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         char *local_buf;
 556         unsigned long seg_byte_size;
 557
 558         dev_info = NULL;
 559         seg_info = NULL;
 560         if (dev != dcssblk_root_dev) {
 561                 rc = -EINVAL;
 562                 goto out_nobuf;
 563         }
 564         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 565                 rc = -ENAMETOOLONG;
 566                 goto out_nobuf;
 567         }
 568
 569         local_buf = kmalloc(count + 1, GFP_KERNEL);
 570         if (local_buf == NULL) {
 571                 rc = -ENOMEM;
 572                 goto out_nobuf;
 573         }
 574
 575         /*
 576          * parse input
 577          */
 578         num_of_segments = 0;
 579         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 580                 for (j = i; j < count &&
 581                         (buf[j] != ':') &&
 582                         (buf[j] != '\0') &&
 583                         (buf[j] != '\n'); j++) {
 584                         local_buf[j-i] = toupper(buf[j]);
 585                 }
 586                 local_buf[j-i] = '\0';
 587                 if (((j - i) == 0) || ((j - i) > 8)) {
 588                         rc = -ENAMETOOLONG;
 589                         goto seg_list_del;
 590                 }
 591
 592                 rc = dcssblk_load_segment(local_buf, &seg_info);
 593                 if (rc < 0)
 594                         goto seg_list_del;
 595                 /*
 596                  * get a struct dcssblk_dev_info
 597                  */
 598                 if (num_of_segments == 0) {
 599                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 600                                         GFP_KERNEL);
 601                         if (dev_info == NULL) {
 602                                 rc = -ENOMEM;
 603                                 goto out;
 604                         }
 605                         strcpy(dev_info->segment_name, local_buf);
 606                         dev_info->segment_type = seg_info->segment_type;
 607                         INIT_LIST_HEAD(&dev_info->seg_list);
 608                 }
 609                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 610                 num_of_segments++;
 611                 i = j;
 612
 613                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 614                         break;
 615         }
 616
 617         /* no trailing colon at the end of the input */
 618         if ((i > 0) && (buf[i-1] == ':')) {
 619                 rc = -ENAMETOOLONG;
 620                 goto seg_list_del;
 621         }
 622         strscpy(local_buf, buf, i + 1);
 623         dev_info->num_of_segments = num_of_segments;
 624         rc = dcssblk_is_continuous(dev_info);
 625         if (rc < 0)
 626                 goto seg_list_del;
 627
 628         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 629         dev_info->end = dcssblk_find_highest_addr(dev_info);
 630
 631         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 632         dev_info->dev.release = dcssblk_release_segment;
 633         dev_info->dev.groups = dcssblk_dev_attr_groups;
 634         INIT_LIST_HEAD(&dev_info->lh);
 635         dev_info->gd = blk_alloc_disk(&lim, NUMA_NO_NODE);
 636         if (IS_ERR(dev_info->gd)) {
 637                 rc = PTR_ERR(dev_info->gd);
 638                 goto seg_list_del;
 639         }
 640         dev_info->gd->major = dcssblk_major;
 641         dev_info->gd->minors = DCSSBLK_MINORS_PER_DISK;
 642         dev_info->gd->fops = &dcssblk_devops;
 643         dev_info->gd->private_data = dev_info;
 644         dev_info->gd->flags |= GENHD_FL_NO_PART;
 645         blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->gd->queue);
 646
 647         seg_byte_size = (dev_info->end - dev_info->start + 1);
 648         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 649         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 650                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 651
 652         dev_info->save_pending = 0;
 653         dev_info->is_shared = 1;
 654         dev_info->dev.parent = dcssblk_root_dev;
 655
 656         /*
 657          *get minor, add to list
 658          */
 659         down_write(&dcssblk_devices_sem);
