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/bitops.h>
  21 #include <linux/blkdev.h>
  22 #include <linux/buffer_head.h>
  23 #include <linux/device.h>
  24 #include <linux/genhd.h>
  25 #include <linux/highmem.h>
  26 #include <linux/slab.h>
  27 #include <linux/lzo.h>
  28 #include <linux/string.h>
  29 #include <linux/vmalloc.h>
  30
  31 #include "zram_drv.h"
  32
  33 /* Globals */
  34 static int zram_major;
  35 static struct zram *devices;
  36
  37 /* Module params (documentation at end) */
  38 static unsigned int num_devices;
  39
  40 static int zram_test_flag(struct zram *zram, u32 index,
  41                         enum zram_pageflags flag)
  42 {
  43         return zram->table[index].flags & BIT(flag);
  44 }
  45
  46 static void zram_set_flag(struct zram *zram, u32 index,
  47                         enum zram_pageflags flag)
  48 {
  49         zram->table[index].flags |= BIT(flag);
  50 }
  51
  52 static void zram_clear_flag(struct zram *zram, u32 index,
  53                         enum zram_pageflags flag)
  54 {
  55         zram->table[index].flags &= ~BIT(flag);
  56 }
  57
  58 static int page_zero_filled(void *ptr)
  59 {
  60         unsigned int pos;
  61         unsigned long *page;
  62
  63         page = (unsigned long *)ptr;
  64
  65         for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
  66                 if (page[pos])
  67                         return 0;
  68         }
  69
  70         return 1;
  71 }
  72
  73 static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
  74 {
  75         if (!zram->disksize) {
  76                 pr_info(
  77                 "disk size not provided. You can use disksize_kb module "
  78                 "param to specify size.\nUsing default: (%u%% of RAM).\n",
  79                 default_disksize_perc_ram
  80                 );
  81                 zram->disksize = default_disksize_perc_ram *
  82                                         (totalram_bytes / 100);
  83         }
  84
  85         if (zram->disksize > 2 * (totalram_bytes)) {
  86                 pr_info(
  87                 "There is little point creating a zram of greater than "
  88                 "twice the size of memory since we expect a 2:1 compression "
  89                 "ratio. Note that zram uses about 0.1%% of the size of "
  90                 "the disk when not in use so a huge zram is "
  91                 "wasteful.\n"
  92                 "\tMemory Size: %zu kB\n"
  93                 "\tSize you selected: %zu kB\n"
  94                 "Continuing anyway ...\n",
  95                 totalram_bytes >> 10, zram->disksize
  96                 );
  97         }
  98
  99         zram->disksize &= PAGE_MASK;
 100 }
 101
 102 static void zram_ioctl_get_stats(struct zram *zram,
 103                         struct zram_ioctl_stats *s)
 104 {
 105         s->disksize = zram->disksize;
 106
 107 #if defined(CONFIG_ZRAM_STATS)
 108         {
 109         struct zram_stats *rs = &zram->stats;
 110         size_t succ_writes, mem_used;
 111         unsigned int good_compress_perc = 0, no_compress_perc = 0;
 112
 113         mem_used = xv_get_total_size_bytes(zram->mem_pool)
 114                         + (rs->pages_expand << PAGE_SHIFT);
 115         succ_writes = zram_stat64_read(zram, &rs->num_writes) -
 116                         zram_stat64_read(zram, &rs->failed_writes);
 117
 118         if (succ_writes && rs->pages_stored) {
 119                 good_compress_perc = rs->good_compress * 100
 120                                         / rs->pages_stored;
 121                 no_compress_perc = rs->pages_expand * 100
 122                                         / rs->pages_stored;
 123         }
 124
 125         s->num_reads = zram_stat64_read(zram, &rs->num_reads);
 126         s->num_writes = zram_stat64_read(zram, &rs->num_writes);
 127         s->failed_reads = zram_stat64_read(zram, &rs->failed_reads);
 128         s->failed_writes = zram_stat64_read(zram, &rs->failed_writes);
 129         s->invalid_io = zram_stat64_read(zram, &rs->invalid_io);
 130         s->notify_free = zram_stat64_read(zram, &rs->notify_free);
 131         s->pages_zero = rs->pages_zero;
 132
 133         s->good_compress_pct = good_compress_perc;
 134         s->pages_expand_pct = no_compress_perc;
 135
 136         s->pages_stored = rs->pages_stored;
 137         s->pages_used = mem_used >> PAGE_SHIFT;
 138         s->orig_data_size = rs->pages_stored << PAGE_SHIFT;
 139         s->compr_data_size = rs->compr_size;
 140         s->mem_used_total = mem_used;
 141         }
 142 #endif /* CONFIG_ZRAM_STATS */
 143 }
 144
 145 static void zram_free_page(struct zram *zram, size_t index)
 146 {
 147         u32 clen;
 148         void *obj;
 149
 150         struct page *page = zram->table[index].page;
 151         u32 offset = zram->table[index].offset;
 152
 153         if (unlikely(!page)) {
 154                 /*
 155                  * No memory is allocated for zero filled pages.
