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 size_t dcssblk_dax_copy_to_iter(struct dax_device *dax_dev,
  55                 pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
  56 {
  57         return copy_to_iter(addr, bytes, i);
  58 }
  59
  60 static const struct dax_operations dcssblk_dax_ops = {
  61         .direct_access = dcssblk_dax_direct_access,
  62         .copy_from_iter = dcssblk_dax_copy_from_iter,
  63         .copy_to_iter = dcssblk_dax_copy_to_iter,
  64 };
  65
  66 struct dcssblk_dev_info {
  67         struct list_head lh;
  68         struct device dev;
  69         char segment_name[DCSS_BUS_ID_SIZE];
  70         atomic_t use_count;
  71         struct gendisk *gd;
  72         unsigned long start;
  73         unsigned long end;
  74         int segment_type;
  75         unsigned char save_pending;
  76         unsigned char is_shared;
  77         struct request_queue *dcssblk_queue;
  78         int num_of_segments;
  79         struct list_head seg_list;
  80         struct dax_device *dax_dev;
  81 };
  82
  83 struct segment_info {
  84         struct list_head lh;
  85         char segment_name[DCSS_BUS_ID_SIZE];
  86         unsigned long start;
  87         unsigned long end;
  88         int segment_type;
  89 };
  90
  91 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  92                                   size_t count);
  93 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  94                                   size_t count);
  95
  96 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  97 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  98
  99 static struct device *dcssblk_root_dev;
 100
 101 static LIST_HEAD(dcssblk_devices);
 102 static struct rw_semaphore dcssblk_devices_sem;
 103
 104 /*
 105  * release function for segment device.
 106  */
 107 static void
 108 dcssblk_release_segment(struct device *dev)
 109 {
 110         struct dcssblk_dev_info *dev_info;
 111         struct segment_info *entry, *temp;
 112
 113         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 114         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 115                 list_del(&entry->lh);
 116                 kfree(entry);
 117         }
 118         kfree(dev_info);
 119         module_put(THIS_MODULE);
 120 }
 121
 122 /*
 123  * get a minor number. needs to be called with
 124  * down_write(&dcssblk_devices_sem) and the
 125  * device needs to be enqueued before the semaphore is
 126  * freed.
 127  */
 128 static int
 129 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 130 {
 131         int minor, found;
 132         struct dcssblk_dev_info *entry;
 133
 134         if (dev_info == NULL)
 135                 return -EINVAL;
 136         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 137                 found = 0;
 138                 // test if minor available
 139                 list_for_each_entry(entry, &dcssblk_devices, lh)
 140                         if (minor == entry->gd->first_minor)
 141                                 found++;
 142                 if (!found) break; // got unused minor
 143         }
 144         if (found)
 145                 return -EBUSY;
 146         dev_info->gd->first_minor = minor;
 147         return 0;
 148 }
 149
 150 /*
 151  * get the struct dcssblk_dev_info from dcssblk_devices
 152  * for the given name.
 153  * down_read(&dcssblk_devices_sem) must be held.
 154  */
 155 static struct dcssblk_dev_info *
 156 dcssblk_get_device_by_name(char *name)
 157 {
 158         struct dcssblk_dev_info *entry;
 159
 160         list_for_each_entry(entry, &dcssblk_devices, lh) {
 161                 if (!strcmp(name, entry->segment_name)) {
 162                         return entry;
 163                 }
 164         }
 165         return NULL;
 166 }
 167
 168 /*
 169  * get the struct segment_info from seg_list
 170  * for the given name.
 171  * down_read(&dcssblk_devices_sem) must be held.
 172  */
 173 static struct segment_info *
 174 dcssblk_get_segment_by_name(char *name)
 175 {
 176         struct dcssblk_dev_info *dev_info;
 177         struct segment_info *entry;
 178
 179         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 180                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 181                         if (!strcmp(name, entry->segment_name))
 182                                 return entry;
 183                 }
 184         }
 185         return NULL;
 186 }
 187
 188 /*
 189  * get the highest address of the multi-segment block.
 190  */
 191 static unsigned long
 192 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 193 {
 194         unsigned long highest_addr;
 195         struct segment_info *entry;
 196
 197         highest_addr = 0;
 198         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 199                 if (highest_addr < entry->end)
 200                         highest_addr = entry->end;
 201         }
 202         return highest_addr;
 203 }
 204
 205 /*
 206  * get the lowest address of the multi-segment block.
