linux/drivers/s390/block/dcssblk.c
<<
>>
Prefs
   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_submit_bio(struct bio *bio);
  35static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
  36                long nr_pages, void **kaddr, pfn_t *pfn);
  37
  38static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  39
  40static int dcssblk_major;
  41static 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
  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 int dcssblk_dax_zero_page_range(struct dax_device *dax_dev,
  61                                       pgoff_t pgoff, size_t nr_pages)
  62{
  63        long rc;
  64        void *kaddr;
  65
  66        rc = dax_direct_access(dax_dev, pgoff, nr_pages, &kaddr, NULL);
  67        if (rc < 0)
  68                return rc;
  69        memset(kaddr, 0, nr_pages << PAGE_SHIFT);
  70        dax_flush(dax_dev, kaddr, nr_pages << PAGE_SHIFT);
  71        return 0;
  72}
  73
  74static const struct dax_operations dcssblk_dax_ops = {
  75        .direct_access = dcssblk_dax_direct_access,
  76        .dax_supported = generic_fsdax_supported,
  77        .copy_from_iter = dcssblk_dax_copy_from_iter,
  78        .copy_to_iter = dcssblk_dax_copy_to_iter,
  79        .zero_page_range = dcssblk_dax_zero_page_range,
  80};
  81
  82struct dcssblk_dev_info {
  83        struct list_head lh;
  84        struct device dev;
  85        char segment_name[DCSS_BUS_ID_SIZE];
  86        atomic_t use_count;
  87        struct gendisk *gd;
  88        unsigned long start;
  89        unsigned long end;
  90        int segment_type;
  91        unsigned char save_pending;
  92        unsigned char is_shared;
  93        struct request_queue *dcssblk_queue;
  94        int num_of_segments;
  95        struct list_head seg_list;
  96        struct dax_device *dax_dev;
  97};
  98
  99struct segment_info {
 100        struct list_head lh;
 101        char segment_name[DCSS_BUS_ID_SIZE];
 102        unsigned long start;
 103        unsigned long end;
 104        int segment_type;
 105};
 106
 107static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
 108                                  size_t count);
 109static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
 110                                  size_t count);
 111
 112static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
 113static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
 114
 115static struct device *dcssblk_root_dev;
 116
 117static LIST_HEAD(dcssblk_devices);
 118static struct rw_semaphore dcssblk_devices_sem;
 119
 120/*
 121 * release function for segment device.
 122 */
 123static void
 124dcssblk_release_segment(struct device *dev)
 125{
 126        struct dcssblk_dev_info *dev_info;
 127        struct segment_info *entry, *temp;
 128
 129        dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 130        list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
 131                list_del(&entry->lh);
 132                kfree(entry);
 133        }
 134        kfree(dev_info);
 135        module_put(THIS_MODULE);
 136}
 137
 138/*
 139 * get a minor number. needs to be called with
 140 * down_write(&dcssblk_devices_sem) and the
 141 * device needs to be enqueued before the semaphore is
 142 * freed.
 143 */
 144static int
 145dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 146{
 147        int minor, found;
 148        struct dcssblk_dev_info *entry;
 149
 150        if (dev_info == NULL)
 151                return -EINVAL;
 152        for (minor = 0; minor < (1<<MINORBITS); minor++) {
 153                found = 0;
 154                // test if minor available
 155                list_for_each_entry(entry, &dcssblk_devices, lh)
 156                        if (minor == entry->gd->first_minor)
 157                                found++;
 158                if (!found) break; // got unused minor
 159        }
 160        if (found)
 161                return -EBUSY;
 162        dev_info->gd->first_minor = minor;
 163        return 0;
 164}
 165
 166/*
 167 * get the struct dcssblk_dev_info from dcssblk_devices
 168 * for the given name.
 169 * down_read(&dcssblk_devices_sem) must be held.
 170 */
 171static struct dcssblk_dev_info *
 172dcssblk_get_device_by_name(char *name)
 173{
 174        struct dcssblk_dev_info *entry;
 175
 176        list_for_each_entry(entry, &dcssblk_devices, lh) {
 177                if (!strcmp(name, entry->segment_name)) {
 178                        return entry;
 179                }
 180        }
 181        return NULL;
 182}
 183
 184/*
 185 * get the struct segment_info from seg_list
 186 * for the given name.
 187 * down_read(&dcssblk_devices_sem) must be held.
