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/pfn_t.h>
  21 #include <linux/uio.h>
  22 #include <linux/dax.h>
  23 #include <asm/extmem.h>
  24 #include <asm/io.h>
  25
  26 #define DCSSBLK_NAME "dcssblk"
  27 #define DCSSBLK_MINORS_PER_DISK 1
  28 #define DCSSBLK_PARM_LEN 400
  29 #define DCSS_BUS_ID_SIZE 20
  30
  31 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
  32 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
  33 static void dcssblk_submit_bio(struct bio *bio);
  34 static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
  35                 long nr_pages, enum dax_access_mode mode, void **kaddr,
  36                 pfn_t *pfn);
  37
  38 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  39
  40 static int dcssblk_major;
  41 static const struct block_device_operations dcssblk_devops = {
  42         .owner          = THIS_MODULE,
  43         .submit_bio     = dcssblk_submit_bio,
  44         .open           = dcssblk_open,
  45         .release        = dcssblk_release,
  46 };
  47
  48 static int dcssblk_dax_zero_page_range(struct dax_device *dax_dev,
  49                                        pgoff_t pgoff, size_t nr_pages)
  50 {
  51         long rc;
  52         void *kaddr;
  53
  54         rc = dax_direct_access(dax_dev, pgoff, nr_pages, DAX_ACCESS,
  55                         &kaddr, NULL);
  56         if (rc < 0)
  57                 return rc;
  58         memset(kaddr, 0, nr_pages << PAGE_SHIFT);
  59         dax_flush(dax_dev, kaddr, nr_pages << PAGE_SHIFT);
  60         return 0;
  61 }
  62
  63 static const struct dax_operations dcssblk_dax_ops = {
  64         .direct_access = dcssblk_dax_direct_access,
  65         .zero_page_range = dcssblk_dax_zero_page_range,
  66 };
  67
  68 struct dcssblk_dev_info {
  69         struct list_head lh;
  70         struct device dev;
  71         char segment_name[DCSS_BUS_ID_SIZE];
  72         atomic_t use_count;
  73         struct gendisk *gd;
  74         unsigned long start;
  75         unsigned long end;
  76         int segment_type;
  77         unsigned char save_pending;
  78         unsigned char is_shared;
  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         put_disk(dev_info->gd);
 418         up_write(&dcssblk_devices_sem);
 419
 420         if (device_remove_file_self(dev, attr)) {
 421                 device_unregister(dev);
 422                 put_device(dev);
 423         }
 424         return rc;
 425 out:
 426         up_write(&dcssblk_devices_sem);
 427         return rc;
 428 }
 429 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 430                    dcssblk_shared_store);
 431
 432 /*
 433  * device attribute for save operation on current copy
 434  * of the segment. If the segment is busy, saving will
 435  * become pending until it gets released, which can be
 436  * undone by storing a non-true value to this entry.
 437  * (show + store)
 438  */
 439 static ssize_t
 440 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 441 {
 442         struct dcssblk_dev_info *dev_info;
 443
 444         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 445         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 446 }
 447
 448 static ssize_t
 449 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 450 {
 451         struct dcssblk_dev_info *dev_info;
 452         struct segment_info *entry;
 453
 454         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 455                 return -EINVAL;
 456         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 457
 458         down_write(&dcssblk_devices_sem);
 459         if (inbuf[0] == '1') {
 460                 if (atomic_read(&dev_info->use_count) == 0) {
 461                         // device is idle => we save immediately
 462                         pr_info("All DCSSs that map to device %s are "
 463                                 "saved\n", dev_info->segment_name);
 464                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 465                                 if (entry->segment_type == SEG_TYPE_EN ||
 466                                     entry->segment_type == SEG_TYPE_SN)
 467                                         pr_warn("DCSS %s is of type SN or EN"
 468                                                 " and cannot be saved\n",
 469                                                 entry->segment_name);
 470                                 else
 471                                         segment_save(entry->segment_name);
 472                         }
 473                 }  else {
 474                         // device is busy => we save it when it becomes
 475                         // idle in dcssblk_release
 476                         pr_info("Device %s is in use, its DCSSs will be "
 477                                 "saved when it becomes idle\n",
 478                                 dev_info->segment_name);
 479                         dev_info->save_pending = 1;
 480                 }
 481         } else if (inbuf[0] == '0') {