 207  */
 208 static unsigned long
 209 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 210 {
 211         int set_first;
 212         unsigned long lowest_addr;
 213         struct segment_info *entry;
 214
 215         set_first = 0;
 216         lowest_addr = 0;
 217         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 218                 if (set_first == 0) {
 219                         lowest_addr = entry->start;
 220                         set_first = 1;
 221                 } else {
 222                         if (lowest_addr > entry->start)
 223                                 lowest_addr = entry->start;
 224                 }
 225         }
 226         return lowest_addr;
 227 }
 228
 229 /*
 230  * Check continuity of segments.
 231  */
 232 static int
 233 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 234 {
 235         int i, j, rc;
 236         struct segment_info *sort_list, *entry, temp;
 237
 238         if (dev_info->num_of_segments <= 1)
 239                 return 0;
 240
 241         sort_list = kcalloc(dev_info->num_of_segments,
 242                             sizeof(struct segment_info),
 243                             GFP_KERNEL);
 244         if (sort_list == NULL)
 245                 return -ENOMEM;
 246         i = 0;
 247         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 248                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 249                 i++;
 250         }
 251
 252         /* sort segments */
 253         for (i = 0; i < dev_info->num_of_segments; i++)
 254                 for (j = 0; j < dev_info->num_of_segments; j++)
 255                         if (sort_list[j].start > sort_list[i].start) {
 256                                 memcpy(&temp, &sort_list[i],
 257                                         sizeof(struct segment_info));
 258                                 memcpy(&sort_list[i], &sort_list[j],
 259                                         sizeof(struct segment_info));
 260                                 memcpy(&sort_list[j], &temp,
 261                                         sizeof(struct segment_info));
 262                         }
 263
 264         /* check continuity */
 265         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 266                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 267                         pr_err("Adjacent DCSSs %s and %s are not "
 268                                "contiguous\n", sort_list[i].segment_name,
 269                                sort_list[i+1].segment_name);
 270                         rc = -EINVAL;
 271                         goto out;
 272                 }
 273                 /* EN and EW are allowed in a block device */
 274                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 275                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 276                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 277                                 !(sort_list[i+1].segment_type &
 278                                 SEGMENT_EXCLUSIVE) ||
 279                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 280                                 pr_err("DCSS %s and DCSS %s have "
 281                                        "incompatible types\n",
 282                                        sort_list[i].segment_name,
 283                                        sort_list[i+1].segment_name);
 284                                 rc = -EINVAL;
 285                                 goto out;
 286                         }
 287                 }
 288         }
 289         rc = 0;
 290 out:
 291         kfree(sort_list);
 292         return rc;
 293 }
 294
 295 /*
 296  * Load a segment
 297  */
 298 static int
 299 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 300 {
 301         int rc;
 302
 303         /* already loaded? */
 304         down_read(&dcssblk_devices_sem);
 305         *seg_info = dcssblk_get_segment_by_name(name);
 306         up_read(&dcssblk_devices_sem);
 307         if (*seg_info != NULL)
 308                 return -EEXIST;
 309
 310         /* get a struct segment_info */
 311         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 312         if (*seg_info == NULL)
 313                 return -ENOMEM;
 314
 315         strcpy((*seg_info)->segment_name, name);
 316
 317         /* load the segment */
 318         rc = segment_load(name, SEGMENT_SHARED,
 319                         &(*seg_info)->start, &(*seg_info)->end);
 320         if (rc < 0) {
 321                 segment_warning(rc, (*seg_info)->segment_name);
