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 <linux/io.h>
  24 #include <asm/extmem.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 gendisk *disk, blk_mode_t mode);
  32 static void dcssblk_release(struct gendisk *disk);
  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 dax_mem2blk_err(rc);
  58
  59         memset(kaddr, 0, nr_pages << PAGE_SHIFT);
  60         dax_flush(dax_dev, kaddr, nr_pages << PAGE_SHIFT);
  61         return 0;
  62 }
  63
  64 static const struct dax_operations dcssblk_dax_ops = {
  65         .direct_access = dcssblk_dax_direct_access,
  66         .zero_page_range = dcssblk_dax_zero_page_range,
  67 };
  68
  69 struct dcssblk_dev_info {
  70         struct list_head lh;
  71         struct device dev;
  72         char segment_name[DCSS_BUS_ID_SIZE];
  73         atomic_t use_count;
  74         struct gendisk *gd;
  75         unsigned long start;
  76         unsigned long end;
  77         int segment_type;
  78         unsigned char save_pending;
  79         unsigned char is_shared;
  80         int num_of_segments;
  81         struct list_head seg_list;
  82         struct dax_device *dax_dev;
  83 };
  84
  85 struct segment_info {
  86         struct list_head lh;
  87         char segment_name[DCSS_BUS_ID_SIZE];
  88         unsigned long start;
  89         unsigned long end;
  90         int segment_type;
  91 };
  92
  93 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  94                                   size_t count);
  95 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  96                                   size_t count);
  97
  98 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  99 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
 100
 101 static struct device *dcssblk_root_dev;
 102
 103 static LIST_HEAD(dcssblk_devices);
 104 static struct rw_semaphore dcssblk_devices_sem;
 105
 106 /*
 107  * release function for segment device.
 108  */
 109 static void
 110 dcssblk_release_segment(struct device *dev)
 111 {
 112         struct dcssblk_dev_info *dev_info;
 113         struct segment_info *entry, *temp;
 114
 115         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 116         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 117                 list_del(&entry->lh);
 118                 kfree(entry);
 119         }
 120         kfree(dev_info);
 121         module_put(THIS_MODULE);
 122 }
 123
 124 /*
 125  * get a minor number. needs to be called with
 126  * down_write(&dcssblk_devices_sem) and the
 127  * device needs to be enqueued before the semaphore is
 128  * freed.
 129  */
 130 static int
 131 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 132 {
 133         int minor, found;
 134         struct dcssblk_dev_info *entry;
 135
 136         if (dev_info == NULL)
 137                 return -EINVAL;
 138         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 139                 found = 0;
 140                 // test if minor available
 141                 list_for_each_entry(entry, &dcssblk_devices, lh)
 142                         if (minor == entry->gd->first_minor)
 143                                 found++;
 144                 if (!found) break; // got unused minor
 145         }
 146         if (found)
 147                 return -EBUSY;
 148         dev_info->gd->first_minor = minor;
 149         return 0;
 150 }
 151
 152 /*
 153  * get the struct dcssblk_dev_info from dcssblk_devices
 154  * for the given name.
 155  * down_read(&dcssblk_devices_sem) must be held.
 156  */
 157 static struct dcssblk_dev_info *
 158 dcssblk_get_device_by_name(char *name)
 159 {
 160         struct dcssblk_dev_info *entry;
 161
 162         list_for_each_entry(entry, &dcssblk_devices, lh) {
 163                 if (!strcmp(name, entry->segment_name)) {
 164                         return entry;
 165                 }
 166         }
 167         return NULL;
 168 }
 169
 170 /*
 171  * get the struct segment_info from seg_list
 172  * for the given name.
 173  * down_read(&dcssblk_devices_sem) must be held.
