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 = 0;
 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                         goto out;
 280         }
 281
 282         /*
 283          * System overwrites unused sectors. Free memory associated
 284          * with this sector now.
 285          */
 286         if (zram->table[index].handle ||
 287             zram_test_flag(zram, index, ZRAM_ZERO))
 288                 zram_free_page(zram, index);
 289
 290         user_mem = kmap_atomic(page);
 291
 292         if (is_partial_io(bvec)) {
 293                 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
 294                        bvec->bv_len);
 295                 kunmap_atomic(user_mem);
 296                 user_mem = NULL;
 297         } else {
 298                 uncmem = user_mem;
 299         }
 300
 301         if (page_zero_filled(uncmem)) {
 302                 kunmap_atomic(user_mem);
 303                 if (is_partial_io(bvec))
 304                         kfree(uncmem);
 305                 zram->stats.pages_zero++;
 306                 zram_set_flag(zram, index, ZRAM_ZERO);
 307                 ret = 0;
 308                 goto out;
 309         }
 310
 311         ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
 312                                zram->compress_workmem);
 313
 314         if (!is_partial_io(bvec)) {
 315                 kunmap_atomic(user_mem);
 316                 user_mem = NULL;
 317                 uncmem = NULL;
 318         }
 319
 320         if (unlikely(ret != LZO_E_OK)) {
 321                 pr_err("Compression failed! err=%d\n", ret);
 322                 goto out;
 323         }
 324
 325         if (unlikely(clen > max_zpage_size)) {
 326                 zram->stats.bad_compress++;
 327                 clen = PAGE_SIZE;
 328                 src = NULL;
 329                 if (is_partial_io(bvec))
 330                         src = uncmem;
 331         }
 332
 333         handle = zs_malloc(zram->mem_pool, clen);
 334         if (!handle) {
 335                 pr_info("Error allocating memory for compressed "
 336                         "page: %u, size=%zu\n", index, clen);
 337                 ret = -ENOMEM;
 338                 goto out;
 339         }
 340         cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
 341
 342         if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
 343                 src = kmap_atomic(page);
 344         memcpy(cmem, src, clen);
 345         if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
 346                 kunmap_atomic(src);
 347
 348         zs_unmap_object(zram->mem_pool, handle);
 349
 350         zram->table[index].handle = handle;
 351         zram->table[index].size = clen;
 352
 353         /* Update stats */
 354         zram_stat64_add(zram, &zram->stats.compr_size, clen);
 355         zram->stats.pages_stored++;
 356         if (clen <= PAGE_SIZE / 2)
 357                 zram->stats.good_compress++;
 358
 359 out:
 360         if (is_partial_io(bvec))
 361                 kfree(uncmem);
 362
 363         if (ret)
 364                 zram_stat64_inc(zram, &zram->stats.failed_writes);
 365         return ret;
 366 }
 367
 368 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 369                         int offset, struct bio *bio, int rw)
 370 {
 371         int ret;
 372
 373         if (rw == READ) {
 374                 down_read(&zram->lock);
 375                 ret = zram_bvec_read(zram, bvec, index, offset, bio);
 376                 up_read(&zram->lock);
 377         } else {
 378                 down_write(&zram->lock);
 379                 ret = zram_bvec_write(zram, bvec, index, offset);
 380                 up_write(&zram->lock);
 381         }
 382
 383         return ret;
 384 }
 385
 386 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
 387 {
 388         if (*offset + bvec->bv_len >= PAGE_SIZE)
 389                 (*index)++;
 390         *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
 391 }
 392
 393 static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
 394 {
 395         int i, offset;
 396         u32 index;
 397         struct bio_vec *bvec;
 398
 399         switch (rw) {
 400         case READ:
 401                 zram_stat64_inc(zram, &zram->stats.num_reads);
 402                 break;
 403         case WRITE:
 404                 zram_stat64_inc(zram, &zram->stats.num_writes);
 405                 break;
 406         }
 407
 408         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 409         offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
 410
 411         bio_for_each_segment(bvec, bio, i) {
 412                 int max_transfer_size = PAGE_SIZE - offset;
 413
 414                 if (bvec->bv_len > max_transfer_size) {
 415                         /*
 416                          * zram_bvec_rw() can only make operation on a single
 417                          * zram page. Split the bio vector.
 418                          */
 419                         struct bio_vec bv;
 420
 421                         bv.bv_page = bvec->bv_page;
 422                         bv.bv_len = max_transfer_size;
 423                         bv.bv_offset = bvec->bv_offset;
 424
 425                         if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
 426                                 goto out;
 427
 428                         bv.bv_len = bvec->bv_len - max_transfer_size;
 429                         bv.bv_offset += max_transfer_size;
 430                         if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
 431                                 goto out;
 432                 } else
 433                         if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
 434                             < 0)
 435                                 goto out;
 436
 437                 update_position(&index, &offset, bvec);
 438         }
 439
 440         set_bit(BIO_UPTODATE, &bio->bi_flags);
 441         bio_endio(bio, 0);
 442         return;
 443
 444 out:
 445         bio_io_error(bio);
 446 }
 447
 448 /*
 449  * Check if request is within bounds and aligned on zram logical blocks.