 322                 kfree(*seg_info);
 323         } else {
 324                 INIT_LIST_HEAD(&(*seg_info)->lh);
 325                 (*seg_info)->segment_type = rc;
 326         }
 327         return rc;
 328 }
 329
 330 /*
 331  * device attribute for switching shared/nonshared (exclusive)
 332  * operation (show + store)
 333  */
 334 static ssize_t
 335 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 336 {
 337         struct dcssblk_dev_info *dev_info;
 338
 339         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 340         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 341 }
 342
 343 static ssize_t
 344 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 345 {
 346         struct dcssblk_dev_info *dev_info;
 347         struct segment_info *entry, *temp;
 348         int rc;
 349
 350         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 351                 return -EINVAL;
 352         down_write(&dcssblk_devices_sem);
 353         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 354         if (atomic_read(&dev_info->use_count)) {
 355                 rc = -EBUSY;
 356                 goto out;
 357         }
 358         if (inbuf[0] == '1') {
 359                 /* reload segments in shared mode */
 360                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 361                         rc = segment_modify_shared(entry->segment_name,
 362                                                 SEGMENT_SHARED);
 363                         if (rc < 0) {
 364                                 BUG_ON(rc == -EINVAL);
 365                                 if (rc != -EAGAIN)
 366                                         goto removeseg;
 367                         }
 368                 }
 369                 dev_info->is_shared = 1;
 370                 switch (dev_info->segment_type) {
 371                 case SEG_TYPE_SR:
 372                 case SEG_TYPE_ER:
 373                 case SEG_TYPE_SC:
 374                         set_disk_ro(dev_info->gd, 1);
 375                 }
 376         } else if (inbuf[0] == '0') {
 377                 /* reload segments in exclusive mode */
 378                 if (dev_info->segment_type == SEG_TYPE_SC) {
 379                         pr_err("DCSS %s is of type SC and cannot be "
 380                                "loaded as exclusive-writable\n",
 381                                dev_info->segment_name);
 382                         rc = -EINVAL;
 383                         goto out;
 384                 }
 385                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 386                         rc = segment_modify_shared(entry->segment_name,
 387                                                    SEGMENT_EXCLUSIVE);
 388                         if (rc < 0) {
 389                                 BUG_ON(rc == -EINVAL);
 390                                 if (rc != -EAGAIN)
 391                                         goto removeseg;
 392                         }
 393                 }
 394                 dev_info->is_shared = 0;
 395                 set_disk_ro(dev_info->gd, 0);
 396         } else {
 397                 rc = -EINVAL;
 398                 goto out;
 399         }
 400         rc = count;
 401         goto out;
 402
 403 removeseg:
 404         pr_err("DCSS device %s is removed after a failed access mode "
 405                "change\n", dev_info->segment_name);
 406         temp = entry;
 407         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 408                 if (entry != temp)
 409                         segment_unload(entry->segment_name);
 410         }
 411         list_del(&dev_info->lh);
 412
 413         kill_dax(dev_info->dax_dev);
 414         put_dax(dev_info->dax_dev);
 415         del_gendisk(dev_info->gd);
 416         blk_cleanup_queue(dev_info->dcssblk_queue);
 417         dev_info->gd->queue = NULL;
 418         put_disk(dev_info->gd);
 419         up_write(&dcssblk_devices_sem);
 420
 421         if (device_remove_file_self(dev, attr)) {
 422                 device_unregister(dev);
 423                 put_device(dev);
 424         }
 425         return rc;
 426 out:
 427         up_write(&dcssblk_devices_sem);
 428         return rc;
 429 }
 430 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 431                    dcssblk_shared_store);
 432
 433 /*
 434  * device attribute for save operation on current copy
 435  * of the segment. If the segment is busy, saving will
 436  * become pending until it gets released, which can be
 437  * undone by storing a non-true value to this entry.
