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 #include <linux/module.h>
  19 #include <linux/kernel.h>
  20 #include <linux/bio.h>
  21 #include <linux/bitops.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/buffer_head.h>
  24 #include <linux/device.h>
  25 #include <linux/genhd.h>
  26 #include <linux/highmem.h>
  27 #include <linux/slab.h>
  28 #include <linux/lzo.h>
  29 #include <linux/string.h>
  30 #include <linux/vmalloc.h>
  31
  32 #include "zram_drv.h"
  33
  34 /* Globals */
  35 static int zram_major;
  36 static struct zram *devices;
  37
  38 /* Module params (documentation at end) */
  39 static unsigned int num_devices;
  40
  41 static int zram_test_flag(struct zram *zram, u32 index,
  42                         enum zram_pageflags flag)
  43 {
  44         return zram->table[index].flags & BIT(flag);
  45 }
  46
  47 static void zram_set_flag(struct zram *zram, u32 index,
  48                         enum zram_pageflags flag)
  49 {
  50         zram->table[index].flags |= BIT(flag);
  51 }
  52
  53 static void zram_clear_flag(struct zram *zram, u32 index,
  54                         enum zram_pageflags flag)
  55 {
  56         zram->table[index].flags &= ~BIT(flag);
  57 }
  58
  59 static int page_zero_filled(void *ptr)
  60 {
  61         unsigned int pos;
  62         unsigned long *page;
  63
  64         page = (unsigned long *)ptr;
  65
  66         for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
  67                 if (page[pos])
  68                         return 0;
  69         }
  70
  71         return 1;
  72 }
  73
  74 static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
  75 {
  76         if (!zram->disksize) {
  77                 pr_info(
  78                 "disk size not provided. You can use disksize_kb module "
  79                 "param to specify size.\nUsing default: (%u%% of RAM).\n",
  80                 default_disksize_perc_ram
  81                 );
  82                 zram->disksize = default_disksize_perc_ram *
  83                                         (totalram_bytes / 100);
  84         }
  85
  86         if (zram->disksize > 2 * (totalram_bytes)) {
  87                 pr_info(
  88                 "There is little point creating a zram of greater than "
  89                 "twice the size of memory since we expect a 2:1 compression "
  90                 "ratio. Note that zram uses about 0.1%% of the size of "
  91                 "the disk when not in use so a huge zram is "
  92                 "wasteful.\n"
  93                 "\tMemory Size: %zu kB\n"
  94                 "\tSize you selected: %zu kB\n"
  95                 "Continuing anyway ...\n",
  96                 totalram_bytes >> 10, zram->disksize
  97                 );
  98         }
  99
 100         zram->disksize &= PAGE_MASK;
 101 }
 102
 103 static void zram_ioctl_get_stats(struct zram *zram,
 104                         struct zram_ioctl_stats *s)
 105 {
 106         s->disksize = zram->disksize;
 107
 108 #if defined(CONFIG_ZRAM_STATS)
 109         {
 110         struct zram_stats *rs = &zram->stats;
 111         size_t succ_writes, mem_used;
 112         unsigned int good_compress_perc = 0, no_compress_perc = 0;
 113
 114         mem_used = xv_get_total_size_bytes(zram->mem_pool)
 115                         + (rs->pages_expand << PAGE_SHIFT);
 116         succ_writes = zram_stat64_read(zram, &rs->num_writes) -
 117                         zram_stat64_read(zram, &rs->failed_writes);
 118
 119         if (succ_writes && rs->pages_stored) {
 120                 good_compress_perc = rs->good_compress * 100
 121                                         / rs->pages_stored;
 122                 no_compress_perc = rs->pages_expand * 100
 123                                         / rs->pages_stored;
 124         }
 125
 126         s->num_reads = zram_stat64_read(zram, &rs->num_reads);
 127         s->num_writes = zram_stat64_read(zram, &rs->num_writes);
 128         s->failed_reads = zram_stat64_read(zram, &rs->failed_reads);
 129         s->failed_writes = zram_stat64_read(zram, &rs->failed_writes);
 130         s->invalid_io = zram_stat64_read(zram, &rs->invalid_io);
 131         s->notify_free = zram_stat64_read(zram, &rs->notify_free);
 132         s->pages_zero = rs->pages_zero;
 133
 134         s->good_compress_pct = good_compress_perc;
 135         s->pages_expand_pct = no_compress_perc;
 136
 137         s->pages_stored = rs->pages_stored;
 138         s->pages_used = mem_used >> PAGE_SHIFT;
 139         s->orig_data_size = rs->pages_stored << PAGE_SHIFT;
 140         s->compr_data_size = rs->compr_size;
 141         s->mem_used_total = mem_used;
 142         }
 143 #endif /* CONFIG_ZRAM_STATS */
 144 }
 145
 146 static void zram_free_page(struct zram *zram, size_t index)
 147 {
 148         u32 clen;
 149         void *obj;
 150
 151         struct page *page = zram->table[index].page;
 152         u32 offset = zram->table[index].offset;
 153
 154         if (unlikely(!page)) {
 155                 /*
 156                  * No memory is allocated for zero filled pages.