 450  */
 451 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 452 {
 453         if (unlikely(
 454                 (bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
 455                 (bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
 456                 (bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
 457
 458                 return 0;
 459         }
 460
 461         /* I/O request is valid */
 462         return 1;
 463 }
 464
 465 /*
 466  * Handler function for all zram I/O requests.
 467  */
 468 static void zram_make_request(struct request_queue *queue, struct bio *bio)
 469 {
 470         struct zram *zram = queue->queuedata;
 471
 472         if (unlikely(!zram->init_done) && zram_init_device(zram))
 473                 goto error;
 474
 475         down_read(&zram->init_lock);
 476         if (unlikely(!zram->init_done))
 477                 goto error_unlock;
 478
 479         if (!valid_io_request(zram, bio)) {
 480                 zram_stat64_inc(zram, &zram->stats.invalid_io);
 481                 goto error_unlock;
 482         }
 483
 484         __zram_make_request(zram, bio, bio_data_dir(bio));
 485         up_read(&zram->init_lock);
 486
 487         return;
 488
 489 error_unlock:
 490         up_read(&zram->init_lock);
 491 error:
 492         bio_io_error(bio);
 493 }
 494
 495 void __zram_reset_device(struct zram *zram)
 496 {
 497         size_t index;
 498
 499         zram->init_done = 0;
 500
 501         /* Free various per-device buffers */
 502         kfree(zram->compress_workmem);
 503         free_pages((unsigned long)zram->compress_buffer, 1);
 504
 505         zram->compress_workmem = NULL;
 506         zram->compress_buffer = NULL;
 507
 508         /* Free all pages that are still in this zram device */
 509         for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 510                 unsigned long handle = zram->table[index].handle;
 511                 if (!handle)
 512                         continue;
 513
 514                 zs_free(zram->mem_pool, handle);
 515         }
 516
 517         vfree(zram->table);
 518         zram->table = NULL;
 519
 520         zs_destroy_pool(zram->mem_pool);
 521         zram->mem_pool = NULL;
 522
 523         /* Reset stats */
 524         memset(&zram->stats, 0, sizeof(zram->stats));
 525
 526         zram->disksize = 0;
 527 }
 528
 529 void zram_reset_device(struct zram *zram)
 530 {
 531         down_write(&zram->init_lock);
 532         __zram_reset_device(zram);
 533         up_write(&zram->init_lock);
 534 }
 535
 536 int zram_init_device(struct zram *zram)
 537 {
 538         int ret;
 539         size_t num_pages;
 540
 541         down_write(&zram->init_lock);
 542
 543         if (zram->init_done) {
 544                 up_write(&zram->init_lock);
 545                 return 0;
 546         }
 547
 548         zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
 549
 550         zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 551         if (!zram->compress_workmem) {
 552                 pr_err("Error allocating compressor working memory!\n");
 553                 ret = -ENOMEM;
 554                 goto fail_no_table;
 555         }
 556
 557         zram->compress_buffer =
 558                 (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
 559         if (!zram->compress_buffer) {
 560                 pr_err("Error allocating compressor buffer space\n");
 561                 ret = -ENOMEM;
 562                 goto fail_no_table;
 563         }
 564
 565         num_pages = zram->disksize >> PAGE_SHIFT;
 566         zram->table = vzalloc(num_pages * sizeof(*zram->table));
 567         if (!zram->table) {
 568                 pr_err("Error allocating zram address table\n");
 569                 ret = -ENOMEM;
 570                 goto fail_no_table;
 571         }
 572
 573         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
 574
 575         /* zram devices sort of resembles non-rotational disks */
 576         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 577
 578         zram->mem_pool = zs_create_pool("zram", GFP_NOIO | __GFP_HIGHMEM);
 579         if (!zram->mem_pool) {
 580                 pr_err("Error creating memory pool\n");
 581                 ret = -ENOMEM;
 582                 goto fail;
 583         }
 584
 585         zram->init_done = 1;
 586         up_write(&zram->init_lock);
 587
 588         pr_debug("Initialization done!\n");
 589         return 0;
 590
 591 fail_no_table:
 592         /* To prevent accessing table entries during cleanup */
 593         zram->disksize = 0;
 594 fail:
 595         __zram_reset_device(zram);
 596         up_write(&zram->init_lock);
 597         pr_err("Initialization failed: err=%d\n", ret);
 598         return ret;
 599 }
 600
 601 static void zram_slot_free_notify(struct block_device *bdev,
 602                                 unsigned long index)
 603 {
 604         struct zram *zram;
 605
 606         zram = bdev->bd_disk->private_data;
 607         zram_free_page(zram, index);
 608         zram_stat64_inc(zram, &zram->stats.notify_free);
 609 }
 610
 611 static const struct block_device_operations zram_devops = {