 438  * (show + store)
 439  */
 440 static ssize_t
 441 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 442 {
 443         struct dcssblk_dev_info *dev_info;
 444
 445         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 446         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 447 }
 448
 449 static ssize_t
 450 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 451 {
 452         struct dcssblk_dev_info *dev_info;
 453         struct segment_info *entry;
 454
 455         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 456                 return -EINVAL;
 457         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 458
 459         down_write(&dcssblk_devices_sem);
 460         if (inbuf[0] == '1') {
 461                 if (atomic_read(&dev_info->use_count) == 0) {
 462                         // device is idle => we save immediately
 463                         pr_info("All DCSSs that map to device %s are "
 464                                 "saved\n", dev_info->segment_name);
 465                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 466                                 if (entry->segment_type == SEG_TYPE_EN ||
 467                                     entry->segment_type == SEG_TYPE_SN)
 468                                         pr_warn("DCSS %s is of type SN or EN"
 469                                                 " and cannot be saved\n",
 470                                                 entry->segment_name);
 471                                 else
 472                                         segment_save(entry->segment_name);
 473                         }
 474                 }  else {
 475                         // device is busy => we save it when it becomes
 476                         // idle in dcssblk_release
 477                         pr_info("Device %s is in use, its DCSSs will be "
 478                                 "saved when it becomes idle\n",
 479                                 dev_info->segment_name);
 480                         dev_info->save_pending = 1;
 481                 }
 482         } else if (inbuf[0] == '0') {
 483                 if (dev_info->save_pending) {
 484                         // device is busy & the user wants to undo his save
 485                         // request
 486                         dev_info->save_pending = 0;
 487                         pr_info("A pending save request for device %s "
 488                                 "has been canceled\n",
 489                                 dev_info->segment_name);
 490                 }
 491         } else {
 492                 up_write(&dcssblk_devices_sem);
 493                 return -EINVAL;
 494         }
 495         up_write(&dcssblk_devices_sem);
 496         return count;
 497 }
 498 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 499                    dcssblk_save_store);
 500
 501 /*
 502  * device attribute for showing all segments in a device
 503  */
 504 static ssize_t
 505 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 506                 char *buf)
 507 {
 508         int i;
 509
 510         struct dcssblk_dev_info *dev_info;
 511         struct segment_info *entry;
 512
 513         down_read(&dcssblk_devices_sem);
 514         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 515         i = 0;
 516         buf[0] = '\0';
 517         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 518                 strcpy(&buf[i], entry->segment_name);
 519                 i += strlen(entry->segment_name);
 520                 buf[i] = '\n';
 521                 i++;
 522         }
 523         up_read(&dcssblk_devices_sem);
 524         return i;
 525 }
 526 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 527
 528 static struct attribute *dcssblk_dev_attrs[] = {
 529         &dev_attr_shared.attr,
 530         &dev_attr_save.attr,
 531         &dev_attr_seglist.attr,
 532         NULL,
 533 };
 534 static struct attribute_group dcssblk_dev_attr_group = {
 535         .attrs = dcssblk_dev_attrs,
 536 };
 537 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 538         &dcssblk_dev_attr_group,
 539         NULL,
 540 };
 541
 542 /*
 543  * device attribute for adding devices
 544  */
 545 static ssize_t
 546 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 547 {
 548         int rc, i, j, num_of_segments;
 549         struct dcssblk_dev_info *dev_info;
 550         struct segment_info *seg_info, *temp;
 551         char *local_buf;
 552         unsigned long seg_byte_size;
 553
 554         dev_info = NULL;
 555         seg_info = NULL;
 556         if (dev != dcssblk_root_dev) {
 557                 rc = -EINVAL;
 558                 goto out_nobuf;
 559         }
 560         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 561                 rc = -ENAMETOOLONG;
 562                 goto out_nobuf;
 563         }
 564
 565         local_buf = kmalloc(count + 1, GFP_KERNEL);
 566         if (local_buf == NULL) {
 567                 rc = -ENOMEM;
 568                 goto out_nobuf;
 569         }
 570
 571         /*
 572          * parse input
 573          */
 574         num_of_segments = 0;
 575         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 576                 for (j = i; j < count &&
 577                         (buf[j] != ':') &&
 578                         (buf[j] != '\0') &&
 579                         (buf[j] != '\n'); j++) {
 580                         local_buf[j-i] = toupper(buf[j]);
 581                 }
 582                 local_buf[j-i] = '\0';
 583                 if (((j - i) == 0) || ((j - i) > 8)) {
 584                         rc = -ENAMETOOLONG;
 585                         goto seg_list_del;
 586                 }
 587
 588                 rc = dcssblk_load_segment(local_buf, &seg_info);
 589                 if (rc < 0)
 590                         goto seg_list_del;
