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/dax.h>
  22 #include <asm/extmem.h>
  23 #include <asm/io.h>
  24
  25 #define DCSSBLK_NAME "dcssblk"
  26 #define DCSSBLK_MINORS_PER_DISK 1
  27 #define DCSSBLK_PARM_LEN 400
  28 #define DCSS_BUS_ID_SIZE 20
  29
  30 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
  31 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
  32 static blk_qc_t dcssblk_make_request(struct request_queue *q,
  33                                                 struct bio *bio);
  34 static long dcssblk_blk_direct_access(struct block_device *bdev, sector_t secnum,
  35                          void **kaddr, pfn_t *pfn, long size);
  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         .direct_access  = dcssblk_blk_direct_access,
  47 };
  48
  49 static const struct dax_operations dcssblk_dax_ops = {
  50         .direct_access = dcssblk_dax_direct_access,
  51 };
  52
  53 struct dcssblk_dev_info {
  54         struct list_head lh;
  55         struct device dev;
  56         char segment_name[DCSS_BUS_ID_SIZE];
  57         atomic_t use_count;
  58         struct gendisk *gd;
  59         unsigned long start;
  60         unsigned long end;
  61         int segment_type;
  62         unsigned char save_pending;
  63         unsigned char is_shared;
  64         struct request_queue *dcssblk_queue;
  65         int num_of_segments;
  66         struct list_head seg_list;
  67         struct dax_device *dax_dev;
  68 };
  69
  70 struct segment_info {
  71         struct list_head lh;
  72         char segment_name[DCSS_BUS_ID_SIZE];
  73         unsigned long start;
  74         unsigned long end;
  75         int segment_type;
  76 };
  77
  78 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  79                                   size_t count);
  80 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  81                                   size_t count);
  82
  83 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  84 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  85
  86 static struct device *dcssblk_root_dev;
  87
  88 static LIST_HEAD(dcssblk_devices);
  89 static struct rw_semaphore dcssblk_devices_sem;
  90
  91 /*
  92  * release function for segment device.
  93  */
  94 static void
  95 dcssblk_release_segment(struct device *dev)
  96 {
  97         struct dcssblk_dev_info *dev_info;
  98         struct segment_info *entry, *temp;
  99
 100         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 101         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 102                 list_del(&entry->lh);
 103                 kfree(entry);
 104         }
 105         kfree(dev_info);
 106         module_put(THIS_MODULE);
 107 }
 108
 109 /*
 110  * get a minor number. needs to be called with
 111  * down_write(&dcssblk_devices_sem) and the
 112  * device needs to be enqueued before the semaphore is
 113  * freed.
 114  */
 115 static int
 116 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 117 {
 118         int minor, found;
 119         struct dcssblk_dev_info *entry;
 120
 121         if (dev_info == NULL)
 122                 return -EINVAL;
 123         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 124                 found = 0;
 125                 // test if minor available
 126                 list_for_each_entry(entry, &dcssblk_devices, lh)
 127                         if (minor == entry->gd->first_minor)
 128                                 found++;
 129                 if (!found) break; // got unused minor
 130         }
 131         if (found)
 132                 return -EBUSY;
 133         dev_info->gd->first_minor = minor;
 134         return 0;
 135 }
 136
 137 /*
 138  * get the struct dcssblk_dev_info from dcssblk_devices
 139  * for the given name.
 140  * down_read(&dcssblk_devices_sem) must be held.
 141  */
 142 static struct dcssblk_dev_info *
 143 dcssblk_get_device_by_name(char *name)
 144 {
 145         struct dcssblk_dev_info *entry;
 146
 147         list_for_each_entry(entry, &dcssblk_devices, lh) {
 148                 if (!strcmp(name, entry->segment_name)) {
 149                         return entry;
 150                 }
 151         }
 152         return NULL;
 153 }
 154
 155 /*
 156  * get the struct segment_info from seg_list
 157  * for the given name.
 158  * down_read(&dcssblk_devices_sem) must be held.
 159  */
 160 static struct segment_info *
 161 dcssblk_get_segment_by_name(char *name)
 162 {
 163         struct dcssblk_dev_info *dev_info;
 164         struct segment_info *entry;
 165
 166         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 167                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 168                         if (!strcmp(name, entry->segment_name))
 169                                 return entry;
 170                 }
 171         }
 172         return NULL;
 173 }
 174
 175 /*
 176  * get the highest address of the multi-segment block.
