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
 415         kill_dax(dev_info->dax_dev);
 416         put_dax(dev_info->dax_dev);
 417         del_gendisk(dev_info->gd);
 418         put_disk(dev_info->gd);
 419         up_write(&dcssblk_devices_sem);
 420
 421         if (device_remove_file_self(dev, attr)) {
 422                 device_unregister(dev);
 423                 put_device(dev);
 424         }
 425         return rc;
 426 out:
 427         up_write(&dcssblk_devices_sem);
 428         return rc;
 429 }
 430 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 431                    dcssblk_shared_store);
 432
 433 /*
 434  * device attribute for save operation on current copy
 435  * of the segment. If the segment is busy, saving will
 436  * become pending until it gets released, which can be
 437  * undone by storing a non-true value to this entry.
 438  * (show + store)
 439  */
 440 static ssize_t
 441 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 442 {
 443         struct dcssblk_dev_info *dev_info;
 444
 445         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 446         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 447 }
 448
 449 static ssize_t
 450 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 451 {
 452         struct dcssblk_dev_info *dev_info;
 453         struct segment_info *entry;
 454
 455         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 456                 return -EINVAL;
 457         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 458
 459         down_write(&dcssblk_devices_sem);
 460         if (inbuf[0] == '1') {
 461                 if (atomic_read(&dev_info->use_count) == 0) {
 462                         // device is idle => we save immediately
 463                         pr_info("All DCSSs that map to device %s are "
 464                                 "saved\n", dev_info->segment_name);
 465                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 466                                 if (entry->segment_type == SEG_TYPE_EN ||
 467                                     entry->segment_type == SEG_TYPE_SN)
 468                                         pr_warn("DCSS %s is of type SN or EN"
 469                                                 " and cannot be saved\n",
 470                                                 entry->segment_name);
 471                                 else
 472                                         segment_save(entry->segment_name);
 473                         }
 474                 }  else {
 475                         // device is busy => we save it when it becomes
 476                         // idle in dcssblk_release
 477                         pr_info("Device %s is in use, its DCSSs will be "
 478                                 "saved when it becomes idle\n",
 479                                 dev_info->segment_name);
 480                         dev_info->save_pending = 1;
 481                 }
 482         } else if (inbuf[0] == '0') {
 483                 if (dev_info->save_pending) {
 484                         // device is busy & the user wants to undo his save
 485                         // request
 486                         dev_info->save_pending = 0;
 487                         pr_info("A pending save request for device %s "
 488                                 "has been canceled\n",
 489                                 dev_info->segment_name);
 490                 }
 491         } else {
 492                 up_write(&dcssblk_devices_sem);
 493                 return -EINVAL;
 494         }
 495         up_write(&dcssblk_devices_sem);
 496         return count;
 497 }
 498 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 499                    dcssblk_save_store);
 500
 501 /*
 502  * device attribute for showing all segments in a device
 503  */
 504 static ssize_t
 505 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 506                 char *buf)
 507 {
 508         int i;
 509
 510         struct dcssblk_dev_info *dev_info;
 511         struct segment_info *entry;
 512
 513         down_read(&dcssblk_devices_sem);
 514         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 515         i = 0;
 516         buf[0] = '\0';
 517         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 518                 strcpy(&buf[i], entry->segment_name);
 519                 i += strlen(entry->segment_name);
 520                 buf[i] = '\n';
 521                 i++;
 522         }
 523         up_read(&dcssblk_devices_sem);
 524         return i;
 525 }
 526 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 527
 528 static struct attribute *dcssblk_dev_attrs[] = {
 529         &dev_attr_shared.attr,
 530         &dev_attr_save.attr,
 531         &dev_attr_seglist.attr,
 532         NULL,
 533 };
 534 static struct attribute_group dcssblk_dev_attr_group = {
 535         .attrs = dcssblk_dev_attrs,
 536 };
 537 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 538         &dcssblk_dev_attr_group,
 539         NULL,
 540 };
 541
 542 /*