 591                 /*
 592                  * get a struct dcssblk_dev_info
 593                  */
 594                 if (num_of_segments == 0) {
 595                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 596                                         GFP_KERNEL);
 597                         if (dev_info == NULL) {
 598                                 rc = -ENOMEM;
 599                                 goto out;
 600                         }
 601                         strcpy(dev_info->segment_name, local_buf);
 602                         dev_info->segment_type = seg_info->segment_type;
 603                         INIT_LIST_HEAD(&dev_info->seg_list);
 604                 }
 605                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 606                 num_of_segments++;
 607                 i = j;
 608
 609                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 610                         break;
 611         }
 612
 613         /* no trailing colon at the end of the input */
 614         if ((i > 0) && (buf[i-1] == ':')) {
 615                 rc = -ENAMETOOLONG;
 616                 goto seg_list_del;
 617         }
 618         strlcpy(local_buf, buf, i + 1);
 619         dev_info->num_of_segments = num_of_segments;
 620         rc = dcssblk_is_continuous(dev_info);
 621         if (rc < 0)
 622                 goto seg_list_del;
 623
 624         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 625         dev_info->end = dcssblk_find_highest_addr(dev_info);
 626
 627         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 628         dev_info->dev.release = dcssblk_release_segment;
 629         dev_info->dev.groups = dcssblk_dev_attr_groups;
 630         INIT_LIST_HEAD(&dev_info->lh);
 631         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 632         if (dev_info->gd == NULL) {
 633                 rc = -ENOMEM;
 634                 goto seg_list_del;
 635         }
 636         dev_info->gd->major = dcssblk_major;
 637         dev_info->gd->fops = &dcssblk_devops;
 638         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 639         dev_info->gd->queue = dev_info->dcssblk_queue;
 640         dev_info->gd->private_data = dev_info;
 641         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 642         blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 643         blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->dcssblk_queue);
 644
 645         seg_byte_size = (dev_info->end - dev_info->start + 1);
 646         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 647         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 648                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 649
 650         dev_info->save_pending = 0;
 651         dev_info->is_shared = 1;
 652         dev_info->dev.parent = dcssblk_root_dev;
 653
 654         /*
 655          *get minor, add to list
 656          */
 657         down_write(&dcssblk_devices_sem);
 658         if (dcssblk_get_segment_by_name(local_buf)) {
 659                 rc = -EEXIST;
 660                 goto release_gd;
 661         }
 662         rc = dcssblk_assign_free_minor(dev_info);
 663         if (rc)
 664                 goto release_gd;
 665         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 666                 dev_info->gd->first_minor);
 667         list_add_tail(&dev_info->lh, &dcssblk_devices);
 668
 669         if (!try_module_get(THIS_MODULE)) {
 670                 rc = -ENODEV;
 671                 goto dev_list_del;
 672         }
 673         /*
 674          * register the device
 675          */
 676         rc = device_register(&dev_info->dev);
 677         if (rc)
 678                 goto put_dev;
 679
 680         dev_info->dax_dev = alloc_dax(dev_info, dev_info->gd->disk_name,
 681                         &dcssblk_dax_ops);
 682         if (!dev_info->dax_dev) {
 683                 rc = -ENOMEM;
 684                 goto put_dev;
 685         }
 686
 687         get_device(&dev_info->dev);
 688         device_add_disk(&dev_info->dev, dev_info->gd, NULL);
 689
 690         switch (dev_info->segment_type) {
 691                 case SEG_TYPE_SR:
 692                 case SEG_TYPE_ER:
 693                 case SEG_TYPE_SC:
 694                         set_disk_ro(dev_info->gd,1);
 695                         break;
 696                 default:
 697                         set_disk_ro(dev_info->gd,0);
 698                         break;
 699         }
 700         up_write(&dcssblk_devices_sem);
 701         rc = count;
 702         goto out;
 703
 704 put_dev:
 705         list_del(&dev_info->lh);
 706         blk_cleanup_queue(dev_info->dcssblk_queue);
 707         dev_info->gd->queue = NULL;
 708         put_disk(dev_info->gd);
 709         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 710                 segment_unload(seg_info->segment_name);
 711         }
 712         put_device(&dev_info->dev);
 713         up_write(&dcssblk_devices_sem);
 714         goto out;
 715 dev_list_del:
 716         list_del(&dev_info->lh);
 717 release_gd:
 718         blk_cleanup_queue(dev_info->dcssblk_queue);
 719         dev_info->gd->queue = NULL;
 720         put_disk(dev_info->gd);
 721         up_write(&dcssblk_devices_sem);
 722 seg_list_del:
 723         if (dev_info == NULL)
 724                 goto out;
 725         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 726                 list_del(&seg_info->lh);
 727                 segment_unload(seg_info->segment_name);
 728                 kfree(seg_info);
 729         }
 730         kfree(dev_info);
 731 out:
 732         kfree(local_buf);
 733 out_nobuf:
 734         return rc;
 735 }
 736
 737 /*
 738  * device attribute for removing devices
 739  */
 740 static ssize_t
 741 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 742 {
