drivers/block/zram/zram_drv.c

   1 /*
   2  * Compressed RAM block device
   3  *
   4  * Copyright (C) 2008, 2009, 2010  Nitin Gupta
   5  *               2012, 2013 Minchan Kim
   6  *
   7  * This code is released using a dual license strategy: BSD/GPL
   8  * You can choose the licence that better fits your requirements.
   9  *
  10  * Released under the terms of 3-clause BSD License
  11  * Released under the terms of GNU General Public License Version 2.0
  12  *
  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 static struct zram *zram_devices;
  41
  42 /* Module params (documentation at end) */
  43 static unsigned int num_devices = 1;
  44
  45 static inline int init_done(struct zram *zram)
  46 {
  47         return zram->meta != NULL;
  48 }
  49
  50 static inline struct zram *dev_to_zram(struct device *dev)
  51 {
  52         return (struct zram *)dev_to_disk(dev)->private_data;
  53 }
  54
  55 static ssize_t disksize_show(struct device *dev,
  56                 struct device_attribute *attr, char *buf)
  57 {
  58         struct zram *zram = dev_to_zram(dev);
  59
  60         return sprintf(buf, "%llu\n", zram->disksize);
  61 }
  62
  63 static ssize_t initstate_show(struct device *dev,
  64                 struct device_attribute *attr, char *buf)
  65 {
  66         struct zram *zram = dev_to_zram(dev);
  67
  68         return sprintf(buf, "%u\n", init_done(zram));
  69 }
  70
  71 static ssize_t num_reads_show(struct device *dev,
  72                 struct device_attribute *attr, char *buf)
  73 {
  74         struct zram *zram = dev_to_zram(dev);
  75
  76         return sprintf(buf, "%llu\n",
  77                         (u64)atomic64_read(&zram->stats.num_reads));
  78 }
  79
  80 static ssize_t num_writes_show(struct device *dev,
  81                 struct device_attribute *attr, char *buf)
  82 {
  83         struct zram *zram = dev_to_zram(dev);
  84
  85         return sprintf(buf, "%llu\n",
  86                         (u64)atomic64_read(&zram->stats.num_writes));
  87 }
  88
  89 static ssize_t invalid_io_show(struct device *dev,
  90                 struct device_attribute *attr, char *buf)
  91 {
  92         struct zram *zram = dev_to_zram(dev);
  93
  94         return sprintf(buf, "%llu\n",
  95                         (u64)atomic64_read(&zram->stats.invalid_io));
  96 }
  97
  98 static ssize_t notify_free_show(struct device *dev,
  99                 struct device_attribute *attr, char *buf)
 100 {
 101         struct zram *zram = dev_to_zram(dev);
 102
 103         return sprintf(buf, "%llu\n",
 104                         (u64)atomic64_read(&zram->stats.notify_free));
 105 }
 106
 107 static ssize_t zero_pages_show(struct device *dev,
 108                 struct device_attribute *attr, char *buf)
 109 {
 110         struct zram *zram = dev_to_zram(dev);
 111
 112         return sprintf(buf, "%llu\n", (u64)atomic64_read(&zram->stats.zero_pages));
 113 }
 114
 115 static ssize_t orig_data_size_show(struct device *dev,
 116                 struct device_attribute *attr, char *buf)
 117 {
 118         struct zram *zram = dev_to_zram(dev);
 119
 120         return sprintf(buf, "%llu\n",
 121                 (u64)(atomic64_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
 122 }
 123
 124 static ssize_t compr_data_size_show(struct device *dev,
 125                 struct device_attribute *attr, char *buf)
 126 {
 127         struct zram *zram = dev_to_zram(dev);
 128
 129         return sprintf(buf, "%llu\n",
 130                         (u64)atomic64_read(&zram->stats.compr_data_size));
 131 }
 132
 133 static ssize_t mem_used_total_show(struct device *dev,
 134                 struct device_attribute *attr, char *buf)
 135 {
 136         u64 val = 0;
 137         struct zram *zram = dev_to_zram(dev);
 138         struct zram_meta *meta = zram->meta;
 139
 140         down_read(&zram->init_lock);
 141         if (init_done(zram))
 142                 val = zs_get_total_size_bytes(meta->mem_pool);
 143         up_read(&zram->init_lock);
 144
 145         return sprintf(buf, "%llu\n", val);
 146 }
 147
 148 /* flag operations needs meta->tb_lock */
 149 static int zram_test_flag(struct zram_meta *meta, u32 index,
 150                         enum zram_pageflags flag)
 151 {
 152         return meta->table[index].flags & BIT(flag);
 153 }
 154
 155 static void zram_set_flag(struct zram_meta *meta, u32 index,
 156                         enum zram_pageflags flag)
 157 {
 158         meta->table[index].flags |= BIT(flag);
 159 }
 160
 161 static void zram_clear_flag(struct zram_meta *meta, u32 index,
 162                         enum zram_pageflags flag)
 163 {
 164         meta->table[index].flags &= ~BIT(flag);
 165 }
 166
 167 static inline int is_partial_io(struct bio_vec *bvec)
 168 {
 169         return bvec->bv_len != PAGE_SIZE;
 170 }
 171
 172 /*
 173  * Check if request is within bounds and aligned on zram logical blocks.