 482                 if (dev_info->save_pending) {
 483                         // device is busy & the user wants to undo his save
 484                         // request
 485                         dev_info->save_pending = 0;
 486                         pr_info("A pending save request for device %s "
 487                                 "has been canceled\n",
 488                                 dev_info->segment_name);
 489                 }
 490         } else {
 491                 up_write(&dcssblk_devices_sem);
 492                 return -EINVAL;
 493         }
 494         up_write(&dcssblk_devices_sem);
 495         return count;
 496 }
 497 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 498                    dcssblk_save_store);
 499
 500 /*
 501  * device attribute for showing all segments in a device
 502  */
 503 static ssize_t
 504 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 505                 char *buf)
 506 {
 507         int i;
 508
 509         struct dcssblk_dev_info *dev_info;
 510         struct segment_info *entry;
 511
 512         down_read(&dcssblk_devices_sem);
 513         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 514         i = 0;
 515         buf[0] = '\0';
 516         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 517                 strcpy(&buf[i], entry->segment_name);
 518                 i += strlen(entry->segment_name);
 519                 buf[i] = '\n';
 520                 i++;
 521         }
 522         up_read(&dcssblk_devices_sem);
 523         return i;
 524 }
 525 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 526
 527 static struct attribute *dcssblk_dev_attrs[] = {
 528         &dev_attr_shared.attr,
 529         &dev_attr_save.attr,
 530         &dev_attr_seglist.attr,
 531         NULL,
 532 };
 533 static struct attribute_group dcssblk_dev_attr_group = {
 534         .attrs = dcssblk_dev_attrs,
 535 };
 536 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 537         &dcssblk_dev_attr_group,
 538         NULL,
 539 };
 540
 541 /*
 542  * device attribute for adding devices
 543  */
 544 static ssize_t
 545 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 546 {
 547         int rc, i, j, num_of_segments;
 548         struct dcssblk_dev_info *dev_info;
 549         struct segment_info *seg_info, *temp;
 550         char *local_buf;
 551         unsigned long seg_byte_size;
 552
 553         dev_info = NULL;
 554         seg_info = NULL;
 555         if (dev != dcssblk_root_dev) {
 556                 rc = -EINVAL;
 557                 goto out_nobuf;
 558         }
 559         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 560                 rc = -ENAMETOOLONG;
 561                 goto out_nobuf;
 562         }
 563
 564         local_buf = kmalloc(count + 1, GFP_KERNEL);
 565         if (local_buf == NULL) {
 566                 rc = -ENOMEM;
 567                 goto out_nobuf;
 568         }
 569
 570         /*
 571          * parse input
 572          */
 573         num_of_segments = 0;
 574         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 575                 for (j = i; j < count &&
 576                         (buf[j] != ':') &&
 577                         (buf[j] != '\0') &&
 578                         (buf[j] != '\n'); j++) {
 579                         local_buf[j-i] = toupper(buf[j]);
 580                 }
 581                 local_buf[j-i] = '\0';
 582                 if (((j - i) == 0) || ((j - i) > 8)) {
 583                         rc = -ENAMETOOLONG;
 584                         goto seg_list_del;
 585                 }
 586
 587                 rc = dcssblk_load_segment(local_buf, &seg_info);
 588                 if (rc < 0)
 589                         goto seg_list_del;
 590                 /*
 591                  * get a struct dcssblk_dev_info
 592                  */
 593                 if (num_of_segments == 0) {
 594                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 595                                         GFP_KERNEL);
 596                         if (dev_info == NULL) {
 597                                 rc = -ENOMEM;
 598                                 goto out;
 599                         }
 600                         strcpy(dev_info->segment_name, local_buf);
 601                         dev_info->segment_type = seg_info->segment_type;
 602                         INIT_LIST_HEAD(&dev_info->seg_list);
 603                 }
 604                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 605                 num_of_segments++;
 606                 i = j;
 607
 608                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 609                         break;
 610         }
 611
 612         /* no trailing colon at the end of the input */
 613         if ((i > 0) && (buf[i-1] == ':')) {
 614                 rc = -ENAMETOOLONG;
 615                 goto seg_list_del;
 616         }
 617         strscpy(local_buf, buf, i + 1);