 157                  * Simply clear zero page flag.
 158                  */
 159                 if (zram_test_flag(zram, index, ZRAM_ZERO)) {
 160                         zram_clear_flag(zram, index, ZRAM_ZERO);
 161                         zram_stat_dec(&zram->stats.pages_zero);
 162                 }
 163                 return;
 164         }
 165
 166         if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
 167                 clen = PAGE_SIZE;
 168                 __free_page(page);
 169                 zram_clear_flag(zram, index, ZRAM_UNCOMPRESSED);
 170                 zram_stat_dec(&zram->stats.pages_expand);
 171                 goto out;
 172         }
 173
 174         obj = kmap_atomic(page, KM_USER0) + offset;
 175         clen = xv_get_object_size(obj) - sizeof(struct zobj_header);
 176         kunmap_atomic(obj, KM_USER0);
 177
 178         xv_free(zram->mem_pool, page, offset);
 179         if (clen <= PAGE_SIZE / 2)
 180                 zram_stat_dec(&zram->stats.good_compress);
 181
 182 out:
 183         zram->stats.compr_size -= clen;
 184         zram_stat_dec(&zram->stats.pages_stored);
 185
 186         zram->table[index].page = NULL;
 187         zram->table[index].offset = 0;
 188 }
 189
 190 static void handle_zero_page(struct page *page)
 191 {
 192         void *user_mem;
 193
 194         user_mem = kmap_atomic(page, KM_USER0);
 195         memset(user_mem, 0, PAGE_SIZE);
 196         kunmap_atomic(user_mem, KM_USER0);
 197
 198         flush_dcache_page(page);
 199 }
 200
 201 static void handle_uncompressed_page(struct zram *zram,
 202                                 struct page *page, u32 index)
 203 {
 204         unsigned char *user_mem, *cmem;
 205
 206         user_mem = kmap_atomic(page, KM_USER0);
 207         cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
 208                         zram->table[index].offset;
 209
 210         memcpy(user_mem, cmem, PAGE_SIZE);
 211         kunmap_atomic(user_mem, KM_USER0);
 212         kunmap_atomic(cmem, KM_USER1);
 213
 214         flush_dcache_page(page);
 215 }
 216
 217 static int zram_read(struct zram *zram, struct bio *bio)
 218 {
 219
 220         int i;
 221         u32 index;
 222         struct bio_vec *bvec;
 223
 224         zram_stat64_inc(zram, &zram->stats.num_reads);
 225
 226         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 227         bio_for_each_segment(bvec, bio, i) {
 228                 int ret;
 229                 size_t clen;
 230                 struct page *page;
 231                 struct zobj_header *zheader;
 232                 unsigned char *user_mem, *cmem;
 233
 234                 page = bvec->bv_page;
 235
 236                 if (zram_test_flag(zram, index, ZRAM_ZERO)) {
 237                         handle_zero_page(page);
 238                         index++;
 239                         continue;
 240                 }
 241
 242                 /* Requested page is not present in compressed area */
 243                 if (unlikely(!zram->table[index].page)) {
 244                         pr_debug("Read before write: sector=%lu, size=%u",
 245                                 (ulong)(bio->bi_sector), bio->bi_size);
 246                         /* Do nothing */
 247                         index++;
 248                         continue;
 249                 }
 250
 251                 /* Page is stored uncompressed since it's incompressible */
 252                 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
 253                         handle_uncompressed_page(zram, page, index);
 254                         index++;
 255                         continue;
 256                 }
 257
 258                 user_mem = kmap_atomic(page, KM_USER0);
 259                 clen = PAGE_SIZE;
 260
 261                 cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
 262                                 zram->table[index].offset;
 263
 264                 ret = lzo1x_decompress_safe(
 265                         cmem + sizeof(*zheader),
 266                         xv_get_object_size(cmem) - sizeof(*zheader),
 267                         user_mem, &clen);
 268
 269                 kunmap_atomic(user_mem, KM_USER0);
 270                 kunmap_atomic(cmem, KM_USER1);
 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",
 275                                 ret, index);
 276                         zram_stat64_inc(zram, &zram->stats.failed_reads);
 277                         goto out;
 278                 }
 279
 280                 flush_dcache_page(page);
 281                 index++;
 282         }
 283
 284         set_bit(BIO_UPTODATE, &bio->bi_flags);
 285         bio_endio(bio, 0);
 286         return 0;
 287
 288 out:
 289         bio_io_error(bio);
 290         return 0;
 291 }
 292
 293 static int zram_write(struct zram *zram, struct bio *bio)
 294 {
 295         int i;
 296         u32 index;
 297         struct bio_vec *bvec;
 298
 299         zram_stat64_inc(zram, &zram->stats.num_writes);
 300
 301         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 302
 303         bio_for_each_segment(bvec, bio, i) {
 304                 int ret;
