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         .dax_supported = generic_fsdax_supported,
  63         .copy_from_iter = dcssblk_dax_copy_from_iter,
  64         .copy_to_iter = dcssblk_dax_copy_to_iter,
  65 };
  66
  67 struct dcssblk_dev_info {
  68         struct list_head lh;
  69         struct device dev;
  70         char segment_name[DCSS_BUS_ID_SIZE];
  71         atomic_t use_count;
  72         struct gendisk *gd;
  73         unsigned long start;
  74         unsigned long end;
  75         int segment_type;
  76         unsigned char save_pending;
  77         unsigned char is_shared;
  78         struct request_queue *dcssblk_queue;
  79         int num_of_segments;
  80         struct list_head seg_list;
  81         struct dax_device *dax_dev;
  82 };
  83
  84 struct segment_info {
  85         struct list_head lh;
  86         char segment_name[DCSS_BUS_ID_SIZE];
  87         unsigned long start;
  88         unsigned long end;
  89         int segment_type;
  90 };
  91
  92 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  93                                   size_t count);
  94 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  95                                   size_t count);
  96
  97 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  98 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  99
 100 static struct device *dcssblk_root_dev;
 101
 102 static LIST_HEAD(dcssblk_devices);
 103 static struct rw_semaphore dcssblk_devices_sem;
 104
 105 /*
 106  * release function for segment device.
 107  */
 108 static void
 109 dcssblk_release_segment(struct device *dev)
 110 {
 111         struct dcssblk_dev_info *dev_info;
 112         struct segment_info *entry, *temp;
 113
 114         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 115         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 116                 list_del(&entry->lh);
 117                 kfree(entry);
 118         }
 119         kfree(dev_info);
 120         module_put(THIS_MODULE);
 121 }
 122
 123 /*
 124  * get a minor number. needs to be called with
 125  * down_write(&dcssblk_devices_sem) and the
 126  * device needs to be enqueued before the semaphore is
 127  * freed.
 128  */
 129 static int
 130 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 131 {
 132         int minor, found;
 133         struct dcssblk_dev_info *entry;
 134
 135         if (dev_info == NULL)
 136                 return -EINVAL;
 137         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 138                 found = 0;
 139                 // test if minor available
 140                 list_for_each_entry(entry, &dcssblk_devices, lh)
 141                         if (minor == entry->gd->first_minor)
 142                                 found++;
 143                 if (!found) break; // got unused minor
 144         }
 145         if (found)
 146                 return -EBUSY;
 147         dev_info->gd->first_minor = minor;
 148         return 0;
 149 }
 150
 151 /*
 152  * get the struct dcssblk_dev_info from dcssblk_devices
 153  * for the given name.
 154  * down_read(&dcssblk_devices_sem) must be held.
 155  */
 156 static struct dcssblk_dev_info *
 157 dcssblk_get_device_by_name(char *name)
 158 {
 159         struct dcssblk_dev_info *entry;
 160
 161         list_for_each_entry(entry, &dcssblk_devices, lh) {
 162                 if (!strcmp(name, entry->segment_name)) {
 163                         return entry;
 164                 }
 165         }
 166         return NULL;
 167 }
 168
 169 /*
 170  * get the struct segment_info from seg_list
 171  * for the given name.
 172  * down_read(&dcssblk_devices_sem) must be held.
 173  */
 174 static struct segment_info *
 175 dcssblk_get_segment_by_name(char *name)
 176 {
 177         struct dcssblk_dev_info *dev_info;
 178         struct segment_info *entry;
 179
 180         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 181                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 182                         if (!strcmp(name, entry->segment_name))
 183                                 return entry;
 184                 }
 185         }
 186         return NULL;
 187 }
 188
 189 /*
 190  * get the highest address of the multi-segment block.
 191  */
 192 static unsigned long
 193 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 194 {
 195         unsigned long highest_addr;
 196         struct segment_info *entry;
 197
 198         highest_addr = 0;
 199         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 200                 if (highest_addr < entry->end)
 201                         highest_addr = entry->end;
 202         }
 203         return highest_addr;
 204 }
 205
 206 /*
 207  * get the lowest address of the multi-segment block.
