drivers/staging/zram/zram_drv.c

   1 /*
   2  * Compressed RAM block device
   3  *
   4  * Copyright (C) 2008, 2009, 2010  Nitin Gupta
   5  *
   6  * This code is released using a dual license strategy: BSD/GPL
   7  * You can choose the licence that better fits your requirements.
   8  *
   9  * Released under the terms of 3-clause BSD License
  10  * Released under the terms of GNU General Public License Version 2.0
  11  *
  12  * Project home: http://compcache.googlecode.com
  13  */
  14
  15 #define KMSG_COMPONENT "zram"
  16 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  17
  18 #ifdef CONFIG_ZRAM_DEBUG
  19 #define DEBUG
  20 #endif
  21
  22 #include <linux/module.h>
  23 #include <linux/kernel.h>
  24 #include <linux/bio.h>
  25 #include <linux/bitops.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/device.h>
  29 #include <linux/genhd.h>
  30 #include <linux/highmem.h>
  31 #include <linux/slab.h>
  32 #include <linux/lzo.h>
  33 #include <linux/string.h>
  34 #include <linux/vmalloc.h>
  35
  36 #include "zram_drv.h"
  37
  38 /* Globals */
  39 static int zram_major;
  40 struct zram *zram_devices;
  41
  42 /* Module params (documentation at end) */
  43 static unsigned int num_devices = 1;
  44
  45 static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc)
  46 {
  47         spin_lock(&zram->stat64_lock);
  48         *v = *v + inc;
  49         spin_unlock(&zram->stat64_lock);
  50 }
  51
  52 static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec)
  53 {
  54         spin_lock(&zram->stat64_lock);
  55         *v = *v - dec;
  56         spin_unlock(&zram->stat64_lock);
  57 }
  58
  59 static void zram_stat64_inc(struct zram *zram, u64 *v)
  60 {
  61         zram_stat64_add(zram, v, 1);
  62 }
  63
  64 static int zram_test_flag(struct zram *zram, u32 index,
  65                         enum zram_pageflags flag)
  66 {
  67         return zram->table[index].flags & BIT(flag);
  68 }
  69
  70 static void zram_set_flag(struct zram *zram, u32 index,
  71                         enum zram_pageflags flag)
  72 {
  73         zram->table[index].flags |= BIT(flag);
  74 }
  75
  76 static void zram_clear_flag(struct zram *zram, u32 index,
  77                         enum zram_pageflags flag)
  78 {
  79         zram->table[index].flags &= ~BIT(flag);
  80 }
  81
  82 static int page_zero_filled(void *ptr)
  83 {
  84         unsigned int pos;
  85         unsigned long *page;
  86
  87         page = (unsigned long *)ptr;
  88
  89         for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
  90                 if (page[pos])
  91                         return 0;
  92         }
  93
  94         return 1;
  95 }
  96
  97 static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
  98 {
  99         if (!zram->disksize) {
 100                 pr_info(
 101                 "disk size not provided. You can use disksize_kb module "
 102                 "param to specify size.\nUsing default: (%u%% of RAM).\n",
 103                 default_disksize_perc_ram
 104                 );
 105                 zram->disksize = default_disksize_perc_ram *
 106                                         (totalram_bytes / 100);
 107         }
 108
 109         if (zram->disksize > 2 * (totalram_bytes)) {
 110                 pr_info(
 111                 "There is little point creating a zram of greater than "
 112                 "twice the size of memory since we expect a 2:1 compression "
 113                 "ratio. Note that zram uses about 0.1%% of the size of "
 114                 "the disk when not in use so a huge zram is "
 115                 "wasteful.\n"
 116                 "\tMemory Size: %zu kB\n"
 117                 "\tSize you selected: %llu kB\n"
 118                 "Continuing anyway ...\n",
 119                 totalram_bytes >> 10, zram->disksize >> 10);
 120         }
 121
 122         zram->disksize &= PAGE_MASK;
 123 }
 124
 125 static void zram_free_page(struct zram *zram, size_t index)
 126 {
 127         unsigned long handle = zram->table[index].handle;
 128         u16 size = zram->table[index].size;
 129
 130         if (unlikely(!handle)) {
 131                 /*
 132                  * No memory is allocated for zero filled pages.