 174  */
 175 static struct segment_info *
 176 dcssblk_get_segment_by_name(char *name)
 177 {
 178         struct dcssblk_dev_info *dev_info;
 179         struct segment_info *entry;
 180
 181         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 182                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 183                         if (!strcmp(name, entry->segment_name))
 184                                 return entry;
 185                 }
 186         }
 187         return NULL;
 188 }
 189
 190 /*
 191  * get the highest address of the multi-segment block.
 192  */
 193 static unsigned long
 194 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 195 {
 196         unsigned long highest_addr;
 197         struct segment_info *entry;
 198
 199         highest_addr = 0;
 200         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 201                 if (highest_addr < entry->end)
 202                         highest_addr = entry->end;
 203         }
 204         return highest_addr;
 205 }
 206
 207 /*
 208  * get the lowest address of the multi-segment block.
 209  */
 210 static unsigned long
 211 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 212 {
 213         int set_first;
 214         unsigned long lowest_addr;
 215         struct segment_info *entry;
 216
 217         set_first = 0;
 218         lowest_addr = 0;
 219         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 220                 if (set_first == 0) {
 221                         lowest_addr = entry->start;
 222                         set_first = 1;
 223                 } else {
 224                         if (lowest_addr > entry->start)
 225                                 lowest_addr = entry->start;
 226                 }
 227         }
 228         return lowest_addr;
 229 }
 230
 231 /*
 232  * Check continuity of segments.
 233  */
 234 static int
 235 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 236 {
 237         int i, j, rc;
 238         struct segment_info *sort_list, *entry, temp;
 239
 240         if (dev_info->num_of_segments <= 1)
 241                 return 0;
 242
 243         sort_list = kcalloc(dev_info->num_of_segments,
 244                             sizeof(struct segment_info),
 245                             GFP_KERNEL);
 246         if (sort_list == NULL)
 247                 return -ENOMEM;
 248         i = 0;
 249         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 250                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 251                 i++;
 252         }
 253
 254         /* sort segments */
 255         for (i = 0; i < dev_info->num_of_segments; i++)
 256                 for (j = 0; j < dev_info->num_of_segments; j++)
 257                         if (sort_list[j].start > sort_list[i].start) {
 258                                 memcpy(&temp, &sort_list[i],
 259                                         sizeof(struct segment_info));
 260                                 memcpy(&sort_list[i], &sort_list[j],
 261                                         sizeof(struct segment_info));
 262                                 memcpy(&sort_list[j], &temp,
 263                                         sizeof(struct segment_info));
 264                         }
 265
 266         /* check continuity */
 267         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 268                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 269                         pr_err("Adjacent DCSSs %s and %s are not "
 270                                "contiguous\n", sort_list[i].segment_name,
 271                                sort_list[i+1].segment_name);
 272                         rc = -EINVAL;
 273                         goto out;
 274                 }
 275                 /* EN and EW are allowed in a block device */
 276                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 277                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 278                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 279                                 !(sort_list[i+1].segment_type &
 280                                 SEGMENT_EXCLUSIVE) ||
 281                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 282                                 pr_err("DCSS %s and DCSS %s have "
 283                                        "incompatible types\n",
 284                                        sort_list[i].segment_name,