 743         struct dcssblk_dev_info *dev_info;
 744         struct segment_info *entry;
 745         int rc, i;
 746         char *local_buf;
 747
 748         if (dev != dcssblk_root_dev) {
 749                 return -EINVAL;
 750         }
 751         local_buf = kmalloc(count + 1, GFP_KERNEL);
 752         if (local_buf == NULL) {
 753                 return -ENOMEM;
 754         }
 755         /*
 756          * parse input
 757          */
 758         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 759                 local_buf[i] = toupper(buf[i]);
 760         }
 761         local_buf[i] = '\0';
 762         if ((i == 0) || (i > 8)) {
 763                 rc = -ENAMETOOLONG;
 764                 goto out_buf;
 765         }
 766
 767         down_write(&dcssblk_devices_sem);
 768         dev_info = dcssblk_get_device_by_name(local_buf);
 769         if (dev_info == NULL) {
 770                 up_write(&dcssblk_devices_sem);
 771                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 772                         local_buf);
 773                 rc = -ENODEV;
 774                 goto out_buf;
 775         }
 776         if (atomic_read(&dev_info->use_count) != 0) {
 777                 up_write(&dcssblk_devices_sem);
 778                 pr_warn("Device %s cannot be removed while it is in use\n",
 779                         local_buf);
 780                 rc = -EBUSY;
 781                 goto out_buf;
 782         }
 783
 784         list_del(&dev_info->lh);
 785         kill_dax(dev_info->dax_dev);
 786         put_dax(dev_info->dax_dev);
 787         del_gendisk(dev_info->gd);
 788         blk_cleanup_queue(dev_info->dcssblk_queue);
 789         dev_info->gd->queue = NULL;
 790         put_disk(dev_info->gd);
 791
 792         /* unload all related segments */
 793         list_for_each_entry(entry, &dev_info->seg_list, lh)
 794                 segment_unload(entry->segment_name);
 795
 796         up_write(&dcssblk_devices_sem);
 797
 798         device_unregister(&dev_info->dev);
 799         put_device(&dev_info->dev);
 800
 801         rc = count;
 802 out_buf:
 803         kfree(local_buf);
 804         return rc;
 805 }
 806
 807 static int
 808 dcssblk_open(struct block_device *bdev, fmode_t mode)
 809 {
 810         struct dcssblk_dev_info *dev_info;
 811         int rc;
 812
 813         dev_info = bdev->bd_disk->private_data;
 814         if (NULL == dev_info) {
 815                 rc = -ENODEV;
 816                 goto out;
 817         }
 818         atomic_inc(&dev_info->use_count);
 819         bdev->bd_block_size = 4096;
 820         rc = 0;
 821 out:
 822         return rc;
 823 }
 824
 825 static void
 826 dcssblk_release(struct gendisk *disk, fmode_t mode)
 827 {
 828         struct dcssblk_dev_info *dev_info = disk->private_data;
 829         struct segment_info *entry;
 830
 831         if (!dev_info) {
 832                 WARN_ON(1);
 833                 return;
 834         }
 835         down_write(&dcssblk_devices_sem);
 836         if (atomic_dec_and_test(&dev_info->use_count)
 837             && (dev_info->save_pending)) {
 838                 pr_info("Device %s has become idle and is being saved "
 839                         "now\n", dev_info->segment_name);
 840                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 841                         if (entry->segment_type == SEG_TYPE_EN ||
 842                             entry->segment_type == SEG_TYPE_SN)
 843                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 844                                         " be saved\n", entry->segment_name);
 845                         else
 846                                 segment_save(entry->segment_name);
 847                 }
 848                 dev_info->save_pending = 0;
 849         }
 850         up_write(&dcssblk_devices_sem);
 851 }
 852
 853 static blk_qc_t
 854 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 855 {
 856         struct dcssblk_dev_info *dev_info;
 857         struct bio_vec bvec;
 858         struct bvec_iter iter;
 859         unsigned long index;
 860         unsigned long page_addr;
 861         unsigned long source_addr;
 862         unsigned long bytes_done;
 863
 864         blk_queue_split(q, &bio);
 865
 866         bytes_done = 0;
 867         dev_info = bio->bi_disk->private_data;
 868         if (dev_info == NULL)
 869                 goto fail;
 870         if ((bio->bi_iter.bi_sector & 7) != 0 ||
 871             (bio->bi_iter.bi_size & 4095) != 0)
 872                 /* Request is not page-aligned. */
 873                 goto fail;
 874         if (bio_end_sector(bio) > get_capacity(bio->bi_disk)) {
 875                 /* Request beyond end of DCSS segment. */
 876                 goto fail;
 877         }
 878         /* verify data transfer direction */
 879         if (dev_info->is_shared) {
 880                 switch (dev_info->segment_type) {
 881                 case SEG_TYPE_SR:
 882                 case SEG_TYPE_ER:
 883                 case SEG_TYPE_SC:
 884                         /* cannot write to these segments */
 885                         if (bio_data_dir(bio) == WRITE) {
 886                                 pr_warn("Writing to %s failed because it is a read-only device\n",
 887                                         dev_name(&dev_info->dev));
 888                                 goto fail;
 889                         }
 890                 }
 891         }
 892
 893         index = (bio->bi_iter.bi_sector >> 3);
 894         bio_for_each_segment(bvec, bio, iter) {
 895                 page_addr = (unsigned long)
 896                         page_address(bvec.bv_page) + bvec.bv_offset;
 897                 source_addr = dev_info->start + (index<<12) + bytes_done;
 898                 if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 899                         // More paranoia.