 188 */
 189static struct segment_info *
 190dcssblk_get_segment_by_name(char *name)
 191{
 192        struct dcssblk_dev_info *dev_info;
 193        struct segment_info *entry;
 194
 195        list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 196                list_for_each_entry(entry, &dev_info->seg_list, lh) {
 197                        if (!strcmp(name, entry->segment_name))
 198                                return entry;
 199                }
 200        }
 201        return NULL;
 202}
 203
 204/*
 205 * get the highest address of the multi-segment block.
 206 */
 207static unsigned long
 208dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 209{
 210        unsigned long highest_addr;
 211        struct segment_info *entry;
 212
 213        highest_addr = 0;
 214        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 215                if (highest_addr < entry->end)
 216                        highest_addr = entry->end;
 217        }
 218        return highest_addr;
 219}
 220
 221/*
 222 * get the lowest address of the multi-segment block.
 223 */
 224static unsigned long
 225dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 226{
 227        int set_first;
 228        unsigned long lowest_addr;
 229        struct segment_info *entry;
 230
 231        set_first = 0;
 232        lowest_addr = 0;
 233        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 234                if (set_first == 0) {
 235                        lowest_addr = entry->start;
 236                        set_first = 1;
 237                } else {
 238                        if (lowest_addr > entry->start)
 239                                lowest_addr = entry->start;
 240                }
 241        }
 242        return lowest_addr;
 243}
 244
 245/*
 246 * Check continuity of segments.
 247 */
 248static int
 249dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 250{
 251        int i, j, rc;
 252        struct segment_info *sort_list, *entry, temp;
 253
 254        if (dev_info->num_of_segments <= 1)
 255                return 0;
 256
 257        sort_list = kcalloc(dev_info->num_of_segments,
 258                            sizeof(struct segment_info),
 259                            GFP_KERNEL);
 260        if (sort_list == NULL)
 261                return -ENOMEM;
 262        i = 0;
 263        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 264                memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 265                i++;
 266        }
 267
 268        /* sort segments */
 269        for (i = 0; i < dev_info->num_of_segments; i++)
 270                for (j = 0; j < dev_info->num_of_segments; j++)
 271                        if (sort_list[j].start > sort_list[i].start) {
 272                                memcpy(&temp, &sort_list[i],
 273                                        sizeof(struct segment_info));
 274                                memcpy(&sort_list[i], &sort_list[j],
 275                                        sizeof(struct segment_info));
 276                                memcpy(&sort_list[j], &temp,
 277                                        sizeof(struct segment_info));
 278                        }
 279
 280        /* check continuity */
 281        for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 282                if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 283                        pr_err("Adjacent DCSSs %s and %s are not "
 284                               "contiguous\n", sort_list[i].segment_name,
 285                               sort_list[i+1].segment_name);
 286                        rc = -EINVAL;
 287                        goto out;
 288                }
 289                /* EN and EW are allowed in a block device */
 290                if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 291                        if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 292                                (sort_list[i].segment_type == SEG_TYPE_ER) ||
 293                                !(sort_list[i+1].segment_type &
 294                                SEGMENT_EXCLUSIVE) ||
 295                                (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 296                                pr_err("DCSS %s and DCSS %s have "
 297                                       "incompatible types\n",
 298                                       sort_list[i].segment_name,
 299                                       sort_list[i+1].segment_name);
 300                                rc = -EINVAL;
 301                                goto out;
 302                        }
 303                }
 304        }
 305        rc = 0;
 306out:
 307        kfree(sort_list);
 308        return rc;
 309}
 310
 311/*
 312 * Load a segment
 313 */
 314static int
 315dcssblk_load_segment(char *name, struct segment_info **seg_info)
 316{
 317        int rc;
 318
 319        /* already loaded? */
 320        down_read(&dcssblk_devices_sem);
 321        *seg_info = dcssblk_get_segment_by_name(name);
 322        up_read(&dcssblk_devices_sem);