 177  */
 178 static unsigned long
 179 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 180 {
 181         unsigned long highest_addr;
 182         struct segment_info *entry;
 183
 184         highest_addr = 0;
 185         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 186                 if (highest_addr < entry->end)
 187                         highest_addr = entry->end;
 188         }
 189         return highest_addr;
 190 }
 191
 192 /*
 193  * get the lowest address of the multi-segment block.
 194  */
 195 static unsigned long
 196 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 197 {
 198         int set_first;
 199         unsigned long lowest_addr;
 200         struct segment_info *entry;
 201
 202         set_first = 0;
 203         lowest_addr = 0;
 204         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 205                 if (set_first == 0) {
 206                         lowest_addr = entry->start;
 207                         set_first = 1;
 208                 } else {
 209                         if (lowest_addr > entry->start)
 210                                 lowest_addr = entry->start;
 211                 }
 212         }
 213         return lowest_addr;
 214 }
 215
 216 /*
 217  * Check continuity of segments.
 218  */
 219 static int
 220 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 221 {
 222         int i, j, rc;
 223         struct segment_info *sort_list, *entry, temp;
 224
 225         if (dev_info->num_of_segments <= 1)
 226                 return 0;
 227
 228         sort_list = kzalloc(
 229                         sizeof(struct segment_info) * dev_info->num_of_segments,
 230                         GFP_KERNEL);
 231         if (sort_list == NULL)
 232                 return -ENOMEM;
 233         i = 0;
 234         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 235                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 236                 i++;
 237         }
 238
 239         /* sort segments */
 240         for (i = 0; i < dev_info->num_of_segments; i++)
 241                 for (j = 0; j < dev_info->num_of_segments; j++)
 242                         if (sort_list[j].start > sort_list[i].start) {
 243                                 memcpy(&temp, &sort_list[i],
 244                                         sizeof(struct segment_info));
 245                                 memcpy(&sort_list[i], &sort_list[j],
 246                                         sizeof(struct segment_info));
 247                                 memcpy(&sort_list[j], &temp,
 248                                         sizeof(struct segment_info));
 249                         }
 250
 251         /* check continuity */
 252         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 253                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 254                         pr_err("Adjacent DCSSs %s and %s are not "
 255                                "contiguous\n", sort_list[i].segment_name,
 256                                sort_list[i+1].segment_name);
 257                         rc = -EINVAL;
 258                         goto out;
 259                 }
 260                 /* EN and EW are allowed in a block device */
 261                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 262                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 263                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 264                                 !(sort_list[i+1].segment_type &
 265                                 SEGMENT_EXCLUSIVE) ||
 266                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 267                                 pr_err("DCSS %s and DCSS %s have "
 268                                        "incompatible types\n",
 269                                        sort_list[i].segment_name,
 270                                        sort_list[i+1].segment_name);
 271                                 rc = -EINVAL;
 272                                 goto out;
 273                         }
 274                 }
 275         }
 276         rc = 0;
 277 out:
 278         kfree(sort_list);
 279         return rc;
 280 }
 281
 282 /*
 283  * Load a segment
 284  */
 285 static int
 286 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 287 {
 288         int rc;
 289
 290         /* already loaded? */
 291         down_read(&dcssblk_devices_sem);
 292         *seg_info = dcssblk_get_segment_by_name(name);
 293         up_read(&dcssblk_devices_sem);
 294         if (*seg_info != NULL)
 295                 return -EEXIST;
 296
 297         /* get a struct segment_info */
 298         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 299         if (*seg_info == NULL)
 300                 return -ENOMEM;
 301
 302         strcpy((*seg_info)->segment_name, name);
 303