 208  */
 209 static unsigned long
 210 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 211 {
 212         int set_first;
 213         unsigned long lowest_addr;
 214         struct segment_info *entry;
 215
 216         set_first = 0;
 217         lowest_addr = 0;
 218         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 219                 if (set_first == 0) {
 220                         lowest_addr = entry->start;
 221                         set_first = 1;
 222                 } else {
 223                         if (lowest_addr > entry->start)
 224                                 lowest_addr = entry->start;
 225                 }
 226         }
 227         return lowest_addr;
 228 }
 229
 230 /*
 231  * Check continuity of segments.
 232  */
 233 static int
 234 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 235 {
 236         int i, j, rc;
 237         struct segment_info *sort_list, *entry, temp;
 238
 239         if (dev_info->num_of_segments <= 1)
 240                 return 0;
 241
 242         sort_list = kcalloc(dev_info->num_of_segments,
 243                             sizeof(struct segment_info),
 244                             GFP_KERNEL);
 245         if (sort_list == NULL)
 246                 return -ENOMEM;
 247         i = 0;
 248         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 249                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 250                 i++;
 251         }
 252
 253         /* sort segments */
 254         for (i = 0; i < dev_info->num_of_segments; i++)
 255                 for (j = 0; j < dev_info->num_of_segments; j++)
 256                         if (sort_list[j].start > sort_list[i].start) {
 257                                 memcpy(&temp, &sort_list[i],
 258                                         sizeof(struct segment_info));
 259                                 memcpy(&sort_list[i], &sort_list[j],
 260                                         sizeof(struct segment_info));
 261                                 memcpy(&sort_list[j], &temp,
 262                                         sizeof(struct segment_info));
 263                         }
 264
 265         /* check continuity */
 266         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 267                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 268                         pr_err("Adjacent DCSSs %s and %s are not "
 269                                "contiguous\n", sort_list[i].segment_name,
 270                                sort_list[i+1].segment_name);
 271                         rc = -EINVAL;
 272                         goto out;
 273                 }
 274                 /* EN and EW are allowed in a block device */
 275                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 276                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 277                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 278                                 !(sort_list[i+1].segment_type &
 279                                 SEGMENT_EXCLUSIVE) ||
 280                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 281                                 pr_err("DCSS %s and DCSS %s have "
 282                                        "incompatible types\n",
 283                                        sort_list[i].segment_name,
 284                                        sort_list[i+1].segment_name);
 285                                 rc = -EINVAL;
 286                                 goto out;
 287                         }
 288                 }
 289         }
 290         rc = 0;
 291 out:
 292         kfree(sort_list);
 293         return rc;
 294 }
 295
 296 /*
 297  * Load a segment
 298  */
 299 static int
 300 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 301 {
 302         int rc;
 303
 304         /* already loaded? */
 305         down_read(&dcssblk_devices_sem);
 306         *seg_info = dcssblk_get_segment_by_name(name);
 307         up_read(&dcssblk_devices_sem);
 308         if (*seg_info != NULL)
 309                 return -EEXIST;
 310
 311         /* get a struct segment_info */
 312         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 313         if (*seg_info == NULL)
 314                 return -ENOMEM;
 315
 316         strcpy((*seg_info)->segment_name, name);
 317
 318         /* load the segment */
 319         rc = segment_load(name, SEGMENT_SHARED,
 320                         &(*seg_info)->start, &(*seg_info)->end);
 321         if (rc < 0) {
 322                 segment_warning(rc, (*seg_info)->segment_name);
 323                 kfree(*seg_info);
 324         } else {
 325                 INIT_LIST_HEAD(&(*seg_info)->lh);
 326                 (*seg_info)->segment_type = rc;
 327         }
 328         return rc;
 329 }
 330
 331 /*
 332  * device attribute for switching shared/nonshared (exclusive)
 333  * operation (show + store)
 334  */
 335 static ssize_t
 336 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 337 {
 338         struct dcssblk_dev_info *dev_info;
 339
 340         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 341         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 342 }
 343
 344 static ssize_t
 345 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 346 {
 347         struct dcssblk_dev_info *dev_info;
 348         struct segment_info *entry, *temp;