 156                  * Simply clear zero page flag.
 157                  */
 158                 if (zram_test_flag(zram, index, ZRAM_ZERO)) {
 159                         zram_clear_flag(zram, index, ZRAM_ZERO);
 160                         zram_stat_dec(&zram->stats.pages_zero);
 161                 }
 162                 return;
 163         }
 164
 165         if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
 166                 clen = PAGE_SIZE;
 167                 __free_page(page);
 168                 zram_clear_flag(zram, index, ZRAM_UNCOMPRESSED);
 169                 zram_stat_dec(&zram->stats.pages_expand);
 170                 goto out;
 171         }
 172
 173         obj = kmap_atomic(page, KM_USER0) + offset;
 174         clen = xv_get_object_size(obj) - sizeof(struct zobj_header);
 175         kunmap_atomic(obj, KM_USER0);
 176
 177         xv_free(zram->mem_pool, page, offset);
 178         if (clen <= PAGE_SIZE / 2)
 179                 zram_stat_dec(&zram->stats.good_compress);
 180
 181 out:
 182         zram->stats.compr_size -= clen;
 183         zram_stat_dec(&zram->stats.pages_stored);
 184
 185         zram->table[index].page = NULL;
 186         zram->table[index].offset = 0;
 187 }
 188
 189 static void handle_zero_page(struct page *page)
 190 {
 191         void *user_mem;
 192
 193         user_mem = kmap_atomic(page, KM_USER0);
 194         memset(user_mem, 0, PAGE_SIZE);
 195         kunmap_atomic(user_mem, KM_USER0);
 196
 197         flush_dcache_page(page);
 198 }
 199
 200 static void handle_uncompressed_page(struct zram *zram,
 201                                 struct page *page, u32 index)
 202 {
 203         unsigned char *user_mem, *cmem;
 204
 205         user_mem = kmap_atomic(page, KM_USER0);
 206         cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
 207                         zram->table[index].offset;
 208
 209         memcpy(user_mem, cmem, PAGE_SIZE);
 210         kunmap_atomic(user_mem, KM_USER0);
 211         kunmap_atomic(cmem, KM_USER1);
 212
 213         flush_dcache_page(page);
 214 }
 215
 216 static int zram_read(struct zram *zram, struct bio *bio)
 217 {
 218
 219         int i;
 220         u32 index;
 221         struct bio_vec *bvec;
 222
 223         zram_stat64_inc(zram, &zram->stats.num_reads);
 224
 225         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 226         bio_for_each_segment(bvec, bio, i) {
 227                 int ret;
 228                 size_t clen;
 229                 struct page *page;
 230                 struct zobj_header *zheader;
 231                 unsigned char *user_mem, *cmem;
 232
 233                 page = bvec->bv_page;
 234
 235                 if (zram_test_flag(zram, index, ZRAM_ZERO)) {
 236                         handle_zero_page(page);
 237                         continue;
 238                 }
 239
 240                 /* Requested page is not present in compressed area */
 241                 if (unlikely(!zram->table[index].page)) {
 242                         pr_debug("Read before write: sector=%lu, size=%u",
 243                                 (ulong)(bio->bi_sector), bio->bi_size);
 244                         /* Do nothing */
 245                         continue;
 246                 }
 247
 248                 /* Page is stored uncompressed since it's incompressible */
 249                 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
 250                         handle_uncompressed_page(zram, page, index);
 251                         continue;
 252                 }
 253
 254                 user_mem = kmap_atomic(page, KM_USER0);
 255                 clen = PAGE_SIZE;
 256
 257                 cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
 258                                 zram->table[index].offset;
 259
 260                 ret = lzo1x_decompress_safe(
 261                         cmem + sizeof(*zheader),
 262                         xv_get_object_size(cmem) - sizeof(*zheader),
 263                         user_mem, &clen);
 264
 265                 kunmap_atomic(user_mem, KM_USER0);
 266                 kunmap_atomic(cmem, KM_USER1);
 267
 268                 /* Should NEVER happen. Return bio error if it does. */
 269                 if (unlikely(ret != LZO_E_OK)) {
 270                         pr_err("Decompression failed! err=%d, page=%u\n",
 271                                 ret, index);
 272                         zram_stat64_inc(zram, &zram->stats.failed_reads);
 273                         goto out;
 274                 }
 275
 276                 flush_dcache_page(page);
 277                 index++;
 278         }
 279
 280         set_bit(BIO_UPTODATE, &bio->bi_flags);
 281         bio_endio(bio, 0);
 282         return 0;
 283
 284 out:
 285         bio_io_error(bio);
 286         return 0;
 287 }
 288
 289 static int zram_write(struct zram *zram, struct bio *bio)
 290 {
 291         int i;
 292         u32 index;
 293         struct bio_vec *bvec;
 294
 295         zram_stat64_inc(zram, &zram->stats.num_writes);
 296
 297         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 298
 299         bio_for_each_segment(bvec, bio, i) {
