto out;
 696
 697 put_dev:
 698         list_del(&dev_info->lh);
 699         blk_cleanup_queue(dev_info->dcssblk_queue);
 700         dev_info->gd->queue = NULL;
 701         put_disk(dev_info->gd);
 702         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 703                 segment_unload(seg_info->segment_name);
 704         }
 705         put_device(&dev_info->dev);
 706         up_write(&dcssblk_devices_sem);
 707         goto out;
 708 dev_list_del:
 709         list_del(&dev_info->lh);
 710 release_gd:
 711         blk_cleanup_queue(dev_info->dcssblk_queue);
 712         dev_info->gd->queue = NULL;
 713         put_disk(dev_info->gd);
 714         up_write(&dcssblk_devices_sem);
 715 seg_list_del:
 716         if (dev_info == NULL)
 717                 goto out;
 718         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 719                 list_del(&seg_info->lh);
 720                 segment_unload(seg_info->segment_name);
 721                 kfree(seg_info);
 722         }
 723         kfree(dev_info);
 724 out:
 725         kfree(local_buf);
 726 out_nobuf:
 727         return rc;
 728 }
 729
 730 /*
 731  * device attribute for removing devices
 732  */
 733 static ssize_t
 734 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 735 {
 736         struct dcssblk_dev_info *dev_info;
 737         struct segment_info *entry;
 738         int rc, i;
 739         char *local_buf;
 740
 741         if (dev != dcssblk_root_dev) {
 742                 return -EINVAL;
 743         }
 744         local_buf = kmalloc(count + 1, GFP_KERNEL);
 745         if (local_buf == NULL) {
 746                 return -ENOMEM;
 747         }
 748         /*
 749          * parse input
 750          */
 751         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 752                 local_buf[i] = toupper(buf[i]);
 753         }
 754         local_buf[i] = '\0';
 755         if ((i == 0) || (i > 8)) {
 756                 rc = -ENAMETOOLONG;
 757                 goto out_buf;
 758         }
 759
 760         down_write(&dcssblk_devices_sem);
 761         dev_info = dcssblk_get_device_by_name(local_buf);
 762         if (dev_info == NULL) {
 763                 up_write(&dcssblk_devices_sem);
 764                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 765                         local_buf);
 766                 rc = -ENODEV;
 767                 goto out_buf;
 768         }
 769         if (atomic_read(&dev_info->use_count) != 0) {
 770                 up_write(&dcssblk_devices_sem);
 771                 pr_warn("Device %s cannot be removed while it is in use\n",
 772                         local_buf);
 773                 rc = -EBUSY;
 774                 goto out_buf;
 775         }
 776
 777         list_del(&dev_info->lh);
 778         kill_dax(dev_info->dax_dev);
 779         put_dax(dev_info->dax_dev);
 780         del_gendisk(dev_info->gd);
 781         blk_cleanup_queue(dev_info->dcssblk_queue);
 782         dev_info->gd->queue = NULL;
 783         put_disk(dev_info->gd);
 784
 785         /* unload all related segments */
 786         list_for_each_entry(entry, &dev_info->seg_list, lh)
 787                 segment_unload(entry->segment_name);
 788
 789         up_write(&dcssblk_devices_sem);
 790
 791         device_unregister(&dev_info->dev);
 792         put_device(&dev_info->dev);
 793
 794         rc = count;
 795 out_buf:
 796         kfree(local_buf);
 797         return rc;
 798 }
 799
 800 static int
 801 dcssblk_open(struct block_device *bdev, fmode_t mode)
 802 {
 803         struct dcssblk_dev_info *dev_info;
 804         int rc;
 805
 806         dev_info = bdev->bd_disk->private_data;
 807         if (NULL == dev_info) {
 808                 rc = -ENODEV;
 809                 goto out;
 810         }
 811         atomic_inc(&dev_info->use_count);
 812         bdev->bd_block_size = 4096;
 813         rc = 0;
 814 out:
 815         return rc;
 816 }
 817
 818 static void
 819 dcssblk_release(struct gendisk *disk, fmode_t mode)
 820 {
 821         struct dcssblk_dev_info *dev_info = disk->private_data;
 822         struct segment_info *entry;
 823
 824         if (!dev_info) {
 825                 WARN_ON(1);
 826                 return;
 827         }
 828         down_write(&dcssblk_devices_sem);
 829         if (atomic_dec_and_test(&dev_info->use_count)
 830             && (dev_info->save_pending)) {
 831                 pr_info("Device %s has become idle and is being saved "
 832                         "now\n", dev_info->segment_name);
 833                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 834                         if (entry->segment_type == SEG_TYPE_EN ||
 835                             entry->segment_type == SEG_TYPE_SN)
 836                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 837                                         " be saved\n", entry->segment_name);
 838                         else
 839                                 segment_save(entry->segment_name);
 840                 }
 841                 dev_info->save_pending = 0;
 842         }
 843         up_write(&dcssblk_devices_sem);
 844 }
 845
 846 static blk_qc_t
 847 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 848 {
 849         struct dcssblk_dev_info *dev_info;
 850         struct bio_vec bvec;