 612         .swap_slot_free_notify = zram_slot_free_notify,
 613         .owner = THIS_MODULE
 614 };
 615
 616 static int create_device(struct zram *zram, int device_id)
 617 {
 618         int ret = 0;
 619
 620         init_rwsem(&zram->lock);
 621         init_rwsem(&zram->init_lock);
 622         spin_lock_init(&zram->stat64_lock);
 623
 624         zram->queue = blk_alloc_queue(GFP_KERNEL);
 625         if (!zram->queue) {
 626                 pr_err("Error allocating disk queue for device %d\n",
 627                         device_id);
 628                 ret = -ENOMEM;
 629                 goto out;
 630         }
 631
 632         blk_queue_make_request(zram->queue, zram_make_request);
 633         zram->queue->queuedata = zram;
 634
 635          /* gendisk structure */
 636         zram->disk = alloc_disk(1);
 637         if (!zram->disk) {
 638                 blk_cleanup_queue(zram->queue);
 639                 pr_warn("Error allocating disk structure for device %d\n",
 640                         device_id);
 641                 ret = -ENOMEM;
 642                 goto out;
 643         }
 644
 645         zram->disk->major = zram_major;
 646         zram->disk->first_minor = device_id;
 647         zram->disk->fops = &zram_devops;
 648         zram->disk->queue = zram->queue;
 649         zram->disk->private_data = zram;
 650         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 651
 652         /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
 653         set_capacity(zram->disk, 0);
 654
 655         /*
 656          * To ensure that we always get PAGE_SIZE aligned
 657          * and n*PAGE_SIZED sized I/O requests.
 658          */
 659         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
 660         blk_queue_logical_block_size(zram->disk->queue,
 661                                         ZRAM_LOGICAL_BLOCK_SIZE);
 662         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
 663         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 664
 665         add_disk(zram->disk);
 666
 667         ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
 668                                 &zram_disk_attr_group);
 669         if (ret < 0) {
 670                 pr_warn("Error creating sysfs group");
 671                 goto out;
 672         }
 673
 674         zram->init_done = 0;
 675
 676 out:
 677         return ret;
 678 }
 679
 680 static void destroy_device(struct zram *zram)
 681 {
 682         sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
 683                         &zram_disk_attr_group);
 684
 685         if (zram->disk) {
 686                 del_gendisk(zram->disk);
 687                 put_disk(zram->disk);
 688         }
 689
 690         if (zram->queue)
 691                 blk_cleanup_queue(zram->queue);
 692 }
 693
 694 unsigned int zram_get_num_devices(void)
 695 {
 696         return num_devices;
 697 }
 698
 699 static int __init zram_init(void)
 700 {
 701         int ret, dev_id;
 702
 703         if (num_devices > max_num_devices) {
 704                 pr_warn("Invalid value for num_devices: %u\n",
 705                                 num_devices);
 706                 ret = -EINVAL;
 707                 goto out;
 708         }
 709
 710         zram_major = register_blkdev(0, "zram");
 711         if (zram_major <= 0) {
 712                 pr_warn("Unable to get major number\n");
 713                 ret = -EBUSY;
 714                 goto out;
 715         }
 716
 717         /* Allocate the device array and initialize each one */
 718         zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
 719         if (!zram_devices) {
 720                 ret = -ENOMEM;
 721                 goto unregister;
 722         }
 723
 724         for (dev_id = 0; dev_id < num_devices; dev_id++) {
 725                 ret = create_device(&zram_devices[dev_id], dev_id);
 726                 if (ret)
 727                         goto free_devices;
 728         }
 729
 730         pr_info("Created %u device(s) ...\n", num_devices);
 731
 732         return 0;
 733
 734 free_devices:
 735         while (dev_id)
 736                 destroy_device(&zram_devices[--dev_id]);
 737         kfree(zram_devices);
 738 unregister:
 739         unregister_blkdev(zram_major, "zram");
 740 out:
 741         return ret;
 742 }
 743
 744 static void __exit zram_exit(void)
 745 {
 746         int i;
 747         struct zram *zram;
 748
 749         for (i = 0; i < num_devices; i++) {
 750                 zram = &zram_devices[i];
 751
 752                 destroy_device(zram);
 753                 if (zram->init_done)
 754                         zram_reset_device(zram);
 755         }
 756
 757         unregister_blkdev(zram_major, "zram");
 758
 759         kfree(zram_devices);
 760         pr_debug("Cleanup done!\n");
 761 }
 762
 763 module_param(num_devices, uint, 0);
 764 MODULE_PARM_DESC(num_devices, "Number of zram devices");
 765
 766 module_init(zram_init);
 767 module_exit(zram_exit);
 768
 769 MODULE_LICENSE("Dual BSD/GPL");
 770 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 771 MODULE_DESCRIPTION("Compressed RAM Block Device");