linux/drivers/s390/block/dcssblk.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * dcssblk.c -- the S/390 block driver for dcss memory
   4 *
   5 * Authors: Carsten Otte, Stefan Weinhuber, Gerald Schaefer
   6 */
   7
   8#define KMSG_COMPONENT "dcssblk"
   9#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  10
  11#include <linux/module.h>
  12#include <linux/moduleparam.h>
  13#include <linux/ctype.h>
  14#include <linux/errno.h>
  15#include <linux/init.h>
  16#include <linux/slab.h>
  17#include <linux/blkdev.h>
  18#include <linux/completion.h>
  19#include <linux/interrupt.h>
  20#include <linux/platform_device.h>
  21#include <linux/pfn_t.h>
  22#include <linux/uio.h>
  23#include <linux/dax.h>
  24#include <asm/extmem.h>
  25#include <asm/io.h>
  26
  27#define DCSSBLK_NAME "dcssblk"
  28#define DCSSBLK_MINORS_PER_DISK 1
  29#define DCSSBLK_PARM_LEN 400
  30#define DCSS_BUS_ID_SIZE 20
  31
  32static int dcssblk_open(struct block_device *bdev, fmode_t mode);
  33static void dcssblk_release(struct gendisk *disk, fmode_t mode);
  34static blk_qc_t dcssblk_make_request(struct request_queue *q,
  35                                                struct bio *bio);
  36static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
  37                long nr_pages, void **kaddr, pfn_t *pfn);
  38
  39static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  40
  41static int dcssblk_major;
  42static const struct block_device_operations dcssblk_devops = {
  43        .owner          = THIS_MODULE,
  44        .open           = dcssblk_open,
  45        .release        = dcssblk_release,
  46};
  47
  48static size_t dcssblk_dax_copy_from_iter(struct dax_device *dax_dev,
  49                pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
  50{
  51        return copy_from_iter(addr, bytes, i);
  52}
  53
  54static size_t dcssblk_dax_copy_to_iter(struct dax_device *dax_dev,
  55                pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
  56{
  57        return copy_to_iter(addr, bytes, i);
  58}
  59
  60static const struct dax_operations dcssblk_dax_ops = {
  61        .direct_access = dcssblk_dax_direct_access,
  62        .dax_supported = generic_fsdax_supported,
  63        .copy_from_iter = dcssblk_dax_copy_from_iter,
  64        .copy_to_iter = dcssblk_dax_copy_to_iter,
  65};
  66
  67struct dcssblk_dev_info {
  68        struct list_head lh;
  69        struct device dev;
  70        char segment_name[DCSS_BUS_ID_SIZE];
  71        atomic_t use_count;
  72        struct gendisk *gd;
  73        unsigned long start;
  74        unsigned long end;
  75        int segment_type;
  76        unsigned char save_pending;
  77        unsigned char is_shared;
  78        struct request_queue *dcssblk_queue;
  79        int num_of_segments;
  80        struct list_head seg_list;
  81        struct dax_device *dax_dev;
  82};
  83
  84struct segment_info {
  85        struct list_head lh;
  86        char segment_name[DCSS_BUS_ID_SIZE];
  87        unsigned long start;
  88        unsigned long end;
  89        int segment_type;
  90};
  91
  92static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  93                                  size_t count);
  94static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  95                                  size_t count);
  96
  97static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  98static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  99
 100static struct device *dcssblk_root_dev;
 101
 102static LIST_HEAD(dcssblk_devices);
 103static struct rw_semaphore dcssblk_devices_sem;
 104
 105/*
 106 * release function for segment device.
 107 */
 108static void
 109dcssblk_release_segment(struct device *dev)
 110{
 111        struct dcssblk_dev_info *dev_info;
 112        struct segment_info *entry, *temp;
 113
 114        dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 115        list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 116                list_del(&entry->lh);
 117                kfree(entry);
 118        }
 119        kfree(dev_info);
 120        module_put(THIS_MODULE);
 121}
 122
 123/*
 124 * get a minor number. needs to be called with
 125 * down_write(&dcssblk_devices_sem) and the
 126 * device needs to be enqueued before the semaphore is
 127 * freed.