 133                  * Simply clear zero page flag.
 134                  */
 135                 if (zram_test_flag(zram, index, ZRAM_ZERO)) {
 136                         zram_clear_flag(zram, index, ZRAM_ZERO);
 137                         zram->stats.pages_zero--;
 138                 }
 139                 return;
 140         }
 141
 142         if (unlikely(size > max_zpage_size))
 143                 zram->stats.bad_compress--;
 144
 145         zs_free(zram->mem_pool, handle);
 146
 147         if (size <= PAGE_SIZE / 2)
 148                 zram->stats.good_compress--;
 149
 150         zram_stat64_sub(zram, &zram->stats.compr_size,
 151                         zram->table[index].size);
 152         zram->stats.pages_stored--;
 153
 154         zram->table[index].handle = 0;
 155         zram->table[index].size = 0;
 156 }
 157
 158 static void handle_zero_page(struct bio_vec *bvec)
 159 {
 160         struct page *page = bvec->bv_page;
 161         void *user_mem;
 162
 163         user_mem = kmap_atomic(page);
 164         memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
 165         kunmap_atomic(user_mem);
 166
 167         flush_dcache_page(page);
 168 }
 169
 170 static inline int is_partial_io(struct bio_vec *bvec)
 171 {
 172         return bvec->bv_len != PAGE_SIZE;
 173 }
 174
 175 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
 176 {
 177         int ret = LZO_E_OK;
 178         size_t clen = PAGE_SIZE;
 179         unsigned char *cmem;
 180         unsigned long handle = zram->table[index].handle;
 181
 182         if (!handle || zram_test_flag(zram, index, ZRAM_ZERO)) {
 183                 memset(mem, 0, PAGE_SIZE);
 184                 return 0;
 185         }
 186
 187         cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
 188         if (zram->table[index].size == PAGE_SIZE)
 189                 memcpy(mem, cmem, PAGE_SIZE);
 190         else
 191                 ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
 192                                                 mem, &clen);
 193         zs_unmap_object(zram->mem_pool, handle);
 194
 195         /* Should NEVER happen. Return bio error if it does. */
 196         if (unlikely(ret != LZO_E_OK)) {
 197                 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
 198                 zram_stat64_inc(zram, &zram->stats.failed_reads);
 199                 return ret;
 200         }
 201
 202         return 0;
 203 }
 204
 205 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 206                           u32 index, int offset, struct bio *bio)
 207 {
 208         int ret;
 209         struct page *page;
 210         unsigned char *user_mem, *uncmem = NULL;
 211
 212         page = bvec->bv_page;
 213
 214         if (unlikely(!zram->table[index].handle) ||
 215                         zram_test_flag(zram, index, ZRAM_ZERO)) {
 216                 handle_zero_page(bvec);
 217                 return 0;
 218         }
 219
 220         user_mem = kmap_atomic(page);
 221         if (is_partial_io(bvec))
 222                 /* Use  a temporary buffer to decompress the page */
 223                 uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
 224         else
 225                 uncmem = user_mem;
 226
 227         if (!uncmem) {
 228                 pr_info("Unable to allocate temp memory\n");
 229                 ret = -ENOMEM;
 230                 goto out_cleanup;
 231         }
 232
 233         ret = zram_decompress_page(zram, uncmem, index);
 234         /* Should NEVER happen. Return bio error if it does. */
 235         if (unlikely(ret != LZO_E_OK)) {
 236                 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
 237                 zram_stat64_inc(zram, &zram->stats.failed_reads);
 238                 goto out_cleanup;
 239         }
 240
 241         if (is_partial_io(bvec))
 242                 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
 243                                 bvec->bv_len);
 244
 245         flush_dcache_page(page);
 246         ret = 0;
 247 out_cleanup:
 248         kunmap_atomic(user_mem);
 249         if (is_partial_io(bvec))
 250                 kfree(uncmem);
 251         return ret;
 252 }
 253
 254 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 255                            int offset)
 256 {
 257         int ret;
 258         size_t clen;
 259         unsigned long handle;
 260         struct page *page;
 261         unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
 262
 263         page = bvec->bv_page;
 264         src = zram->compress_buffer;
 265
 266         if (is_partial_io(bvec)) {
 267                 /*
 268                  * This is a partial IO. We need to read the full page
 269                  * before to write the changes.