 304         /* load the segment */
 305         rc = segment_load(name, SEGMENT_SHARED,
 306                         &(*seg_info)->start, &(*seg_info)->end);
 307         if (rc < 0) {
 308                 segment_warning(rc, (*seg_info)->segment_name);
 309                 kfree(*seg_info);
 310         } else {
 311                 INIT_LIST_HEAD(&(*seg_info)->lh);
 312                 (*seg_info)->segment_type = rc;
 313         }
 314         return rc;
 315 }
 316
 317 /*
 318  * device attribute for switching shared/nonshared (exclusive)
 319  * operation (show + store)
 320  */
 321 static ssize_t
 322 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 323 {
 324         struct dcssblk_dev_info *dev_info;
 325
 326         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 327         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 328 }
 329
 330 static ssize_t
 331 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 332 {
 333         struct dcssblk_dev_info *dev_info;
 334         struct segment_info *entry, *temp;
 335         int rc;
 336
 337         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 338                 return -EINVAL;
 339         down_write(&dcssblk_devices_sem);
 340         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 341         if (atomic_read(&dev_info->use_count)) {
 342                 rc = -EBUSY;
 343                 goto out;
 344         }
 345         if (inbuf[0] == '1') {
 346                 /* reload segments in shared mode */
 347                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 348                         rc = segment_modify_shared(entry->segment_name,
 349                                                 SEGMENT_SHARED);
 350                         if (rc < 0) {
 351                                 BUG_ON(rc == -EINVAL);
 352                                 if (rc != -EAGAIN)
 353                                         goto removeseg;
 354                         }
 355                 }
 356                 dev_info->is_shared = 1;
 357                 switch (dev_info->segment_type) {
 358                 case SEG_TYPE_SR:
 359                 case SEG_TYPE_ER:
 360                 case SEG_TYPE_SC:
 361                         set_disk_ro(dev_info->gd, 1);
 362                 }
 363         } else if (inbuf[0] == '0') {
 364                 /* reload segments in exclusive mode */
 365                 if (dev_info->segment_type == SEG_TYPE_SC) {
 366                         pr_err("DCSS %s is of type SC and cannot be "
 367                                "loaded as exclusive-writable\n",
 368                                dev_info->segment_name);
 369                         rc = -EINVAL;
 370                         goto out;
 371                 }
 372                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 373                         rc = segment_modify_shared(entry->segment_name,
 374                                                    SEGMENT_EXCLUSIVE);
 375                         if (rc < 0) {
 376                                 BUG_ON(rc == -EINVAL);
 377                                 if (rc != -EAGAIN)
 378                                         goto removeseg;
 379                         }
 380                 }
 381                 dev_info->is_shared = 0;
 382                 set_disk_ro(dev_info->gd, 0);
 383         } else {
 384                 rc = -EINVAL;
 385                 goto out;
 386         }
 387         rc = count;
 388         goto out;
 389
 390 removeseg:
 391         pr_err("DCSS device %s is removed after a failed access mode "
 392                "change\n", dev_info->segment_name);
 393         temp = entry;
 394         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 395                 if (entry != temp)
 396                         segment_unload(entry->segment_name);
 397         }
 398         list_del(&dev_info->lh);
 399
 400         kill_dax(dev_info->dax_dev);
 401         put_dax(dev_info->dax_dev);
 402         del_gendisk(dev_info->gd);
 403         blk_cleanup_queue(dev_info->dcssblk_queue);
 404         dev_info->gd->queue = NULL;
 405         put_disk(dev_info->gd);
 406         up_write(&dcssblk_devices_sem);
 407
 408         if (device_remove_file_self(dev, attr)) {
 409                 device_unregister(dev);
 410                 put_device(dev);
 411         }
 412         return rc;
 413 out:
 414         up_write(&dcssblk_devices_sem);
 415         return rc;
 416 }
 417 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 418                    dcssblk_shared_store);
 419
 420 /*
 421  * device attribute for save operation on current copy
 422  * of the segment. If the segment is busy, saving will
 423  * become pending until it gets released, which can be
 424  * undone by storing a non-true value to this entry.
