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;
  44
  45 static void zram_stat_inc(u32 *v)
  46 {
  47         *v = *v + 1;
  48 }
  49
  50 static void zram_stat_dec(u32 *v)
  51 {
  52         *v = *v - 1;
  53 }
  54
  55 static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc)
  56 {
  57         spin_lock(&zram->stat64_lock);
  58         *v = *v + inc;
  59         spin_unlock(&zram->stat64_lock);
  60 }
  61
  62 static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec)
  63 {
  64         spin_lock(&zram->stat64_lock);
  65         *v = *v - dec;
  66         spin_unlock(&zram->stat64_lock);
  67 }
  68
  69 static void zram_stat64_inc(struct zram *zram, u64 *v)
  70 {
  71         zram_stat64_add(zram, v, 1);
  72 }
  73
  74 static int zram_test_flag(struct zram *zram, u32 index,
  75                         enum zram_pageflags flag)
  76 {
  77         return zram->table[index].flags & BIT(flag);
  78 }
  79
  80 static void zram_set_flag(struct zram *zram, u32 index,
  81                         enum zram_pageflags flag)
  82 {
  83         zram->table[index].flags |= BIT(flag);
  84 }
  85
  86 static void zram_clear_flag(struct zram *zram, u32 index,
  87                         enum zram_pageflags flag)
  88 {
  89         zram->table[index].flags &= ~BIT(flag);
  90 }
  91
  92 static int page_zero_filled(void *ptr)
  93 {
  94         unsigned int pos;
  95         unsigned long *page;
  96
  97         page = (unsigned long *)ptr;
  98
  99         for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
 100                 if (page[pos])
 101                         return 0;
 102         }
 103
 104         return 1;
 105 }
 106
 107 static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
 108 {
 109         if (!zram->disksize) {
 110                 pr_info(
 111                 "disk size not provided. You can use disksize_kb module "
 112                 "param to specify size.\nUsing default: (%u%% of RAM).\n",
 113                 default_disksize_perc_ram
 114                 );
 115                 zram->disksize = default_disksize_perc_ram *
 116                                         (totalram_bytes / 100);
 117         }
 118
 119         if (zram->disksize > 2 * (totalram_bytes)) {
 120                 pr_info(
 121                 "There is little point creating a zram of greater than "
 122                 "twice the size of memory since we expect a 2:1 compression "
 123                 "ratio. Note that zram uses about 0.1%% of the size of "
 124                 "the disk when not in use so a huge zram is "
 125                 "wasteful.\n"
 126                 "\tMemory Size: %zu kB\n"
 127                 "\tSize you selected: %llu kB\n"
 128                 "Continuing anyway ...\n",
 129                 totalram_bytes >> 10, zram->disksize
 130                 );
 131         }
 132
 133         zram->disksize &= PAGE_MASK;
 134 }
 135
 136 static void zram_free_page(struct zram *zram, size_t index)
 137 {
 138         unsigned long handle = zram->table[index].handle;
 139         u16 size = zram->table[index].size;
 140
 141         if (unlikely(!handle)) {
 142                 /*
 143                  * No memory is allocated for zero filled pages.
 144                  * Simply clear zero page flag.
 145                  */
 146                 if (zram_test_flag(zram, index, ZRAM_ZERO)) {
 147                         zram_clear_flag(zram, index, ZRAM_ZERO);
 148                         zram_stat_dec(&zram->stats.pages_zero);
 149                 }
 150                 return;
 151         }
 152
 153         if (unlikely(size > max_zpage_size))
 154                 zram_stat_dec(&zram->stats.bad_compress);
 155
 156         zs_free(zram->mem_pool, handle);
 157
 158         if (size <= PAGE_SIZE / 2)
 159                 zram_stat_dec(&zram->stats.good_compress);
 160
 161         zram_stat64_sub(zram, &zram->stats.compr_size,
 162                         zram->table[index].size);
 163         zram_stat_dec(&zram->stats.pages_stored);
 164
 165         zram->table[index].handle = 0;
 166         zram->table[index].size = 0;
 167 }
 168
 169 static void handle_zero_page(struct bio_vec *bvec)
 170 {
 171         struct page *page = bvec->bv_page;
 172         void *user_mem;
 173
 174         user_mem = kmap_atomic(page);
 175         memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
 176         kunmap_atomic(user_mem);
 177
 178         flush_dcache_page(page);
 179 }
 180
 181 static inline int is_partial_io(struct bio_vec *bvec)
 182 {
 183         return bvec->bv_len != PAGE_SIZE;
 184 }
 185
 186 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 187                           u32 index, int offset, struct bio *bio)