 174  */
 175 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 176 {
 177         u64 start, end, bound;
 178
 179         /* unaligned request */
 180         if (unlikely(bio->bi_iter.bi_sector &
 181                      (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
 182                 return 0;
 183         if (unlikely(bio->bi_iter.bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
 184                 return 0;
 185
 186         start = bio->bi_iter.bi_sector;
 187         end = start + (bio->bi_iter.bi_size >> SECTOR_SHIFT);
 188         bound = zram->disksize >> SECTOR_SHIFT;
 189         /* out of range range */
 190         if (unlikely(start >= bound || end > bound || start > end))
 191                 return 0;
 192
 193         /* I/O request is valid */
 194         return 1;
 195 }
 196
 197 static void zram_meta_free(struct zram_meta *meta)
 198 {
 199         zs_destroy_pool(meta->mem_pool);
 200         kfree(meta->compress_workmem);
 201         free_pages((unsigned long)meta->compress_buffer, 1);
 202         vfree(meta->table);
 203         kfree(meta);
 204 }
 205
 206 static struct zram_meta *zram_meta_alloc(u64 disksize)
 207 {
 208         size_t num_pages;
 209         struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
 210         if (!meta)
 211                 goto out;
 212
 213         meta->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 214         if (!meta->compress_workmem)
 215                 goto free_meta;
 216
 217         meta->compress_buffer =
 218                 (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
 219         if (!meta->compress_buffer) {
 220                 pr_err("Error allocating compressor buffer space\n");
 221                 goto free_workmem;
 222         }
 223
 224         num_pages = disksize >> PAGE_SHIFT;
 225         meta->table = vzalloc(num_pages * sizeof(*meta->table));
 226         if (!meta->table) {
 227                 pr_err("Error allocating zram address table\n");
 228                 goto free_buffer;
 229         }
 230
 231         meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
 232         if (!meta->mem_pool) {
 233                 pr_err("Error creating memory pool\n");
 234                 goto free_table;
 235         }
 236
 237         rwlock_init(&meta->tb_lock);
 238         mutex_init(&meta->buffer_lock);
 239         return meta;
 240
 241 free_table:
 242         vfree(meta->table);
 243 free_buffer:
 244         free_pages((unsigned long)meta->compress_buffer, 1);
 245 free_workmem:
 246         kfree(meta->compress_workmem);
 247 free_meta:
 248         kfree(meta);
 249         meta = NULL;
 250 out:
 251         return meta;
 252 }
 253
 254 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
 255 {
 256         if (*offset + bvec->bv_len >= PAGE_SIZE)
 257                 (*index)++;
 258         *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
 259 }
 260
 261 static int page_zero_filled(void *ptr)
 262 {
 263         unsigned int pos;
 264         unsigned long *page;
 265
 266         page = (unsigned long *)ptr;
 267
 268         for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
 269                 if (page[pos])
 270                         return 0;
 271         }
 272
 273         return 1;
 274 }
 275
 276 static void handle_zero_page(struct bio_vec *bvec)
 277 {
 278         struct page *page = bvec->bv_page;
 279         void *user_mem;
 280
 281         user_mem = kmap_atomic(page);
 282         if (is_partial_io(bvec))
 283                 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
 284         else
 285                 clear_page(user_mem);
 286         kunmap_atomic(user_mem);
 287
 288         flush_dcache_page(page);
 289 }
 290
 291 /* NOTE: caller should hold meta->tb_lock with write-side */
 292 static void zram_free_page(struct zram *zram, size_t index)
 293 {
 294         struct zram_meta *meta = zram->meta;
 295         unsigned long handle = meta->table[index].handle;
 296
 297         if (unlikely(!handle)) {
 298                 /*
 299                  * No memory is allocated for zero filled pages.