 660         if (dcssblk_get_segment_by_name(local_buf)) {
 661                 rc = -EEXIST;
 662                 goto release_gd;
 663         }
 664         rc = dcssblk_assign_free_minor(dev_info);
 665         if (rc)
 666                 goto release_gd;
 667         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 668                 dev_info->gd->first_minor);
 669         list_add_tail(&dev_info->lh, &dcssblk_devices);
 670
 671         if (!try_module_get(THIS_MODULE)) {
 672                 rc = -ENODEV;
 673                 goto dev_list_del;
 674         }
 675         /*
 676          * register the device
 677          */
 678         rc = device_register(&dev_info->dev);
 679         if (rc)
 680                 goto put_dev;
 681
 682         dev_info->dax_dev = alloc_dax(dev_info, &dcssblk_dax_ops);
 683         if (IS_ERR(dev_info->dax_dev)) {
 684                 rc = PTR_ERR(dev_info->dax_dev);
 685                 dev_info->dax_dev = NULL;
 686                 goto put_dev;
 687         }
 688         set_dax_synchronous(dev_info->dax_dev);
 689         rc = dax_add_host(dev_info->dax_dev, dev_info->gd);
 690         if (rc)
 691                 goto out_dax;
 692
 693         get_device(&dev_info->dev);
 694         rc = device_add_disk(&dev_info->dev, dev_info->gd, NULL);
 695         if (rc)
 696                 goto out_dax_host;
 697
 698         switch (dev_info->segment_type) {
 699                 case SEG_TYPE_SR:
 700                 case SEG_TYPE_ER:
 701                 case SEG_TYPE_SC:
 702                         set_disk_ro(dev_info->gd,1);
 703                         break;
 704                 default:
 705                         set_disk_ro(dev_info->gd,0);
 706                         break;
 707         }
 708         up_write(&dcssblk_devices_sem);
 709         rc = count;
 710         goto out;
 711
 712 out_dax_host:
 713         put_device(&dev_info->dev);
 714         dax_remove_host(dev_info->gd);
 715 out_dax:
 716         kill_dax(dev_info->dax_dev);
 717         put_dax(dev_info->dax_dev);
 718 put_dev:
 719         list_del(&dev_info->lh);
 720         put_disk(dev_info->gd);
 721         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 722                 segment_unload(seg_info->segment_name);
 723         }
 724         put_device(&dev_info->dev);
 725         up_write(&dcssblk_devices_sem);
 726         goto out;
 727 dev_list_del:
 728         list_del(&dev_info->lh);
 729 release_gd:
 730         put_disk(dev_info->gd);
 731         up_write(&dcssblk_devices_sem);
 732 seg_list_del:
 733         if (dev_info == NULL)
 734                 goto out;
 735         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 736                 list_del(&seg_info->lh);
 737                 segment_unload(seg_info->segment_name);
 738                 kfree(seg_info);
 739         }
 740         kfree(dev_info);
 741 out:
 742         kfree(local_buf);
 743 out_nobuf:
 744         return rc;
 745 }
 746
 747 /*
 748  * device attribute for removing devices
 749  */
 750 static ssize_t
 751 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 752 {
 753         struct dcssblk_dev_info *dev_info;
 754         struct segment_info *entry;
 755         int rc, i;
 756         char *local_buf;
 757
 758         if (dev != dcssblk_root_dev) {
 759                 return -EINVAL;
 760         }
 761         local_buf = kmalloc(count + 1, GFP_KERNEL);
 762         if (local_buf == NULL) {
 763                 return -ENOMEM;
 764         }
 765         /*
 766          * parse input
 767          */
 768         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 769                 local_buf[i] = toupper(buf[i]);
 770         }
 771         local_buf[i] = '\0';
 772         if ((i == 0) || (i > 8)) {
 773                 rc = -ENAMETOOLONG;
 774                 goto out_buf;
 775         }
 776
 777         down_write(&dcssblk_devices_sem);
 778         dev_info = dcssblk_get_device_by_name(local_buf);
 779         if (dev_info == NULL) {
 780                 up_write(&dcssblk_devices_sem);
 781                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 782                         local_buf);
 783                 rc = -ENODEV;
 784                 goto out_buf;
 785         }
 786         if (atomic_read(&dev_info->use_count) != 0) {