 285                                        sort_list[i+1].segment_name);
 286                                 rc = -EINVAL;
 287                                 goto out;
 288                         }
 289                 }
 290         }
 291         rc = 0;
 292 out:
 293         kfree(sort_list);
 294         return rc;
 295 }
 296
 297 /*
 298  * Load a segment
 299  */
 300 static int
 301 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 302 {
 303         int rc;
 304
 305         /* already loaded? */
 306         down_read(&dcssblk_devices_sem);
 307         *seg_info = dcssblk_get_segment_by_name(name);
 308         up_read(&dcssblk_devices_sem);
 309         if (*seg_info != NULL)
 310                 return -EEXIST;
 311
 312         /* get a struct segment_info */
 313         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 314         if (*seg_info == NULL)
 315                 return -ENOMEM;
 316
 317         strcpy((*seg_info)->segment_name, name);
 318
 319         /* load the segment */
 320         rc = segment_load(name, SEGMENT_SHARED,
 321                         &(*seg_info)->start, &(*seg_info)->end);
 322         if (rc < 0) {
 323                 segment_warning(rc, (*seg_info)->segment_name);
 324                 kfree(*seg_info);
 325         } else {
 326                 INIT_LIST_HEAD(&(*seg_info)->lh);
 327                 (*seg_info)->segment_type = rc;
 328         }
 329         return rc;
 330 }
 331
 332 /*
 333  * device attribute for switching shared/nonshared (exclusive)
 334  * operation (show + store)
 335  */
 336 static ssize_t
 337 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 338 {
 339         struct dcssblk_dev_info *dev_info;
 340
 341         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 342         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 343 }
 344
 345 static ssize_t
 346 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 347 {
 348         struct dcssblk_dev_info *dev_info;
 349         struct segment_info *entry, *temp;
 350         int rc;
 351
 352         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 353                 return -EINVAL;
 354         down_write(&dcssblk_devices_sem);
 355         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 356         if (atomic_read(&dev_info->use_count)) {
 357                 rc = -EBUSY;
 358                 goto out;
 359         }
 360         if (inbuf[0] == '1') {
 361                 /* reload segments in shared mode */
 362                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 363                         rc = segment_modify_shared(entry->segment_name,
 364                                                 SEGMENT_SHARED);
 365                         if (rc < 0) {
 366                                 BUG_ON(rc == -EINVAL);
 367                                 if (rc != -EAGAIN)
 368                                         goto removeseg;
 369                         }
 370                 }
 371                 dev_info->is_shared = 1;
 372                 switch (dev_info->segment_type) {
 373                 case SEG_TYPE_SR:
 374                 case SEG_TYPE_ER:
 375                 case SEG_TYPE_SC:
 376                         set_disk_ro(dev_info->gd, 1);
 377                 }
 378         } else if (inbuf[0] == '0') {
 379                 /* reload segments in exclusive mode */
 380                 if (dev_info->segment_type == SEG_TYPE_SC) {
 381                         pr_err("DCSS %s is of type SC and cannot be "
 382                                "loaded as exclusive-writable\n",
 383                                dev_info->segment_name);
 384                         rc = -EINVAL;
 385                         goto out;
 386                 }
 387                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 388                         rc = segment_modify_shared(entry->segment_name,
 389                                                    SEGMENT_EXCLUSIVE);
 390                         if (rc < 0) {
 391                                 BUG_ON(rc == -EINVAL);
 392                                 if (rc != -EAGAIN)
 393                                         goto removeseg;
 394                         }
 395                 }
 396                 dev_info->is_shared = 0;
 397                 set_disk_ro(dev_info->gd, 0);
 398         } else {