 349         int rc;
 350
 351         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 352                 return -EINVAL;
 353         down_write(&dcssblk_devices_sem);
 354         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 355         if (atomic_read(&dev_info->use_count)) {
 356                 rc = -EBUSY;
 357                 goto out;
 358         }
 359         if (inbuf[0] == '1') {
 360                 /* reload segments in shared mode */
 361                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 362                         rc = segment_modify_shared(entry->segment_name,
 363                                                 SEGMENT_SHARED);
 364                         if (rc < 0) {
 365                                 BUG_ON(rc == -EINVAL);
 366                                 if (rc != -EAGAIN)
 367                                         goto removeseg;
 368                         }
 369                 }
 370                 dev_info->is_shared = 1;
 371                 switch (dev_info->segment_type) {
 372                 case SEG_TYPE_SR:
 373                 case SEG_TYPE_ER:
 374                 case SEG_TYPE_SC:
 375                         set_disk_ro(dev_info->gd, 1);
 376                 }
 377         } else if (inbuf[0] == '0') {
 378                 /* reload segments in exclusive mode */
 379                 if (dev_info->segment_type == SEG_TYPE_SC) {
 380                         pr_err("DCSS %s is of type SC and cannot be "
 381                                "loaded as exclusive-writable\n",
 382                                dev_info->segment_name);
 383                         rc = -EINVAL;
 384                         goto out;
 385                 }
 386                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 387                         rc = segment_modify_shared(entry->segment_name,
 388                                                    SEGMENT_EXCLUSIVE);
 389                         if (rc < 0) {
 390                                 BUG_ON(rc == -EINVAL);
 391                                 if (rc != -EAGAIN)
 392                                         goto removeseg;
 393                         }
 394                 }
 395                 dev_info->is_shared = 0;
 396                 set_disk_ro(dev_info->gd, 0);
 397         } else {
 398                 rc = -EINVAL;
 399                 goto out;
 400         }
 401         rc = count;
 402         goto out;
 403
 404 removeseg:
 405         pr_err("DCSS device %s is removed after a failed access mode "
 406                "change\n", dev_info->segment_name);
 407         temp = entry;
 408         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 409                 if (entry != temp)
 410                         segment_unload(entry->segment_name);
 411         }
 412         list_del(&dev_info->lh);
 413
 414         kill_dax(dev_info->dax_dev);
 415         put_dax(dev_info->dax_dev);
 416         del_gendisk(dev_info->gd);
 417         blk_cleanup_queue(dev_info->dcssblk_queue);
 418         dev_info->gd->queue = NULL;
 419         put_disk(dev_info->gd);
 420         up_write(&dcssblk_devices_sem);
 421
 422         if (device_remove_file_self(dev, attr)) {
 423                 device_unregister(dev);
 424                 put_device(dev);
 425         }
 426         return rc;
 427 out:
 428         up_write(&dcssblk_devices_sem);
 429         return rc;
 430 }
 431 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 432                    dcssblk_shared_store);
 433
 434 /*
 435  * device attribute for save operation on current copy
 436  * of the segment. If the segment is busy, saving will
 437  * become pending until it gets released, which can be
 438  * undone by storing a non-true value to this entry.
 439  * (show + store)
 440  */
 441 static ssize_t
 442 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 443 {
 444         struct dcssblk_dev_info *dev_info;
 445
 446         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 447         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 448 }
 449
 450 static ssize_t
 451 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 452 {
 453         struct dcssblk_dev_info *dev_info;
 454         struct segment_info *entry;
 455
 456         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 457                 return -EINVAL;
 458         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 459
 460         down_write(&dcssblk_devices_sem);
 461         if (inbuf[0] == '1') {
 462                 if (atomic_read(&dev_info->use_count) == 0) {
 463                         // device is idle => we save immediately
 464                         pr_info("All DCSSs that map to device %s are "
 465                                 "saved\n", dev_info->segment_name);
 466                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 467                                 if (entry->segment_type == SEG_TYPE_EN ||
 468                                     entry->segment_type == SEG_TYPE_SN)
 469                                         pr_warn("DCSS %s is of type SN or EN"
 470                                                 " and cannot be saved\n",
 471                                                 entry->segment_name);
 472                                 else