 618         dev_info->num_of_segments = num_of_segments;
 619         rc = dcssblk_is_continuous(dev_info);
 620         if (rc < 0)
 621                 goto seg_list_del;
 622
 623         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 624         dev_info->end = dcssblk_find_highest_addr(dev_info);
 625
 626         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 627         dev_info->dev.release = dcssblk_release_segment;
 628         dev_info->dev.groups = dcssblk_dev_attr_groups;
 629         INIT_LIST_HEAD(&dev_info->lh);
 630         dev_info->gd = blk_alloc_disk(NUMA_NO_NODE);
 631         if (dev_info->gd == NULL) {
 632                 rc = -ENOMEM;
 633                 goto seg_list_del;
 634         }
 635         dev_info->gd->major = dcssblk_major;
 636         dev_info->gd->minors = DCSSBLK_MINORS_PER_DISK;
 637         dev_info->gd->fops = &dcssblk_devops;
 638         dev_info->gd->private_data = dev_info;
 639         dev_info->gd->flags |= GENHD_FL_NO_PART;
 640         blk_queue_logical_block_size(dev_info->gd->queue, 4096);
 641         blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->gd->queue);
 642
 643         seg_byte_size = (dev_info->end - dev_info->start + 1);
 644         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 645         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 646                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 647
 648         dev_info->save_pending = 0;
 649         dev_info->is_shared = 1;
 650         dev_info->dev.parent = dcssblk_root_dev;
 651
 652         /*
 653          *get minor, add to list
 654          */
 655         down_write(&dcssblk_devices_sem);
 656         if (dcssblk_get_segment_by_name(local_buf)) {
 657                 rc = -EEXIST;
 658                 goto release_gd;
 659         }
 660         rc = dcssblk_assign_free_minor(dev_info);
 661         if (rc)
 662                 goto release_gd;
 663         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 664                 dev_info->gd->first_minor);
 665         list_add_tail(&dev_info->lh, &dcssblk_devices);
 666
 667         if (!try_module_get(THIS_MODULE)) {
 668                 rc = -ENODEV;
 669                 goto dev_list_del;
 670         }
 671         /*
 672          * register the device
 673          */
 674         rc = device_register(&dev_info->dev);
 675         if (rc)
 676                 goto put_dev;
 677
 678         dev_info->dax_dev = alloc_dax(dev_info, &dcssblk_dax_ops);
 679         if (IS_ERR(dev_info->dax_dev)) {
 680                 rc = PTR_ERR(dev_info->dax_dev);
 681                 dev_info->dax_dev = NULL;
 682                 goto put_dev;
 683         }
 684         set_dax_synchronous(dev_info->dax_dev);
 685         rc = dax_add_host(dev_info->dax_dev, dev_info->gd);
 686         if (rc)
 687                 goto out_dax;
 688
 689         get_device(&dev_info->dev);
 690         rc = device_add_disk(&dev_info->dev, dev_info->gd, NULL);
 691         if (rc)
 692                 goto out_dax_host;
 693
 694         switch (dev_info->segment_type) {
 695                 case SEG_TYPE_SR:
 696                 case SEG_TYPE_ER:
 697                 case SEG_TYPE_SC:
 698                         set_disk_ro(dev_info->gd,1);
 699                         break;
 700                 default:
 701                         set_disk_ro(dev_info->gd,0);
 702                         break;
 703         }
 704         up_write(&dcssblk_devices_sem);
 705         rc = count;
 706         goto out;
 707
 708 out_dax_host:
 709         dax_remove_host(dev_info->gd);
 710 out_dax:
 711         put_device(&dev_info->dev);
 712         kill_dax(dev_info->dax_dev);
 713         put_dax(dev_info->dax_dev);
 714 put_dev:
 715         list_del(&dev_info->lh);
 716         put_disk(dev_info->gd);
 717         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 718                 segment_unload(seg_info->segment_name);
 719         }
 720         put_device(&dev_info->dev);
 721         up_write(&dcssblk_devices_sem);
 722         goto out;
 723 dev_list_del:
 724         list_del(&dev_info->lh);
 725 release_gd:
 726         put_disk(dev_info->gd);
 727         up_write(&dcssblk_devices_sem);
 728 seg_list_del:
 729         if (dev_info == NULL)
 730                 goto out;
 731         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 732                 list_del(&seg_info->lh);
 733                 segment_unload(seg_info->segment_name);
 734                 kfree(seg_info);
 735         }
 736         kfree(dev_info);
 737 out:
 738         kfree(local_buf);
 739 out_nobuf:
 740         return rc;
 741 }
 742
 743 /*
 744  * device attribute for removing devices
 745  */
 746 static ssize_t
 747 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 748 {
 749         struct dcssblk_dev_info *dev_info;
 750         struct segment_info *entry;
 751         int rc, i;
 752         char *local_buf;
 753
 754         if (dev != dcssblk_root_dev) {
 755                 return -EINVAL;