 399                 rc = -EINVAL;
 400                 goto out;
 401         }
 402         rc = count;
 403         goto out;
 404
 405 removeseg:
 406         pr_err("DCSS device %s is removed after a failed access mode "
 407                "change\n", dev_info->segment_name);
 408         temp = entry;
 409         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 410                 if (entry != temp)
 411                         segment_unload(entry->segment_name);
 412         }
 413         list_del(&dev_info->lh);
 414         up_write(&dcssblk_devices_sem);
 415
 416         dax_remove_host(dev_info->gd);
 417         kill_dax(dev_info->dax_dev);
 418         put_dax(dev_info->dax_dev);
 419         del_gendisk(dev_info->gd);
 420         put_disk(dev_info->gd);
 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         struct queue_limits lim = {
 550                 .logical_block_size     = 4096,
 551         };
 552         int rc, i, j, num_of_segments;
 553         struct dcssblk_dev_info *dev_info;
 554         struct segment_info *seg_info, *temp;
 555         struct dax_device *dax_dev;
 556         char *local_buf;
 557         unsigned long seg_byte_size;
 558
 559         dev_info = NULL;
 560         seg_info = NULL;
 561         if (dev != dcssblk_root_dev) {
 562                 rc = -EINVAL;
 563                 goto out_nobuf;
 564         }
 565         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 566                 rc = -ENAMETOOLONG;
 567                 goto out_nobuf;
 568         }
 569
 570         local_buf = kmalloc(count + 1, GFP_KERNEL);
 571         if (local_buf == NULL) {
 572                 rc = -ENOMEM;
 573                 goto out_nobuf;
 574         }
 575
 576         /*
 577          * parse input
 578          */
 579         num_of_segments = 0;
 580         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 581                 for (j = i; j < count &&
 582                         (buf[j] != ':') &&
 583                         (buf[j] != '\0') &&
 584                         (buf[j] != '\n'); j++) {
 585                         local_buf[j-i] = toupper(buf[j]);
 586                 }
 587                 local_buf[j-i] = '\0';
 588                 if (((j - i) == 0) || ((j - i) > 8)) {
 589                         rc = -ENAMETOOLONG;
 590                         goto seg_list_del;
 591                 }
 592
 593                 rc = dcssblk_load_segment(local_buf, &seg_info);
 594                 if (rc < 0)
 595                         goto seg_list_del;
 596                 /*
 597                  * get a struct dcssblk_dev_info
 598                  */
 599                 if (num_of_segments == 0) {
 600                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 601                                         GFP_KERNEL);
 602                         if (dev_info == NULL) {
 603                                 rc = -ENOMEM;
 604                                 goto out;
 605                         }
 606                         strcpy(dev_info->segment_name, local_buf);
 607                         dev_info->segment_type = seg_info->segment_type;
 608                         INIT_LIST_HEAD(&dev_info->seg_list);
 609                 }
 610                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 611                 num_of_segments++;
 612                 i = j;
 613
 614                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 615                         break;
 616         }
 617
 618         /* no trailing colon at the end of the input */
 619         if ((i > 0) && (buf[i-1] == ':')) {
 620                 rc = -ENAMETOOLONG;
 621                 goto seg_list_del;
 622         }
 623         strscpy(local_buf, buf, i + 1);
 624         dev_info->num_of_segments = num_of_segments;
 625         rc = dcssblk_is_continuous(dev_info);
 626         if (rc < 0)
 627                 goto seg_list_del;
 628
 629         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 630         dev_info->end = dcssblk_find_highest_addr(dev_info);
 631
 632         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 633         dev_info->dev.release = dcssblk_release_segment;
 634         dev_info->dev.groups = dcssblk_dev_attr_groups;
 635         INIT_LIST_HEAD(&dev_info->lh);
 636         dev_info->gd = blk_alloc_disk(&lim, NUMA_NO_NODE);
 637         if (IS_ERR(dev_info->gd)) {