 425  * (show + store)
 426  */
 427 static ssize_t
 428 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 429 {
 430         struct dcssblk_dev_info *dev_info;
 431
 432         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 433         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 434 }
 435
 436 static ssize_t
 437 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 438 {
 439         struct dcssblk_dev_info *dev_info;
 440         struct segment_info *entry;
 441
 442         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 443                 return -EINVAL;
 444         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 445
 446         down_write(&dcssblk_devices_sem);
 447         if (inbuf[0] == '1') {
 448                 if (atomic_read(&dev_info->use_count) == 0) {
 449                         // device is idle => we save immediately
 450                         pr_info("All DCSSs that map to device %s are "
 451                                 "saved\n", dev_info->segment_name);
 452                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 453                                 if (entry->segment_type == SEG_TYPE_EN ||
 454                                     entry->segment_type == SEG_TYPE_SN)
 455                                         pr_warn("DCSS %s is of type SN or EN"
 456                                                 " and cannot be saved\n",
 457                                                 entry->segment_name);
 458                                 else
 459                                         segment_save(entry->segment_name);
 460                         }
 461                 }  else {
 462                         // device is busy => we save it when it becomes
 463                         // idle in dcssblk_release
 464                         pr_info("Device %s is in use, its DCSSs will be "
 465                                 "saved when it becomes idle\n",
 466                                 dev_info->segment_name);
 467                         dev_info->save_pending = 1;
 468                 }
 469         } else if (inbuf[0] == '0') {
 470                 if (dev_info->save_pending) {
 471                         // device is busy & the user wants to undo his save
 472                         // request
 473                         dev_info->save_pending = 0;
 474                         pr_info("A pending save request for device %s "
 475                                 "has been canceled\n",
 476                                 dev_info->segment_name);
 477                 }
 478         } else {
 479                 up_write(&dcssblk_devices_sem);
 480                 return -EINVAL;
 481         }
 482         up_write(&dcssblk_devices_sem);
 483         return count;
 484 }
 485 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 486                    dcssblk_save_store);
 487
 488 /*
 489  * device attribute for showing all segments in a device
 490  */
 491 static ssize_t
 492 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 493                 char *buf)
 494 {
 495         int i;
 496
 497         struct dcssblk_dev_info *dev_info;
 498         struct segment_info *entry;
 499
 500         down_read(&dcssblk_devices_sem);
 501         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 502         i = 0;
 503         buf[0] = '\0';
 504         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 505                 strcpy(&buf[i], entry->segment_name);
 506                 i += strlen(entry->segment_name);
 507                 buf[i] = '\n';
 508                 i++;
 509         }
 510         up_read(&dcssblk_devices_sem);
 511         return i;
 512 }
 513 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 514
 515 static struct attribute *dcssblk_dev_attrs[] = {
 516         &dev_attr_shared.attr,
 517         &dev_attr_save.attr,
 518         &dev_attr_seglist.attr,
 519         NULL,
 520 };
 521 static struct attribute_group dcssblk_dev_attr_group = {
 522         .attrs = dcssblk_dev_attrs,
 523 };
 524 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 525         &dcssblk_dev_attr_group,
 526         NULL,
 527 };
 528
 529 /*
 530  * device attribute for adding devices
 531  */
 532 static ssize_t
 533 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 534 {
 535         int rc, i, j, num_of_segments;
 536         struct dcssblk_dev_info *dev_info;
 537         struct segment_info *seg_info, *temp;
 538         char *local_buf;
 539         unsigned long seg_byte_size;
 540
 541         dev_info = NULL;
 542         seg_info = NULL;
 543         if (dev != dcssblk_root_dev) {
 544                 rc = -EINVAL;
 545                 goto out_nobuf;
 546         }
 547         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 548                 rc = -ENAMETOOLONG;
 549                 goto out_nobuf;
 550         }
 551
 552         local_buf = kmalloc(count + 1, GFP_KERNEL);
 553         if (local_buf == NULL) {
 554                 rc = -ENOMEM;
 555                 goto out_nobuf;
 556         }
 557
 558         /*
 559          * parse input
 560          */
 561         num_of_segments = 0;
 562         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 563                 for (j = i; j < count &&
 564                         (buf[j] != ':') &&
 565                         (buf[j] != '\0') &&
 566                         (buf[j] != '\n'); j++) {
 567                         local_buf[j-i] = toupper(buf[j]);
 568                 }
 569                 local_buf[j-i] = '\0';
 570                 if (((j - i) == 0) || ((j - i) > 8)) {
 571                         rc = -ENAMETOOLONG;
 572                         goto seg_list_del;
 573                 }
 574
 575                 rc = dcssblk_load_segment(local_buf, &seg_info);
 576                 if (rc < 0)
 577                         goto seg_list_del;