 851         struct bvec_iter iter;
 852         unsigned long index;
 853         unsigned long page_addr;
 854         unsigned long source_addr;
 855         unsigned long bytes_done;
 856
 857         blk_queue_split(q, &bio);
 858
 859         bytes_done = 0;
 860         dev_info = bio->bi_disk->private_data;
 861         if (dev_info == NULL)
 862                 goto fail;
 863         if ((bio->bi_iter.bi_sector & 7) != 0 ||
 864             (bio->bi_iter.bi_size & 4095) != 0)
 865                 /* Request is not page-aligned. */
 866                 goto fail;
 867         if (bio_end_sector(bio) > get_capacity(bio->bi_disk)) {
 868                 /* Request beyond end of DCSS segment. */
 869                 goto fail;
 870         }
 871         /* verify data transfer direction */
 872         if (dev_info->is_shared) {
 873                 switch (dev_info->segment_type) {
 874                 case SEG_TYPE_SR:
 875                 case SEG_TYPE_ER:
 876                 case SEG_TYPE_SC:
 877                         /* cannot write to these segments */
 878                         if (bio_data_dir(bio) == WRITE) {
 879                                 pr_warn("Writing to %s failed because it is a read-only device\n",
 880                                         dev_name(&dev_info->dev));
 881                                 goto fail;
 882                         }
 883                 }
 884         }
 885
 886         index = (bio->bi_iter.bi_sector >> 3);
 887         bio_for_each_segment(bvec, bio, iter) {
 888                 page_addr = (unsigned long)
 889                         page_address(bvec.bv_page) + bvec.bv_offset;
 890                 source_addr = dev_info->start + (index<<12) + bytes_done;
 891                 if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 892                         // More paranoia.
 893                         goto fail;
 894                 if (bio_data_dir(bio) == READ) {
 895                         memcpy((void*)page_addr, (void*)source_addr,
 896                                 bvec.bv_len);
 897                 } else {
 898                         memcpy((void*)source_addr, (void*)page_addr,
 899                                 bvec.bv_len);
 900                 }
 901                 bytes_done += bvec.bv_len;
 902         }
 903         bio_endio(bio);
 904         return BLK_QC_T_NONE;
 905 fail:
 906         bio_io_error(bio);
 907         return BLK_QC_T_NONE;
 908 }
 909
 910 static long
 911 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 912                 long nr_pages, void **kaddr, pfn_t *pfn)
 913 {
 914         resource_size_t offset = pgoff * PAGE_SIZE;
 915         unsigned long dev_sz;
 916
 917         dev_sz = dev_info->end - dev_info->start + 1;
 918         *kaddr = (void *) dev_info->start + offset;
 919         *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), PFN_DEV);
 920
 921         return (dev_sz - offset) / PAGE_SIZE;
 922 }
 923
 924 static long
 925 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 926                 long nr_pages, void **kaddr, pfn_t *pfn)
 927 {
 928         struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 929
 930         return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 931 }
 932
 933 static void
 934 dcssblk_check_params(void)
 935 {
 936         int rc, i, j, k;
 937         char buf[DCSSBLK_PARM_LEN + 1];
 938         struct dcssblk_dev_info *dev_info;
 939
 940         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 941              i++) {
 942                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 943                             (dcssblk_segments[j] != ',')  &&
 944                             (dcssblk_segments[j] != '\0') &&
 945                             (dcssblk_segments[j] != '('); j++)
 946                 {
 947                         buf[j-i] = dcssblk_segments[j];
 948                 }
 949                 buf[j-i] = '\0';
 950                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 951                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 952                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 953                                 buf[k] = toupper(buf[k]);
 954                         buf[k] = '\0';
 955                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 956                                 down_read(&dcssblk_devices_sem);
 957                                 dev_info = dcssblk_get_device_by_name(buf);
 958                                 up_read(&dcssblk_devices_sem);
 959                                 if (dev_info)
 960                                         dcssblk_shared_store(&dev_info->dev,
 961                                                              NULL, "0\n", 2);
 962                         }
 963                 }
 964                 while ((dcssblk_segments[j] != ',') &&
 965                        (dcssblk_segments[j] != '\0'))
 966                 {
 967                         j++;
 968                 }
 969                 if (dcssblk_segments[j] == '\0')
 970                         break;
 971                 i = j;
 972         }
 973 }
 974
 975 /*
 976  * Suspend / Resume
 977  */
 978 static int dcssblk_freeze(struct device *dev)
 979 {
 980         struct dcssblk_dev_info *dev_info;