 270                  */
 271                 uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
 272                 if (!uncmem) {
 273                         pr_info("Error allocating temp memory!\n");
 274                         ret = -ENOMEM;
 275                         goto out;
 276                 }
 277                 ret = zram_decompress_page(zram, uncmem, index);
 278                 if (ret) {
 279                         kfree(uncmem);
 280                         goto out;
 281                 }
 282         }
 283
 284         /*
 285          * System overwrites unused sectors. Free memory associated
 286          * with this sector now.
 287          */
 288         if (zram->table[index].handle ||
 289             zram_test_flag(zram, index, ZRAM_ZERO))
 290                 zram_free_page(zram, index);
 291
 292         user_mem = kmap_atomic(page);
 293
 294         if (is_partial_io(bvec))
 295                 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
 296                        bvec->bv_len);
 297         else
 298                 uncmem = user_mem;
 299
 300         if (page_zero_filled(uncmem)) {
 301                 kunmap_atomic(user_mem);
 302                 if (is_partial_io(bvec))
 303                         kfree(uncmem);
 304                 zram->stats.pages_zero++;
 305                 zram_set_flag(zram, index, ZRAM_ZERO);
 306                 ret = 0;
 307                 goto out;
 308         }
 309
 310         ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
 311                                zram->compress_workmem);
 312
 313         kunmap_atomic(user_mem);
 314         if (is_partial_io(bvec))
 315                         kfree(uncmem);
 316
 317         if (unlikely(ret != LZO_E_OK)) {
 318                 pr_err("Compression failed! err=%d\n", ret);
 319                 goto out;
 320         }
 321
 322         if (unlikely(clen > max_zpage_size)) {
 323                 zram->stats.bad_compress++;
 324                 src = uncmem;
 325                 clen = PAGE_SIZE;
 326         }
 327
 328         handle = zs_malloc(zram->mem_pool, clen);
 329         if (!handle) {
 330                 pr_info("Error allocating memory for compressed "
 331                         "page: %u, size=%zu\n", index, clen);
 332                 ret = -ENOMEM;
 333                 goto out;
 334         }
 335         cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
 336
 337         memcpy(cmem, src, clen);
 338
 339         zs_unmap_object(zram->mem_pool, handle);
 340
 341         zram->table[index].handle = handle;
 342         zram->table[index].size = clen;
 343
 344         /* Update stats */
 345         zram_stat64_add(zram, &zram->stats.compr_size, clen);
 346         zram->stats.pages_stored++;
 347         if (clen <= PAGE_SIZE / 2)
 348                 zram->stats.good_compress++;
 349
 350         return 0;
 351
 352 out:
 353         if (ret)
 354                 zram_stat64_inc(zram, &zram->stats.failed_writes);
 355         return ret;
 356 }
 357
 358 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 359                         int offset, struct bio *bio, int rw)
 360 {
 361         int ret;
 362
 363         if (rw == READ) {
 364                 down_read(&zram->lock);
 365                 ret = zram_bvec_read(zram, bvec, index, offset, bio);
 366                 up_read(&zram->lock);
 367         } else {
 368                 down_write(&zram->lock);
 369                 ret = zram_bvec_write(zram, bvec, index, offset);
 370                 up_write(&zram->lock);
 371         }
 372
 373         return ret;
 374 }
 375
 376 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
 377 {
 378         if (*offset + bvec->bv_len >= PAGE_SIZE)
 379                 (*index)++;
 380         *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
 381 }
 382
 383 static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
 384 {
 385         int i, offset;
 386         u32 index;
 387         struct bio_vec *bvec;
 388
 389         switch (rw) {
 390         case READ:
 391                 zram_stat64_inc(zram, &zram->stats.num_reads);
 392                 break;
 393         case WRITE:
 394                 zram_stat64_inc(zram, &zram->stats.num_writes);
 395                 break;
 396         }
 397
 398         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 399         offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
 400
 401         bio_for_each_segment(bvec, bio, i) {
 402                 int max_transfer_size = PAGE_SIZE - offset;
 403
 404                 if (bvec->bv_len > max_transfer_size) {
 405                         /*
 406                          * zram_bvec_rw() can only make operation on a single
 407                          * zram page. Split the bio vector.