 188 {
 189         int ret;
 190         size_t clen;
 191         struct page *page;
 192         unsigned char *user_mem, *cmem, *uncmem = NULL;
 193
 194         page = bvec->bv_page;
 195
 196         if (zram_test_flag(zram, index, ZRAM_ZERO)) {
 197                 handle_zero_page(bvec);
 198                 return 0;
 199         }
 200
 201         /* Requested page is not present in compressed area */
 202         if (unlikely(!zram->table[index].handle)) {
 203                 pr_debug("Read before write: sector=%lu, size=%u",
 204                          (ulong)(bio->bi_sector), bio->bi_size);
 205                 handle_zero_page(bvec);
 206                 return 0;
 207         }
 208
 209         if (is_partial_io(bvec)) {
 210                 /* Use  a temporary buffer to decompress the page */
 211                 uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
 212                 if (!uncmem) {
 213                         pr_info("Error allocating temp memory!\n");
 214                         return -ENOMEM;
 215                 }
 216         }
 217
 218         user_mem = kmap_atomic(page);
 219         if (!is_partial_io(bvec))
 220                 uncmem = user_mem;
 221         clen = PAGE_SIZE;
 222
 223         cmem = zs_map_object(zram->mem_pool, zram->table[index].handle,
 224                                 ZS_MM_RO);
 225
 226         if (zram->table[index].size == PAGE_SIZE) {
 227                 memcpy(uncmem, cmem, PAGE_SIZE);
 228                 ret = LZO_E_OK;
 229         } else {
 230                 ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
 231                                     uncmem, &clen);
 232         }
 233
 234         if (is_partial_io(bvec)) {
 235                 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
 236                        bvec->bv_len);
 237                 kfree(uncmem);
 238         }
 239
 240         zs_unmap_object(zram->mem_pool, zram->table[index].handle);
 241         kunmap_atomic(user_mem);
 242
 243         /* Should NEVER happen. Return bio error if it does. */
 244         if (unlikely(ret != LZO_E_OK)) {
 245                 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
 246                 zram_stat64_inc(zram, &zram->stats.failed_reads);
 247                 return ret;
 248         }
 249
 250         flush_dcache_page(page);
 251
 252         return 0;
 253 }
 254
 255 static int zram_read_before_write(struct zram *zram, char *mem, u32 index)
 256 {
 257         int ret;
 258         size_t clen = PAGE_SIZE;
 259         unsigned char *cmem;
 260         unsigned long handle = zram->table[index].handle;
 261
 262         if (zram_test_flag(zram, index, ZRAM_ZERO) || !handle) {
 263                 memset(mem, 0, PAGE_SIZE);
 264                 return 0;
 265         }
 266
 267         cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
 268         ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
 269                                     mem, &clen);
 270         zs_unmap_object(zram->mem_pool, handle);
 271
 272         /* Should NEVER happen. Return bio error if it does. */
 273         if (unlikely(ret != LZO_E_OK)) {
 274                 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
 275                 zram_stat64_inc(zram, &zram->stats.failed_reads);
 276                 return ret;
 277         }
 278
 279         return 0;
 280 }
 281
 282 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 283                            int offset)
 284 {
 285         int ret;
 286         size_t clen;
 287         unsigned long handle;
 288         struct page *page;
 289         unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
 290
 291         page = bvec->bv_page;
 292         src = zram->compress_buffer;
 293
 294         if (is_partial_io(bvec)) {
 295                 /*
 296                  * This is a partial IO. We need to read the full page
 297                  * before to write the changes.
 298                  */
 299                 uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
 300                 if (!uncmem) {
 301                         pr_info("Error allocating temp memory!\n");
 302                         ret = -ENOMEM;
 303                         goto out;
 304                 }
 305                 ret = zram_read_before_write(zram, uncmem, index);
 306                 if (ret) {
 307                         kfree(uncmem);
 308                         goto out;
 309                 }
 310         }
 311
 312         /*
 313          * System overwrites unused sectors. Free memory associated
 314          * with this sector now.