 300                  * Simply clear zero page flag.
 301                  */
 302                 if (zram_test_flag(meta, index, ZRAM_ZERO)) {
 303                         zram_clear_flag(meta, index, ZRAM_ZERO);
 304                         atomic64_dec(&zram->stats.zero_pages);
 305                 }
 306                 return;
 307         }
 308
 309         zs_free(meta->mem_pool, handle);
 310
 311         atomic64_sub(meta->table[index].size, &zram->stats.compr_data_size);
 312         atomic64_dec(&zram->stats.pages_stored);
 313
 314         meta->table[index].handle = 0;
 315         meta->table[index].size = 0;
 316 }
 317
 318 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
 319 {
 320         int ret = LZO_E_OK;
 321         size_t clen = PAGE_SIZE;
 322         unsigned char *cmem;
 323         struct zram_meta *meta = zram->meta;
 324         unsigned long handle;
 325         u16 size;
 326
 327         read_lock(&meta->tb_lock);
 328         handle = meta->table[index].handle;
 329         size = meta->table[index].size;
 330
 331         if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
 332                 read_unlock(&meta->tb_lock);
 333                 clear_page(mem);
 334                 return 0;
 335         }
 336
 337         cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
 338         if (size == PAGE_SIZE)
 339                 copy_page(mem, cmem);
 340         else
 341                 ret = lzo1x_decompress_safe(cmem, size, mem, &clen);
 342         zs_unmap_object(meta->mem_pool, handle);
 343         read_unlock(&meta->tb_lock);
 344
 345         /* Should NEVER happen. Return bio error if it does. */
 346         if (unlikely(ret != LZO_E_OK)) {
 347                 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
 348                 atomic64_inc(&zram->stats.failed_reads);
 349                 return ret;
 350         }
 351
 352         return 0;
 353 }
 354
 355 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 356                           u32 index, int offset, struct bio *bio)
 357 {
 358         int ret;
 359         struct page *page;
 360         unsigned char *user_mem, *uncmem = NULL;
 361         struct zram_meta *meta = zram->meta;
 362         page = bvec->bv_page;
 363
 364         read_lock(&meta->tb_lock);
 365         if (unlikely(!meta->table[index].handle) ||
 366                         zram_test_flag(meta, index, ZRAM_ZERO)) {
 367                 read_unlock(&meta->tb_lock);
 368                 handle_zero_page(bvec);
 369                 return 0;
 370         }
 371         read_unlock(&meta->tb_lock);
 372
 373         if (is_partial_io(bvec))
 374                 /* Use  a temporary buffer to decompress the page */
 375                 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
 376
 377         user_mem = kmap_atomic(page);
 378         if (!is_partial_io(bvec))
 379                 uncmem = user_mem;
 380
 381         if (!uncmem) {
 382                 pr_info("Unable to allocate temp memory\n");
 383                 ret = -ENOMEM;
 384                 goto out_cleanup;
 385         }
 386
 387         ret = zram_decompress_page(zram, uncmem, index);
 388         /* Should NEVER happen. Return bio error if it does. */
 389         if (unlikely(ret != LZO_E_OK))
 390                 goto out_cleanup;
 391
 392         if (is_partial_io(bvec))
 393                 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
 394                                 bvec->bv_len);
 395
 396         flush_dcache_page(page);
 397         ret = 0;
 398 out_cleanup:
 399         kunmap_atomic(user_mem);
 400         if (is_partial_io(bvec))
 401                 kfree(uncmem);
 402         return ret;
 403 }
 404
 405 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 406                            int offset)
 407 {
 408         int ret = 0;
 409         size_t clen;
 410         unsigned long handle;
 411         struct page *page;
 412         unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
 413         struct zram_meta *meta = zram->meta;
 414         bool locked = false;
 415
 416         page = bvec->bv_page;
 417         src = meta->compress_buffer;
 418
 419         if (is_partial_io(bvec)) {
 420                 /*
 421                  * This is a partial IO. We need to read the full page
 422                  * before to write the changes.