 900                         goto fail;
 901                 if (bio_data_dir(bio) == READ) {
 902                         memcpy((void*)page_addr, (void*)source_addr,
 903                                 bvec.bv_len);
 904                 } else {
 905                         memcpy((void*)source_addr, (void*)page_addr,
 906                                 bvec.bv_len);
 907                 }
 908                 bytes_done += bvec.bv_len;
 909         }
 910         bio_endio(bio);
 911         return BLK_QC_T_NONE;
 912 fail:
 913         bio_io_error(bio);
 914         return BLK_QC_T_NONE;
 915 }
 916
 917 static long
 918 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 919                 long nr_pages, void **kaddr, pfn_t *pfn)
 920 {
 921         resource_size_t offset = pgoff * PAGE_SIZE;
 922         unsigned long dev_sz;
 923
 924         dev_sz = dev_info->end - dev_info->start + 1;
 925         if (kaddr)
 926                 *kaddr = (void *) dev_info->start + offset;
 927         if (pfn)
 928                 *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
 929                                 PFN_DEV|PFN_SPECIAL);
 930
 931         return (dev_sz - offset) / PAGE_SIZE;
 932 }
 933
 934 static long
 935 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 936                 long nr_pages, void **kaddr, pfn_t *pfn)
 937 {
 938         struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 939
 940         return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 941 }
 942
 943 static void
 944 dcssblk_check_params(void)
 945 {
 946         int rc, i, j, k;
 947         char buf[DCSSBLK_PARM_LEN + 1];
 948         struct dcssblk_dev_info *dev_info;
 949
 950         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 951              i++) {
 952                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 953                             (dcssblk_segments[j] != ',')  &&
 954                             (dcssblk_segments[j] != '\0') &&
 955                             (dcssblk_segments[j] != '('); j++)
 956                 {
 957                         buf[j-i] = dcssblk_segments[j];
 958                 }
 959                 buf[j-i] = '\0';
 960                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 961                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 962                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 963                                 buf[k] = toupper(buf[k]);
 964                         buf[k] = '\0';
 965                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 966                                 down_read(&dcssblk_devices_sem);
 967                                 dev_info = dcssblk_get_device_by_name(buf);
 968                                 up_read(&dcssblk_devices_sem);
 969                                 if (dev_info)
 970                                         dcssblk_shared_store(&dev_info->dev,
 971                                                              NULL, "0\n", 2);
 972                         }
 973                 }
 974                 while ((dcssblk_segments[j] != ',') &&
 975                        (dcssblk_segments[j] != '\0'))
 976                 {
 977                         j++;
 978                 }
 979                 if (dcssblk_segments[j] == '\0')
 980                         break;
 981                 i = j;
 982         }
 983 }
 984
 985 /*
 986  * Suspend / Resume
 987  */
 988 static int dcssblk_freeze(struct device *dev)
 989 {
 990         struct dcssblk_dev_info *dev_info;
 991         int rc = 0;
 992
 993         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 994                 switch (dev_info->segment_type) {
 995                         case SEG_TYPE_SR:
 996                         case SEG_TYPE_ER:
 997                         case SEG_TYPE_SC:
 998                                 if (!dev_info->is_shared)
 999                                         rc = -EINVAL;
1000                                 break;
1001                         default:
1002                                 rc = -EINVAL;
1003                                 break;
1004                 }
1005                 if (rc)
1006                         break;
1007         }
1008         if (rc)
1009                 pr_err("Suspending the system failed because DCSS device %s "
1010                        "is writable\n",
1011                        dev_info->segment_name);
1012         return rc;
1013 }
1014
1015 static int dcssblk_restore(struct device *dev)
1016 {
1017         struct dcssblk_dev_info *dev_info;
1018         struct segment_info *entry;
1019         unsigned long start, end;
1020         int rc = 0;
1021
1022         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
1023                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
1024                         segment_unload(entry->segment_name);
1025                         rc = segment_load(entry->segment_name, SEGMENT_SHARED,
1026                                           &start, &end);
1027                         if (rc < 0) {
1028 // TODO in_use check ?