 981         int rc = 0;
 982
 983         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 984                 switch (dev_info->segment_type) {
 985                         case SEG_TYPE_SR:
 986                         case SEG_TYPE_ER:
 987                         case SEG_TYPE_SC:
 988                                 if (!dev_info->is_shared)
 989                                         rc = -EINVAL;
 990                                 break;
 991                         default:
 992                                 rc = -EINVAL;
 993                                 break;
 994                 }
 995                 if (rc)
 996                         break;
 997         }
 998         if (rc)
 999                 pr_err("Suspending the system failed because DCSS device %s "
1000                        "is writable\n",
1001                        dev_info->segment_name);
1002         return rc;
1003 }
1004
1005 static int dcssblk_restore(struct device *dev)
1006 {
1007         struct dcssblk_dev_info *dev_info;
1008         struct segment_info *entry;
1009         unsigned long start, end;
1010         int rc = 0;
1011
1012         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
1013                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
1014                         segment_unload(entry->segment_name);
1015                         rc = segment_load(entry->segment_name, SEGMENT_SHARED,
1016                                           &start, &end);
1017                         if (rc < 0) {
1018 // TODO in_use check ?
1019                                 segment_warning(rc, entry->segment_name);
1020                                 goto out_panic;
1021                         }
1022                         if (start != entry->start || end != entry->end) {
1023                                 pr_err("The address range of DCSS %s changed "
1024                                        "while the system was suspended\n",
1025                                        entry->segment_name);
1026                                 goto out_panic;
1027                         }
1028                 }
1029         }
1030         return 0;
1031 out_panic:
1032         panic("fatal dcssblk resume error\n");
1033 }
1034
1035 static int dcssblk_thaw(struct device *dev)
1036 {
1037         return 0;
1038 }
1039
1040 static const struct dev_pm_ops dcssblk_pm_ops = {
1041         .freeze         = dcssblk_freeze,
1042         .thaw           = dcssblk_thaw,
1043         .restore        = dcssblk_restore,
1044 };
1045
1046 static struct platform_driver dcssblk_pdrv = {
1047         .driver = {
1048                 .name   = "dcssblk",
1049                 .pm     = &dcssblk_pm_ops,
1050         },
1051 };
1052
1053 static struct platform_device *dcssblk_pdev;
1054
1055
1056 /*
1057  * The init/exit functions.
1058  */
1059 static void __exit
1060 dcssblk_exit(void)
1061 {
1062         platform_device_unregister(dcssblk_pdev);
1063         platform_driver_unregister(&dcssblk_pdrv);
1064         root_device_unregister(dcssblk_root_dev);
1065         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1066 }
1067
1068 static int __init
1069 dcssblk_init(void)
1070 {
1071         int rc;
1072
1073         rc = platform_driver_register(&dcssblk_pdrv);
1074         if (rc)
1075                 return rc;
1076
1077         dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1078                                                         0);
1079         if (IS_ERR(dcssblk_pdev)) {
1080                 rc = PTR_ERR(dcssblk_pdev);
1081                 goto out_pdrv;
1082         }
1083
1084         dcssblk_root_dev = root_device_register("dcssblk");
1085         if (IS_ERR(dcssblk_root_dev)) {
1086                 rc = PTR_ERR(dcssblk_root_dev);
1087                 goto out_pdev;
1088         }
1089         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1090         if (rc)
1091                 goto out_root;
1092         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1093         if (rc)
1094                 goto out_root;
1095         rc = register_blkdev(0, DCSSBLK_NAME);
1096         if (rc < 0)
1097                 goto out_root;
1098         dcssblk_major = rc;
1099         init_rwsem(&dcssblk_devices_sem);
1100
1101         dcssblk_check_params();
1102         return 0;
1103
1104 out_root:
1105         root_device_unregister(dcssblk_root_dev);
1106 out_pdev:
1107         platform_device_unregister(dcssblk_pdev);
1108 out_pdrv:
1109         platform_driver_unregister(&dcssblk_pdrv);
1110         return rc;
1111 }
1112
1113 module_init(dcssblk_init);
1114 module_exit(dcssblk_exit);
1115
1116 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1117 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1118                  "comma-separated list, names in each set separated "
1119                  "by commas are separated by colons, each set contains "
1120                  "names of contiguous segments and each name max. 8 chars.\n"
1121                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1122                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1123                  "the contiguous segments - \n"
1124                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1125
1126 MODULE_LICENSE("GPL");