 756         }
 757         local_buf = kmalloc(count + 1, GFP_KERNEL);
 758         if (local_buf == NULL) {
 759                 return -ENOMEM;
 760         }
 761         /*
 762          * parse input
 763          */
 764         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 765                 local_buf[i] = toupper(buf[i]);
 766         }
 767         local_buf[i] = '\0';
 768         if ((i == 0) || (i > 8)) {
 769                 rc = -ENAMETOOLONG;
 770                 goto out_buf;
 771         }
 772
 773         down_write(&dcssblk_devices_sem);
 774         dev_info = dcssblk_get_device_by_name(local_buf);
 775         if (dev_info == NULL) {
 776                 up_write(&dcssblk_devices_sem);
 777                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 778                         local_buf);
 779                 rc = -ENODEV;
 780                 goto out_buf;
 781         }
 782         if (atomic_read(&dev_info->use_count) != 0) {
 783                 up_write(&dcssblk_devices_sem);
 784                 pr_warn("Device %s cannot be removed while it is in use\n",
 785                         local_buf);
 786                 rc = -EBUSY;
 787                 goto out_buf;
 788         }
 789
 790         list_del(&dev_info->lh);
 791         kill_dax(dev_info->dax_dev);
 792         put_dax(dev_info->dax_dev);
 793         del_gendisk(dev_info->gd);
 794         put_disk(dev_info->gd);
 795
 796         /* unload all related segments */
 797         list_for_each_entry(entry, &dev_info->seg_list, lh)
 798                 segment_unload(entry->segment_name);
 799
 800         up_write(&dcssblk_devices_sem);
 801
 802         device_unregister(&dev_info->dev);
 803         put_device(&dev_info->dev);
 804
 805         rc = count;
 806 out_buf:
 807         kfree(local_buf);
 808         return rc;
 809 }
 810
 811 static int
 812 dcssblk_open(struct block_device *bdev, fmode_t mode)
 813 {
 814         struct dcssblk_dev_info *dev_info;
 815         int rc;
 816
 817         dev_info = bdev->bd_disk->private_data;
 818         if (NULL == dev_info) {
 819                 rc = -ENODEV;
 820                 goto out;
 821         }
 822         atomic_inc(&dev_info->use_count);
 823         rc = 0;
 824 out:
 825         return rc;
 826 }
 827
 828 static void
 829 dcssblk_release(struct gendisk *disk, fmode_t mode)
 830 {
 831         struct dcssblk_dev_info *dev_info = disk->private_data;
 832         struct segment_info *entry;
 833
 834         if (!dev_info) {
 835                 WARN_ON(1);
 836                 return;
 837         }
 838         down_write(&dcssblk_devices_sem);
 839         if (atomic_dec_and_test(&dev_info->use_count)
 840             && (dev_info->save_pending)) {
 841                 pr_info("Device %s has become idle and is being saved "
 842                         "now\n", dev_info->segment_name);
 843                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 844                         if (entry->segment_type == SEG_TYPE_EN ||
 845                             entry->segment_type == SEG_TYPE_SN)
 846                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 847                                         " be saved\n", entry->segment_name);
 848                         else
 849                                 segment_save(entry->segment_name);
 850                 }
 851                 dev_info->save_pending = 0;
 852         }
 853         up_write(&dcssblk_devices_sem);
 854 }
 855
 856 static void
 857 dcssblk_submit_bio(struct bio *bio)
 858 {
 859         struct dcssblk_dev_info *dev_info;
 860         struct bio_vec bvec;
 861         struct bvec_iter iter;
 862         unsigned long index;
 863         unsigned long page_addr;
 864         unsigned long source_addr;
 865         unsigned long bytes_done;
 866
 867         bytes_done = 0;
 868         dev_info = bio->bi_bdev->bd_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         /* verify data transfer direction */
 876         if (dev_info->is_shared) {
 877                 switch (dev_info->segment_type) {
 878                 case SEG_TYPE_SR:
 879                 case SEG_TYPE_ER:
 880                 case SEG_TYPE_SC:
 881                         /* cannot write to these segments */
 882                         if (bio_data_dir(bio) == WRITE) {
 883                                 pr_warn("Writing to %s failed because it is a read-only device\n",
 884                                         dev_name(&dev_info->dev));
 885                                 goto fail;
 886                         }
 887                 }
 888         }
 889
 890         index = (bio->bi_iter.bi_sector >> 3);
 891         bio_for_each_segment(bvec, bio, iter) {
 892                 page_addr = (unsigned long)bvec_virt(&bvec);
 893                 source_addr = dev_info->start + (index<<12) + bytes_done;
 894                 if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 895                         // More paranoia.