 543  * device attribute for adding devices
 544  */
 545 static ssize_t
 546 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 547 {
 548         int rc, i, j, num_of_segments;
 549         struct dcssblk_dev_info *dev_info;
 550         struct segment_info *seg_info, *temp;
 551         char *local_buf;
 552         unsigned long seg_byte_size;
 553
 554         dev_info = NULL;
 555         seg_info = NULL;
 556         if (dev != dcssblk_root_dev) {
 557                 rc = -EINVAL;
 558                 goto out_nobuf;
 559         }
 560         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 561                 rc = -ENAMETOOLONG;
 562                 goto out_nobuf;
 563         }
 564
 565         local_buf = kmalloc(count + 1, GFP_KERNEL);
 566         if (local_buf == NULL) {
 567                 rc = -ENOMEM;
 568                 goto out_nobuf;
 569         }
 570
 571         /*
 572          * parse input
 573          */
 574         num_of_segments = 0;
 575         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 576                 for (j = i; j < count &&
 577                         (buf[j] != ':') &&
 578                         (buf[j] != '\0') &&
 579                         (buf[j] != '\n'); j++) {
 580                         local_buf[j-i] = toupper(buf[j]);
 581                 }
 582                 local_buf[j-i] = '\0';
 583                 if (((j - i) == 0) || ((j - i) > 8)) {
 584                         rc = -ENAMETOOLONG;
 585                         goto seg_list_del;
 586                 }
 587
 588                 rc = dcssblk_load_segment(local_buf, &seg_info);
 589                 if (rc < 0)
 590                         goto seg_list_del;
 591                 /*
 592                  * get a struct dcssblk_dev_info
 593                  */
 594                 if (num_of_segments == 0) {
 595                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 596                                         GFP_KERNEL);
 597                         if (dev_info == NULL) {
 598                                 rc = -ENOMEM;
 599                                 goto out;
 600                         }
 601                         strcpy(dev_info->segment_name, local_buf);
 602                         dev_info->segment_type = seg_info->segment_type;
 603                         INIT_LIST_HEAD(&dev_info->seg_list);
 604                 }
 605                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 606                 num_of_segments++;
 607                 i = j;
 608
 609                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 610                         break;
 611         }
 612
 613         /* no trailing colon at the end of the input */
 614         if ((i > 0) && (buf[i-1] == ':')) {
 615                 rc = -ENAMETOOLONG;
 616                 goto seg_list_del;
 617         }
 618         strscpy(local_buf, buf, i + 1);
 619         dev_info->num_of_segments = num_of_segments;
 620         rc = dcssblk_is_continuous(dev_info);
 621         if (rc < 0)
 622                 goto seg_list_del;
 623
 624         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 625         dev_info->end = dcssblk_find_highest_addr(dev_info);
 626
 627         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 628         dev_info->dev.release = dcssblk_release_segment;
 629         dev_info->dev.groups = dcssblk_dev_attr_groups;
 630         INIT_LIST_HEAD(&dev_info->lh);
 631         dev_info->gd = blk_alloc_disk(NUMA_NO_NODE);
 632         if (dev_info->gd == NULL) {
 633                 rc = -ENOMEM;
 634                 goto seg_list_del;
 635         }
 636         dev_info->gd->major = dcssblk_major;
 637         dev_info->gd->minors = DCSSBLK_MINORS_PER_DISK;
 638         dev_info->gd->fops = &dcssblk_devops;
 639         dev_info->gd->private_data = dev_info;
 640         dev_info->gd->flags |= GENHD_FL_NO_PART;
 641         blk_queue_logical_block_size(dev_info->gd->queue, 4096);
 642         blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->gd->queue);
 643
 644         seg_byte_size = (dev_info->end - dev_info->start + 1);
 645         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 646         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 647                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 648
 649         dev_info->save_pending = 0;
 650         dev_info->is_shared = 1;
 651         dev_info->dev.parent = dcssblk_root_dev;
 652
 653         /*
 654          *get minor, add to list
 655          */
 656         down_write(&dcssblk_devices_sem);
 657         if (dcssblk_get_segment_by_name(local_buf)) {
 658                 rc = -EEXIST;
 659                 goto release_gd;
 660         }
 661         rc = dcssblk_assign_free_minor(dev_info);
 662         if (rc)
 663                 goto release_gd;
 664         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 665                 dev_info->gd->first_minor);
 666         list_add_tail(&dev_info->lh, &dcssblk_devices);
 667