 423                  */
 424                 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
 425                 if (!uncmem) {
 426                         ret = -ENOMEM;
 427                         goto out;
 428                 }
 429                 ret = zram_decompress_page(zram, uncmem, index);
 430                 if (ret)
 431                         goto out;
 432         }
 433
 434         mutex_lock(&meta->buffer_lock);
 435         locked = true;
 436         user_mem = kmap_atomic(page);
 437
 438         if (is_partial_io(bvec)) {
 439                 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
 440                        bvec->bv_len);
 441                 kunmap_atomic(user_mem);
 442                 user_mem = NULL;
 443         } else {
 444                 uncmem = user_mem;
 445         }
 446
 447         if (page_zero_filled(uncmem)) {
 448                 kunmap_atomic(user_mem);
 449                 /* Free memory associated with this sector now. */
 450                 write_lock(&zram->meta->tb_lock);
 451                 zram_free_page(zram, index);
 452                 zram_set_flag(meta, index, ZRAM_ZERO);
 453                 write_unlock(&zram->meta->tb_lock);
 454
 455                 atomic64_inc(&zram->stats.zero_pages);
 456                 ret = 0;
 457                 goto out;
 458         }
 459
 460         ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
 461                                meta->compress_workmem);
 462         if (!is_partial_io(bvec)) {
 463                 kunmap_atomic(user_mem);
 464                 user_mem = NULL;
 465                 uncmem = NULL;
 466         }
 467
 468         if (unlikely(ret != LZO_E_OK)) {
 469                 pr_err("Compression failed! err=%d\n", ret);
 470                 goto out;
 471         }
 472
 473         if (unlikely(clen > max_zpage_size)) {
 474                 clen = PAGE_SIZE;
 475                 src = NULL;
 476                 if (is_partial_io(bvec))
 477                         src = uncmem;
 478         }
 479
 480         handle = zs_malloc(meta->mem_pool, clen);
 481         if (!handle) {
 482                 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
 483                         index, clen);
 484                 ret = -ENOMEM;
 485                 goto out;
 486         }
 487         cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
 488
 489         if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
 490                 src = kmap_atomic(page);
 491                 copy_page(cmem, src);
 492                 kunmap_atomic(src);
 493         } else {
 494                 memcpy(cmem, src, clen);
 495         }
 496
 497         zs_unmap_object(meta->mem_pool, handle);
 498
 499         /*
 500          * Free memory associated with this sector
 501          * before overwriting unused sectors.
 502          */
 503         write_lock(&zram->meta->tb_lock);
 504         zram_free_page(zram, index);
 505
 506         meta->table[index].handle = handle;
 507         meta->table[index].size = clen;
 508         write_unlock(&zram->meta->tb_lock);
 509
 510         /* Update stats */
 511         atomic64_add(clen, &zram->stats.compr_data_size);
 512         atomic64_inc(&zram->stats.pages_stored);
 513 out:
 514         if (locked)
 515                 mutex_unlock(&meta->buffer_lock);
 516         if (is_partial_io(bvec))
 517                 kfree(uncmem);
 518
 519         if (ret)
 520                 atomic64_inc(&zram->stats.failed_writes);
 521         return ret;
 522 }
 523
 524 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 525                         int offset, struct bio *bio)
 526 {
 527         int ret;
 528         int rw = bio_data_dir(bio);
 529
 530         if (rw == READ) {
 531                 atomic64_inc(&zram->stats.num_reads);
 532                 ret = zram_bvec_read(zram, bvec, index, offset, bio);
 533         } else {
 534                 atomic64_inc(&zram->stats.num_writes);
 535                 ret = zram_bvec_write(zram, bvec, index, offset);
 536         }
 537
 538         return ret;
 539 }
 540
 541 static void zram_reset_device(struct zram *zram, bool reset_capacity)
 542 {
 543         size_t index;
 544         struct zram_meta *meta;
 545
 546         down_write(&zram->init_lock);
 547         if (!init_done(zram)) {
 548                 up_write(&zram->init_lock);
 549                 return;
 550         }
 551
 552         meta = zram->meta;
 553         /* Free all pages that are still in this zram device */