 305                 u32 offset;
 306                 size_t clen;
 307                 struct zobj_header *zheader;
 308                 struct page *page, *page_store;
 309                 unsigned char *user_mem, *cmem, *src;
 310
 311                 page = bvec->bv_page;
 312                 src = zram->compress_buffer;
 313
 314                 /*
 315                  * System overwrites unused sectors. Free memory associated
 316                  * with this sector now.
 317                  */
 318                 if (zram->table[index].page ||
 319                                 zram_test_flag(zram, index, ZRAM_ZERO))
 320                         zram_free_page(zram, index);
 321
 322                 mutex_lock(&zram->lock);
 323
 324                 user_mem = kmap_atomic(page, KM_USER0);
 325                 if (page_zero_filled(user_mem)) {
 326                         kunmap_atomic(user_mem, KM_USER0);
 327                         mutex_unlock(&zram->lock);
 328                         zram_stat_inc(&zram->stats.pages_zero);
 329                         zram_set_flag(zram, index, ZRAM_ZERO);
 330                         index++;
 331                         continue;
 332                 }
 333
 334                 ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen,
 335                                         zram->compress_workmem);
 336
 337                 kunmap_atomic(user_mem, KM_USER0);
 338
 339                 if (unlikely(ret != LZO_E_OK)) {
 340                         mutex_unlock(&zram->lock);
 341                         pr_err("Compression failed! err=%d\n", ret);
 342                         zram_stat64_inc(zram, &zram->stats.failed_writes);
 343                         goto out;
 344                 }
 345
 346                 /*
 347                  * Page is incompressible. Store it as-is (uncompressed)
 348                  * since we do not want to return too many disk write
 349                  * errors which has side effect of hanging the system.
 350                  */
 351                 if (unlikely(clen > max_zpage_size)) {
 352                         clen = PAGE_SIZE;
 353                         page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
 354                         if (unlikely(!page_store)) {
 355                                 mutex_unlock(&zram->lock);
 356                                 pr_info("Error allocating memory for "
 357                                         "incompressible page: %u\n", index);
 358                                 zram_stat64_inc(zram,
 359                                         &zram->stats.failed_writes);
 360                                 goto out;
 361                         }
 362
 363                         offset = 0;
 364                         zram_set_flag(zram, index, ZRAM_UNCOMPRESSED);
 365                         zram_stat_inc(&zram->stats.pages_expand);
 366                         zram->table[index].page = page_store;
 367                         src = kmap_atomic(page, KM_USER0);
 368                         goto memstore;
 369                 }
 370
 371                 if (xv_malloc(zram->mem_pool, clen + sizeof(*zheader),
 372                                 &zram->table[index].page, &offset,
 373                                 GFP_NOIO | __GFP_HIGHMEM)) {
 374                         mutex_unlock(&zram->lock);
 375                         pr_info("Error allocating memory for compressed "
 376                                 "page: %u, size=%zu\n", index, clen);
 377                         zram_stat64_inc(zram, &zram->stats.failed_writes);
 378                         goto out;
 379                 }
 380
 381 memstore:
 382                 zram->table[index].offset = offset;
 383
 384                 cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
 385                                 zram->table[index].offset;
 386
 387 #if 0
 388                 /* Back-reference needed for memory defragmentation */
 389                 if (!zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)) {
 390                         zheader = (struct zobj_header *)cmem;
 391                         zheader->table_idx = index;
 392                         cmem += sizeof(*zheader);
 393                 }
 394 #endif
 395
 396                 memcpy(cmem, src, clen);
 397
 398                 kunmap_atomic(cmem, KM_USER1);
 399                 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
 400                         kunmap_atomic(src, KM_USER0);
 401
 402                 /* Update stats */
 403                 zram->stats.compr_size += clen;
 404                 zram_stat_inc(&zram->stats.pages_stored);
 405                 if (clen <= PAGE_SIZE / 2)
 406                         zram_stat_inc(&zram->stats.good_compress);
 407
 408                 mutex_unlock(&zram->lock);
 409                 index++;
 410         }
 411
 412         set_bit(BIO_UPTODATE, &bio->bi_flags);
 413         bio_endio(bio, 0);
 414         return 0;
 415
 416 out:
 417         bio_io_error(bio);
 418         return 0;
 419 }
 420
 421 /*
 422  * Check if request is within bounds and page aligned.