 300                 int ret;
 301                 u32 offset;
 302                 size_t clen;
 303                 struct zobj_header *zheader;
 304                 struct page *page, *page_store;
 305                 unsigned char *user_mem, *cmem, *src;
 306
 307                 page = bvec->bv_page;
 308                 src = zram->compress_buffer;
 309
 310                 /*
 311                  * System overwrites unused sectors. Free memory associated
 312                  * with this sector now.
 313                  */
 314                 if (zram->table[index].page ||
 315                                 zram_test_flag(zram, index, ZRAM_ZERO))
 316                         zram_free_page(zram, index);
 317
 318                 mutex_lock(&zram->lock);
 319
 320                 user_mem = kmap_atomic(page, KM_USER0);
 321                 if (page_zero_filled(user_mem)) {
 322                         kunmap_atomic(user_mem, KM_USER0);
 323                         mutex_unlock(&zram->lock);
 324                         zram_stat_inc(&zram->stats.pages_zero);
 325                         zram_set_flag(zram, index, ZRAM_ZERO);
 326                         continue;
 327                 }
 328
 329                 ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen,
 330                                         zram->compress_workmem);
 331
 332                 kunmap_atomic(user_mem, KM_USER0);
 333
 334                 if (unlikely(ret != LZO_E_OK)) {
 335                         mutex_unlock(&zram->lock);
 336                         pr_err("Compression failed! err=%d\n", ret);
 337                         zram_stat64_inc(zram, &zram->stats.failed_writes);
 338                         goto out;
 339                 }
 340
 341                 /*
 342                  * Page is incompressible. Store it as-is (uncompressed)
 343                  * since we do not want to return too many disk write
 344                  * errors which has side effect of hanging the system.
 345                  */
 346                 if (unlikely(clen > max_zpage_size)) {
 347                         clen = PAGE_SIZE;
 348                         page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
 349                         if (unlikely(!page_store)) {
 350                                 mutex_unlock(&zram->lock);
 351                                 pr_info("Error allocating memory for "
 352                                         "incompressible page: %u\n", index);
 353                                 zram_stat64_inc(zram,
 354                                         &zram->stats.failed_writes);
 355                                 goto out;
 356                         }
 357
 358                         offset = 0;
 359                         zram_set_flag(zram, index, ZRAM_UNCOMPRESSED);
 360                         zram_stat_inc(&zram->stats.pages_expand);
 361                         zram->table[index].page = page_store;
 362                         src = kmap_atomic(page, KM_USER0);
 363                         goto memstore;
 364                 }
 365
 366                 if (xv_malloc(zram->mem_pool, clen + sizeof(*zheader),
 367                                 &zram->table[index].page, &offset,
 368                                 GFP_NOIO | __GFP_HIGHMEM)) {
 369                         mutex_unlock(&zram->lock);
 370                         pr_info("Error allocating memory for compressed "
 371                                 "page: %u, size=%zu\n", index, clen);
 372                         zram_stat64_inc(zram, &zram->stats.failed_writes);
 373                         goto out;
 374                 }
 375
 376 memstore:
 377                 zram->table[index].offset = offset;
 378
 379                 cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
 380                                 zram->table[index].offset;
 381
 382 #if 0
 383                 /* Back-reference needed for memory defragmentation */
 384                 if (!zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)) {
 385                         zheader = (struct zobj_header *)cmem;
 386                         zheader->table_idx = index;
 387                         cmem += sizeof(*zheader);
 388                 }
 389 #endif
 390
 391                 memcpy(cmem, src, clen);
 392
 393                 kunmap_atomic(cmem, KM_USER1);
 394                 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
 395                         kunmap_atomic(src, KM_USER0);
 396
 397                 /* Update stats */
 398                 zram->stats.compr_size += clen;
 399                 zram_stat_inc(&zram->stats.pages_stored);
 400                 if (clen <= PAGE_SIZE / 2)
 401                         zram_stat_inc(&zram->stats.good_compress);
 402
 403                 mutex_unlock(&zram->lock);
 404                 index++;
 405         }
 406
 407         set_bit(BIO_UPTODATE, &bio->bi_flags);
 408         bio_endio(bio, 0);
 409         return 0;
 410
 411 out:
 412         bio_io_error(bio);
 413         return 0;
 414 }
 415
 416 /*
 417  * Check if request is within bounds and page aligned.