 128 */
 129static int
 130dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 131{
 132        int minor, found;
 133        struct dcssblk_dev_info *entry;
 134
 135        if (dev_info == NULL)
 136                return -EINVAL;
 137        for (minor = 0; minor < (1<<MINORBITS); minor++) {
 138                found = 0;
 139                // test if minor available
 140                list_for_each_entry(entry, &dcssblk_devices, lh)
 141                        if (minor == entry->gd->first_minor)
 142                                found++;
 143                if (!found) break; // got unused minor
 144        }
 145        if (found)
 146                return -EBUSY;
 147        dev_info->gd->first_minor = minor;
 148        return 0;
 149}
 150
 151/*
 152 * get the struct dcssblk_dev_info from dcssblk_devices
 153 * for the given name.
 154 * down_read(&dcssblk_devices_sem) must be held.
 155 */
 156static struct dcssblk_dev_info *
 157dcssblk_get_device_by_name(char *name)
 158{
 159        struct dcssblk_dev_info *entry;
 160
 161        list_for_each_entry(entry, &dcssblk_devices, lh) {
 162                if (!strcmp(name, entry->segment_name)) {
 163                        return entry;
 164                }
 165        }
 166        return NULL;
 167}
 168
 169/*
 170 * get the struct segment_info from seg_list
 171 * for the given name.
 172 * down_read(&dcssblk_devices_sem) must be held.
 173 */
 174static struct segment_info *
 175dcssblk_get_segment_by_name(char *name)
 176{
 177        struct dcssblk_dev_info *dev_info;
 178        struct segment_info *entry;
 179
 180        list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 181                list_for_each_entry(entry, &dev_info->seg_list, lh) {
 182                        if (!strcmp(name, entry->segment_name))
 183                                return entry;
 184                }
 185        }
 186        return NULL;
 187}
 188
 189/*
 190 * get the highest address of the multi-segment block.
 191 */
 192static unsigned long
 193dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 194{
 195        unsigned long highest_addr;
 196        struct segment_info *entry;
 197
 198        highest_addr = 0;
 199        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 200                if (highest_addr < entry->end)
 201                        highest_addr = entry->end;
 202        }
 203        return highest_addr;
 204}
 205
 206/*
 207 * get the lowest address of the multi-segment block.
 208 */
 209static unsigned long
 210dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 211{
 212        int set_first;
 213        unsigned long lowest_addr;
 214        struct segment_info *entry;
 215
 216        set_first = 0;
 217        lowest_addr = 0;
 218        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 219                if (set_first == 0) {
 220                        lowest_addr = entry->start;
 221                        set_first = 1;
 222                } else {
 223                        if (lowest_addr > entry->start)
 224                                lowest_addr = entry->start;
 225                }
 226        }
 227        return lowest_addr;
 228}
 229
 230/*
 231 * Check continuity of segments.
 232 */
 233static int
 234dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 235{
 236        int i, j, rc;
 237        struct segment_info *sort_list, *entry, temp;
 238
 239        if (dev_info->num_of_segments <= 1)
 240                return 0;
 241
 242        sort_list = kcalloc(dev_info->num_of_segments,
 243                            sizeof(struct segment_info),
 244                            GFP_KERNEL);
 245        if (sort_list == NULL)
 246                return -ENOMEM;
 247        i = 0;
 248        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 249                memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 250                i++;
 251        }
 252
 253        /* sort segments */
 254        for (i = 0; i < dev_info->num_of_segments; i++)
 255                for (j = 0; j < dev_info->num_of_segments; j++)
 256                        if (sort_list[j].start > sort_list[i].start) {
 257                                memcpy(&temp, &sort_list[i],
 258                                        sizeof(struct segment_info));
 259                                memcpy(&sort_list[i], &sort_list[j],
 260                                        sizeof(struct segment_info));
 261                                memcpy(&sort_list[j], &temp,
 262                                        sizeof(struct segment_info));
 263                        }
 264
 265        /* check continuity */
 266        for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 267                if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 268                        pr_err("Adjacent DCSSs %s and %s are not "
 269                               "contiguous\n", sort_list[i].segment_name,
 270                               sort_list[i+1].segment_name);
 271                        rc = -EINVAL;