 473                                         segment_save(entry->segment_name);
 474                         }
 475                 }  else {
 476                         // device is busy => we save it when it becomes
 477                         // idle in dcssblk_release
 478                         pr_info("Device %s is in use, its DCSSs will be "
 479                                 "saved when it becomes idle\n",
 480                                 dev_info->segment_name);
 481                         dev_info->save_pending = 1;
 482                 }
 483         } else if (inbuf[0] == '0') {
 484                 if (dev_info->save_pending) {
 485                         // device is busy & the user wants to undo his save
 486                         // request
 487                         dev_info->save_pending = 0;
 488                         pr_info("A pending save request for device %s "
 489                                 "has been canceled\n",
 490                                 dev_info->segment_name);
 491                 }
 492         } else {
 493                 up_write(&dcssblk_devices_sem);
 494                 return -EINVAL;
 495         }
 496         up_write(&dcssblk_devices_sem);
 497         return count;
 498 }
 499 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 500                    dcssblk_save_store);
 501
 502 /*
 503  * device attribute for showing all segments in a device
 504  */
 505 static ssize_t
 506 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 507                 char *buf)
 508 {
 509         int i;
 510
 511         struct dcssblk_dev_info *dev_info;
 512         struct segment_info *entry;
 513
 514         down_read(&dcssblk_devices_sem);
 515         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 516         i = 0;
 517         buf[0] = '\0';
 518         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 519                 strcpy(&buf[i], entry->segment_name);
 520                 i += strlen(entry->segment_name);
 521                 buf[i] = '\n';
 522                 i++;
 523         }
 524         up_read(&dcssblk_devices_sem);
 525         return i;
 526 }
 527 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 528
 529 static struct attribute *dcssblk_dev_attrs[] = {
 530         &dev_attr_shared.attr,
 531         &dev_attr_save.attr,
 532         &dev_attr_seglist.attr,
 533         NULL,
 534 };
 535 static struct attribute_group dcssblk_dev_attr_group = {
 536         .attrs = dcssblk_dev_attrs,
 537 };
 538 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 539         &dcssblk_dev_attr_group,
 540         NULL,
 541 };
 542
 543 /*
 544  * device attribute for adding devices
 545  */
 546 static ssize_t
 547 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 548 {
 549         int rc, i, j, num_of_segments;
 550         struct dcssblk_dev_info *dev_info;
 551         struct segment_info *seg_info, *temp;
 552         char *local_buf;
 553         unsigned long seg_byte_size;
 554
 555         dev_info = NULL;
 556         seg_info = NULL;
 557         if (dev != dcssblk_root_dev) {
 558                 rc = -EINVAL;
 559                 goto out_nobuf;
 560         }
 561         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 562                 rc = -ENAMETOOLONG;
 563                 goto out_nobuf;
 564         }
 565
 566         local_buf = kmalloc(count + 1, GFP_KERNEL);
 567         if (local_buf == NULL) {
 568                 rc = -ENOMEM;
 569                 goto out_nobuf;
 570         }
 571
 572         /*
 573          * parse input
 574          */
 575         num_of_segments = 0;
 576         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 577                 for (j = i; j < count &&
 578                         (buf[j] != ':') &&
 579                         (buf[j] != '\0') &&
 580                         (buf[j] != '\n'); j++) {
 581                         local_buf[j-i] = toupper(buf[j]);
 582                 }
 583                 local_buf[j-i] = '\0';
 584                 if (((j - i) == 0) || ((j - i) > 8)) {
 585                         rc = -ENAMETOOLONG;
 586                         goto seg_list_del;
 587                 }
 588
 589                 rc = dcssblk_load_segment(local_buf, &seg_info);
 590                 if (rc < 0)
 591                         goto seg_list_del;
 592                 /*
 593                  * get a struct dcssblk_dev_info
 594                  */
 595                 if (num_of_segments == 0) {
 596                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 597                                         GFP_KERNEL);
 598                         if (dev_info == NULL) {
 599                                 rc = -ENOMEM;
 600                                 goto out;
 601                         }
 602                         strcpy(dev_info->segment_name, local_buf);
 603                         dev_info->segment_type = seg_info->segment_type;
 604                         INIT_LIST_HEAD(&dev_info->seg_list);
 605                 }
 606                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 607                 num_of_segments++;
 608                 i = j;
 609
 610                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 611                         break;
 612         }
 613
 614         /* no trailing colon at the end of the input */