 896                         goto fail;
 897                 if (bio_data_dir(bio) == READ) {
 898                         memcpy((void*)page_addr, (void*)source_addr,
 899                                 bvec.bv_len);
 900                 } else {
 901                         memcpy((void*)source_addr, (void*)page_addr,
 902                                 bvec.bv_len);
 903                 }
 904                 bytes_done += bvec.bv_len;
 905         }
 906         bio_endio(bio);
 907         return;
 908 fail:
 909         bio_io_error(bio);
 910 }
 911
 912 static long
 913 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 914                 long nr_pages, void **kaddr, pfn_t *pfn)
 915 {
 916         resource_size_t offset = pgoff * PAGE_SIZE;
 917         unsigned long dev_sz;
 918
 919         dev_sz = dev_info->end - dev_info->start + 1;
 920         if (kaddr)
 921                 *kaddr = (void *) dev_info->start + offset;
 922         if (pfn)
 923                 *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
 924                                 PFN_DEV|PFN_SPECIAL);
 925
 926         return (dev_sz - offset) / PAGE_SIZE;
 927 }
 928
 929 static long
 930 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 931                 long nr_pages, enum dax_access_mode mode, void **kaddr,
 932                 pfn_t *pfn)
 933 {
 934         struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 935
 936         return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 937 }
 938
 939 static void
 940 dcssblk_check_params(void)
 941 {
 942         int rc, i, j, k;
 943         char buf[DCSSBLK_PARM_LEN + 1];
 944         struct dcssblk_dev_info *dev_info;
 945
 946         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 947              i++) {
 948                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 949                             (dcssblk_segments[j] != ',')  &&
 950                             (dcssblk_segments[j] != '\0') &&
 951                             (dcssblk_segments[j] != '('); j++)
 952                 {
 953                         buf[j-i] = dcssblk_segments[j];
 954                 }
 955                 buf[j-i] = '\0';
 956                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 957                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 958                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 959                                 buf[k] = toupper(buf[k]);
 960                         buf[k] = '\0';
 961                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 962                                 down_read(&dcssblk_devices_sem);
 963                                 dev_info = dcssblk_get_device_by_name(buf);
 964                                 up_read(&dcssblk_devices_sem);
 965                                 if (dev_info)
 966                                         dcssblk_shared_store(&dev_info->dev,
 967                                                              NULL, "0\n", 2);
 968                         }
 969                 }
 970                 while ((dcssblk_segments[j] != ',') &&
 971                        (dcssblk_segments[j] != '\0'))
 972                 {
 973                         j++;
 974                 }
 975                 if (dcssblk_segments[j] == '\0')
 976                         break;
 977                 i = j;
 978         }
 979 }
 980
 981 /*
 982  * The init/exit functions.
 983  */
 984 static void __exit
 985 dcssblk_exit(void)
 986 {
 987         root_device_unregister(dcssblk_root_dev);
 988         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 989 }
 990
 991 static int __init
 992 dcssblk_init(void)
 993 {
 994         int rc;
 995
 996         dcssblk_root_dev = root_device_register("dcssblk");
 997         if (IS_ERR(dcssblk_root_dev))
 998                 return PTR_ERR(dcssblk_root_dev);
 999         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1000         if (rc)
1001                 goto out_root;
1002         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1003         if (rc)
1004                 goto out_root;
1005         rc = register_blkdev(0, DCSSBLK_NAME);
1006         if (rc < 0)
1007                 goto out_root;
1008         dcssblk_major = rc;
1009         init_rwsem(&dcssblk_devices_sem);
1010
1011         dcssblk_check_params();
1012         return 0;
1013
1014 out_root:
1015         root_device_unregister(dcssblk_root_dev);
1016
1017         return rc;
1018 }
1019
1020 module_init(dcssblk_init);
1021 module_exit(dcssblk_exit);
1022
1023 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1024 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1025                  "comma-separated list, names in each set separated "
1026                  "by commas are separated by colons, each set contains "
1027                  "names of contiguous segments and each name max. 8 chars.\n"
1028                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1029                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1030                  "the contiguous segments - \n"
1031                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1032
1033 MODULE_LICENSE("GPL");