 408                          */
 409                         struct bio_vec bv;
 410
 411                         bv.bv_page = bvec->bv_page;
 412                         bv.bv_len = max_transfer_size;
 413                         bv.bv_offset = bvec->bv_offset;
 414
 415                         if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
 416                                 goto out;
 417
 418                         bv.bv_len = bvec->bv_len - max_transfer_size;
 419                         bv.bv_offset += max_transfer_size;
 420                         if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
 421                                 goto out;
 422                 } else
 423                         if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
 424                             < 0)
 425                                 goto out;
 426
 427                 update_position(&index, &offset, bvec);
 428         }
 429
 430         set_bit(BIO_UPTODATE, &bio->bi_flags);
 431         bio_endio(bio, 0);
 432         return;
 433
 434 out:
 435         bio_io_error(bio);
 436 }
 437
 438 /*
 439  * Check if request is within bounds and aligned on zram logical blocks.
 440  */
 441 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 442 {
 443         if (unlikely(
 444                 (bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
 445                 (bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
 446                 (bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
 447
 448                 return 0;
 449         }
 450
 451         /* I/O request is valid */
 452         return 1;
 453 }
 454
 455 /*
 456  * Handler function for all zram I/O requests.
 457  */
 458 static void zram_make_request(struct request_queue *queue, struct bio *bio)
 459 {
 460         struct zram *zram = queue->queuedata;
 461
 462         if (unlikely(!zram->init_done) && zram_init_device(zram))
 463                 goto error;
 464
 465         down_read(&zram->init_lock);
 466         if (unlikely(!zram->init_done))
 467                 goto error_unlock;
 468
 469         if (!valid_io_request(zram, bio)) {
 470                 zram_stat64_inc(zram, &zram->stats.invalid_io);
 471                 goto error_unlock;
 472         }
 473
 474         __zram_make_request(zram, bio, bio_data_dir(bio));
 475         up_read(&zram->init_lock);
 476
 477         return;
 478
 479 error_unlock:
 480         up_read(&zram->init_lock);
 481 error:
 482         bio_io_error(bio);
 483 }
 484
 485 void __zram_reset_device(struct zram *zram)
 486 {
 487         size_t index;
 488
 489         zram->init_done = 0;
 490
 491         /* Free various per-device buffers */
 492         kfree(zram->compress_workmem);
 493         free_pages((unsigned long)zram->compress_buffer, 1);
 494
 495         zram->compress_workmem = NULL;
 496         zram->compress_buffer = NULL;
 497
 498         /* Free all pages that are still in this zram device */
 499         for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 500                 unsigned long handle = zram->table[index].handle;
 501                 if (!handle)
 502                         continue;
 503
 504                 zs_free(zram->mem_pool, handle);
 505         }
 506
 507         vfree(zram->table);
 508         zram->table = NULL;
 509
 510         zs_destroy_pool(zram->mem_pool);
 511         zram->mem_pool = NULL;
 512
 513         /* Reset stats */
 514         memset(&zram->stats, 0, sizeof(zram->stats));
 515
 516         zram->disksize = 0;
 517 }
 518
 519 void zram_reset_device(struct zram *zram)
 520 {
 521         down_write(&zram->init_lock);
 522         __zram_reset_device(zram);
 523         up_write(&zram->init_lock);
 524 }
 525
 526 int zram_init_device(struct zram *zram)
 527 {
 528         int ret;
 529         size_t num_pages;
 530
 531         down_write(&zram->init_lock);
 532
 533         if (zram->init_done) {
 534                 up_write(&zram->init_lock);
 535                 return 0;