 615         if ((i > 0) && (buf[i-1] == ':')) {
 616                 rc = -ENAMETOOLONG;
 617                 goto seg_list_del;
 618         }
 619         strlcpy(local_buf, buf, i + 1);
 620         dev_info->num_of_segments = num_of_segments;
 621         rc = dcssblk_is_continuous(dev_info);
 622         if (rc < 0)
 623                 goto seg_list_del;
 624
 625         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 626         dev_info->end = dcssblk_find_highest_addr(dev_info);
 627
 628         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 629         dev_info->dev.release = dcssblk_release_segment;
 630         dev_info->dev.groups = dcssblk_dev_attr_groups;
 631         INIT_LIST_HEAD(&dev_info->lh);
 632         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 633         if (dev_info->gd == NULL) {
 634                 rc = -ENOMEM;
 635                 goto seg_list_del;
 636         }
 637         dev_info->gd->major = dcssblk_major;
 638         dev_info->gd->fops = &dcssblk_devops;
 639         dev_info->dcssblk_queue =
 640                 blk_alloc_queue(dcssblk_make_request, NUMA_NO_NODE);
 641         dev_info->gd->queue = dev_info->dcssblk_queue;
 642         dev_info->gd->private_data = dev_info;
 643         blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 644         blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->dcssblk_queue);
 645
 646         seg_byte_size = (dev_info->end - dev_info->start + 1);
 647         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 648         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 649                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 650
 651         dev_info->save_pending = 0;
 652         dev_info->is_shared = 1;
 653         dev_info->dev.parent = dcssblk_root_dev;
 654
 655         /*
 656          *get minor, add to list
 657          */
 658         down_write(&dcssblk_devices_sem);
 659         if (dcssblk_get_segment_by_name(local_buf)) {
 660                 rc = -EEXIST;
 661                 goto release_gd;
 662         }
 663         rc = dcssblk_assign_free_minor(dev_info);
 664         if (rc)
 665                 goto release_gd;
 666         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 667                 dev_info->gd->first_minor);
 668         list_add_tail(&dev_info->lh, &dcssblk_devices);
 669
 670         if (!try_module_get(THIS_MODULE)) {
 671                 rc = -ENODEV;
 672                 goto dev_list_del;
 673         }
 674         /*
 675          * register the device
 676          */
 677         rc = device_register(&dev_info->dev);
 678         if (rc)
 679                 goto put_dev;
 680
 681         dev_info->dax_dev = alloc_dax(dev_info, dev_info->gd->disk_name,
 682                         &dcssblk_dax_ops, DAXDEV_F_SYNC);
 683         if (!dev_info->dax_dev) {
 684                 rc = -ENOMEM;
 685                 goto put_dev;
 686         }
 687
 688         get_device(&dev_info->dev);
 689         device_add_disk(&dev_info->dev, dev_info->gd, NULL);
 690
 691         switch (dev_info->segment_type) {
 692                 case SEG_TYPE_SR:
 693                 case SEG_TYPE_ER:
 694                 case SEG_TYPE_SC:
 695                         set_disk_ro(dev_info->gd,1);
 696                         break;
 697                 default:
 698                         set_disk_ro(dev_info->gd,0);
 699                         break;
 700         }
 701         up_write(&dcssblk_devices_sem);
 702         rc = count;
 703         goto out;
 704
 705 put_dev:
 706         list_del(&dev_info->lh);
 707         blk_cleanup_queue(dev_info->dcssblk_queue);
 708         dev_info->gd->queue = NULL;
 709         put_disk(dev_info->gd);
 710         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 711                 segment_unload(seg_info->segment_name);
 712         }
 713         put_device(&dev_info->dev);
 714         up_write(&dcssblk_devices_sem);
 715         goto out;
 716 dev_list_del:
 717         list_del(&dev_info->lh);
 718 release_gd:
 719         blk_cleanup_queue(dev_info->dcssblk_queue);
 720         dev_info->gd->queue = NULL;
 721         put_disk(dev_info->gd);
 722         up_write(&dcssblk_devices_sem);
 723 seg_list_del:
 724         if (dev_info == NULL)
 725                 goto out;
 726         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 727                 list_del(&seg_info->lh);
 728                 segment_unload(seg_info->segment_name);
 729                 kfree(seg_info);
 730         }
 731         kfree(dev_info);
 732 out:
 733         kfree(local_buf);
 734 out_nobuf:
 735         return rc;
 736 }
 737
 738 /*
 739  * device attribute for removing devices
 740  */
 741 static ssize_t
 742 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 743 {
 744         struct dcssblk_dev_info *dev_info;
 745         struct segment_info *entry;
 746         int rc, i;
 747         char *local_buf;
 748
 749         if (dev != dcssblk_root_dev) {
 750                 return -EINVAL;
 751         }
 752         local_buf = kmalloc(count + 1, GFP_KERNEL);
 753         if (local_buf == NULL) {
 754                 return -ENOMEM;
 755         }
 756         /*
 757          * parse input
 758          */
 759         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 760                 local_buf[i] = toupper(buf[i]);