1029                                 segment_warning(rc, entry->segment_name);
1030                                 goto out_panic;
1031                         }
1032                         if (start != entry->start || end != entry->end) {
1033                                 pr_err("The address range of DCSS %s changed "
1034                                        "while the system was suspended\n",
1035                                        entry->segment_name);
1036                                 goto out_panic;
1037                         }
1038                 }
1039         }
1040         return 0;
1041 out_panic:
1042         panic("fatal dcssblk resume error\n");
1043 }
1044
1045 static int dcssblk_thaw(struct device *dev)
1046 {
1047         return 0;
1048 }
1049
1050 static const struct dev_pm_ops dcssblk_pm_ops = {
1051         .freeze         = dcssblk_freeze,
1052         .thaw           = dcssblk_thaw,
1053         .restore        = dcssblk_restore,
1054 };
1055
1056 static struct platform_driver dcssblk_pdrv = {
1057         .driver = {
1058                 .name   = "dcssblk",
1059                 .pm     = &dcssblk_pm_ops,
1060         },
1061 };
1062
1063 static struct platform_device *dcssblk_pdev;
1064
1065
1066 /*
1067  * The init/exit functions.
1068  */
1069 static void __exit
1070 dcssblk_exit(void)
1071 {
1072         platform_device_unregister(dcssblk_pdev);
1073         platform_driver_unregister(&dcssblk_pdrv);
1074         root_device_unregister(dcssblk_root_dev);
1075         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1076 }
1077
1078 static int __init
1079 dcssblk_init(void)
1080 {
1081         int rc;
1082
1083         rc = platform_driver_register(&dcssblk_pdrv);
1084         if (rc)
1085                 return rc;
1086
1087         dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1088                                                         0);
1089         if (IS_ERR(dcssblk_pdev)) {
1090                 rc = PTR_ERR(dcssblk_pdev);
1091                 goto out_pdrv;
1092         }
1093
1094         dcssblk_root_dev = root_device_register("dcssblk");
1095         if (IS_ERR(dcssblk_root_dev)) {
1096                 rc = PTR_ERR(dcssblk_root_dev);
1097                 goto out_pdev;
1098         }
1099         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1100         if (rc)
1101                 goto out_root;
1102         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1103         if (rc)
1104                 goto out_root;
1105         rc = register_blkdev(0, DCSSBLK_NAME);
1106         if (rc < 0)
1107                 goto out_root;
1108         dcssblk_major = rc;
1109         init_rwsem(&dcssblk_devices_sem);
1110
1111         dcssblk_check_params();
1112         return 0;
1113
1114 out_root:
1115         root_device_unregister(dcssblk_root_dev);
1116 out_pdev:
1117         platform_device_unregister(dcssblk_pdev);
1118 out_pdrv:
1119         platform_driver_unregister(&dcssblk_pdrv);
1120         return rc;
1121 }
1122
1123 module_init(dcssblk_init);
1124 module_exit(dcssblk_exit);
1125
1126 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1127 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1128                  "comma-separated list, names in each set separated "
1129                  "by commas are separated by colons, each set contains "
1130                  "names of contiguous segments and each name max. 8 chars.\n"
1131                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1132                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1133                  "the contiguous segments - \n"
1134                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1135
1136 MODULE_LICENSE("GPL");