 638                 rc = PTR_ERR(dev_info->gd);
 639                 goto seg_list_del;
 640         }
 641         dev_info->gd->major = dcssblk_major;
 642         dev_info->gd->minors = DCSSBLK_MINORS_PER_DISK;
 643         dev_info->gd->fops = &dcssblk_devops;
 644         dev_info->gd->private_data = dev_info;
 645         dev_info->gd->flags |= GENHD_FL_NO_PART;
 646         blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->gd->queue);
 647
 648         seg_byte_size = (dev_info->end - dev_info->start + 1);
 649         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 650         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 651                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 652
 653         dev_info->save_pending = 0;
 654         dev_info->is_shared = 1;
 655         dev_info->dev.parent = dcssblk_root_dev;
 656
 657         /*
 658          *get minor, add to list
 659          */
 660         down_write(&dcssblk_devices_sem);
 661         if (dcssblk_get_segment_by_name(local_buf)) {
 662                 rc = -EEXIST;
 663                 goto release_gd;
 664         }
 665         rc = dcssblk_assign_free_minor(dev_info);
 666         if (rc)
 667                 goto release_gd;
 668         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 669                 dev_info->gd->first_minor);
 670         list_add_tail(&dev_info->lh, &dcssblk_devices);
 671
 672         if (!try_module_get(THIS_MODULE)) {
 673                 rc = -ENODEV;
 674                 goto dev_list_del;
 675         }
 676         /*
 677          * register the device
 678          */
 679         rc = device_register(&dev_info->dev);
 680         if (rc)
 681                 goto put_dev;
 682
 683         dax_dev = alloc_dax(dev_info, &dcssblk_dax_ops);
 684         if (IS_ERR(dax_dev)) {
 685                 rc = PTR_ERR(dax_dev);
 686                 goto put_dev;
 687         }
 688         set_dax_synchronous(dax_dev);
 689         dev_info->dax_dev = dax_dev;
 690         rc = dax_add_host(dev_info->dax_dev, dev_info->gd);
 691         if (rc)
 692                 goto out_dax;
 693
 694         get_device(&dev_info->dev);
 695         rc = device_add_disk(&dev_info->dev, dev_info->gd, NULL);
 696         if (rc)
 697                 goto out_dax_host;
 698
 699         switch (dev_info->segment_type) {
 700                 case SEG_TYPE_SR:
 701                 case SEG_TYPE_ER:
 702                 case SEG_TYPE_SC:
 703                         set_disk_ro(dev_info->gd,1);
 704                         break;
 705                 default:
 706                         set_disk_ro(dev_info->gd,0);
 707                         break;
 708         }
 709         up_write(&dcssblk_devices_sem);
 710         rc = count;
 711         goto out;
 712
 713 out_dax_host:
 714         put_device(&dev_info->dev);
 715         dax_remove_host(dev_info->gd);
 716 out_dax:
 717         kill_dax(dev_info->dax_dev);
 718         put_dax(dev_info->dax_dev);
 719 put_dev:
 720         list_del(&dev_info->lh);
 721         put_disk(dev_info->gd);
 722         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 723                 segment_unload(seg_info->segment_name);
 724         }
 725         put_device(&dev_info->dev);
 726         up_write(&dcssblk_devices_sem);
 727         goto out;
 728 dev_list_del:
 729         list_del(&dev_info->lh);
 730 release_gd:
 731         put_disk(dev_info->gd);
 732         up_write(&dcssblk_devices_sem);
 733 seg_list_del:
 734         if (dev_info == NULL)
 735                 goto out;
 736         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 737                 list_del(&seg_info->lh);
 738                 segment_unload(seg_info->segment_name);
 739                 kfree(seg_info);
 740         }
 741         kfree(dev_info);
 742 out:
 743         kfree(local_buf);
 744 out_nobuf:
 745         return rc;
 746 }
 747
 748 /*
 749  * device attribute for removing devices
 750  */
 751 static ssize_t
 752 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 753 {
 754         struct dcssblk_dev_info *dev_info;
 755         struct segment_info *entry;
 756         int rc, i;
 757         char *local_buf;
 758
 759         if (dev != dcssblk_root_dev) {
 760                 return -EINVAL;
 761         }
 762         local_buf = kmalloc(count + 1, GFP_KERNEL);
 763         if (local_buf == NULL) {