 323        if (*seg_info != NULL)
 324                return -EEXIST;
 325
 326        /* get a struct segment_info */
 327        *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 328        if (*seg_info == NULL)
 329                return -ENOMEM;
 330
 331        strcpy((*seg_info)->segment_name, name);
 332
 333        /* load the segment */
 334        rc = segment_load(name, SEGMENT_SHARED,
 335                        &(*seg_info)->start, &(*seg_info)->end);
 336        if (rc < 0) {
 337                segment_warning(rc, (*seg_info)->segment_name);
 338                kfree(*seg_info);
 339        } else {
 340                INIT_LIST_HEAD(&(*seg_info)->lh);
 341                (*seg_info)->segment_type = rc;
 342        }
 343        return rc;
 344}
 345
 346/*
 347 * device attribute for switching shared/nonshared (exclusive)
 348 * operation (show + store)
 349 */
 350static ssize_t
 351dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 352{
 353        struct dcssblk_dev_info *dev_info;
 354
 355        dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 356        return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 357}
 358
 359static ssize_t
 360dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 361{
 362        struct dcssblk_dev_info *dev_info;
 363        struct segment_info *entry, *temp;
 364        int rc;
 365
 366        if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 367                return -EINVAL;
 368        down_write(&dcssblk_devices_sem);
 369        dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 370        if (atomic_read(&dev_info->use_count)) {
 371                rc = -EBUSY;
 372                goto out;
 373        }
 374        if (inbuf[0] == '1') {
 375                /* reload segments in shared mode */
 376                list_for_each_entry(entry, &dev_info->seg_list, lh) {
 377                        rc = segment_modify_shared(entry->segment_name,
 378                                                SEGMENT_SHARED);
 379                        if (rc < 0) {
 380                                BUG_ON(rc == -EINVAL);
 381                                if (rc != -EAGAIN)
 382                                        goto removeseg;
 383                        }
 384                }
 385                dev_info->is_shared = 1;
 386                switch (dev_info->segment_type) {
 387                case SEG_TYPE_SR:
 388                case SEG_TYPE_ER:
 389                case SEG_TYPE_SC:
 390                        set_disk_ro(dev_info->gd, 1);
 391                }
 392        } else if (inbuf[0] == '0') {
 393                /* reload segments in exclusive mode */
 394                if (dev_info->segment_type == SEG_TYPE_SC) {
 395                        pr_err("DCSS %s is of type SC and cannot be "
 396                               "loaded as exclusive-writable\n",
 397                               dev_info->segment_name);
 398                        rc = -EINVAL;
 399                        goto out;
 400                }
 401                list_for_each_entry(entry, &dev_info->seg_list, lh) {
 402                        rc = segment_modify_shared(entry->segment_name,
 403                                                   SEGMENT_EXCLUSIVE);
 404                        if (rc < 0) {
 405                                BUG_ON(rc == -EINVAL);
 406                                if (rc != -EAGAIN)
 407                                        goto removeseg;
 408                        }
 409                }
 410                dev_info->is_shared = 0;
 411                set_disk_ro(dev_info->gd, 0);
 412        } else {
 413                rc = -EINVAL;
 414                goto out;
 415        }
 416        rc = count;
 417        goto out;
 418
 419removeseg:
 420        pr_err("DCSS device %s is removed after a failed access mode "
 421               "change\n", dev_info->segment_name);
 422        temp = entry;
 423        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 424                if (entry != temp)
 425                        segment_unload(entry->segment_name);
 426        }
 427        list_del(&dev_info->lh);
 428
 429        kill_dax(dev_info->dax_dev);
 430        put_dax(dev_info->dax_dev);
 431        del_gendisk(dev_info->gd);
 432        blk_cleanup_queue(dev_info->dcssblk_queue);
 433        dev_info->gd->queue = NULL;
 434        put_disk(dev_info->gd);
 435        up_write(&dcssblk_devices_sem);
 436
 437        if (device_remove_file_self(dev, attr)) {
 438                device_unregister(dev);
 439                put_device(dev);
 440        }
 441        return rc;
 442out:
 443        up_write(&dcssblk_devices_sem);
 444        return rc;
 445}
 446static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 447                   dcssblk_shared_store);
 448
 449/*
 450 * device attribute for save operation on current copy
 451 * of the segment. If the segment is busy, saving will
 452 * become pending until it gets released, which can be
 453 * undone by storing a non-true value to this entry.