 578                 /*
 579                  * get a struct dcssblk_dev_info
 580                  */
 581                 if (num_of_segments == 0) {
 582                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 583                                         GFP_KERNEL);
 584                         if (dev_info == NULL) {
 585                                 rc = -ENOMEM;
 586                                 goto out;
 587                         }
 588                         strcpy(dev_info->segment_name, local_buf);
 589                         dev_info->segment_type = seg_info->segment_type;
 590                         INIT_LIST_HEAD(&dev_info->seg_list);
 591                 }
 592                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 593                 num_of_segments++;
 594                 i = j;
 595
 596                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 597                         break;
 598         }
 599
 600         /* no trailing colon at the end of the input */
 601         if ((i > 0) && (buf[i-1] == ':')) {
 602                 rc = -ENAMETOOLONG;
 603                 goto seg_list_del;
 604         }
 605         strlcpy(local_buf, buf, i + 1);
 606         dev_info->num_of_segments = num_of_segments;
 607         rc = dcssblk_is_continuous(dev_info);
 608         if (rc < 0)
 609                 goto seg_list_del;
 610
 611         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 612         dev_info->end = dcssblk_find_highest_addr(dev_info);
 613
 614         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 615         dev_info->dev.release = dcssblk_release_segment;
 616         dev_info->dev.groups = dcssblk_dev_attr_groups;
 617         INIT_LIST_HEAD(&dev_info->lh);
 618         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 619         if (dev_info->gd == NULL) {
 620                 rc = -ENOMEM;
 621                 goto seg_list_del;
 622         }
 623         dev_info->gd->major = dcssblk_major;
 624         dev_info->gd->fops = &dcssblk_devops;
 625         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 626         dev_info->gd->queue = dev_info->dcssblk_queue;
 627         dev_info->gd->private_data = dev_info;
 628         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 629         blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 630         queue_flag_set_unlocked(QUEUE_FLAG_DAX, dev_info->dcssblk_queue);
 631
 632         seg_byte_size = (dev_info->end - dev_info->start + 1);
 633         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 634         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 635                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 636
 637         dev_info->save_pending = 0;
 638         dev_info->is_shared = 1;
 639         dev_info->dev.parent = dcssblk_root_dev;
 640
 641         /*
 642          *get minor, add to list
 643          */
 644         down_write(&dcssblk_devices_sem);
 645         if (dcssblk_get_segment_by_name(local_buf)) {
 646                 rc = -EEXIST;
 647                 goto release_gd;
 648         }
 649         rc = dcssblk_assign_free_minor(dev_info);
 650         if (rc)
 651                 goto release_gd;
 652         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 653                 dev_info->gd->first_minor);
 654         list_add_tail(&dev_info->lh, &dcssblk_devices);
 655
 656         if (!try_module_get(THIS_MODULE)) {
 657                 rc = -ENODEV;
 658                 goto dev_list_del;
 659         }
 660         /*
 661          * register the device
 662          */
 663         rc = device_register(&dev_info->dev);
 664         if (rc)
 665                 goto put_dev;
 666
 667         dev_info->dax_dev = alloc_dax(dev_info, dev_info->gd->disk_name,
 668                         &dcssblk_dax_ops);
 669         if (!dev_info->dax_dev) {
 670                 rc = -ENOMEM;
 671                 goto put_dev;
 672         }
 673
 674         get_device(&dev_info->dev);
 675         device_add_disk(&dev_info->dev, dev_info->gd);
 676
 677         switch (dev_info->segment_type) {
 678                 case SEG_TYPE_SR:
 679                 case SEG_TYPE_ER:
 680                 case SEG_TYPE_SC:
 681                         set_disk_ro(dev_info->gd,1);
 682                         break;
 683                 default:
 684                         set_disk_ro(dev_info->gd,0);
 685                         break;
 686         }
 687         up_write(&dcssblk_devices_sem);
 688         rc = count;
 689         goto out;
 690
 691 put_dev:
 692         list_del(&dev_info->lh);
 693         blk_cleanup_queue(dev_info->dcssblk_queue);
 694         dev_info->gd->queue = NULL;
 695         put_disk(dev_info->gd);
 696         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 697                 segment_unload(seg_info->segment_name);
 698         }
 699         put_device(&dev_info->dev);
 700         up_write(&dcssblk_devices_sem);
 701         goto out;
 702 dev_list_del:
 703         list_del(&dev_info->lh);
 704 release_gd:
 705         blk_cleanup_queue(dev_info->dcssblk_queue);
 706         dev_info->gd->queue = NULL;
 707         put_disk(dev_info->gd);
 708         up_write(&dcssblk_devices_sem);
 709 seg_list_del:
 710         if (dev_info == NULL)
 711                 goto out;
 712         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 713                 list_del(&seg_info->lh);
 714                 segment_unload(seg_info->segment_name);
 715                 kfree(seg_info);
 716         }
 717         kfree(dev_info);
 718 out:
 719         kfree(local_buf);
 720 out_nobuf:
 721         return rc;
 722 }
 723
 724 /*
 725  * device attribute for removing devices
 726  */
 727 static ssize_t
 728 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 729 {
 730         struct dcssblk_dev_info *dev_info;