 668         if (!try_module_get(THIS_MODULE)) {
 669                 rc = -ENODEV;
 670                 goto dev_list_del;
 671         }
 672         /*
 673          * register the device
 674          */
 675         rc = device_register(&dev_info->dev);
 676         if (rc)
 677                 goto put_dev;
 678
 679         dev_info->dax_dev = alloc_dax(dev_info, &dcssblk_dax_ops);
 680         if (IS_ERR(dev_info->dax_dev)) {
 681                 rc = PTR_ERR(dev_info->dax_dev);
 682                 dev_info->dax_dev = NULL;
 683                 goto put_dev;
 684         }
 685         set_dax_synchronous(dev_info->dax_dev);
 686         rc = dax_add_host(dev_info->dax_dev, dev_info->gd);
 687         if (rc)
 688                 goto out_dax;
 689
 690         get_device(&dev_info->dev);
 691         rc = device_add_disk(&dev_info->dev, dev_info->gd, NULL);
 692         if (rc)
 693                 goto out_dax_host;
 694
 695         switch (dev_info->segment_type) {
 696                 case SEG_TYPE_SR:
 697                 case SEG_TYPE_ER:
 698                 case SEG_TYPE_SC:
 699                         set_disk_ro(dev_info->gd,1);
 700                         break;
 701                 default:
 702                         set_disk_ro(dev_info->gd,0);
 703                         break;
 704         }
 705         up_write(&dcssblk_devices_sem);
 706         rc = count;
 707         goto out;
 708
 709 out_dax_host:
 710         dax_remove_host(dev_info->gd);
 711 out_dax:
 712         put_device(&dev_info->dev);
 713         kill_dax(dev_info->dax_dev);
 714         put_dax(dev_info->dax_dev);
 715 put_dev:
 716         list_del(&dev_info->lh);
 717         put_disk(dev_info->gd);
 718         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 719                 segment_unload(seg_info->segment_name);
 720         }
 721         put_device(&dev_info->dev);
 722         up_write(&dcssblk_devices_sem);
 723         goto out;
 724 dev_list_del:
 725         list_del(&dev_info->lh);
 726 release_gd:
 727         put_disk(dev_info->gd);
 728         up_write(&dcssblk_devices_sem);
 729 seg_list_del:
 730         if (dev_info == NULL)
 731                 goto out;
 732         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 733                 list_del(&seg_info->lh);
 734                 segment_unload(seg_info->segment_name);
 735                 kfree(seg_info);
 736         }
 737         kfree(dev_info);
 738 out:
 739         kfree(local_buf);
 740 out_nobuf:
 741         return rc;
 742 }
 743
 744 /*
 745  * device attribute for removing devices
 746  */
 747 static ssize_t
 748 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 749 {
 750         struct dcssblk_dev_info *dev_info;
 751         struct segment_info *entry;
 752         int rc, i;
 753         char *local_buf;
 754
 755         if (dev != dcssblk_root_dev) {
 756                 return -EINVAL;
 757         }
 758         local_buf = kmalloc(count + 1, GFP_KERNEL);
 759         if (local_buf == NULL) {
 760                 return -ENOMEM;
 761         }
 762         /*
 763          * parse input
 764          */
 765         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 766                 local_buf[i] = toupper(buf[i]);
 767         }
 768         local_buf[i] = '\0';
 769         if ((i == 0) || (i > 8)) {
 770                 rc = -ENAMETOOLONG;
 771                 goto out_buf;
 772         }
 773
 774         down_write(&dcssblk_devices_sem);
 775         dev_info = dcssblk_get_device_by_name(local_buf);
 776         if (dev_info == NULL) {
 777                 up_write(&dcssblk_devices_sem);
 778                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 779                         local_buf);
 780                 rc = -ENODEV;
 781                 goto out_buf;
 782         }
 783         if (atomic_read(&dev_info->use_count) != 0) {
 784                 up_write(&dcssblk_devices_sem);
 785                 pr_warn("Device %s cannot be removed while it is in use\n",
 786                         local_buf);
 787                 rc = -EBUSY;
 788                 goto out_buf;
 789         }
 790
 791         list_del(&dev_info->lh);
 792         kill_dax(dev_info->dax_dev);
 793         put_dax(dev_info->dax_dev);
 794         del_gendisk(dev_info->gd);
 795         put_disk(dev_info->gd);
 796
 797         /* unload all related segments */
 798         list_for_each_entry(entry, &dev_info->seg_list, lh)
 799                 segment_unload(entry->segment_name);
 800
 801         up_write(&dcssblk_devices_sem);
 802
 803         device_unregister(&dev_info->dev);
 804         put_device(&dev_info->dev);
 805
 806         rc = count;
 807 out_buf:
 808         kfree(local_buf);
 809         return rc;
 810 }
 811
 812 static int
 813 dcssblk_open(struct gendisk *disk, blk_mode_t mode)
 814 {
 815         struct dcssblk_dev_info *dev_info = disk->private_data;
 816         int rc;
 817
 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)
 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");