 554         for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 555                 unsigned long handle = meta->table[index].handle;
 556                 if (!handle)
 557                         continue;
 558
 559                 zs_free(meta->mem_pool, handle);
 560         }
 561
 562         zram_meta_free(zram->meta);
 563         zram->meta = NULL;
 564         /* Reset stats */
 565         memset(&zram->stats, 0, sizeof(zram->stats));
 566
 567         zram->disksize = 0;
 568         if (reset_capacity)
 569                 set_capacity(zram->disk, 0);
 570         up_write(&zram->init_lock);
 571 }
 572
 573 static void zram_init_device(struct zram *zram, struct zram_meta *meta)
 574 {
 575         if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
 576                 pr_info(
 577                 "There is little point creating a zram of greater than "
 578                 "twice the size of memory since we expect a 2:1 compression "
 579                 "ratio. Note that zram uses about 0.1%% of the size of "
 580                 "the disk when not in use so a huge zram is "
 581                 "wasteful.\n"
 582                 "\tMemory Size: %lu kB\n"
 583                 "\tSize you selected: %llu kB\n"
 584                 "Continuing anyway ...\n",
 585                 (totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
 586                 );
 587         }
 588
 589         /* zram devices sort of resembles non-rotational disks */
 590         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 591
 592         zram->meta = meta;
 593         pr_debug("Initialization done!\n");
 594 }
 595
 596 static ssize_t disksize_store(struct device *dev,
 597                 struct device_attribute *attr, const char *buf, size_t len)
 598 {
 599         u64 disksize;
 600         struct zram_meta *meta;
 601         struct zram *zram = dev_to_zram(dev);
 602
 603         disksize = memparse(buf, NULL);
 604         if (!disksize)
 605                 return -EINVAL;
 606
 607         disksize = PAGE_ALIGN(disksize);
 608         meta = zram_meta_alloc(disksize);
 609         if (!meta)
 610                 return -ENOMEM;
 611         down_write(&zram->init_lock);
 612         if (init_done(zram)) {
 613                 up_write(&zram->init_lock);
 614                 zram_meta_free(meta);
 615                 pr_info("Cannot change disksize for initialized device\n");
 616                 return -EBUSY;
 617         }
 618
 619         zram->disksize = disksize;
 620         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
 621         zram_init_device(zram, meta);
 622         up_write(&zram->init_lock);
 623
 624         return len;
 625 }
 626
 627 static ssize_t reset_store(struct device *dev,
 628                 struct device_attribute *attr, const char *buf, size_t len)
 629 {
 630         int ret;
 631         unsigned short do_reset;
 632         struct zram *zram;
 633         struct block_device *bdev;
 634
 635         zram = dev_to_zram(dev);
 636         bdev = bdget_disk(zram->disk, 0);
 637
 638         if (!bdev)
 639                 return -ENOMEM;
 640
 641         /* Do not reset an active device! */
 642         if (bdev->bd_holders) {
 643                 ret = -EBUSY;
 644                 goto out;
 645         }
 646
 647         ret = kstrtou16(buf, 10, &do_reset);
 648         if (ret)
 649                 goto out;
 650
 651         if (!do_reset) {
 652                 ret = -EINVAL;
 653                 goto out;
 654         }
 655
 656         /* Make sure all pending I/O is finished */
 657         fsync_bdev(bdev);
 658         bdput(bdev);
 659
 660         zram_reset_device(zram, true);
 661         return len;
 662
 663 out:
 664         bdput(bdev);
 665         return ret;
 666 }
 667
 668 static void __zram_make_request(struct zram *zram, struct bio *bio)
 669 {
 670         int offset;
 671         u32 index;
 672         struct bio_vec bvec;
 673         struct bvec_iter iter;
 674
 675         index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
 676         offset = (bio->bi_iter.bi_sector &
 677                   (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
 678
 679         bio_for_each_segment(bvec, bio, iter) {
 680                 int max_transfer_size = PAGE_SIZE - offset;
 681
 682                 if (bvec.bv_len > max_transfer_size) {
 683                         /*
 684                          * zram_bvec_rw() can only make operation on a single
 685                          * zram page. Split the bio vector.