 315          */
 316         if (zram->table[index].handle ||
 317             zram_test_flag(zram, index, ZRAM_ZERO))
 318                 zram_free_page(zram, index);
 319
 320         user_mem = kmap_atomic(page);
 321
 322         if (is_partial_io(bvec))
 323                 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
 324                        bvec->bv_len);
 325         else
 326                 uncmem = user_mem;
 327
 328         if (page_zero_filled(uncmem)) {
 329                 kunmap_atomic(user_mem);
 330                 if (is_partial_io(bvec))
 331                         kfree(uncmem);
 332                 zram_stat_inc(&zram->stats.pages_zero);
 333                 zram_set_flag(zram, index, ZRAM_ZERO);
 334                 ret = 0;
 335                 goto out;
 336         }
 337
 338         ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
 339                                zram->compress_workmem);
 340
 341         kunmap_atomic(user_mem);
 342         if (is_partial_io(bvec))
 343                         kfree(uncmem);
 344
 345         if (unlikely(ret != LZO_E_OK)) {
 346                 pr_err("Compression failed! err=%d\n", ret);
 347                 goto out;
 348         }
 349
 350         if (unlikely(clen > max_zpage_size)) {
 351                 zram_stat_inc(&zram->stats.bad_compress);
 352                 src = uncmem;
 353                 clen = PAGE_SIZE;
 354         }
 355
 356         handle = zs_malloc(zram->mem_pool, clen);
 357         if (!handle) {
 358                 pr_info("Error allocating memory for compressed "
 359                         "page: %u, size=%zu\n", index, clen);
 360                 ret = -ENOMEM;
 361                 goto out;
 362         }
 363         cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
 364
 365         memcpy(cmem, src, clen);
 366
 367         zs_unmap_object(zram->mem_pool, handle);
 368
 369         zram->table[index].handle = handle;
 370         zram->table[index].size = clen;
 371
 372         /* Update stats */
 373         zram_stat64_add(zram, &zram->stats.compr_size, clen);
 374         zram_stat_inc(&zram->stats.pages_stored);
 375         if (clen <= PAGE_SIZE / 2)
 376                 zram_stat_inc(&zram->stats.good_compress);
 377
 378         return 0;
 379
 380 out:
 381         if (ret)
 382                 zram_stat64_inc(zram, &zram->stats.failed_writes);
 383         return ret;
 384 }
 385
 386 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 387                         int offset, struct bio *bio, int rw)
 388 {
 389         int ret;
 390
 391         if (rw == READ) {
 392                 down_read(&zram->lock);
 393                 ret = zram_bvec_read(zram, bvec, index, offset, bio);
 394                 up_read(&zram->lock);
 395         } else {
 396                 down_write(&zram->lock);
 397                 ret = zram_bvec_write(zram, bvec, index, offset);
 398                 up_write(&zram->lock);
 399         }
 400
 401         return ret;
 402 }
 403
 404 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
 405 {
 406         if (*offset + bvec->bv_len >= PAGE_SIZE)
 407                 (*index)++;
 408         *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
 409 }
 410
 411 static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
 412 {
 413         int i, offset;
 414         u32 index;
 415         struct bio_vec *bvec;
 416
 417         switch (rw) {
 418         case READ:
 419                 zram_stat64_inc(zram, &zram->stats.num_reads);
 420                 break;
 421         case WRITE:
 422                 zram_stat64_inc(zram, &zram->stats.num_writes);
 423                 break;
 424         }
 425
 426         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 427         offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
 428
 429         bio_for_each_segment(bvec, bio, i) {
 430                 int max_transfer_size = PAGE_SIZE - offset;
 431
 432                 if (bvec->bv_len > max_transfer_size) {
 433                         /*
 434                          * zram_bvec_rw() can only make operation on a single
 435                          * zram page. Split the bio vector.
 436                          */
 437                         struct bio_vec bv;
 438
 439                         bv.bv_page = bvec->bv_page;
 440                         bv.bv_len = max_transfer_size;
 441                         bv.bv_offset = bvec->bv_offset;
 442
 443                         if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
 444                                 goto out;
 445
 446                         bv.bv_len = bvec->bv_len - max_transfer_size;
 447                         bv.bv_offset += max_transfer_size;
 448                         if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
 449                                 goto out;
 450                 } else
 451                         if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
 452                             < 0)
 453                                 goto out;
 454
 455                 update_position(&index, &offset, bvec);
 456         }
 457
 458         set_bit(BIO_UPTODATE, &bio->bi_flags);
 459         bio_endio(bio, 0);
 460         return;
 461
 462 out:
 463         bio_io_error(bio);
 464 }
 465
 466 /*
 467  * Check if request is within bounds and aligned on zram logical blocks.
 468  */
 469 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 470 {
 471         if (unlikely(
 472                 (bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
 473                 (bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
 474                 (bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
 475
 476                 return 0;
 477         }
 478
 479         /* I/O request is valid */
 480         return 1;
 481 }
 482
 483 /*
 484  * Handler function for all zram I/O requests.