 423  */
 424 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 425 {
 426         if (unlikely(
 427                 (bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
 428                 (bio->bi_sector & (SECTORS_PER_PAGE - 1)) ||
 429                 (bio->bi_size & (PAGE_SIZE - 1)))) {
 430
 431                 return 0;
 432         }
 433
 434         /* I/O request is valid */
 435         return 1;
 436 }
 437
 438 /*
 439  * Handler function for all zram I/O requests.
 440  */
 441 static int zram_make_request(struct request_queue *queue, struct bio *bio)
 442 {
 443         int ret = 0;
 444         struct zram *zram = queue->queuedata;
 445
 446         if (unlikely(!zram->init_done)) {
 447                 bio_io_error(bio);
 448                 return 0;
 449         }
 450
 451         if (!valid_io_request(zram, bio)) {
 452                 zram_stat64_inc(zram, &zram->stats.invalid_io);
 453                 bio_io_error(bio);
 454                 return 0;
 455         }
 456
 457         switch (bio_data_dir(bio)) {
 458         case READ:
 459                 ret = zram_read(zram, bio);
 460                 break;
 461
 462         case WRITE:
 463                 ret = zram_write(zram, bio);
 464                 break;
 465         }
 466
 467         return ret;
 468 }
 469
 470 static void reset_device(struct zram *zram)
 471 {
 472         size_t index;
 473
 474         /* Do not accept any new I/O request */
 475         zram->init_done = 0;
 476
 477         /* Free various per-device buffers */
 478         kfree(zram->compress_workmem);
 479         free_pages((unsigned long)zram->compress_buffer, 1);
 480
 481         zram->compress_workmem = NULL;
 482         zram->compress_buffer = NULL;
 483
 484         /* Free all pages that are still in this zram device */
 485         for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 486                 struct page *page;
 487                 u16 offset;
 488
 489                 page = zram->table[index].page;
 490                 offset = zram->table[index].offset;
 491
 492                 if (!page)
 493                         continue;
 494
 495                 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
 496                         __free_page(page);
 497                 else
 498                         xv_free(zram->mem_pool, page, offset);
 499         }
 500
 501         vfree(zram->table);
 502         zram->table = NULL;
 503
 504         xv_destroy_pool(zram->mem_pool);
 505         zram->mem_pool = NULL;
 506
 507         /* Reset stats */
 508         memset(&zram->stats, 0, sizeof(zram->stats));
 509
 510         zram->disksize = 0;
 511 }
 512
 513 static int zram_ioctl_init_device(struct zram *zram)
 514 {
 515         int ret;
 516         size_t num_pages;
 517
 518         if (zram->init_done) {
 519                 pr_info("Device already initialized!\n");
 520                 return -EBUSY;
 521         }
 522
 523         zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
 524
 525         zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 526         if (!zram->compress_workmem) {
 527                 pr_err("Error allocating compressor working memory!\n");
 528                 ret = -ENOMEM;
 529                 goto fail;
 530         }
 531
 532         zram->compress_buffer = (void *)__get_free_pages(__GFP_ZERO, 1);
 533         if (!zram->compress_buffer) {
 534                 pr_err("Error allocating compressor buffer space\n");
 535                 ret = -ENOMEM;
 536                 goto fail;
 537         }
 538
 539         num_pages = zram->disksize >> PAGE_SHIFT;
 540         zram->table = vmalloc(num_pages * sizeof(*zram->table));
 541         if (!zram->table) {
 542                 pr_err("Error allocating zram address table\n");
 543                 /* To prevent accessing table entries during cleanup */
 544                 zram->disksize = 0;
 545                 ret = -ENOMEM;
 546                 goto fail;
 547         }
 548         memset(zram->table, 0, num_pages * sizeof(*zram->table));
 549
 550         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
 551