 536         }
 537
 538         zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
 539
 540         zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 541         if (!zram->compress_workmem) {
 542                 pr_err("Error allocating compressor working memory!\n");
 543                 ret = -ENOMEM;
 544                 goto fail_no_table;
 545         }
 546
 547         zram->compress_buffer =
 548                 (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
 549         if (!zram->compress_buffer) {
 550                 pr_err("Error allocating compressor buffer space\n");
 551                 ret = -ENOMEM;
 552                 goto fail_no_table;
 553         }
 554
 555         num_pages = zram->disksize >> PAGE_SHIFT;
 556         zram->table = vzalloc(num_pages * sizeof(*zram->table));
 557         if (!zram->table) {
 558                 pr_err("Error allocating zram address table\n");
 559                 ret = -ENOMEM;
 560                 goto fail_no_table;
 561         }
 562
 563         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
 564
 565         /* zram devices sort of resembles non-rotational disks */
 566         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 567
 568         zram->mem_pool = zs_create_pool("zram", GFP_NOIO | __GFP_HIGHMEM);
 569         if (!zram->mem_pool) {
 570                 pr_err("Error creating memory pool\n");
 571                 ret = -ENOMEM;
 572                 goto fail;
 573         }
 574
 575         zram->init_done = 1;
 576         up_write(&zram->init_lock);
 577
 578         pr_debug("Initialization done!\n");
 579         return 0;
 580
 581 fail_no_table:
 582         /* To prevent accessing table entries during cleanup */
 583         zram->disksize = 0;
 584 fail:
 585         __zram_reset_device(zram);
 586         up_write(&zram->init_lock);
 587         pr_err("Initialization failed: err=%d\n", ret);
 588         return ret;
 589 }
 590
 591 static void zram_slot_free_notify(struct block_device *bdev,
 592                                 unsigned long index)
 593 {
 594         struct zram *zram;
 595
 596         zram = bdev->bd_disk->private_data;
 597         zram_free_page(zram, index);
 598         zram_stat64_inc(zram, &zram->stats.notify_free);
 599 }
 600
 601 static const struct block_device_operations zram_devops = {
 602         .swap_slot_free_notify = zram_slot_free_notify,
 603         .owner = THIS_MODULE
 604 };
 605
 606 static int create_device(struct zram *zram, int device_id)
 607 {
 608         int ret = 0;
 609
 610         init_rwsem(&zram->lock);
 611         init_rwsem(&zram->init_lock);
 612         spin_lock_init(&zram->stat64_lock);
 613
 614         zram->queue = blk_alloc_queue(GFP_KERNEL);
 615         if (!zram->queue) {
 616                 pr_err("Error allocating disk queue for device %d\n",
 617                         device_id);
 618                 ret = -ENOMEM;
 619                 goto out;
 620         }
 621
 622         blk_queue_make_request(zram->queue, zram_make_request);
 623         zram->queue->queuedata = zram;
 624
 625          /* gendisk structure */
 626         zram->disk = alloc_disk(1);
 627         if (!zram->disk) {
 628                 blk_cleanup_queue(zram->queue);
 629                 pr_warn("Error allocating disk structure for device %d\n",
 630                         device_id);
 631                 ret = -ENOMEM;
 632                 goto out;
 633         }
 634
 635         zram->disk->major = zram_major;
 636         zram->disk->first_minor = device_id;
 637         zram->disk->fops = &zram_devops;
 638         zram->disk->queue = zram->queue;
 639         zram->disk->private_data = zram;
 640         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 641
 642         /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
 643         set_capacity(zram->disk, 0);
 644
 645         /*
 646          * To ensure that we always get PAGE_SIZE aligned
 647          * and n*PAGE_SIZED sized I/O requests.