 272                        goto out;
 273                }
 274                /* EN and EW are allowed in a block device */
 275                if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 276                        if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 277                                (sort_list[i].segment_type == SEG_TYPE_ER) ||
 278                                !(sort_list[i+1].segment_type &
 279                                SEGMENT_EXCLUSIVE) ||
 280                                (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 281                                pr_err("DCSS %s and DCSS %s have "
 282                                       "incompatible types\n",
 283                                       sort_list[i].segment_name,
 284                                       sort_list[i+1].segment_name);
 285                                rc = -EINVAL;
 286                                goto out;
 287                        }
 288                }
 289        }
 290        rc = 0;
 291out:
 292        kfree(sort_list);
 293        return rc;
 294}
 295
 296/*
 297 * Load a segment
 298 */
 299static int
 300dcssblk_load_segment(char *name, struct segment_info **seg_info)
 301{
 302        int rc;
 303
 304        /* already loaded? */
 305        down_read(&dcssblk_devices_sem);
 306        *seg_info = dcssblk_get_segment_by_name(name);
 307        up_read(&dcssblk_devices_sem);
 308        if (*seg_info != NULL)
 309                return -EEXIST;
 310
 311        /* get a struct segment_info */
 312        *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 313        if (*seg_info == NULL)
 314                return -ENOMEM;
 315
 316        strcpy((*seg_info)->segment_name, name);
 317
 318        /* load the segment */
 319        rc = segment_load(name, SEGMENT_SHARED,
 320                        &(*seg_info)->start, &(*seg_info)->end);
 321        if (rc < 0) {
 322                segment_warning(rc, (*seg_info)->segment_name);
 323                kfree(*seg_info);
 324        } else {
 325                INIT_LIST_HEAD(&(*seg_info)->lh);
 326                (*seg_info)->segment_type = rc;
 327        }
 328        return rc;
 329}
 330
 331/*
 332 * device attribute for switching shared/nonshared (exclusive)
 333 * operation (show + store)
 334 */
 335static ssize_t
 336dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 337{
 338        struct dcssblk_dev_info *dev_info;
 339
 340        dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 341        return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 342}
 343
 344static ssize_t
 345dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 346{
 347        struct dcssblk_dev_info *dev_info;
 348        struct segment_info *entry, *temp;
 349        int rc;
 350
 351        if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 352                return -EINVAL;
 353        down_write(&dcssblk_devices_sem);
 354        dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 355        if (atomic_read(&dev_info->use_count)) {
 356                rc = -EBUSY;
 357                goto out;
 358        }
 359        if (inbuf[0] == '1') {
 360                /* reload segments in shared mode */
 361                list_for_each_entry(entry, &dev_info->seg_list, lh) {
 362                        rc = segment_modify_shared(entry->segment_name,
 363                                                SEGMENT_SHARED);
 364                        if (rc < 0) {
 365                                BUG_ON(rc == -EINVAL);
 366                                if (rc != -EAGAIN)
 367                                        goto removeseg;
 368                        }
 369                }
 370                dev_info->is_shared = 1;
 371                switch (dev_info->segment_type) {
 372                case SEG_TYPE_SR:
 373                case SEG_TYPE_ER:
 374                case SEG_TYPE_SC:
 375                        set_disk_ro(dev_info->gd, 1);
 376                }
 377        } else if (inbuf[0] == '0') {
 378                /* reload segments in exclusive mode */
 379                if (dev_info->segment_type == SEG_TYPE_SC) {
 380                        pr_err("DCSS %s is of type SC and cannot be "
 381                               "loaded as exclusive-writable\n",
 382                               dev_info->segment_name);
 383                        rc = -EINVAL;
 384                        goto out;
 385                }
 386                list_for_each_entry(entry, &dev_info->seg_list, lh) {
 387                        rc = segment_modify_shared(entry->segment_name,
 388                                                   SEGMENT_EXCLUSIVE);
 389                        if (rc < 0) {
 390                                BUG_ON(rc == -EINVAL);
 391                                if (rc != -EAGAIN)
 392                                        goto removeseg;
 393                        }
 394                }
 395                dev_info->is_shared = 0;