 418  */
 419 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 420 {
 421         if (unlikely(
 422                 (bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
 423                 (bio->bi_sector & (SECTORS_PER_PAGE - 1)) ||
 424                 (bio->bi_size & (PAGE_SIZE - 1)))) {
 425
 426                 return 0;
 427         }
 428
 429         /* I/O request is valid */
 430         return 1;
 431 }
 432
 433 /*
 434  * Handler function for all zram I/O requests.
 435  */
 436 static int zram_make_request(struct request_queue *queue, struct bio *bio)
 437 {
 438         int ret = 0;
 439         struct zram *zram = queue->queuedata;
 440
 441         if (unlikely(!zram->init_done)) {
 442                 bio_io_error(bio);
 443                 return 0;
 444         }
 445
 446         if (!valid_io_request(zram, bio)) {
 447                 zram_stat64_inc(zram, &zram->stats.invalid_io);
 448                 bio_io_error(bio);
 449                 return 0;
 450         }
 451
 452         switch (bio_data_dir(bio)) {
 453         case READ:
 454                 ret = zram_read(zram, bio);
 455                 break;
 456
 457         case WRITE:
 458                 ret = zram_write(zram, bio);
 459                 break;
 460         }
 461
 462         return ret;
 463 }
 464
 465 static void reset_device(struct zram *zram)
 466 {
 467         size_t index;
 468
 469         /* Do not accept any new I/O request */
 470         zram->init_done = 0;
 471
 472         /* Free various per-device buffers */
 473         kfree(zram->compress_workmem);
 474         free_pages((unsigned long)zram->compress_buffer, 1);
 475
 476         zram->compress_workmem = NULL;
 477         zram->compress_buffer = NULL;
 478
 479         /* Free all pages that are still in this zram device */
 480         for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 481                 struct page *page;
 482                 u16 offset;
 483
 484                 page = zram->table[index].page;
 485                 offset = zram->table[index].offset;
 486
 487                 if (!page)
 488                         continue;
 489
 490                 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
 491                         __free_page(page);
 492                 else
 493                         xv_free(zram->mem_pool, page, offset);
 494         }
 495
 496         vfree(zram->table);
 497         zram->table = NULL;
 498
 499         xv_destroy_pool(zram->mem_pool);
 500         zram->mem_pool = NULL;
 501
 502         /* Reset stats */
 503         memset(&zram->stats, 0, sizeof(zram->stats));
 504
 505         zram->disksize = 0;
 506 }
 507
 508 static int zram_ioctl_init_device(struct zram *zram)
 509 {
 510         int ret;
 511         size_t num_pages;
 512
 513         if (zram->init_done) {
 514                 pr_info("Device already initialized!\n");
 515                 return -EBUSY;
 516         }
 517
 518         zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
 519
 520         zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 521         if (!zram->compress_workmem) {
 522                 pr_err("Error allocating compressor working memory!\n");
 523                 ret = -ENOMEM;
 524                 goto fail;
 525         }
 526
 527         zram->compress_buffer = (void *)__get_free_pages(__GFP_ZERO, 1);
 528         if (!zram->compress_buffer) {
 529                 pr_err("Error allocating compressor buffer space\n");
 530                 ret = -ENOMEM;
 531                 goto fail;
 532         }
 533
 534         num_pages = zram->disksize >> PAGE_SHIFT;
 535         zram->table = vmalloc(num_pages * sizeof(*zram->table));
 536         if (!zram->table) {
 537                 pr_err("Error allocating zram address table\n");
 538                 /* To prevent accessing table entries during cleanup */
 539                 zram->disksize = 0;
 540                 ret = -ENOMEM;
 541                 goto fail;
 542         }
 543         memset(zram->table, 0, num_pages * sizeof(*zram->table));
 544
 545         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
 546