 454 * (show + store)
 455 */
 456static ssize_t
 457dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 458{
 459        struct dcssblk_dev_info *dev_info;
 460
 461        dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 462        return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 463}
 464
 465static ssize_t
 466dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 467{
 468        struct dcssblk_dev_info *dev_info;
 469        struct segment_info *entry;
 470
 471        if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 472                return -EINVAL;
 473        dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 474
 475        down_write(&dcssblk_devices_sem);
 476        if (inbuf[0] == '1') {
 477                if (atomic_read(&dev_info->use_count) == 0) {
 478                        // device is idle => we save immediately
 479                        pr_info("All DCSSs that map to device %s are "
 480                                "saved\n", dev_info->segment_name);
 481                        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 482                                if (entry->segment_type == SEG_TYPE_EN ||
 483                                    entry->segment_type == SEG_TYPE_SN)
 484                                        pr_warn("DCSS %s is of type SN or EN"
 485                                                " and cannot be saved\n",
 486                                                entry->segment_name);
 487                                else
 488                                        segment_save(entry->segment_name);
 489                        }
 490                }  else {
 491                        // device is busy => we save it when it becomes
 492                        // idle in dcssblk_release
 493                        pr_info("Device %s is in use, its DCSSs will be "
 494                                "saved when it becomes idle\n",
 495                                dev_info->segment_name);
 496                        dev_info->save_pending = 1;
 497                }
 498        } else if (inbuf[0] == '0') {
 499                if (dev_info->save_pending) {
 500                        // device is busy & the user wants to undo his save
 501                        // request
 502                        dev_info->save_pending = 0;
 503                        pr_info("A pending save request for device %s "
 504                                "has been canceled\n",
 505                                dev_info->segment_name);
 506                }
 507        } else {
 508                up_write(&dcssblk_devices_sem);
 509                return -EINVAL;
 510        }
 511        up_write(&dcssblk_devices_sem);
 512        return count;
 513}
 514static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 515                   dcssblk_save_store);
 516
 517/*
 518 * device attribute for showing all segments in a device
 519 */
 520static ssize_t
 521dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 522                char *buf)
 523{
 524        int i;
 525
 526        struct dcssblk_dev_info *dev_info;
 527        struct segment_info *entry;
 528
 529        down_read(&dcssblk_devices_sem);
 530        dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 531        i = 0;
 532        buf[0] = '\0';
 533        list_for_each_entry(entry, &dev_info->seg_list, lh) {
 534                strcpy(&buf[i], entry->segment_name);
 535                i += strlen(entry->segment_name);
 536                buf[i] = '\n';
 537                i++;
 538        }
 539        up_read(&dcssblk_devices_sem);
 540        return i;
 541}
 542static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 543
 544static struct attribute *dcssblk_dev_attrs[] = {
 545        &dev_attr_shared.attr,
 546        &dev_attr_save.attr,
 547        &dev_attr_seglist.attr,
 548        NULL,
 549};
 550static struct attribute_group dcssblk_dev_attr_group = {
 551        .attrs = dcssblk_dev_attrs,
 552};
 553static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 554        &dcssblk_dev_attr_group,
 555        NULL,
 556};
 557
 558/*
 559 * device attribute for adding devices
 560 */
 561static ssize_t
 562dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 563{
 564        int rc, i, j, num_of_segments;
 565        struct dcssblk_dev_info *dev_info;
 566        struct segment_info *seg_info, *temp;
 567        char *local_buf;
 568        unsigned long seg_byte_size;
 569
 570        dev_info = NULL;
 571        seg_info = NULL;
 572        if (dev != dcssblk_root_dev) {
 573                rc = -EINVAL;
 574                goto out_nobuf;
 575        }
 576        if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 577                rc = -ENAMETOOLONG;
 578                goto out_nobuf;
 579        }
 580
 581        local_buf = kmalloc(count + 1, GFP_KERNEL);
 582        if (local_buf == NULL) {
 583                rc = -ENOMEM;
 584                goto out_nobuf;
 585        }
 586
 587        /*
 588         * parse input
 589         */
 590        num_of_segments = 0;
 591        for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 592                for (j = i; j < count &&
 593                        (buf[j] != ':') &&
 594                        (buf[j] != '\0') &&
 595                        (buf[j] != '\n'); j++) {
 596                        local_buf[j-i] = toupper(buf[j]);
 597                }
 598                local_buf[j-i] = '\0';
 599                if (((j - i) == 0) || ((j - i) > 8)) {