 761         }
 762         local_buf[i] = '\0';
 763         if ((i == 0) || (i > 8)) {
 764                 rc = -ENAMETOOLONG;
 765                 goto out_buf;
 766         }
 767
 768         down_write(&dcssblk_devices_sem);
 769         dev_info = dcssblk_get_device_by_name(local_buf);
 770         if (dev_info == NULL) {
 771                 up_write(&dcssblk_devices_sem);
 772                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 773                         local_buf);
 774                 rc = -ENODEV;
 775                 goto out_buf;
 776         }
 777         if (atomic_read(&dev_info->use_count) != 0) {
 778                 up_write(&dcssblk_devices_sem);
 779                 pr_warn("Device %s cannot be removed while it is in use\n",
 780                         local_buf);
 781                 rc = -EBUSY;
 782                 goto out_buf;
 783         }
 784
 785         list_del(&dev_info->lh);
 786         kill_dax(dev_info->dax_dev);
 787         put_dax(dev_info->dax_dev);
 788         del_gendisk(dev_info->gd);
 789         blk_cleanup_queue(dev_info->dcssblk_queue);
 790         dev_info->gd->queue = NULL;
 791         put_disk(dev_info->gd);
 792
 793         /* unload all related segments */
 794         list_for_each_entry(entry, &dev_info->seg_list, lh)
 795                 segment_unload(entry->segment_name);
 796
 797         up_write(&dcssblk_devices_sem);
 798
 799         device_unregister(&dev_info->dev);
 800         put_device(&dev_info->dev);
 801
 802         rc = count;
 803 out_buf:
 804         kfree(local_buf);
 805         return rc;
 806 }
 807
 808 static int
 809 dcssblk_open(struct block_device *bdev, fmode_t mode)
 810 {
 811         struct dcssblk_dev_info *dev_info;
 812         int rc;
 813
 814         dev_info = bdev->bd_disk->private_data;
 815         if (NULL == dev_info) {
 816                 rc = -ENODEV;
 817                 goto out;
 818         }
 819         atomic_inc(&dev_info->use_count);
 820         bdev->bd_block_size = 4096;
 821         rc = 0;
 822 out:
 823         return rc;
 824 }
 825
 826 static void
 827 dcssblk_release(struct gendisk *disk, fmode_t mode)
 828 {
 829         struct dcssblk_dev_info *dev_info = disk->private_data;
 830         struct segment_info *entry;
 831
 832         if (!dev_info) {
 833                 WARN_ON(1);
 834                 return;
 835         }
 836         down_write(&dcssblk_devices_sem);
 837         if (atomic_dec_and_test(&dev_info->use_count)
 838             && (dev_info->save_pending)) {
 839                 pr_info("Device %s has become idle and is being saved "
 840                         "now\n", dev_info->segment_name);
 841                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 842                         if (entry->segment_type == SEG_TYPE_EN ||
 843                             entry->segment_type == SEG_TYPE_SN)
 844                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 845                                         " be saved\n", entry->segment_name);
 846                         else
 847                                 segment_save(entry->segment_name);
 848                 }
 849                 dev_info->save_pending = 0;
 850         }
 851         up_write(&dcssblk_devices_sem);
 852 }
 853
 854 static blk_qc_t
 855 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 856 {
 857         struct dcssblk_dev_info *dev_info;
 858         struct bio_vec bvec;
 859         struct bvec_iter iter;
 860         unsigned long index;
 861         unsigned long page_addr;
 862         unsigned long source_addr;
 863         unsigned long bytes_done;
 864
 865         blk_queue_split(q, &bio);
 866
 867         bytes_done = 0;
 868         dev_info = bio->bi_disk->private_data;
 869         if (dev_info == NULL)
 870                 goto fail;
 871         if ((bio->bi_iter.bi_sector & 7) != 0 ||
 872             (bio->bi_iter.bi_size & 4095) != 0)
 873                 /* Request is not page-aligned. */
 874                 goto fail;
 875         if (bio_end_sector(bio) > get_capacity(bio->bi_disk)) {
 876                 /* Request beyond end of DCSS segment. */
 877                 goto fail;
 878         }
 879         /* verify data transfer direction */
 880         if (dev_info->is_shared) {
 881                 switch (dev_info->segment_type) {
 882                 case SEG_TYPE_SR:
 883                 case SEG_TYPE_ER:
 884                 case SEG_TYPE_SC:
 885                         /* cannot write to these segments */
 886                         if (bio_data_dir(bio) == WRITE) {
 887                                 pr_warn("Writing to %s failed because it is a read-only device\n",
 888                                         dev_name(&dev_info->dev));
 889                                 goto fail;
 890                         }
 891                 }
 892         }
 893
 894         index = (bio->bi_iter.bi_sector >> 3);
 895         bio_for_each_segment(bvec, bio, iter) {
 896                 page_addr = (unsigned long)
 897                         page_address(bvec.bv_page) + bvec.bv_offset;
 898                 source_addr = dev_info->start + (index<<12) + bytes_done;
 899                 if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 900                         // More paranoia.