 686                          */
 687                         struct bio_vec bv;
 688
 689                         bv.bv_page = bvec.bv_page;
 690                         bv.bv_len = max_transfer_size;
 691                         bv.bv_offset = bvec.bv_offset;
 692
 693                         if (zram_bvec_rw(zram, &bv, index, offset, bio) < 0)
 694                                 goto out;
 695
 696                         bv.bv_len = bvec.bv_len - max_transfer_size;
 697                         bv.bv_offset += max_transfer_size;
 698                         if (zram_bvec_rw(zram, &bv, index + 1, 0, bio) < 0)
 699                                 goto out;
 700                 } else
 701                         if (zram_bvec_rw(zram, &bvec, index, offset, bio) < 0)
 702                                 goto out;
 703
 704                 update_position(&index, &offset, &bvec);
 705         }
 706
 707         set_bit(BIO_UPTODATE, &bio->bi_flags);
 708         bio_endio(bio, 0);
 709         return;
 710
 711 out:
 712         bio_io_error(bio);
 713 }
 714
 715 /*
 716  * Handler function for all zram I/O requests.
 717  */
 718 static void zram_make_request(struct request_queue *queue, struct bio *bio)
 719 {
 720         struct zram *zram = queue->queuedata;
 721
 722         down_read(&zram->init_lock);
 723         if (unlikely(!init_done(zram)))
 724                 goto error;
 725
 726         if (!valid_io_request(zram, bio)) {
 727                 atomic64_inc(&zram->stats.invalid_io);
 728                 goto error;
 729         }
 730
 731         __zram_make_request(zram, bio);
 732         up_read(&zram->init_lock);
 733
 734         return;
 735
 736 error:
 737         up_read(&zram->init_lock);
 738         bio_io_error(bio);
 739 }
 740
 741 static void zram_slot_free_notify(struct block_device *bdev,
 742                                 unsigned long index)
 743 {
 744         struct zram *zram;
 745         struct zram_meta *meta;
 746
 747         zram = bdev->bd_disk->private_data;
 748         meta = zram->meta;
 749
 750         write_lock(&meta->tb_lock);
 751         zram_free_page(zram, index);
 752         write_unlock(&meta->tb_lock);
 753         atomic64_inc(&zram->stats.notify_free);
 754 }
 755
 756 static const struct block_device_operations zram_devops = {
 757         .swap_slot_free_notify = zram_slot_free_notify,
 758         .owner = THIS_MODULE
 759 };
 760
 761 static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
 762                 disksize_show, disksize_store);
 763 static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
 764 static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
 765 static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
 766 static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);
 767 static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
 768 static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
 769 static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
 770 static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
 771 static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
 772 static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
 773
 774 static struct attribute *zram_disk_attrs[] = {
 775         &dev_attr_disksize.attr,
 776         &dev_attr_initstate.attr,
 777         &dev_attr_reset.attr,
 778         &dev_attr_num_reads.attr,
 779         &dev_attr_num_writes.attr,
 780         &dev_attr_invalid_io.attr,
 781         &dev_attr_notify_free.attr,
 782         &dev_attr_zero_pages.attr,
 783         &dev_attr_orig_data_size.attr,
 784         &dev_attr_compr_data_size.attr,
 785         &dev_attr_mem_used_total.attr,
 786         NULL,
 787 };
 788
 789 static struct attribute_group zram_disk_attr_group = {
 790         .attrs = zram_disk_attrs,
 791 };
 792
 793 static int create_device(struct zram *zram, int device_id)
 794 {
 795         int ret = -ENOMEM;
 796
 797         init_rwsem(&zram->init_lock);
 798
 799         zram->queue = blk_alloc_queue(GFP_KERNEL);
 800         if (!zram->queue) {
 801                 pr_err("Error allocating disk queue for device %d\n",
 802                         device_id);
 803                 goto out;
 804         }
 805
 806         blk_queue_make_request(zram->queue, zram_make_request);
 807         zram->queue->queuedata = zram;
 808
 809          /* gendisk structure */
 810         zram->disk = alloc_disk(1);
 811         if (!zram->disk) {
 812                 pr_warn("Error allocating disk structure for device %d\n",
 813                         device_id);
 814                 goto out_free_queue;
 815         }
 816
 817         zram->disk->major = zram_major;
 818         zram->disk->first_minor = device_id;
 819         zram->disk->fops = &zram_devops;
 820         zram->disk->queue = zram->queue;
 821         zram->disk->private_data = zram;
 822         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 823
 824         /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
 825         set_capacity(zram->disk, 0);
 826
 827         /*
 828          * To ensure that we always get PAGE_SIZE aligned
 829          * and n*PAGE_SIZED sized I/O requests.