 396                set_disk_ro(dev_info->gd, 0);
 397        } else {
 398                rc = -EINVAL;
 399                goto out;
 400        }
 401        rc = count;
 402        goto out;
 403
 404removeseg:
 405        pr_err("DCSS device %s is removed after a failed access mode "
 406               "change\n", dev_info->segment_name);
 407        temp = entry;
 408        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 409                if (entry != temp)
 410                        segment_unload(entry->segment_name);
 411        }
 412        list_del(&dev_info->lh);
 413
 414        kill_dax(dev_info->dax_dev);
 415        put_dax(dev_info->dax_dev);
 416        del_gendisk(dev_info->gd);
 417        blk_cleanup_queue(dev_info->dcssblk_queue);
 418        dev_info->gd->queue = NULL;
 419        put_disk(dev_info->gd);
 420        up_write(&dcssblk_devices_sem);
 421
 422        if (device_remove_file_self(dev, attr)) {
 423                device_unregister(dev);
 424                put_device(dev);
 425        }
 426        return rc;
 427out:
 428        up_write(&dcssblk_devices_sem);
 429        return rc;
 430}
 431static 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 */
 441static ssize_t
 442dcssblk_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
 450static ssize_t
 451dcssblk_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}
 499static 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 */
 505static ssize_t
 506dcssblk_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}
 527static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 528
 529static struct attribute *dcssblk_dev_attrs[] = {
 530        &dev_attr_shared.attr,
 531        &dev_attr_save.attr,
 532        &dev_attr_seglist.attr,
 533        NULL,
 534};
 535static struct attribute_group dcssblk_dev_attr_group = {
 536        .attrs = dcssblk_dev_attrs,
 537};
 538static 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 */
 546static ssize_t
 547dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 548{
 549        int rc, i, j, num_of_segments;
 550        struct dcssblk_dev_info *dev_info;
 551        struct segment_info *seg_info, *temp;
 552        char *local_buf;
 553        unsigned long seg_byte_size;
 554
 555        dev_info = NULL;
 556        seg_info = NULL;
 557        if (dev != dcssblk_root_dev) {
 558                rc = -EINVAL;
 559                goto out_nobuf;
 560        }
 561        if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 562                rc = -ENAMETOOLONG;
 563                goto out_nobuf;
 564        }
 565
 566        local_buf = kmalloc(count + 1, GFP_KERNEL);
 567        if (local_buf == NULL) {
 568                rc = -ENOMEM;
 569                goto out_nobuf;
 570        }
 571
 572        /*
 573         * parse input
 574         */
 575        num_of_segments = 0;
 576        for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 577                for (j = i; j < count &&
 578                        (buf[j] != ':') &&
 579                        (buf[j] != '\0') &&
 580                        (buf[j] != '\n'); j++) {
 581                        local_buf[j-i] = toupper(buf[j]);
 582                }
 583                local_buf[j-i] = '\0';
 584                if (((j - i) == 0) || ((j - i) > 8)) {
 585                        rc = -ENAMETOOLONG;
 586                        goto seg_list_del;
 587                }
 588
 589                rc = dcssblk_load_segment(local_buf, &seg_info);
 590                if (rc < 0)
 591                        goto seg_list_del;
 592                /*
 593                 * get a struct dcssblk_dev_info
 594                 */
 595                if (num_of_segments == 0) {
 596                        dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 597                                        GFP_KERNEL);
 598                        if (dev_info == NULL) {
 599                                rc = -ENOMEM;
 600                                goto out;
 601                        }
 602                        strcpy(dev_info->segment_name, local_buf);
 603                        dev_info->segment_type = seg_info->segment_type;
 604                        INIT_LIST_HEAD(&dev_info->seg_list);
 605                }
 606                list_add_tail(&seg_info->lh, &dev_info->seg_list);
 607                num_of_segments++;
 608                i = j;
 609
 610                if ((buf[j] == '\0') || (buf[j] == '\n'))
 611                        break;
 612        }
 613
 614        /* no trailing colon at the end of the input */
 615        if ((i > 0) && (buf[i-1] == ':')) {
 616                rc = -ENAMETOOLONG;
 617                goto seg_list_del;
 618        }
 619        strlcpy(local_buf, buf, i + 1);
 620        dev_info->num_of_segments = num_of_segments;
 621        rc = dcssblk_is_continuous(dev_info);
 622        if (rc < 0)
 623                goto seg_list_del;
 624
 625        dev_info->start = dcssblk_find_lowest_addr(dev_info);
 626        dev_info->end = dcssblk_find_highest_addr(dev_info);