 600                        rc = -ENAMETOOLONG;
 601                        goto seg_list_del;
 602                }
 603
 604                rc = dcssblk_load_segment(local_buf, &seg_info);
 605                if (rc < 0)
 606                        goto seg_list_del;
 607                /*
 608                 * get a struct dcssblk_dev_info
 609                 */
 610                if (num_of_segments == 0) {
 611                        dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 612                                        GFP_KERNEL);
 613                        if (dev_info == NULL) {
 614                                rc = -ENOMEM;
 615                                goto out;
 616                        }
 617                        strcpy(dev_info->segment_name, local_buf);
 618                        dev_info->segment_type = seg_info->segment_type;
 619                        INIT_LIST_HEAD(&dev_info->seg_list);
 620                }
 621                list_add_tail(&seg_info->lh, &dev_info->seg_list);
 622                num_of_segments++;
 623                i = j;
 624
 625                if ((buf[j] == '\0') || (buf[j] == '\n'))
 626                        break;
 627        }
 628
 629        /* no trailing colon at the end of the input */
 630        if ((i > 0) && (buf[i-1] == ':')) {
 631                rc = -ENAMETOOLONG;
 632                goto seg_list_del;
 633        }
 634        strlcpy(local_buf, buf, i + 1);
 635        dev_info->num_of_segments = num_of_segments;
 636        rc = dcssblk_is_continuous(dev_info);
 637        if (rc < 0)
 638                goto seg_list_del;
 639
 640        dev_info->start = dcssblk_find_lowest_addr(dev_info);
 641        dev_info->end = dcssblk_find_highest_addr(dev_info);
 642
 643        dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 644        dev_info->dev.release = dcssblk_release_segment;
 645        dev_info->dev.groups = dcssblk_dev_attr_groups;
 646        INIT_LIST_HEAD(&dev_info->lh);
 647        dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 648        if (dev_info->gd == NULL) {
 649                rc = -ENOMEM;
 650                goto seg_list_del;
 651        }
 652        dev_info->gd->major = dcssblk_major;
 653        dev_info->gd->fops = &dcssblk_devops;
 654        dev_info->dcssblk_queue = blk_alloc_queue(NUMA_NO_NODE);
 655        dev_info->gd->queue = dev_info->dcssblk_queue;
 656        dev_info->gd->private_data = dev_info;
 657        blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 658        blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->dcssblk_queue);
 659
 660        seg_byte_size = (dev_info->end - dev_info->start + 1);
 661        set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 662        pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 663                "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 664
 665        dev_info->save_pending = 0;
 666        dev_info->is_shared = 1;
 667        dev_info->dev.parent = dcssblk_root_dev;
 668
 669        /*
 670         *get minor, add to list
 671         */
 672        down_write(&dcssblk_devices_sem);
 673        if (dcssblk_get_segment_by_name(local_buf)) {
 674                rc = -EEXIST;
 675                goto release_gd;
 676        }
 677        rc = dcssblk_assign_free_minor(dev_info);
 678        if (rc)
 679                goto release_gd;
 680        sprintf(dev_info->gd->disk_name, "dcssblk%d",
 681                dev_info->gd->first_minor);
 682        list_add_tail(&dev_info->lh, &dcssblk_devices);
 683
 684        if (!try_module_get(THIS_MODULE)) {
 685                rc = -ENODEV;
 686                goto dev_list_del;
 687        }
 688        /*
 689         * register the device
 690         */
 691        rc = device_register(&dev_info->dev);
 692        if (rc)
 693                goto put_dev;
 694
 695        dev_info->dax_dev = alloc_dax(dev_info, dev_info->gd->disk_name,
 696                        &dcssblk_dax_ops, DAXDEV_F_SYNC);
 697        if (IS_ERR(dev_info->dax_dev)) {
 698                rc = PTR_ERR(dev_info->dax_dev);
 699                dev_info->dax_dev = NULL;
 700                goto put_dev;
 701        }
 702
 703        get_device(&dev_info->dev);
 704        device_add_disk(&dev_info->dev, dev_info->gd, NULL);
 705
 706        switch (dev_info->segment_type) {
 707                case SEG_TYPE_SR:
 708                case SEG_TYPE_ER:
 709                case SEG_TYPE_SC:
 710                        set_disk_ro(dev_info->gd,1);
 711                        break;
 712                default:
 713                        set_disk_ro(dev_info->gd,0);
 714                        break;
 715        }
 716        up_write(&dcssblk_devices_sem);
 717        rc = count;
 718        goto out;
 719
 720put_dev:
 721        list_del(&dev_info->lh);
 722        blk_cleanup_queue(dev_info->dcssblk_queue);
 723        dev_info->gd->queue = NULL;
 724        put_disk(dev_info->gd);
 725        list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 726                segment_unload(seg_info->segment_name);
 727        }
 728        put_device(&dev_info->dev);
 729        up_write(&dcssblk_devices_sem);
 730        goto out;
 731dev_list_del:
 732        list_del(&dev_info->lh);
 733release_gd:
 734        blk_cleanup_queue(dev_info->dcssblk_queue);
 735        dev_info->gd->queue = NULL;
 736        put_disk(dev_info->gd);
 737        up_write(&dcssblk_devices_sem);
 738seg_list_del:
 739        if (dev_info == NULL)
 740                goto out;