 485  */
 486 static void zram_make_request(struct request_queue *queue, struct bio *bio)
 487 {
 488         struct zram *zram = queue->queuedata;
 489
 490         if (unlikely(!zram->init_done) && zram_init_device(zram))
 491                 goto error;
 492
 493         down_read(&zram->init_lock);
 494         if (unlikely(!zram->init_done))
 495                 goto error_unlock;
 496
 497         if (!valid_io_request(zram, bio)) {
 498                 zram_stat64_inc(zram, &zram->stats.invalid_io);
 499                 goto error_unlock;
 500         }
 501
 502         __zram_make_request(zram, bio, bio_data_dir(bio));
 503         up_read(&zram->init_lock);
 504
 505         return;
 506
 507 error_unlock:
 508         up_read(&zram->init_lock);
 509 error:
 510         bio_io_error(bio);
 511 }
 512
 513 void __zram_reset_device(struct zram *zram)
 514 {
 515         size_t index;
 516
 517         zram->init_done = 0;
 518
 519         /* Free various per-device buffers */
 520         kfree(zram->compress_workmem);
 521         free_pages((unsigned long)zram->compress_buffer, 1);
 522
 523         zram->compress_workmem = NULL;
 524         zram->compress_buffer = NULL;
 525
 526         /* Free all pages that are still in this zram device */
 527         for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 528                 unsigned long handle = zram->table[index].handle;
 529                 if (!handle)
 530                         continue;
 531
 532                 zs_free(zram->mem_pool, handle);
 533         }
 534
 535         vfree(zram->table);
 536         zram->table = NULL;
 537
 538         zs_destroy_pool(zram->mem_pool);
 539         zram->mem_pool = NULL;
 540
 541         /* Reset stats */
 542         memset(&zram->stats, 0, sizeof(zram->stats));
 543
 544         zram->disksize = 0;
 545 }
 546
 547 void zram_reset_device(struct zram *zram)
 548 {
 549         down_write(&zram->init_lock);
 550         __zram_reset_device(zram);
 551         up_write(&zram->init_lock);
 552 }
 553
 554 int zram_init_device(struct zram *zram)
 555 {
 556         int ret;
 557         size_t num_pages;
 558
 559         down_write(&zram->init_lock);
 560
 561         if (zram->init_done) {
 562                 up_write(&zram->init_lock);
 563                 return 0;
 564         }
 565
 566         zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
 567
 568         zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 569         if (!zram->compress_workmem) {
 570                 pr_err("Error allocating compressor working memory!\n");
 571                 ret = -ENOMEM;
 572                 goto fail_no_table;
 573         }
 574
 575         zram->compress_buffer =
 576                 (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
 577         if (!zram->compress_buffer) {
 578                 pr_err("Error allocating compressor buffer space\n");
 579                 ret = -ENOMEM;
 580                 goto fail_no_table;
 581         }
 582
 583         num_pages = zram->disksize >> PAGE_SHIFT;
 584         zram->table = vzalloc(num_pages * sizeof(*zram->table));
 585         if (!zram->table) {
 586                 pr_err("Error allocating zram address table\n");
 587                 ret = -ENOMEM;
 588                 goto fail_no_table;
 589         }
 590
 591         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
 592
 593         /* zram devices sort of resembles non-rotational disks */
 594         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 595
 596         zram->mem_pool = zs_create_pool("zram", GFP_NOIO | __GFP_HIGHMEM);
 597         if (!zram->mem_pool) {
 598                 pr_err("Error creating memory pool\n");
 599                 ret = -ENOMEM;
 600                 goto fail;
 601         }
 602
 603         zram->init_done = 1;
 604         up_write(&zram->init_lock);
 605
 606         pr_debug("Initialization done!\n");
 607         return 0;
 608
 609 fail_no_table:
 610         /* To prevent accessing table entries during cleanup */
 611         zram->disksize = 0;
 612 fail:
 613         __zram_reset_device(zram);
 614         up_write(&zram->init_lock);
 615         pr_err("Initialization failed: err=%d\n", ret);
 616         return ret;
 617 }
 618
 619 static void zram_slot_free_notify(struct block_device *bdev,
 620                                 unsigned long index)
 621 {
 622         struct zram *zram;
 623
 624         zram = bdev->bd_disk->private_data;
 625         zram_free_page(zram, index);
 626         zram_stat64_inc(zram, &zram->stats.notify_free);
 627 }
 628
 629 static const struct block_device_operations zram_devops = {
 630         .swap_slot_free_notify = zram_slot_free_notify,
 631         .owner = THIS_MODULE
 632 };
 633
 634 static int create_device(struct zram *zram, int device_id)
 635 {
 636         int ret = 0;
 637
 638         init_rwsem(&zram->lock);
 639         init_rwsem(&zram->init_lock);
 640         spin_lock_init(&zram->stat64_lock);
 641
 642         zram->queue = blk_alloc_queue(GFP_KERNEL);
 643         if (!zram->queue) {
 644                 pr_err("Error allocating disk queue for device %d\n",
 645                         device_id);
 646                 ret = -ENOMEM;
 647                 goto out;
 648         }
 649
 650         blk_queue_make_request(zram->queue, zram_make_request);
 651         zram->queue->queuedata = zram;
 652
 653          /* gendisk structure */
 654         zram->disk = alloc_disk(1);
 655         if (!zram->disk) {
 656                 blk_cleanup_queue(zram->queue);
 657                 pr_warn("Error allocating disk structure for device %d\n",
 658                         device_id);
 659                 ret = -ENOMEM;
 660                 goto out;
 661         }
 662
 663         zram->disk->major = zram_major;
 664         zram->disk->first_minor = device_id;
 665         zram->disk->fops = &zram_devops;
 666         zram->disk->queue = zram->queue;
 667         zram->disk->private_data = zram;
 668         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 669
 670         /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
 671         set_capacity(zram->disk, 0);
 672
 673         /*
 674          * To ensure that we always get PAGE_SIZE aligned
 675          * and n*PAGE_SIZED sized I/O requests.