 627
 628        dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 629        dev_info->dev.release = dcssblk_release_segment;
 630        dev_info->dev.groups = dcssblk_dev_attr_groups;
 631        INIT_LIST_HEAD(&dev_info->lh);
 632        dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 633        if (dev_info->gd == NULL) {
 634                rc = -ENOMEM;
 635                goto seg_list_del;
 636        }
 637        dev_info->gd->major = dcssblk_major;
 638        dev_info->gd->fops = &dcssblk_devops;
 639        dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 640        dev_info->gd->queue = dev_info->dcssblk_queue;
 641        dev_info->gd->private_data = dev_info;
 642        blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 643        blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 644        blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->dcssblk_queue);
 645
 646        seg_byte_size = (dev_info->end - dev_info->start + 1);
 647        set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 648        pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 649                "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 650
 651        dev_info->save_pending = 0;
 652        dev_info->is_shared = 1;
 653        dev_info->dev.parent = dcssblk_root_dev;
 654
 655        /*
 656         *get minor, add to list
 657         */
 658        down_write(&dcssblk_devices_sem);
 659        if (dcssblk_get_segment_by_name(local_buf)) {
 660                rc = -EEXIST;
 661                goto release_gd;
 662        }
 663        rc = dcssblk_assign_free_minor(dev_info);
 664        if (rc)
 665                goto release_gd;
 666        sprintf(dev_info->gd->disk_name, "dcssblk%d",
 667                dev_info->gd->first_minor);
 668        list_add_tail(&dev_info->lh, &dcssblk_devices);
 669
 670        if (!try_module_get(THIS_MODULE)) {
 671                rc = -ENODEV;
 672                goto dev_list_del;
 673        }
 674        /*
 675         * register the device
 676         */
 677        rc = device_register(&dev_info->dev);
 678        if (rc)
 679                goto put_dev;
 680
 681        dev_info->dax_dev = alloc_dax(dev_info, dev_info->gd->disk_name,
 682                        &dcssblk_dax_ops);
 683        if (!dev_info->dax_dev) {
 684                rc = -ENOMEM;
 685                goto put_dev;
 686        }
 687
 688        get_device(&dev_info->dev);
 689        device_add_disk(&dev_info->dev, dev_info->gd, NULL);
 690
 691        switch (dev_info->segment_type) {
 692                case SEG_TYPE_SR:
 693                case SEG_TYPE_ER:
 694                case SEG_TYPE_SC:
 695                        set_disk_ro(dev_info->gd,1);
 696                        break;
 697                default:
 698                        set_disk_ro(dev_info->gd,0);
 699                        break;
 700        }
 701        up_write(&dcssblk_devices_sem);
 702        rc = count;
 703        goto out;
 704
 705put_dev:
 706        list_del(&dev_info->lh);
 707        blk_cleanup_queue(dev_info->dcssblk_queue);
 708        dev_info->gd->queue = NULL;
 709        put_disk(dev_info->gd);
 710        list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 711                segment_unload(seg_info->segment_name);
 712        }
 713        put_device(&dev_info->dev);
 714        up_write(&dcssblk_devices_sem);
 715        goto out;
 716dev_list_del:
 717        list_del(&dev_info->lh);
 718release_gd:
 719        blk_cleanup_queue(dev_info->dcssblk_queue);
 720        dev_info->gd->queue = NULL;
 721        put_disk(dev_info->gd);
 722        up_write(&dcssblk_devices_sem);
 723seg_list_del:
 724        if (dev_info == NULL)
 725                goto out;
 726        list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 727                list_del(&seg_info->lh);
 728                segment_unload(seg_info->segment_name);
 729                kfree(seg_info);
 730        }
 731        kfree(dev_info);
 732out:
 733        kfree(local_buf);
 734out_nobuf:
 735        return rc;
 736}
 737
 738/*
 739 * device attribute for removing devices
 740 */
 741static ssize_t
 742dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 743{
 744        struct dcssblk_dev_info *dev_info;
 745        struct segment_info *entry;
 746        int rc, i;
 747        char *local_buf;
 748
 749        if (dev != dcssblk_root_dev) {
 750                return -EINVAL;
 751        }
 752        local_buf = kmalloc(count + 1, GFP_KERNEL);
 753        if (local_buf == NULL) {
 754                return -ENOMEM;
 755        }
 756        /*
 757         * parse input
 758         */
 759        for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 760                local_buf[i] = toupper(buf[i]);
 761        }
 762        local_buf[i] = '\0';
 763        if ((i == 0) || (i > 8)) {
 764                rc = -ENAMETOOLONG;
 765                goto out_buf;
 766        }
 767
 768        down_write(&dcssblk_devices_sem);