 731         struct segment_info *entry;
 732         int rc, i;
 733         char *local_buf;
 734
 735         if (dev != dcssblk_root_dev) {
 736                 return -EINVAL;
 737         }
 738         local_buf = kmalloc(count + 1, GFP_KERNEL);
 739         if (local_buf == NULL) {
 740                 return -ENOMEM;
 741         }
 742         /*
 743          * parse input
 744          */
 745         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 746                 local_buf[i] = toupper(buf[i]);
 747         }
 748         local_buf[i] = '\0';
 749         if ((i == 0) || (i > 8)) {
 750                 rc = -ENAMETOOLONG;
 751                 goto out_buf;
 752         }
 753
 754         down_write(&dcssblk_devices_sem);
 755         dev_info = dcssblk_get_device_by_name(local_buf);
 756         if (dev_info == NULL) {
 757                 up_write(&dcssblk_devices_sem);
 758                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 759                         local_buf);
 760                 rc = -ENODEV;
 761                 goto out_buf;
 762         }
 763         if (atomic_read(&dev_info->use_count) != 0) {
 764                 up_write(&dcssblk_devices_sem);
 765                 pr_warn("Device %s cannot be removed while it is in use\n",
 766                         local_buf);
 767                 rc = -EBUSY;
 768                 goto out_buf;
 769         }
 770
 771         list_del(&dev_info->lh);
 772         kill_dax(dev_info->dax_dev);
 773         put_dax(dev_info->dax_dev);
 774         del_gendisk(dev_info->gd);
 775         blk_cleanup_queue(dev_info->dcssblk_queue);
 776         dev_info->gd->queue = NULL;
 777         put_disk(dev_info->gd);
 778
 779         /* unload all related segments */
 780         list_for_each_entry(entry, &dev_info->seg_list, lh)
 781                 segment_unload(entry->segment_name);
 782
 783         up_write(&dcssblk_devices_sem);
 784
 785         device_unregister(&dev_info->dev);
 786         put_device(&dev_info->dev);
 787
 788         rc = count;
 789 out_buf:
 790         kfree(local_buf);
 791         return rc;
 792 }
 793
 794 static int
 795 dcssblk_open(struct block_device *bdev, fmode_t mode)
 796 {
 797         struct dcssblk_dev_info *dev_info;
 798         int rc;
 799
 800         dev_info = bdev->bd_disk->private_data;
 801         if (NULL == dev_info) {
 802                 rc = -ENODEV;
 803                 goto out;
 804         }
 805         atomic_inc(&dev_info->use_count);
 806         bdev->bd_block_size = 4096;
 807         rc = 0;
 808 out:
 809         return rc;
 810 }
 811
 812 static void
 813 dcssblk_release(struct gendisk *disk, fmode_t mode)
 814 {
 815         struct dcssblk_dev_info *dev_info = disk->private_data;
 816         struct segment_info *entry;
 817
 818         if (!dev_info) {
 819                 WARN_ON(1);
 820                 return;
 821         }
 822         down_write(&dcssblk_devices_sem);
 823         if (atomic_dec_and_test(&dev_info->use_count)
 824             && (dev_info->save_pending)) {
 825                 pr_info("Device %s has become idle and is being saved "
 826                         "now\n", dev_info->segment_name);
 827                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 828                         if (entry->segment_type == SEG_TYPE_EN ||
 829                             entry->segment_type == SEG_TYPE_SN)
 830                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 831                                         " be saved\n", entry->segment_name);
 832                         else
 833                                 segment_save(entry->segment_name);
 834                 }
 835                 dev_info->save_pending = 0;
 836         }
 837         up_write(&dcssblk_devices_sem);
 838 }
 839
 840 static blk_qc_t
 841 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 842 {
 843         struct dcssblk_dev_info *dev_info;
 844         struct bio_vec bvec;
 845         struct bvec_iter iter;
 846         unsigned long index;
 847         unsigned long page_addr;
 848         unsigned long source_addr;
 849         unsigned long bytes_done;
 850
 851         blk_queue_split(q, &bio, q->bio_split);
 852
 853         bytes_done = 0;
 854         dev_info = bio->bi_bdev->bd_disk->private_data;
 855         if (dev_info == NULL)
 856                 goto fail;
 857         if ((bio->bi_iter.bi_sector & 7) != 0 ||
 858             (bio->bi_iter.bi_size & 4095) != 0)
 859                 /* Request is not page-aligned. */
 860                 goto fail;
 861         if (bio_end_sector(bio) > get_capacity(bio->bi_bdev->bd_disk)) {
 862                 /* Request beyond end of DCSS segment. */
 863                 goto fail;
 864         }
 865         /* verify data transfer direction */
 866         if (dev_info->is_shared) {
 867                 switch (dev_info->segment_type) {
 868                 case SEG_TYPE_SR:
 869                 case SEG_TYPE_ER:
 870                 case SEG_TYPE_SC:
 871                         /* cannot write to these segments */
 872                         if (bio_data_dir(bio) == WRITE) {
 873                                 pr_warn("Writing to %s failed because it is a read-only device\n",
 874                                         dev_name(&dev_info->dev));
 875                                 goto fail;
 876                         }
 877                 }
 878         }
 879
 880         index = (bio->bi_iter.bi_sector >> 3);
 881         bio_for_each_segment(bvec, bio, iter) {
 882                 page_addr = (unsigned long)
 883                         page_address(bvec.bv_page) + bvec.bv_offset;
 884                 source_addr = dev_info->start + (index<<12) + bytes_done;
 885                 if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 886                         // More paranoia.