 552         /* zram devices sort of resembles non-rotational disks */
 553         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 554
 555         zram->mem_pool = xv_create_pool();
 556         if (!zram->mem_pool) {
 557                 pr_err("Error creating memory pool\n");
 558                 ret = -ENOMEM;
 559                 goto fail;
 560         }
 561
 562         zram->init_done = 1;
 563
 564         pr_debug("Initialization done!\n");
 565         return 0;
 566
 567 fail:
 568         reset_device(zram);
 569
 570         pr_err("Initialization failed: err=%d\n", ret);
 571         return ret;
 572 }
 573
 574 static int zram_ioctl_reset_device(struct zram *zram)
 575 {
 576         if (zram->init_done)
 577                 reset_device(zram);
 578
 579         return 0;
 580 }
 581
 582 static int zram_ioctl(struct block_device *bdev, fmode_t mode,
 583                         unsigned int cmd, unsigned long arg)
 584 {
 585         int ret = 0;
 586         size_t disksize_kb;
 587
 588         struct zram *zram = bdev->bd_disk->private_data;
 589
 590         switch (cmd) {
 591         case ZRAMIO_SET_DISKSIZE_KB:
 592                 if (zram->init_done) {
 593                         ret = -EBUSY;
 594                         goto out;
 595                 }
 596                 if (copy_from_user(&disksize_kb, (void *)arg,
 597                                                 _IOC_SIZE(cmd))) {
 598                         ret = -EFAULT;
 599                         goto out;
 600                 }
 601                 zram->disksize = disksize_kb << 10;
 602                 pr_info("Disk size set to %zu kB\n", disksize_kb);
 603                 break;
 604
 605         case ZRAMIO_GET_STATS:
 606         {
 607                 struct zram_ioctl_stats *stats;
 608                 if (!zram->init_done) {
 609                         ret = -ENOTTY;
 610                         goto out;
 611                 }
 612                 stats = kzalloc(sizeof(*stats), GFP_KERNEL);
 613                 if (!stats) {
 614                         ret = -ENOMEM;
 615                         goto out;
 616                 }
 617                 zram_ioctl_get_stats(zram, stats);
 618                 if (copy_to_user((void *)arg, stats, sizeof(*stats))) {
 619                         kfree(stats);
 620                         ret = -EFAULT;
 621                         goto out;
 622                 }
 623                 kfree(stats);
 624                 break;
 625         }
 626         case ZRAMIO_INIT:
 627                 ret = zram_ioctl_init_device(zram);
 628                 break;
 629
 630         case ZRAMIO_RESET:
 631                 /* Do not reset an active device! */
 632                 if (bdev->bd_holders) {
 633                         ret = -EBUSY;
 634                         goto out;
 635                 }
 636
 637                 /* Make sure all pending I/O is finished */
 638                 if (bdev)
 639                         fsync_bdev(bdev);
 640
 641                 ret = zram_ioctl_reset_device(zram);
 642                 break;
 643
 644         default:
 645                 pr_info("Invalid ioctl %u\n", cmd);
 646                 ret = -ENOTTY;
 647         }
 648
 649 out:
 650         return ret;
 651 }
 652
 653 void zram_slot_free_notify(struct block_device *bdev, unsigned long index)
 654 {
 655         struct zram *zram;
 656
 657         zram = bdev->bd_disk->private_data;
 658         zram_free_page(zram, index);
 659         zram_stat64_inc(zram, &zram->stats.notify_free);
 660 }
 661
 662 static const struct block_device_operations zram_devops = {
 663         .ioctl = zram_ioctl,
 664         .swap_slot_free_notify = zram_slot_free_notify,
 665         .owner = THIS_MODULE
 666 };
 667
 668 static int create_device(struct zram *zram, int device_id)
 669 {
 670         int ret = 0;
 671
 672         mutex_init(&zram->lock);
 673         spin_lock_init(&zram->stat64_lock);
 674
 675         zram->queue = blk_alloc_queue(GFP_KERNEL);
 676         if (!zram->queue) {
 677                 pr_err("Error allocating disk queue for device %d\n",
 678                         device_id);
 679                 ret = -ENOMEM;