 769        dev_info = dcssblk_get_device_by_name(local_buf);
 770        if (dev_info == NULL) {
 771                up_write(&dcssblk_devices_sem);
 772                pr_warn("Device %s cannot be removed because it is not a known device\n",
 773                        local_buf);
 774                rc = -ENODEV;
 775                goto out_buf;
 776        }
 777        if (atomic_read(&dev_info->use_count) != 0) {
 778                up_write(&dcssblk_devices_sem);
 779                pr_warn("Device %s cannot be removed while it is in use\n",
 780                        local_buf);
 781                rc = -EBUSY;
 782                goto out_buf;
 783        }
 784
 785        list_del(&dev_info->lh);
 786        kill_dax(dev_info->dax_dev);
 787        put_dax(dev_info->dax_dev);
 788        del_gendisk(dev_info->gd);
 789        blk_cleanup_queue(dev_info->dcssblk_queue);
 790        dev_info->gd->queue = NULL;
 791        put_disk(dev_info->gd);
 792
 793        /* unload all related segments */
 794        list_for_each_entry(entry, &dev_info->seg_list, lh)
 795                segment_unload(entry->segment_name);
 796
 797        up_write(&dcssblk_devices_sem);
 798
 799        device_unregister(&dev_info->dev);
 800        put_device(&dev_info->dev);
 801
 802        rc = count;
 803out_buf:
 804        kfree(local_buf);
 805        return rc;
 806}
 807
 808static int
 809dcssblk_open(struct block_device *bdev, fmode_t mode)
 810{
 811        struct dcssblk_dev_info *dev_info;
 812        int rc;
 813
 814        dev_info = bdev->bd_disk->private_data;
 815        if (NULL == dev_info) {
 816                rc = -ENODEV;
 817                goto out;
 818        }
 819        atomic_inc(&dev_info->use_count);
 820        bdev->bd_block_size = 4096;
 821        rc = 0;
 822out:
 823        return rc;
 824}
 825
 826static void
 827dcssblk_release(struct gendisk *disk, fmode_t mode)
 828{
 829        struct dcssblk_dev_info *dev_info = disk->private_data;
 830        struct segment_info *entry;
 831
 832        if (!dev_info) {
 833                WARN_ON(1);
 834                return;
 835        }
 836        down_write(&dcssblk_devices_sem);
 837        if (atomic_dec_and_test(&dev_info->use_count)
 838            && (dev_info->save_pending)) {
 839                pr_info("Device %s has become idle and is being saved "
 840                        "now\n", dev_info->segment_name);
 841                list_for_each_entry(entry, &dev_info->seg_list, lh) {
 842                        if (entry->segment_type == SEG_TYPE_EN ||
 843                            entry->segment_type == SEG_TYPE_SN)
 844                                pr_warn("DCSS %s is of type SN or EN and cannot"
 845                                        " be saved\n", entry->segment_name);
 846                        else
 847                                segment_save(entry->segment_name);
 848                }
 849                dev_info->save_pending = 0;
 850        }
 851        up_write(&dcssblk_devices_sem);
 852}
 853
 854static blk_qc_t
 855dcssblk_make_request(struct request_queue *q, struct bio *bio)
 856{
 857        struct dcssblk_dev_info *dev_info;
 858        struct bio_vec bvec;
 859        struct bvec_iter iter;
 860        unsigned long index;
 861        unsigned long page_addr;
 862        unsigned long source_addr;
 863        unsigned long bytes_done;
 864
 865        blk_queue_split(q, &bio);
 866
 867        bytes_done = 0;
 868        dev_info = bio->bi_disk->private_data;
 869        if (dev_info == NULL)
 870                goto fail;
 871        if ((bio->bi_iter.bi_sector & 7) != 0 ||
 872            (bio->bi_iter.bi_size & 4095) != 0)
 873                /* Request is not page-aligned. */
 874                goto fail;
 875        if (bio_end_sector(bio) > get_capacity(bio->bi_disk)) {
 876                /* Request beyond end of DCSS segment. */
 877                goto fail;
 878        }
 879        /* verify data transfer direction */
 880        if (dev_info->is_shared) {
 881                switch (dev_info->segment_type) {
 882                case SEG_TYPE_SR:
 883                case SEG_TYPE_ER:
 884                case SEG_TYPE_SC:
 885                        /* cannot write to these segments */
 886                        if (bio_data_dir(bio) == WRITE) {
 887                                pr_warn("Writing to %s failed because it is a read-only device\n",
 888                                        dev_name(&dev_info->dev));
 889                                goto fail;
 890                        }
 891                }
 892        }
 893
 894        index = (bio->bi_iter.bi_sector >> 3);
 895        bio_for_each_segment(bvec, bio, iter) {
 896                page_addr = (unsigned long)
 897                        page_address(bvec.bv_page) + bvec.bv_offset;
 898                source_addr = dev_info->start + (index<<12) + bytes_done;
 899                if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 900                        // More paranoia.