 764                 return -ENOMEM;
 765         }
 766         /*
 767          * parse input
 768          */
 769         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 770                 local_buf[i] = toupper(buf[i]);
 771         }
 772         local_buf[i] = '\0';
 773         if ((i == 0) || (i > 8)) {
 774                 rc = -ENAMETOOLONG;
 775                 goto out_buf;
 776         }
 777
 778         down_write(&dcssblk_devices_sem);
 779         dev_info = dcssblk_get_device_by_name(local_buf);
 780         if (dev_info == NULL) {
 781                 up_write(&dcssblk_devices_sem);
 782                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 783                         local_buf);
 784                 rc = -ENODEV;
 785                 goto out_buf;
 786         }
 787         if (atomic_read(&dev_info->use_count) != 0) {
 788                 up_write(&dcssblk_devices_sem);
 789                 pr_warn("Device %s cannot be removed while it is in use\n",
 790                         local_buf);
 791                 rc = -EBUSY;
 792                 goto out_buf;
 793         }
 794
 795         list_del(&dev_info->lh);
 796         /* unload all related segments */
 797         list_for_each_entry(entry, &dev_info->seg_list, lh)
 798                 segment_unload(entry->segment_name);
 799         up_write(&dcssblk_devices_sem);
 800
 801         dax_remove_host(dev_info->gd);
 802         kill_dax(dev_info->dax_dev);
 803         put_dax(dev_info->dax_dev);
 804         del_gendisk(dev_info->gd);
 805         put_disk(dev_info->gd);
 806
 807         device_unregister(&dev_info->dev);
 808         put_device(&dev_info->dev);
 809
 810         rc = count;
 811 out_buf:
 812         kfree(local_buf);
 813         return rc;
 814 }
 815
 816 static int
 817 dcssblk_open(struct gendisk *disk, blk_mode_t mode)
 818 {
 819         struct dcssblk_dev_info *dev_info = disk->private_data;
 820         int rc;
 821
 822         if (NULL == dev_info) {
 823                 rc = -ENODEV;
 824                 goto out;
 825         }
 826         atomic_inc(&dev_info->use_count);
 827         rc = 0;
 828 out:
 829         return rc;
 830 }
 831
 832 static void
 833 dcssblk_release(struct gendisk *disk)
 834 {
 835         struct dcssblk_dev_info *dev_info = disk->private_data;
 836         struct segment_info *entry;
 837
 838         if (!dev_info) {
 839                 WARN_ON(1);
 840                 return;
 841         }
 842         down_write(&dcssblk_devices_sem);
 843         if (atomic_dec_and_test(&dev_info->use_count)
 844             && (dev_info->save_pending)) {
 845                 pr_info("Device %s has become idle and is being saved "
 846                         "now\n", dev_info->segment_name);
 847                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 848                         if (entry->segment_type == SEG_TYPE_EN ||
 849                             entry->segment_type == SEG_TYPE_SN)
 850                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 851                                         " be saved\n", entry->segment_name);
 852                         else
 853                                 segment_save(entry->segment_name);
 854                 }
 855                 dev_info->save_pending = 0;
 856         }
 857         up_write(&dcssblk_devices_sem);
 858 }
 859
 860 static void
 861 dcssblk_submit_bio(struct bio *bio)
 862 {
 863         struct dcssblk_dev_info *dev_info;
 864         struct bio_vec bvec;
 865         struct bvec_iter iter;
 866         unsigned long index;
 867         void *page_addr;
 868         unsigned long source_addr;
 869         unsigned long bytes_done;
 870
 871         bytes_done = 0;
 872         dev_info = bio->bi_bdev->bd_disk->private_data;
 873         if (dev_info == NULL)
 874                 goto fail;
 875         if (!IS_ALIGNED(bio->bi_iter.bi_sector, 8) ||
 876             !IS_ALIGNED(bio->bi_iter.bi_size, PAGE_SIZE))
 877                 /* Request is not page-aligned. */
 878                 goto fail;
 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 = bvec_virt(&bvec);
 897                 source_addr = dev_info->start + (index<<12) + bytes_done;
 898                 if (unlikely(!IS_ALIGNED((unsigned long)page_addr, PAGE_SIZE) ||
 899                              !IS_ALIGNED(bvec.bv_len, PAGE_SIZE)))
 900                         // More paranoia.