 741        list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 742                list_del(&seg_info->lh);
 743                segment_unload(seg_info->segment_name);
 744                kfree(seg_info);
 745        }
 746        kfree(dev_info);
 747out:
 748        kfree(local_buf);
 749out_nobuf:
 750        return rc;
 751}
 752
 753/*
 754 * device attribute for removing devices
 755 */
 756static ssize_t
 757dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 758{
 759        struct dcssblk_dev_info *dev_info;
 760        struct segment_info *entry;
 761        int rc, i;
 762        char *local_buf;
 763
 764        if (dev != dcssblk_root_dev) {
 765                return -EINVAL;
 766        }
 767        local_buf = kmalloc(count + 1, GFP_KERNEL);
 768        if (local_buf == NULL) {
 769                return -ENOMEM;
 770        }
 771        /*
 772         * parse input
 773         */
 774        for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 775                local_buf[i] = toupper(buf[i]);
 776        }
 777        local_buf[i] = '\0';
 778        if ((i == 0) || (i > 8)) {
 779                rc = -ENAMETOOLONG;
 780                goto out_buf;
 781        }
 782
 783        down_write(&dcssblk_devices_sem);
 784        dev_info = dcssblk_get_device_by_name(local_buf);
 785        if (dev_info == NULL) {
 786                up_write(&dcssblk_devices_sem);
 787                pr_warn("Device %s cannot be removed because it is not a known device\n",
 788                        local_buf);
 789                rc = -ENODEV;
 790                goto out_buf;
 791        }
 792        if (atomic_read(&dev_info->use_count) != 0) {
 793                up_write(&dcssblk_devices_sem);
 794                pr_warn("Device %s cannot be removed while it is in use\n",
 795                        local_buf);
 796                rc = -EBUSY;
 797                goto out_buf;
 798        }
 799
 800        list_del(&dev_info->lh);
 801        kill_dax(dev_info->dax_dev);
 802        put_dax(dev_info->dax_dev);
 803        del_gendisk(dev_info->gd);
 804        blk_cleanup_queue(dev_info->dcssblk_queue);
 805        dev_info->gd->queue = NULL;
 806        put_disk(dev_info->gd);
 807
 808        /* unload all related segments */
 809        list_for_each_entry(entry, &dev_info->seg_list, lh)
 810                segment_unload(entry->segment_name);
 811
 812        up_write(&dcssblk_devices_sem);
 813
 814        device_unregister(&dev_info->dev);
 815        put_device(&dev_info->dev);
 816
 817        rc = count;
 818out_buf:
 819        kfree(local_buf);
 820        return rc;
 821}
 822
 823static int
 824dcssblk_open(struct block_device *bdev, fmode_t mode)
 825{
 826        struct dcssblk_dev_info *dev_info;
 827        int rc;
 828
 829        dev_info = bdev->bd_disk->private_data;
 830        if (NULL == dev_info) {
 831                rc = -ENODEV;
 832                goto out;
 833        }
 834        atomic_inc(&dev_info->use_count);
 835        rc = 0;
 836out:
 837        return rc;
 838}
 839
 840static void
 841dcssblk_release(struct gendisk *disk, fmode_t mode)
 842{
 843        struct dcssblk_dev_info *dev_info = disk->private_data;
 844        struct segment_info *entry;
 845
 846        if (!dev_info) {
 847                WARN_ON(1);
 848                return;
 849        }
 850        down_write(&dcssblk_devices_sem);
 851        if (atomic_dec_and_test(&dev_info->use_count)
 852            && (dev_info->save_pending)) {
 853                pr_info("Device %s has become idle and is being saved "
 854                        "now\n", dev_info->segment_name);
 855                list_for_each_entry(entry, &dev_info->seg_list, lh) {
 856                        if (entry->segment_type == SEG_TYPE_EN ||
 857                            entry->segment_type == SEG_TYPE_SN)
 858                                pr_warn("DCSS %s is of type SN or EN and cannot"
 859                                        " be saved\n", entry->segment_name);
 860                        else
 861                                segment_save(entry->segment_name);
 862                }
 863                dev_info->save_pending = 0;
 864        }
 865        up_write(&dcssblk_devices_sem);
 866}
 867
 868static blk_qc_t
 869dcssblk_submit_bio(struct bio *bio)
 870{
 871        struct dcssblk_dev_info *dev_info;
 872        struct bio_vec bvec;
 873        struct bvec_iter iter;
 874        unsigned long index;
 875        unsigned long page_addr;
 876        unsigned long source_addr;
 877        unsigned long bytes_done;
 878
 879        blk_queue_split(&bio);
 880
 881        bytes_done = 0;
 882        dev_info = bio->bi_bdev->bd_disk->private_data;
 883        if (dev_info == NULL)
 884                goto fail;
 885        if ((bio->bi_iter.bi_sector & 7) != 0 ||
 886            (bio->bi_iter.bi_size & 4095) != 0)
 887                /* Request is not page-aligned. */
 888                goto fail;
 889        /* verify data transfer direction */
 890        if (dev_info->is_shared) {
 891                switch (dev_info->segment_type) {
 892                case SEG_TYPE_SR:
 893                case SEG_TYPE_ER:
 894                case SEG_TYPE_SC:
 895                        /* cannot write to these segments */
 896                        if (bio_data_dir(bio) == WRITE) {
 897                                pr_warn("Writing to %s failed because it is a read-only device\n",
 898                                        dev_name(&dev_info->dev));
 899                                goto fail;