 901                        goto fail;
 902                if (bio_data_dir(bio) == READ) {
 903                        memcpy((void*)page_addr, (void*)source_addr,
 904                                bvec.bv_len);
 905                } else {
 906                        memcpy((void*)source_addr, (void*)page_addr,
 907                                bvec.bv_len);
 908                }
 909                bytes_done += bvec.bv_len;
 910        }
 911        bio_endio(bio);
 912        return BLK_QC_T_NONE;
 913fail:
 914        bio_io_error(bio);
 915        return BLK_QC_T_NONE;
 916}
 917
 918static long
 919__dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 920                long nr_pages, void **kaddr, pfn_t *pfn)
 921{
 922        resource_size_t offset = pgoff * PAGE_SIZE;
 923        unsigned long dev_sz;
 924
 925        dev_sz = dev_info->end - dev_info->start + 1;
 926        if (kaddr)
 927                *kaddr = (void *) dev_info->start + offset;
 928        if (pfn)
 929                *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
 930                                PFN_DEV|PFN_SPECIAL);
 931
 932        return (dev_sz - offset) / PAGE_SIZE;
 933}
 934
 935static long
 936dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 937                long nr_pages, void **kaddr, pfn_t *pfn)
 938{
 939        struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 940
 941        return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 942}
 943
 944static void
 945dcssblk_check_params(void)
 946{
 947        int rc, i, j, k;
 948        char buf[DCSSBLK_PARM_LEN + 1];
 949        struct dcssblk_dev_info *dev_info;
 950
 951        for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 952             i++) {
 953                for (j = i; (j < DCSSBLK_PARM_LEN) &&
 954                            (dcssblk_segments[j] != ',')  &&
 955                            (dcssblk_segments[j] != '\0') &&
 956                            (dcssblk_segments[j] != '('); j++)
 957                {
 958                        buf[j-i] = dcssblk_segments[j];
 959                }
 960                buf[j-i] = '\0';
 961                rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 962                if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 963                        for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 964                                buf[k] = toupper(buf[k]);
 965                        buf[k] = '\0';
 966                        if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 967                                down_read(&dcssblk_devices_sem);
 968                                dev_info = dcssblk_get_device_by_name(buf);
 969                                up_read(&dcssblk_devices_sem);
 970                                if (dev_info)
 971                                        dcssblk_shared_store(&dev_info->dev,
 972                                                             NULL, "0\n", 2);
 973                        }
 974                }
 975                while ((dcssblk_segments[j] != ',') &&
 976                       (dcssblk_segments[j] != '\0'))
 977                {
 978                        j++;
 979                }
 980                if (dcssblk_segments[j] == '\0')
 981                        break;
 982                i = j;
 983        }
 984}
 985
 986/*
 987 * Suspend / Resume
 988 */
 989static int dcssblk_freeze(struct device *dev)
 990{
 991        struct dcssblk_dev_info *dev_info;
 992        int rc = 0;
 993
 994        list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 995                switch (dev_info->segment_type) {
 996                        case SEG_TYPE_SR:
 997                        case SEG_TYPE_ER:
 998                        case SEG_TYPE_SC:
 999                                if (!dev_info->is_shared)
1000                                        rc = -EINVAL;
1001                                break;
1002                        default:
1003                                rc = -EINVAL;
1004                                break;
1005                }
1006                if (rc)
1007                        break;
1008        }
1009        if (rc)
1010                pr_err("Suspending the system failed because DCSS device %s "
1011                       "is writable\n",
1012                       dev_info->segment_name);
1013        return rc;
1014}
1015
1016static int dcssblk_restore(struct device *dev)
1017{
1018        struct dcssblk_dev_info *dev_info;
1019        struct segment_info *entry;
1020        unsigned long start, end;
1021        int rc = 0;
1022
1023        list_for_each_entry(dev_info, &dcssblk_devices, lh) {
1024                list_for_each_entry(entry, &dev_info->seg_list, lh) {
1025                        segment_unload(entry->segment_name);
1026                        rc = segment_load(entry->segment_name, SEGMENT_SHARED,
1027                                          &start, &end);
1028                        if (rc < 0) {
1029// TODO in_use check ?