 887                         goto fail;
 888                 if (bio_data_dir(bio) == READ) {
 889                         memcpy((void*)page_addr, (void*)source_addr,
 890                                 bvec.bv_len);
 891                 } else {
 892                         memcpy((void*)source_addr, (void*)page_addr,
 893                                 bvec.bv_len);
 894                 }
 895                 bytes_done += bvec.bv_len;
 896         }
 897         bio_endio(bio);
 898         return BLK_QC_T_NONE;
 899 fail:
 900         bio_io_error(bio);
 901         return BLK_QC_T_NONE;
 902 }
 903
 904 static long
 905 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 906                 long nr_pages, void **kaddr, pfn_t *pfn)
 907 {
 908         resource_size_t offset = pgoff * PAGE_SIZE;
 909         unsigned long dev_sz;
 910
 911         dev_sz = dev_info->end - dev_info->start + 1;
 912         *kaddr = (void *) dev_info->start + offset;
 913         *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), PFN_DEV);
 914
 915         return (dev_sz - offset) / PAGE_SIZE;
 916 }
 917
 918 static long
 919 dcssblk_blk_direct_access(struct block_device *bdev, sector_t secnum,
 920                         void **kaddr, pfn_t *pfn, long size)
 921 {
 922         struct dcssblk_dev_info *dev_info;
 923
 924         dev_info = bdev->bd_disk->private_data;
 925         if (!dev_info)
 926                 return -ENODEV;
 927         return __dcssblk_direct_access(dev_info, PHYS_PFN(secnum * 512),
 928                         PHYS_PFN(size), kaddr, pfn) * PAGE_SIZE;
 929 }
 930
 931 static long
 932 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 933                 long nr_pages, void **kaddr, pfn_t *pfn)
 934 {
 935         struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 936
 937         return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 938 }
 939
 940 static void
 941 dcssblk_check_params(void)
 942 {
 943         int rc, i, j, k;
 944         char buf[DCSSBLK_PARM_LEN + 1];
 945         struct dcssblk_dev_info *dev_info;
 946
 947         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 948              i++) {
 949                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 950                             (dcssblk_segments[j] != ',')  &&
 951                             (dcssblk_segments[j] != '\0') &&
 952                             (dcssblk_segments[j] != '('); j++)
 953                 {
 954                         buf[j-i] = dcssblk_segments[j];
 955                 }
 956                 buf[j-i] = '\0';
 957                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 958                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 959                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 960                                 buf[k] = toupper(buf[k]);
 961                         buf[k] = '\0';
 962                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 963                                 down_read(&dcssblk_devices_sem);
 964                                 dev_info = dcssblk_get_device_by_name(buf);
 965                                 up_read(&dcssblk_devices_sem);
 966                                 if (dev_info)
 967                                         dcssblk_shared_store(&dev_info->dev,
 968                                                              NULL, "0\n", 2);
 969                         }
 970                 }
 971                 while ((dcssblk_segments[j] != ',') &&
 972                        (dcssblk_segments[j] != '\0'))
 973                 {
 974                         j++;
 975                 }
 976                 if (dcssblk_segments[j] == '\0')
 977                         break;
 978                 i = j;
 979         }
 980 }
 981
 982 /*
 983  * Suspend / Resume
 984  */
 985 static int dcssblk_freeze(struct device *dev)
 986 {
 987         struct dcssblk_dev_info *dev_info;
 988         int rc = 0;
 989
 990         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 991                 switch (dev_info->segment_type) {
 992                         case SEG_TYPE_SR:
 993                         case SEG_TYPE_ER:
 994                         case SEG_TYPE_SC:
 995                                 if (!dev_info->is_shared)
 996                                         rc = -EINVAL;
 997                                 break;
 998                         default:
 999                                 rc = -EINVAL;
1000                                 break;
1001                 }
1002                 if (rc)
1003                         break;
1004         }
1005         if (rc)
1006                 pr_err("Suspending the system failed because DCSS device %s "
1007                        "is writable\n",
1008                        dev_info->segment_name);
1009         return rc;
1010 }
1011
1012 static int dcssblk_restore(struct device *dev)
1013 {
1014         struct dcssblk_dev_info *dev_info;
1015         struct segment_info *entry;
1016         unsigned long start, end;
1017         int rc = 0;
1018
1019         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
1020                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
1021                         segment_unload(entry->segment_name);
1022                         rc = segment_load(entry->segment_name, SEGMENT_SHARED,
1023                                           &start, &end);
1024                         if (rc < 0) {
1025 // TODO in_use check ?