 900                        }
 901                }
 902        }
 903
 904        index = (bio->bi_iter.bi_sector >> 3);
 905        bio_for_each_segment(bvec, bio, iter) {
 906                page_addr = (unsigned long)
 907                        page_address(bvec.bv_page) + bvec.bv_offset;
 908                source_addr = dev_info->start + (index<<12) + bytes_done;
 909                if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 910                        // More paranoia.
 911                        goto fail;
 912                if (bio_data_dir(bio) == READ) {
 913                        memcpy((void*)page_addr, (void*)source_addr,
 914                                bvec.bv_len);
 915                } else {
 916                        memcpy((void*)source_addr, (void*)page_addr,
 917                                bvec.bv_len);
 918                }
 919                bytes_done += bvec.bv_len;
 920        }
 921        bio_endio(bio);
 922        return BLK_QC_T_NONE;
 923fail:
 924        bio_io_error(bio);
 925        return BLK_QC_T_NONE;
 926}
 927
 928static long
 929__dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 930                long nr_pages, void **kaddr, pfn_t *pfn)
 931{
 932        resource_size_t offset = pgoff * PAGE_SIZE;
 933        unsigned long dev_sz;
 934
 935        dev_sz = dev_info->end - dev_info->start + 1;
 936        if (kaddr)
 937                *kaddr = (void *) dev_info->start + offset;
 938        if (pfn)
 939                *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
 940                                PFN_DEV|PFN_SPECIAL);
 941
 942        return (dev_sz - offset) / PAGE_SIZE;
 943}
 944
 945static long
 946dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 947                long nr_pages, void **kaddr, pfn_t *pfn)
 948{
 949        struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 950
 951        return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 952}
 953
 954static void
 955dcssblk_check_params(void)
 956{
 957        int rc, i, j, k;
 958        char buf[DCSSBLK_PARM_LEN + 1];
 959        struct dcssblk_dev_info *dev_info;
 960
 961        for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 962             i++) {
 963                for (j = i; (j < DCSSBLK_PARM_LEN) &&
 964                            (dcssblk_segments[j] != ',')  &&
 965                            (dcssblk_segments[j] != '\0') &&
 966                            (dcssblk_segments[j] != '('); j++)
 967                {
 968                        buf[j-i] = dcssblk_segments[j];
 969                }
 970                buf[j-i] = '\0';
 971                rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 972                if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 973                        for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 974                                buf[k] = toupper(buf[k]);
 975                        buf[k] = '\0';
 976                        if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 977                                down_read(&dcssblk_devices_sem);
 978                                dev_info = dcssblk_get_device_by_name(buf);
 979                                up_read(&dcssblk_devices_sem);
 980                                if (dev_info)
 981                                        dcssblk_shared_store(&dev_info->dev,
 982                                                             NULL, "0\n", 2);
 983                        }
 984                }
 985                while ((dcssblk_segments[j] != ',') &&
 986                       (dcssblk_segments[j] != '\0'))
 987                {
 988                        j++;
 989                }
 990                if (dcssblk_segments[j] == '\0')
 991                        break;
 992                i = j;
 993        }
 994}
 995
 996/*
 997 * Suspend / Resume
 998 */
 999static int dcssblk_freeze(struct device *dev)
1000{
1001        struct dcssblk_dev_info *dev_info;
1002        int rc = 0;
1003
1004        list_for_each_entry(dev_info, &dcssblk_devices, lh) {
1005                switch (dev_info->segment_type) {
1006                        case SEG_TYPE_SR:
1007                        case SEG_TYPE_ER:
1008                        case SEG_TYPE_SC:
1009                                if (!dev_info->is_shared)
1010                                        rc = -EINVAL;
1011                                break;
1012                        default:
1013                                rc = -EINVAL;
1014                                break;
1015                }
1016                if (rc)
1017                        break;
1018        }
1019        if (rc)
1020                pr_err("Suspending the system failed because DCSS device %s "
1021                       "is writable\n",
1022                       dev_info->segment_name);
1023        return rc;
1024}
1025
1026static int dcssblk_restore(struct device *dev)
1027{
1028        struct dcssblk_dev_info *dev_info;
1029        struct segment_info *entry;
1030        unsigned long start, end;
1031        int rc = 0;
1032
1033        list_for_each_entry(dev_info, &dcssblk_devices, lh) {
1034                list_for_each_entry(entry, &dev_info->seg_list, lh) {
1035                        segment_unload(entry->segment_name);
1036                        rc = segment_load(entry->segment_name, SEGMENT_SHARED,
1037                                          &start, &end);
1038                        if (rc < 0) {
1039// TODO in_use check ?