 547         /* zram devices sort of resembles non-rotational disks */
 548         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 549
 550         zram->mem_pool = xv_create_pool();
 551         if (!zram->mem_pool) {
 552                 pr_err("Error creating memory pool\n");
 553                 ret = -ENOMEM;
 554                 goto fail;
 555         }
 556
 557         zram->init_done = 1;
 558
 559         pr_debug("Initialization done!\n");
 560         return 0;
 561
 562 fail:
 563         reset_device(zram);
 564
 565         pr_err("Initialization failed: err=%d\n", ret);
 566         return ret;
 567 }
 568
 569 static int zram_ioctl_reset_device(struct zram *zram)
 570 {
 571         if (zram->init_done)
 572                 reset_device(zram);
 573
 574         return 0;
 575 }
 576
 577 static int zram_ioctl(struct block_device *bdev, fmode_t mode,
 578                         unsigned int cmd, unsigned long arg)
 579 {
 580         int ret = 0;
 581         size_t disksize_kb;
 582
 583         struct zram *zram = bdev->bd_disk->private_data;
 584
 585         switch (cmd) {
 586         case ZRAMIO_SET_DISKSIZE_KB:
 587                 if (zram->init_done) {
 588                         ret = -EBUSY;
 589                         goto out;
 590                 }
 591                 if (copy_from_user(&disksize_kb, (void *)arg,
 592                                                 _IOC_SIZE(cmd))) {
 593                         ret = -EFAULT;
 594                         goto out;
 595                 }
 596                 zram->disksize = disksize_kb << 10;
 597                 pr_info("Disk size set to %zu kB\n", disksize_kb);
 598                 break;
 599
 600         case ZRAMIO_GET_STATS:
 601         {
 602                 struct zram_ioctl_stats *stats;
 603                 if (!zram->init_done) {
 604                         ret = -ENOTTY;
 605                         goto out;
 606                 }
 607                 stats = kzalloc(sizeof(*stats), GFP_KERNEL);
 608                 if (!stats) {
 609                         ret = -ENOMEM;
 610                         goto out;
 611                 }
 612                 zram_ioctl_get_stats(zram, stats);
 613                 if (copy_to_user((void *)arg, stats, sizeof(*stats))) {
 614                         kfree(stats);
 615                         ret = -EFAULT;
 616                         goto out;
 617                 }
 618                 kfree(stats);
 619                 break;
 620         }
 621         case ZRAMIO_INIT:
 622                 ret = zram_ioctl_init_device(zram);
 623                 break;
 624
 625         case ZRAMIO_RESET:
 626                 /* Do not reset an active device! */
 627                 if (bdev->bd_holders) {
 628                         ret = -EBUSY;
 629                         goto out;
 630                 }
 631
 632                 /* Make sure all pending I/O is finished */
 633                 if (bdev)
 634                         fsync_bdev(bdev);
 635
 636                 ret = zram_ioctl_reset_device(zram);
 637                 break;
 638
 639         default:
 640                 pr_info("Invalid ioctl %u\n", cmd);
 641                 ret = -ENOTTY;
 642         }
 643
 644 out:
 645         return ret;
 646 }
 647
 648 void zram_slot_free_notify(struct block_device *bdev, unsigned long index)
 649 {
 650         struct zram *zram;
 651
 652         zram = bdev->bd_disk->private_data;
 653         zram_free_page(zram, index);
 654         zram_stat64_inc(zram, &zram->stats.notify_free);
 655 }
 656
 657 static const struct block_device_operations zram_devops = {
 658         .ioctl = zram_ioctl,
 659         .swap_slot_free_notify = zram_slot_free_notify,
 660         .owner = THIS_MODULE
 661 };
 662
 663 static int create_device(struct zram *zram, int device_id)
 664 {
 665         int ret = 0;
 666
 667         mutex_init(&zram->lock);
 668         spin_lock_init(&zram->stat64_lock);
 669
 670         zram->queue = blk_alloc_queue(GFP_KERNEL);
 671         if (!zram->queue) {
 672                 pr_err("Error allocating disk queue for device %d\n",
 673                         device_id);