 680                 goto out;
 681         }
 682
 683         blk_queue_make_request(zram->queue, zram_make_request);
 684         zram->queue->queuedata = zram;
 685
 686          /* gendisk structure */
 687         zram->disk = alloc_disk(1);
 688         if (!zram->disk) {
 689                 blk_cleanup_queue(zram->queue);
 690                 pr_warning("Error allocating disk structure for device %d\n",
 691                         device_id);
 692                 ret = -ENOMEM;
 693                 goto out;
 694         }
 695
 696         zram->disk->major = zram_major;
 697         zram->disk->first_minor = device_id;
 698         zram->disk->fops = &zram_devops;
 699         zram->disk->queue = zram->queue;
 700         zram->disk->private_data = zram;
 701         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 702
 703         /* Actual capacity set using ZRAMIO_SET_DISKSIZE_KB ioctl */
 704         set_capacity(zram->disk, 0);
 705
 706         /*
 707          * To ensure that we always get PAGE_SIZE aligned
 708          * and n*PAGE_SIZED sized I/O requests.
 709          */
 710         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
 711         blk_queue_logical_block_size(zram->disk->queue, PAGE_SIZE);
 712         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
 713         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 714
 715         add_disk(zram->disk);
 716
 717         zram->init_done = 0;
 718
 719 out:
 720         return ret;
 721 }
 722
 723 static void destroy_device(struct zram *zram)
 724 {
 725         if (zram->disk) {
 726                 del_gendisk(zram->disk);
 727                 put_disk(zram->disk);
 728         }
 729
 730         if (zram->queue)
 731                 blk_cleanup_queue(zram->queue);
 732 }
 733
 734 static int __init zram_init(void)
 735 {
 736         int ret, dev_id;
 737
 738         if (num_devices > max_num_devices) {
 739                 pr_warning("Invalid value for num_devices: %u\n",
 740                                 num_devices);
 741                 ret = -EINVAL;
 742                 goto out;
 743         }
 744
 745         zram_major = register_blkdev(0, "zram");
 746         if (zram_major <= 0) {
 747                 pr_warning("Unable to get major number\n");
 748                 ret = -EBUSY;
 749                 goto out;
 750         }
 751
 752         if (!num_devices) {
 753                 pr_info("num_devices not specified. Using default: 1\n");
 754                 num_devices = 1;
 755         }
 756
 757         /* Allocate the device array and initialize each one */
 758         pr_info("Creating %u devices ...\n", num_devices);
 759         devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
 760         if (!devices) {
 761                 ret = -ENOMEM;
 762                 goto unregister;
 763         }
 764
 765         for (dev_id = 0; dev_id < num_devices; dev_id++) {
 766                 ret = create_device(&devices[dev_id], dev_id);
 767                 if (ret)
 768                         goto free_devices;
 769         }
 770
 771         return 0;
 772
 773 free_devices:
 774         while (dev_id)
 775                 destroy_device(&devices[--dev_id]);
 776         kfree(devices);
 777 unregister:
 778         unregister_blkdev(zram_major, "zram");
 779 out:
 780         return ret;
 781 }
 782
 783 static void __exit zram_exit(void)
 784 {
 785         int i;
 786         struct zram *zram;
 787
 788         for (i = 0; i < num_devices; i++) {
 789                 zram = &devices[i];
 790
 791                 destroy_device(zram);
 792                 if (zram->init_done)
 793                         reset_device(zram);
 794         }
 795
 796         unregister_blkdev(zram_major, "zram");
 797
 798         kfree(devices);
 799         pr_debug("Cleanup done!\n");
 800 }
 801
 802 module_param(num_devices, uint, 0);
 803 MODULE_PARM_DESC(num_devices, "Number of zram devices");
 804
 805 module_init(zram_init);
 806 module_exit(zram_exit);
 807
 808 MODULE_LICENSE("Dual BSD/GPL");
 809 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 810 MODULE_DESCRIPTION("Compressed RAM Block Device");