1040                                segment_warning(rc, entry->segment_name);
1041                                goto out_panic;
1042                        }
1043                        if (start != entry->start || end != entry->end) {
1044                                pr_err("The address range of DCSS %s changed "
1045                                       "while the system was suspended\n",
1046                                       entry->segment_name);
1047                                goto out_panic;
1048                        }
1049                }
1050        }
1051        return 0;
1052out_panic:
1053        panic("fatal dcssblk resume error\n");
1054}
1055
1056static int dcssblk_thaw(struct device *dev)
1057{
1058        return 0;
1059}
1060
1061static const struct dev_pm_ops dcssblk_pm_ops = {
1062        .freeze         = dcssblk_freeze,
1063        .thaw           = dcssblk_thaw,
1064        .restore        = dcssblk_restore,
1065};
1066
1067static struct platform_driver dcssblk_pdrv = {
1068        .driver = {
1069                .name   = "dcssblk",
1070                .pm     = &dcssblk_pm_ops,
1071        },
1072};
1073
1074static struct platform_device *dcssblk_pdev;
1075
1076
1077/*
1078 * The init/exit functions.
1079 */
1080static void __exit
1081dcssblk_exit(void)
1082{
1083        platform_device_unregister(dcssblk_pdev);
1084        platform_driver_unregister(&dcssblk_pdrv);
1085        root_device_unregister(dcssblk_root_dev);
1086        unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1087}
1088
1089static int __init
1090dcssblk_init(void)
1091{
1092        int rc;
1093
1094        rc = platform_driver_register(&dcssblk_pdrv);
1095        if (rc)
1096                return rc;
1097
1098        dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1099                                                        0);
1100        if (IS_ERR(dcssblk_pdev)) {
1101                rc = PTR_ERR(dcssblk_pdev);
1102                goto out_pdrv;
1103        }
1104
1105        dcssblk_root_dev = root_device_register("dcssblk");
1106        if (IS_ERR(dcssblk_root_dev)) {
1107                rc = PTR_ERR(dcssblk_root_dev);
1108                goto out_pdev;
1109        }
1110        rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1111        if (rc)
1112                goto out_root;
1113        rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1114        if (rc)
1115                goto out_root;
1116        rc = register_blkdev(0, DCSSBLK_NAME);
1117        if (rc < 0)
1118                goto out_root;
1119        dcssblk_major = rc;
1120        init_rwsem(&dcssblk_devices_sem);
1121
1122        dcssblk_check_params();
1123        return 0;
1124
1125out_root:
1126        root_device_unregister(dcssblk_root_dev);
1127out_pdev:
1128        platform_device_unregister(dcssblk_pdev);
1129out_pdrv:
1130        platform_driver_unregister(&dcssblk_pdrv);
1131        return rc;
1132}
1133
1134module_init(dcssblk_init);
1135module_exit(dcssblk_exit);
1136
1137module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1138MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1139                 "comma-separated list, names in each set separated "
1140                 "by commas are separated by colons, each set contains "
1141                 "names of contiguous segments and each name max. 8 chars.\n"
1142                 "Adding \"(local)\" to the end of each set equals echoing 0 "
1143                 "to /sys/devices/dcssblk/<device name>/shared after loading "
1144                 "the contiguous segments - \n"
1145                 "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1146
1147MODULE_LICENSE("GPL");
1148