1026                                 segment_warning(rc, entry->segment_name);
1027                                 goto out_panic;
1028                         }
1029                         if (start != entry->start || end != entry->end) {
1030                                 pr_err("The address range of DCSS %s changed "
1031                                        "while the system was suspended\n",
1032                                        entry->segment_name);
1033                                 goto out_panic;
1034                         }
1035                 }
1036         }
1037         return 0;
1038 out_panic:
1039         panic("fatal dcssblk resume error\n");
1040 }
1041
1042 static int dcssblk_thaw(struct device *dev)
1043 {
1044         return 0;
1045 }
1046
1047 static const struct dev_pm_ops dcssblk_pm_ops = {
1048         .freeze         = dcssblk_freeze,
1049         .thaw           = dcssblk_thaw,
1050         .restore        = dcssblk_restore,
1051 };
1052
1053 static struct platform_driver dcssblk_pdrv = {
1054         .driver = {
1055                 .name   = "dcssblk",
1056                 .pm     = &dcssblk_pm_ops,
1057         },
1058 };
1059
1060 static struct platform_device *dcssblk_pdev;
1061
1062
1063 /*
1064  * The init/exit functions.
1065  */
1066 static void __exit
1067 dcssblk_exit(void)
1068 {
1069         platform_device_unregister(dcssblk_pdev);
1070         platform_driver_unregister(&dcssblk_pdrv);
1071         root_device_unregister(dcssblk_root_dev);
1072         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1073 }
1074
1075 static int __init
1076 dcssblk_init(void)
1077 {
1078         int rc;
1079
1080         rc = platform_driver_register(&dcssblk_pdrv);
1081         if (rc)
1082                 return rc;
1083
1084         dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1085                                                         0);
1086         if (IS_ERR(dcssblk_pdev)) {
1087                 rc = PTR_ERR(dcssblk_pdev);
1088                 goto out_pdrv;
1089         }
1090
1091         dcssblk_root_dev = root_device_register("dcssblk");
1092         if (IS_ERR(dcssblk_root_dev)) {
1093                 rc = PTR_ERR(dcssblk_root_dev);
1094                 goto out_pdev;
1095         }
1096         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1097         if (rc)
1098                 goto out_root;
1099         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1100         if (rc)
1101                 goto out_root;
1102         rc = register_blkdev(0, DCSSBLK_NAME);
1103         if (rc < 0)
1104                 goto out_root;
1105         dcssblk_major = rc;
1106         init_rwsem(&dcssblk_devices_sem);
1107
1108         dcssblk_check_params();
1109         return 0;
1110
1111 out_root:
1112         root_device_unregister(dcssblk_root_dev);
1113 out_pdev:
1114         platform_device_unregister(dcssblk_pdev);
1115 out_pdrv:
1116         platform_driver_unregister(&dcssblk_pdrv);
1117         return rc;
1118 }
1119
1120 module_init(dcssblk_init);
1121 module_exit(dcssblk_exit);
1122
1123 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1124 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1125                  "comma-separated list, names in each set separated "
1126                  "by commas are separated by colons, each set contains "
1127                  "names of contiguous segments and each name max. 8 chars.\n"
1128                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1129                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1130                  "the contiguous segments - \n"
1131                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1132
1133 MODULE_LICENSE("GPL");