 901                         goto fail;
 902                 if (bio_data_dir(bio) == READ) {
 903                         memcpy((void*)page_addr, (void*)source_addr,
 904                                 bvec.bv_len);
 905                 } else {
 906                         memcpy((void*)source_addr, (void*)page_addr,
 907                                 bvec.bv_len);
 908                 }
 909                 bytes_done += bvec.bv_len;
 910         }
 911         bio_endio(bio);
 912         return BLK_QC_T_NONE;
 913 fail:
 914         bio_io_error(bio);
 915         return BLK_QC_T_NONE;
 916 }
 917
 918 static long
 919 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 920                 long nr_pages, void **kaddr, pfn_t *pfn)
 921 {
 922         resource_size_t offset = pgoff * PAGE_SIZE;
 923         unsigned long dev_sz;
 924
 925         dev_sz = dev_info->end - dev_info->start + 1;
 926         if (kaddr)
 927                 *kaddr = (void *) dev_info->start + offset;
 928         if (pfn)
 929                 *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
 930                                 PFN_DEV|PFN_SPECIAL);
 931
 932         return (dev_sz - offset) / PAGE_SIZE;
 933 }
 934
 935 static long
 936 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 937                 long nr_pages, void **kaddr, pfn_t *pfn)
 938 {
 939         struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 940
 941         return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 942 }
 943
 944 static void
 945 dcssblk_check_params(void)
 946 {
 947         int rc, i, j, k;
 948         char buf[DCSSBLK_PARM_LEN + 1];
 949         struct dcssblk_dev_info *dev_info;
 950
 951         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 952              i++) {
 953                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 954                             (dcssblk_segments[j] != ',')  &&
 955                             (dcssblk_segments[j] != '\0') &&
 956                             (dcssblk_segments[j] != '('); j++)
 957                 {
 958                         buf[j-i] = dcssblk_segments[j];
 959                 }
 960                 buf[j-i] = '\0';
 961                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 962                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 963                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 964                                 buf[k] = toupper(buf[k]);
 965                         buf[k] = '\0';
 966                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 967                                 down_read(&dcssblk_devices_sem);
 968                                 dev_info = dcssblk_get_device_by_name(buf);
 969                                 up_read(&dcssblk_devices_sem);
 970                                 if (dev_info)
 971                                         dcssblk_shared_store(&dev_info->dev,
 972                                                              NULL, "0\n", 2);
 973                         }
 974                 }
 975                 while ((dcssblk_segments[j] != ',') &&
 976                        (dcssblk_segments[j] != '\0'))
 977                 {
 978                         j++;
 979                 }
 980                 if (dcssblk_segments[j] == '\0')
 981                         break;
 982                 i = j;
 983         }
 984 }
 985
 986 /*
 987  * Suspend / Resume
 988  */
 989 static int dcssblk_freeze(struct device *dev)
 990 {
 991         struct dcssblk_dev_info *dev_info;
 992         int rc = 0;
 993
 994         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 995                 switch (dev_info->segment_type) {
 996                         case SEG_TYPE_SR:
 997                         case SEG_TYPE_ER:
 998                         case SEG_TYPE_SC:
 999                                 if (!dev_info->is_shared)
1000                                         rc = -EINVAL;
1001                                 break;
1002                         default:
1003                                 rc = -EINVAL;
1004                                 break;
1005                 }
1006                 if (rc)
1007                         break;
1008         }
1009         if (rc)
1010                 pr_err("Suspending the system failed because DCSS device %s "
1011                        "is writable\n",
1012                        dev_info->segment_name);
1013         return rc;
1014 }
1015
1016 static int dcssblk_restore(struct device *dev)
1017 {
1018         struct dcssblk_dev_info *dev_info;
1019         struct segment_info *entry;
1020         unsigned long start, end;
1021         int rc = 0;
1022
1023         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
1024                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
1025                         segment_unload(entry->segment_name);
1026                         rc = segment_load(entry->segment_name, SEGMENT_SHARED,
1027                                           &start, &end);
1028                         if (rc < 0) {
1029 // TODO in_use check ?