 676          */
 677         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
 678         blk_queue_logical_block_size(zram->disk->queue,
 679                                         ZRAM_LOGICAL_BLOCK_SIZE);
 680         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
 681         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 682
 683         add_disk(zram->disk);
 684
 685         ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
 686                                 &zram_disk_attr_group);
 687         if (ret < 0) {
 688                 pr_warn("Error creating sysfs group");
 689                 goto out;
 690         }
 691
 692         zram->init_done = 0;
 693
 694 out:
 695         return ret;
 696 }
 697
 698 static void destroy_device(struct zram *zram)
 699 {
 700         sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
 701                         &zram_disk_attr_group);
 702
 703         if (zram->disk) {
 704                 del_gendisk(zram->disk);
 705                 put_disk(zram->disk);
 706         }
 707
 708         if (zram->queue)
 709                 blk_cleanup_queue(zram->queue);
 710 }
 711
 712 unsigned int zram_get_num_devices(void)
 713 {
 714         return num_devices;
 715 }
 716
 717 static int __init zram_init(void)
 718 {
 719         int ret, dev_id;
 720
 721         if (num_devices > max_num_devices) {
 722                 pr_warn("Invalid value for num_devices: %u\n",
 723                                 num_devices);
 724                 ret = -EINVAL;
 725                 goto out;
 726         }
 727
 728         zram_major = register_blkdev(0, "zram");
 729         if (zram_major <= 0) {
 730                 pr_warn("Unable to get major number\n");
 731                 ret = -EBUSY;
 732                 goto out;
 733         }
 734
 735         if (!num_devices) {
 736                 pr_info("num_devices not specified. Using default: 1\n");
 737                 num_devices = 1;
 738         }
 739
 740         /* Allocate the device array and initialize each one */
 741         pr_info("Creating %u devices ...\n", num_devices);
 742         zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
 743         if (!zram_devices) {
 744                 ret = -ENOMEM;
 745                 goto unregister;
 746         }
 747
 748         for (dev_id = 0; dev_id < num_devices; dev_id++) {
 749                 ret = create_device(&zram_devices[dev_id], dev_id);
 750                 if (ret)
 751                         goto free_devices;
 752         }
 753
 754         return 0;
 755
 756 free_devices:
 757         while (dev_id)
 758                 destroy_device(&zram_devices[--dev_id]);
 759         kfree(zram_devices);
 760 unregister:
 761         unregister_blkdev(zram_major, "zram");
 762 out:
 763         return ret;
 764 }
 765
 766 static void __exit zram_exit(void)
 767 {
 768         int i;
 769         struct zram *zram;
 770
 771         for (i = 0; i < num_devices; i++) {
 772                 zram = &zram_devices[i];
 773
 774                 destroy_device(zram);
 775                 if (zram->init_done)
 776                         zram_reset_device(zram);
 777         }
 778
 779         unregister_blkdev(zram_major, "zram");
 780
 781         kfree(zram_devices);
 782         pr_debug("Cleanup done!\n");
 783 }
 784
 785 module_param(num_devices, uint, 0);
 786 MODULE_PARM_DESC(num_devices, "Number of zram devices");
 787
 788 module_init(zram_init);
 789 module_exit(zram_exit);
 790
 791 MODULE_LICENSE("Dual BSD/GPL");
 792 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 793 MODULE_DESCRIPTION("Compressed RAM Block Device");