 648          */
 649         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
 650         blk_queue_logical_block_size(zram->disk->queue,
 651                                         ZRAM_LOGICAL_BLOCK_SIZE);
 652         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
 653         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 654
 655         add_disk(zram->disk);
 656
 657         ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
 658                                 &zram_disk_attr_group);
 659         if (ret < 0) {
 660                 pr_warn("Error creating sysfs group");
 661                 goto out;
 662         }
 663
 664         zram->init_done = 0;
 665
 666 out:
 667         return ret;
 668 }
 669
 670 static void destroy_device(struct zram *zram)
 671 {
 672         sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
 673                         &zram_disk_attr_group);
 674
 675         if (zram->disk) {
 676                 del_gendisk(zram->disk);
 677                 put_disk(zram->disk);
 678         }
 679
 680         if (zram->queue)
 681                 blk_cleanup_queue(zram->queue);
 682 }
 683
 684 unsigned int zram_get_num_devices(void)
 685 {
 686         return num_devices;
 687 }
 688
 689 static int __init zram_init(void)
 690 {
 691         int ret, dev_id;
 692
 693         if (num_devices > max_num_devices) {
 694                 pr_warn("Invalid value for num_devices: %u\n",
 695                                 num_devices);
 696                 ret = -EINVAL;
 697                 goto out;
 698         }
 699
 700         zram_major = register_blkdev(0, "zram");
 701         if (zram_major <= 0) {
 702                 pr_warn("Unable to get major number\n");
 703                 ret = -EBUSY;
 704                 goto out;
 705         }
 706
 707         /* Allocate the device array and initialize each one */
 708         zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
 709         if (!zram_devices) {
 710                 ret = -ENOMEM;
 711                 goto unregister;
 712         }
 713
 714         for (dev_id = 0; dev_id < num_devices; dev_id++) {
 715                 ret = create_device(&zram_devices[dev_id], dev_id);
 716                 if (ret)
 717                         goto free_devices;
 718         }
 719
 720         pr_info("Created %u device(s) ...\n", num_devices);
 721
 722         return 0;
 723
 724 free_devices:
 725         while (dev_id)
 726                 destroy_device(&zram_devices[--dev_id]);
 727         kfree(zram_devices);
 728 unregister:
 729         unregister_blkdev(zram_major, "zram");
 730 out:
 731         return ret;
 732 }
 733
 734 static void __exit zram_exit(void)
 735 {
 736         int i;
 737         struct zram *zram;
 738
 739         for (i = 0; i < num_devices; i++) {
 740                 zram = &zram_devices[i];
 741
 742                 destroy_device(zram);
 743                 if (zram->init_done)
 744                         zram_reset_device(zram);
 745         }
 746
 747         unregister_blkdev(zram_major, "zram");
 748
 749         kfree(zram_devices);
 750         pr_debug("Cleanup done!\n");
 751 }
 752
 753 module_param(num_devices, uint, 0);
 754 MODULE_PARM_DESC(num_devices, "Number of zram devices");
 755
 756 module_init(zram_init);
 757 module_exit(zram_exit);
 758
 759 MODULE_LICENSE("Dual BSD/GPL");
 760 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 761 MODULE_DESCRIPTION("Compressed RAM Block Device");