 901                         goto fail;
 902                 if (bio_data_dir(bio) == READ)
 903                         memcpy(page_addr, __va(source_addr), bvec.bv_len);
 904                 else
 905                         memcpy(__va(source_addr), page_addr, bvec.bv_len);
 906                 bytes_done += bvec.bv_len;
 907         }
 908         bio_endio(bio);
 909         return;
 910 fail:
 911         bio_io_error(bio);
 912 }
 913
 914 static long
 915 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 916                 long nr_pages, void **kaddr, pfn_t *pfn)
 917 {
 918         resource_size_t offset = pgoff * PAGE_SIZE;
 919         unsigned long dev_sz;
 920
 921         dev_sz = dev_info->end - dev_info->start + 1;
 922         if (kaddr)
 923                 *kaddr = (void *) dev_info->start + offset;
 924         if (pfn)
 925                 *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
 926                                 PFN_DEV|PFN_SPECIAL);
 927
 928         return (dev_sz - offset) / PAGE_SIZE;
 929 }
 930
 931 static long
 932 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 933                 long nr_pages, enum dax_access_mode mode, void **kaddr,
 934                 pfn_t *pfn)
 935 {
 936         struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 937
 938         return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 939 }
 940
 941 static void
 942 dcssblk_check_params(void)
 943 {
 944         int rc, i, j, k;
 945         char buf[DCSSBLK_PARM_LEN + 1];
 946         struct dcssblk_dev_info *dev_info;
 947
 948         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 949              i++) {
 950                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 951                             (dcssblk_segments[j] != ',')  &&
 952                             (dcssblk_segments[j] != '\0') &&
 953                             (dcssblk_segments[j] != '('); j++)
 954                 {
 955                         buf[j-i] = dcssblk_segments[j];
 956                 }
 957                 buf[j-i] = '\0';
 958                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 959                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 960                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 961                                 buf[k] = toupper(buf[k]);
 962                         buf[k] = '\0';
 963                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 964                                 down_read(&dcssblk_devices_sem);
 965                                 dev_info = dcssblk_get_device_by_name(buf);
 966                                 up_read(&dcssblk_devices_sem);
 967                                 if (dev_info)
 968                                         dcssblk_shared_store(&dev_info->dev,
 969                                                              NULL, "0\n", 2);
 970                         }
 971                 }
 972                 while ((dcssblk_segments[j] != ',') &&
 973                        (dcssblk_segments[j] != '\0'))
 974                 {
 975                         j++;
 976                 }
 977                 if (dcssblk_segments[j] == '\0')
 978                         break;
 979                 i = j;
 980         }
 981 }
 982
 983 /*
 984  * The init/exit functions.
 985  */
 986 static void __exit
 987 dcssblk_exit(void)
 988 {
 989         root_device_unregister(dcssblk_root_dev);
 990         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 991 }
 992
 993 static int __init
 994 dcssblk_init(void)
 995 {
 996         int rc;
 997
 998         dcssblk_root_dev = root_device_register("dcssblk");
 999         if (IS_ERR(dcssblk_root_dev))
1000                 return PTR_ERR(dcssblk_root_dev);
1001         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1002         if (rc)
1003                 goto out_root;
1004         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1005         if (rc)
1006                 goto out_root;
1007         rc = register_blkdev(0, DCSSBLK_NAME);
1008         if (rc < 0)
1009                 goto out_root;
1010         dcssblk_major = rc;
1011         init_rwsem(&dcssblk_devices_sem);
1012
1013         dcssblk_check_params();
1014         return 0;
1015
1016 out_root:
1017         root_device_unregister(dcssblk_root_dev);
1018
1019         return rc;
1020 }
1021
1022 module_init(dcssblk_init);
1023 module_exit(dcssblk_exit);
1024
1025 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1026 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1027                  "comma-separated list, names in each set separated "
1028                  "by commas are separated by colons, each set contains "
1029                  "names of contiguous segments and each name max. 8 chars.\n"
1030                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1031                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1032                  "the contiguous segments - \n"
1033                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1034
1035 MODULE_LICENSE("GPL");