 830          */
 831         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
 832         blk_queue_logical_block_size(zram->disk->queue,
 833                                         ZRAM_LOGICAL_BLOCK_SIZE);
 834         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
 835         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 836
 837         add_disk(zram->disk);
 838
 839         ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
 840                                 &zram_disk_attr_group);
 841         if (ret < 0) {
 842                 pr_warn("Error creating sysfs group");
 843                 goto out_free_disk;
 844         }
 845
 846         zram->meta = NULL;
 847         return 0;
 848
 849 out_free_disk:
 850         del_gendisk(zram->disk);
 851         put_disk(zram->disk);
 852 out_free_queue:
 853         blk_cleanup_queue(zram->queue);
 854 out:
 855         return ret;
 856 }
 857
 858 static void destroy_device(struct zram *zram)
 859 {
 860         sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
 861                         &zram_disk_attr_group);
 862
 863         del_gendisk(zram->disk);
 864         put_disk(zram->disk);
 865
 866         blk_cleanup_queue(zram->queue);
 867 }
 868
 869 static int __init zram_init(void)
 870 {
 871         int ret, dev_id;
 872
 873         if (num_devices > max_num_devices) {
 874                 pr_warn("Invalid value for num_devices: %u\n",
 875                                 num_devices);
 876                 ret = -EINVAL;
 877                 goto out;
 878         }
 879
 880         zram_major = register_blkdev(0, "zram");
 881         if (zram_major <= 0) {
 882                 pr_warn("Unable to get major number\n");
 883                 ret = -EBUSY;
 884                 goto out;
 885         }
 886
 887         /* Allocate the device array and initialize each one */
 888         zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
 889         if (!zram_devices) {
 890                 ret = -ENOMEM;
 891                 goto unregister;
 892         }
 893
 894         for (dev_id = 0; dev_id < num_devices; dev_id++) {
 895                 ret = create_device(&zram_devices[dev_id], dev_id);
 896                 if (ret)
 897                         goto free_devices;
 898         }
 899
 900         pr_info("Created %u device(s) ...\n", num_devices);
 901
 902         return 0;
 903
 904 free_devices:
 905         while (dev_id)
 906                 destroy_device(&zram_devices[--dev_id]);
 907         kfree(zram_devices);
 908 unregister:
 909         unregister_blkdev(zram_major, "zram");
 910 out:
 911         return ret;
 912 }
 913
 914 static void __exit zram_exit(void)
 915 {
 916         int i;
 917         struct zram *zram;
 918
 919         for (i = 0; i < num_devices; i++) {
 920                 zram = &zram_devices[i];
 921
 922                 destroy_device(zram);
 923                 /*
 924                  * Shouldn't access zram->disk after destroy_device
 925                  * because destroy_device already released zram->disk.
 926                  */
 927                 zram_reset_device(zram, false);
 928         }
 929
 930         unregister_blkdev(zram_major, "zram");
 931
 932         kfree(zram_devices);
 933         pr_debug("Cleanup done!\n");
 934 }
 935
 936 module_init(zram_init);
 937 module_exit(zram_exit);
 938
 939 module_param(num_devices, uint, 0);
 940 MODULE_PARM_DESC(num_devices, "Number of zram devices");
 941
 942 MODULE_LICENSE("Dual BSD/GPL");
 943 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 944 MODULE_DESCRIPTION("Compressed RAM Block Device");