1030                                 segment_warning(rc, entry->segment_name);
1031                                 goto out_panic;
1032                         }
1033                         if (start != entry->start || end != entry->end) {
1034                                 pr_err("The address range of DCSS %s changed "
1035                                        "while the system was suspended\n",
1036                                        entry->segment_name);
1037                                 goto out_panic;
1038                         }
1039                 }
1040         }
1041         return 0;
1042 out_panic:
1043         panic("fatal dcssblk resume error\n");
1044 }
1045
1046 static int dcssblk_thaw(struct device *dev)
1047 {
1048         return 0;
1049 }
1050
1051 static const struct dev_pm_ops dcssblk_pm_ops = {
1052         .freeze         = dcssblk_freeze,
1053         .thaw           = dcssblk_thaw,
1054         .restore        = dcssblk_restore,
1055 };
1056
1057 static struct platform_driver dcssblk_pdrv = {
1058         .driver = {
1059                 .name   = "dcssblk",
1060                 .pm     = &dcssblk_pm_ops,
1061         },
1062 };
1063
1064 static struct platform_device *dcssblk_pdev;
1065
1066
1067 /*
1068  * The init/exit functions.
1069  */
1070 static void __exit
1071 dcssblk_exit(void)
1072 {
1073         platform_device_unregister(dcssblk_pdev);
1074         platform_driver_unregister(&dcssblk_pdrv);
1075         root_device_unregister(dcssblk_root_dev);
1076         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1077 }
1078
1079 static int __init
1080 dcssblk_init(void)
1081 {
1082         int rc;
1083
1084         rc = platform_driver_register(&dcssblk_pdrv);
1085         if (rc)
1086                 return rc;
1087
1088         dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1089                                                         0);
1090         if (IS_ERR(dcssblk_pdev)) {
1091                 rc = PTR_ERR(dcssblk_pdev);
1092                 goto out_pdrv;
1093         }
1094
1095         dcssblk_root_dev = root_device_register("dcssblk");
1096         if (IS_ERR(dcssblk_root_dev)) {
1097                 rc = PTR_ERR(dcssblk_root_dev);
1098                 goto out_pdev;
1099         }
1100         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1101         if (rc)
1102                 goto out_root;
1103         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1104         if (rc)
1105                 goto out_root;
1106         rc = register_blkdev(0, DCSSBLK_NAME);
1107         if (rc < 0)
1108                 goto out_root;
1109         dcssblk_major = rc;
1110         init_rwsem(&dcssblk_devices_sem);
1111
1112         dcssblk_check_params();
1113         return 0;
1114
1115 out_root:
1116         root_device_unregister(dcssblk_root_dev);
1117 out_pdev:
1118         platform_device_unregister(dcssblk_pdev);
1119 out_pdrv:
1120         platform_driver_unregister(&dcssblk_pdrv);
1121         return rc;
1122 }
1123
1124 module_init(dcssblk_init);
1125 module_exit(dcssblk_exit);
1126
1127 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1128 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1129                  "comma-separated list, names in each set separated "
1130                  "by commas are separated by colons, each set contains "
1131                  "names of contiguous segments and each name max. 8 chars.\n"
1132                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1133                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1134                  "the contiguous segments - \n"
1135                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1136
1137 MODULE_LICENSE("GPL");