1030                                segment_warning(rc, entry->segment_name);
1031                                goto out_panic;
1032                        }
1033                        if (start != entry->start || end != entry->end) {
1034                                pr_err("The address range of DCSS %s changed "
1035                                       "while the system was suspended\n",
1036                                       entry->segment_name);
1037                                goto out_panic;
1038                        }
1039                }
1040        }
1041        return 0;
1042out_panic:
1043        panic("fatal dcssblk resume error\n");
1044}
1045
1046static int dcssblk_thaw(struct device *dev)
1047{
1048        return 0;
1049}
1050
1051static const struct dev_pm_ops dcssblk_pm_ops = {
1052        .freeze         = dcssblk_freeze,
1053        .thaw           = dcssblk_thaw,
1054        .restore        = dcssblk_restore,
1055};
1056
1057static struct platform_driver dcssblk_pdrv = {
1058        .driver = {
1059                .name   = "dcssblk",
1060                .pm     = &dcssblk_pm_ops,
1061        },
1062};
1063
1064static struct platform_device *dcssblk_pdev;
1065
1066
1067/*
1068 * The init/exit functions.
1069 */
1070static void __exit
1071dcssblk_exit(void)
1072{
1073        platform_device_unregister(dcssblk_pdev);
1074        platform_driver_unregister(&dcssblk_pdrv);
1075        root_device_unregister(dcssblk_root_dev);
1076        unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1077}
1078
1079static int __init
1080dcssblk_init(void)
1081{
1082        int rc;
1083
1084        rc = platform_driver_register(&dcssblk_pdrv);
1085        if (rc)
1086                return rc;
1087
1088        dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1089                                                        0);
1090        if (IS_ERR(dcssblk_pdev)) {
1091                rc = PTR_ERR(dcssblk_pdev);
1092                goto out_pdrv;
1093        }
1094
1095        dcssblk_root_dev = root_device_register("dcssblk");
1096        if (IS_ERR(dcssblk_root_dev)) {
1097                rc = PTR_ERR(dcssblk_root_dev);
1098                goto out_pdev;
1099        }
1100        rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1101        if (rc)
1102                goto out_root;
1103        rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1104        if (rc)
1105                goto out_root;
1106        rc = register_blkdev(0, DCSSBLK_NAME);
1107        if (rc < 0)
1108                goto out_root;
1109        dcssblk_major = rc;
1110        init_rwsem(&dcssblk_devices_sem);
1111
1112        dcssblk_check_params();
1113        return 0;
1114
1115out_root:
1116        root_device_unregister(dcssblk_root_dev);
1117out_pdev:
1118        platform_device_unregister(dcssblk_pdev);
1119out_pdrv:
1120        platform_driver_unregister(&dcssblk_pdrv);
1121        return rc;
1122}
1123
1124module_init(dcssblk_init);
1125module_exit(dcssblk_exit);
1126
1127module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1128MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1129                 "comma-separated list, names in each set separated "
1130                 "by commas are separated by colons, each set contains "
1131                 "names of contiguous segments and each name max. 8 chars.\n"
1132                 "Adding \"(local)\" to the end of each set equals echoing 0 "
1133                 "to /sys/devices/dcssblk/<device name>/shared after loading "
1134                 "the contiguous segments - \n"
1135                 "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1136
1137MODULE_LICENSE("GPL");
1138