 787                 up_write(&dcssblk_devices_sem);
 788                 pr_warn("Device %s cannot be removed while it is in use\n",
 789                         local_buf);
 790                 rc = -EBUSY;
 791                 goto out_buf;
 792         }
 793
 794         list_del(&dev_info->lh);
 795         /* unload all related segments */
 796         list_for_each_entry(entry, &dev_info->seg_list, lh)
 797                 segment_unload(entry->segment_name);
 798         up_write(&dcssblk_devices_sem);
 799
 800         dax_remove_host(dev_info->gd);
 801         kill_dax(dev_info->dax_dev);
 802         put_dax(dev_info->dax_dev);
 803         del_gendisk(dev_info->gd);
 804         put_disk(dev_info->gd);
 805
 806         device_unregister(&dev_info->dev);
 807         put_device(&dev_info->dev);
 808
 809         rc = count;
 810 out_buf:
 811         kfree(local_buf);
 812         return rc;
 813 }
 814
 815 static int
 816 dcssblk_open(struct gendisk *disk, blk_mode_t mode)
 817 {
 818         struct dcssblk_dev_info *dev_info = disk->private_data;
 819         int rc;
 820
 821         if (NULL == dev_info) {
 822                 rc = -ENODEV;
 823                 goto out;
 824         }
 825         atomic_inc(&dev_info->use_count);
 826         rc = 0;
 827 out:
 828         return rc;
 829 }
 830
 831 static void
 832 dcssblk_release(struct gendisk *disk)
 833 {
 834         struct dcssblk_dev_info *dev_info = disk->private_data;
 835         struct segment_info *entry;
 836
 837         if (!dev_info) {
 838                 WARN_ON(1);
 839                 return;
 840         }
 841         down_write(&dcssblk_devices_sem);
 842         if (atomic_dec_and_test(&dev_info->use_count)
 843             && (dev_info->save_pending)) {
 844                 pr_info("Device %s has become idle and is being saved "
 845                         "now\n", dev_info->segment_name);
 846                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 847                         if (entry->segment_type == SEG_TYPE_EN ||
 848                             entry->segment_type == SEG_TYPE_SN)
 849                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 850                                         " be saved\n", entry->segment_name);
 851                         else
 852                                 segment_save(entry->segment_name);
 853                 }
 854                 dev_info->save_pending = 0;
 855         }
 856         up_write(&dcssblk_devices_sem);
 857 }
 858
 859 static void
 860 dcssblk_submit_bio(struct bio *bio)
 861 {
 862         struct dcssblk_dev_info *dev_info;
 863         struct bio_vec bvec;
 864         struct bvec_iter iter;
 865         unsigned long index;
 866         void *page_addr;
 867         unsigned long source_addr;
 868         unsigned long bytes_done;
 869
 870         bytes_done = 0;
 871         dev_info = bio->bi_bdev->bd_disk->private_data;
 872         if (dev_info == NULL)
 873                 goto fail;
 874         if (!IS_ALIGNED(bio->bi_iter.bi_sector, 8) ||
 875             !IS_ALIGNED(bio->bi_iter.bi_size, PAGE_SIZE))
 876                 /* Request is not page-aligned. */
 877                 goto fail;
 878         /* verify data transfer direction */
 879         if (dev_info->is_shared) {
 880                 switch (dev_info->segment_type) {
 881                 case SEG_TYPE_SR:
 882                 case SEG_TYPE_ER:
 883                 case SEG_TYPE_SC:
 884                         /* cannot write to these segments */
 885                         if (bio_data_dir(bio) == WRITE) {
 886                                 pr_warn("Writing to %s failed because it is a read-only device\n",
 887                                         dev_name(&dev_info->dev));
 888                                 goto fail;
 889                         }
 890                 }
 891         }
 892
 893         index = (bio->bi_iter.bi_sector >> 3);
 894         bio_for_each_segment(bvec, bio, iter) {
 895                 page_addr = bvec_virt(&bvec);
 896                 source_addr = dev_info->start + (index<<12) + bytes_done;
 897                 if (unlikely(!IS_ALIGNED((unsigned long)page_addr, PAGE_SIZE) ||
 898                              !IS_ALIGNED(bvec.bv_len, PAGE_SIZE)))
 899                         // More paranoia.