 674                 ret = -ENOMEM;
 675                 goto out;
 676         }
 677
 678         blk_queue_make_request(zram->queue, zram_make_request);
 679         zram->queue->queuedata = zram;
 680
 681          /* gendisk structure */
 682         zram->disk = alloc_disk(1);
 683         if (!zram->disk) {
 684                 blk_cleanup_queue(zram->queue);
 685                 pr_warning("Error allocating disk structure for device %d\n",
 686                         device_id);
 687                 ret = -ENOMEM;
 688                 goto out;
 689         }
 690
 691         zram->disk->major = zram_major;
 692         zram->disk->first_minor = device_id;
 693         zram->disk->fops = &zram_devops;
 694         zram->disk->queue = zram->queue;
 695         zram->disk->private_data = zram;
 696         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 697
 698         /* Actual capacity set using ZRAMIO_SET_DISKSIZE_KB ioctl */
 699         set_capacity(zram->disk, 0);
 700
 701         /*
 702          * To ensure that we always get PAGE_SIZE aligned
 703          * and n*PAGE_SIZED sized I/O requests.
 704          */
 705         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
 706         blk_queue_logical_block_size(zram->disk->queue, PAGE_SIZE);
 707         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
 708         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 709
 710         add_disk(zram->disk);
 711
 712         zram->init_done = 0;
 713
 714 out:
 715         return ret;
 716 }
 717
 718 static void destroy_device(struct zram *zram)
 719 {
 720         if (zram->disk) {
 721                 del_gendisk(zram->disk);
 722                 put_disk(zram->disk);
 723         }
 724
 725         if (zram->queue)
 726                 blk_cleanup_queue(zram->queue);
 727 }
 728
 729 static int __init zram_init(void)
 730 {
 731         int ret, dev_id;
 732
 733         if (num_devices > max_num_devices) {
 734                 pr_warning("Invalid value for num_devices: %u\n",
 735                                 num_devices);
 736                 ret = -EINVAL;
 737                 goto out;
 738         }
 739
 740         zram_major = register_blkdev(0, "zram");
 741         if (zram_major <= 0) {
 742                 pr_warning("Unable to get major number\n");
 743                 ret = -EBUSY;
 744                 goto out;
 745         }
 746
 747         if (!num_devices) {
 748                 pr_info("num_devices not specified. Using default: 1\n");
 749                 num_devices = 1;
 750         }
 751
 752         /* Allocate the device array and initialize each one */
 753         pr_info("Creating %u devices ...\n", num_devices);
 754         devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
 755         if (!devices) {
 756                 ret = -ENOMEM;
 757                 goto unregister;
 758         }
 759
 760         for (dev_id = 0; dev_id < num_devices; dev_id++) {
 761                 ret = create_device(&devices[dev_id], dev_id);
 762                 if (ret)
 763                         goto free_devices;
 764         }
 765
 766         return 0;
 767
 768 free_devices:
 769         while (dev_id)
 770                 destroy_device(&devices[--dev_id]);
 771 unregister:
 772         unregister_blkdev(zram_major, "zram");
 773 out:
 774         return ret;
 775 }
 776
 777 static void __exit zram_exit(void)
 778 {
 779         int i;
 780         struct zram *zram;
 781
 782         for (i = 0; i < num_devices; i++) {
 783                 zram = &devices[i];
 784
 785                 destroy_device(zram);
 786                 if (zram->init_done)
 787                         reset_device(zram);
 788         }
 789
 790         unregister_blkdev(zram_major, "zram");
 791
 792         kfree(devices);
 793         pr_debug("Cleanup done!\n");
 794 }
 795
 796 module_param(num_devices, uint, 0);
 797 MODULE_PARM_DESC(num_devices, "Number of zram devices");
 798
 799 module_init(zram_init);
 800 module_exit(zram_exit);
 801
 802 MODULE_LICENSE("Dual BSD/GPL");
 803 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 804 MODULE_DESCRIPTION("Compressed RAM Block Device");