 900                         goto fail;
 901                 if (bio_data_dir(bio) == READ)
 902                         memcpy(page_addr, __va(source_addr), bvec.bv_len);
 903                 else
 904                         memcpy(__va(source_addr), page_addr, bvec.bv_len);
 905                 bytes_done += bvec.bv_len;
 906         }
 907         bio_endio(bio);
 908         return;
 909 fail:
 910         bio_io_error(bio);
 911 }
 912
 913 static long
 914 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 915                 long nr_pages, void **kaddr, pfn_t *pfn)
 916 {
 917         resource_size_t offset = pgoff * PAGE_SIZE;
 918         unsigned long dev_sz;
 919
 920         dev_sz = dev_info->end - dev_info->start + 1;
 921         if (kaddr)
 922                 *kaddr = (void *) dev_info->start + offset;
 923         if (pfn)
 924                 *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
 925                                 PFN_DEV|PFN_SPECIAL);
 926
 927         return (dev_sz - offset) / PAGE_SIZE;
 928 }
 929
 930 static long
 931 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 932                 long nr_pages, enum dax_access_mode mode, void **kaddr,
 933                 pfn_t *pfn)
 934 {
 935         struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 936
 937         return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 938 }
 939
 940 static void
 941 dcssblk_check_params(void)
 942 {
 943         int rc, i, j, k;
 944         char buf[DCSSBLK_PARM_LEN + 1];
 945         struct dcssblk_dev_info *dev_info;
 946
 947         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 948              i++) {
 949                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 950                             (dcssblk_segments[j] != ',')  &&
 951                             (dcssblk_segments[j] != '\0') &&
 952                             (dcssblk_segments[j] != '('); j++)
 953                 {
 954                         buf[j-i] = dcssblk_segments[j];
 955                 }
 956                 buf[j-i] = '\0';
 957                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 958                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 959                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 960                                 buf[k] = toupper(buf[k]);
 961                         buf[k] = '\0';
 962                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 963                                 down_read(&dcssblk_devices_sem);
 964                                 dev_info = dcssblk_get_device_by_name(buf);
 965                                 up_read(&dcssblk_devices_sem);
 966                                 if (dev_info)
 967                                         dcssblk_shared_store(&dev_info->dev,
 968                                                              NULL, "0\n", 2);
 969                         }
 970                 }
 971                 while ((dcssblk_segments[j] != ',') &&
 972                        (dcssblk_segments[j] != '\0'))
 973                 {
 974                         j++;
 975                 }
 976                 if (dcssblk_segments[j] == '\0')
 977                         break;
 978                 i = j;
 979         }
 980 }
 981
 982 /*
 983  * The init/exit functions.
 984  */
 985 static void __exit
 986 dcssblk_exit(void)
 987 {
 988         root_device_unregister(dcssblk_root_dev);
 989         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 990 }
 991
 992 static int __init
 993 dcssblk_init(void)
 994 {
 995         int rc;
 996
 997         dcssblk_root_dev = root_device_register("dcssblk");
 998         if (IS_ERR(dcssblk_root_dev))
 999                 return PTR_ERR(dcssblk_root_dev);
1000         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1001         if (rc)
1002                 goto out_root;
1003         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1004         if (rc)
1005                 goto out_root;
1006         rc = register_blkdev(0, DCSSBLK_NAME);
1007         if (rc < 0)
1008                 goto out_root;
1009         dcssblk_major = rc;
1010         init_rwsem(&dcssblk_devices_sem);
1011
1012         dcssblk_check_params();
1013         return 0;
1014
1015 out_root:
1016         root_device_unregister(dcssblk_root_dev);
1017
1018         return rc;
1019 }
1020
1021 module_init(dcssblk_init);
1022 module_exit(dcssblk_exit);
1023
1024 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1025 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1026                  "comma-separated list, names in each set separated "
1027                  "by commas are separated by colons, each set contains "
1028                  "names of contiguous segments and each name max. 8 chars.\n"
1029                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1030                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1031                  "the contiguous segments - \n"
1032                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1033
1034 MODULE_LICENSE("GPL");