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 static struct zram *zram_devices;
  41
  42 /* Module params (documentation at end) */
  43 static unsigned int num_devices = 1;
  44
  45 static inline struct zram *dev_to_zram(struct device *dev)
  46 {
  47         return (struct zram *)dev_to_disk(dev)->private_data;
  48 }
  49
  50 static ssize_t disksize_show(struct device *dev,
  51                 struct device_attribute *attr, char *buf)
  52 {
  53         struct zram *zram = dev_to_zram(dev);
  54
  55         return sprintf(buf, "%llu\n", zram->disksize);
  56 }
  57
  58 static ssize_t initstate_show(struct device *dev,
  59                 struct device_attribute *attr, char *buf)
  60 {
  61         struct zram *zram = dev_to_zram(dev);
  62
  63         return sprintf(buf, "%u\n", zram->init_done);
  64 }
  65
  66 static ssize_t num_reads_show(struct device *dev,
  67                 struct device_attribute *attr, char *buf)
  68 {
  69         struct zram *zram = dev_to_zram(dev);
  70
  71         return sprintf(buf, "%llu\n",
  72                         (u64)atomic64_read(&zram->stats.num_reads));
  73 }
  74
  75 static ssize_t num_writes_show(struct device *dev,
  76                 struct device_attribute *attr, char *buf)
  77 {
  78         struct zram *zram = dev_to_zram(dev);
  79
  80         return sprintf(buf, "%llu\n",
  81                         (u64)atomic64_read(&zram->stats.num_writes));
  82 }
  83
  84 static ssize_t invalid_io_show(struct device *dev,
  85                 struct device_attribute *attr, char *buf)
  86 {
  87         struct zram *zram = dev_to_zram(dev);
  88
  89         return sprintf(buf, "%llu\n",
  90                         (u64)atomic64_read(&zram->stats.invalid_io));
  91 }
  92
  93 static ssize_t notify_free_show(struct device *dev,
  94                 struct device_attribute *attr, char *buf)
  95 {
  96         struct zram *zram = dev_to_zram(dev);
  97
  98         return sprintf(buf, "%llu\n",
  99                         (u64)atomic64_read(&zram->stats.notify_free));
 100 }
 101
 102 static ssize_t zero_pages_show(struct device *dev,
 103                 struct device_attribute *attr, char *buf)
 104 {
 105         struct zram *zram = dev_to_zram(dev);
 106
 107         return sprintf(buf, "%u\n", zram->stats.pages_zero);
 108 }
 109
 110 static ssize_t orig_data_size_show(struct device *dev,
 111                 struct device_attribute *attr, char *buf)
 112 {
 113         struct zram *zram = dev_to_zram(dev);
 114
 115         return sprintf(buf, "%llu\n",
 116                 (u64)(zram->stats.pages_stored) << PAGE_SHIFT);
 117 }
 118
 119 static ssize_t compr_data_size_show(struct device *dev,
 120                 struct device_attribute *attr, char *buf)
 121 {
 122         struct zram *zram = dev_to_zram(dev);
 123
 124         return sprintf(buf, "%llu\n",
 125                         (u64)atomic64_read(&zram->stats.compr_size));
 126 }
 127
 128 static ssize_t mem_used_total_show(struct device *dev,
 129                 struct device_attribute *attr, char *buf)
 130 {
 131         u64 val = 0;
 132         struct zram *zram = dev_to_zram(dev);
 133         struct zram_meta *meta = zram->meta;
 134
 135         down_read(&zram->init_lock);
 136         if (zram->init_done)
 137                 val = zs_get_total_size_bytes(meta->mem_pool);
 138         up_read(&zram->init_lock);
 139
 140         return sprintf(buf, "%llu\n", val);
 141 }
 142
 143 static int zram_test_flag(struct zram_meta *meta, u32 index,
 144                         enum zram_pageflags flag)
 145 {
 146         return meta->table[index].flags & BIT(flag);
 147 }
 148
 149 static void zram_set_flag(struct zram_meta *meta, u32 index,
 150                         enum zram_pageflags flag)
 151 {
 152         meta->table[index].flags |= BIT(flag);
 153 }
 154
 155 static void zram_clear_flag(struct zram_meta *meta, u32 index,
 156                         enum zram_pageflags flag)
 157 {
 158         meta->table[index].flags &= ~BIT(flag);
 159 }
 160
 161 static inline int is_partial_io(struct bio_vec *bvec)
 162 {
 163         return bvec->bv_len != PAGE_SIZE;
 164 }
 165
 166 /*
 167  * Check if request is within bounds and aligned on zram logical blocks.
 168  */
 169 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 170 {
 171         u64 start, end, bound;
 172
 173         /* unaligned request */
 174         if (unlikely(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
 175                 return 0;
 176         if (unlikely(bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
 177                 return 0;
 178
 179         start = bio->bi_sector;
 180         end = start + (bio->bi_size >> SECTOR_SHIFT);
 181         bound = zram->disksize >> SECTOR_SHIFT;
 182         /* out of range range */
 183         if (unlikely(start >= bound || end > bound || start > end))
 184                 return 0;
 185
 186         /* I/O request is valid */
 187         return 1;
 188 }
 189
 190 static void zram_meta_free(struct zram_meta *meta)
 191 {
 192         zs_destroy_pool(meta->mem_pool);
 193         kfree(meta->compress_workmem);
 194         free_pages((unsigned long)meta->compress_buffer, 1);
 195         vfree(meta->table);
 196         kfree(meta);
 197 }
 198
 199 static struct zram_meta *zram_meta_alloc(u64 disksize)
 200 {
 201         size_t num_pages;
 202         struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
 203         if (!meta)
 204                 goto out;
 205
 206         meta->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 207         if (!meta->compress_workmem)
 208                 goto free_meta;
 209
 210         meta->compress_buffer =
 211                 (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
 212         if (!meta->compress_buffer) {
 213                 pr_err("Error allocating compressor buffer space\n");
 214                 goto free_workmem;
 215         }
 216
 217         num_pages = disksize >> PAGE_SHIFT;
 218         meta->table = vzalloc(num_pages * sizeof(*meta->table));
 219         if (!meta->table) {
 220                 pr_err("Error allocating zram address table\n");
 221                 goto free_buffer;
 222         }
 223
 224         meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
 225         if (!meta->mem_pool) {
 226                 pr_err("Error creating memory pool\n");
 227                 goto free_table;
 228         }
 229
 230         return meta;
 231
 232 free_table:
 233         vfree(meta->table);
 234 free_buffer:
 235         free_pages((unsigned long)meta->compress_buffer, 1);
 236 free_workmem:
 237         kfree(meta->compress_workmem);
 238 free_meta:
 239         kfree(meta);
 240         meta = NULL;
 241 out:
 242         return meta;
 243 }
 244
 245 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
 246 {
 247         if (*offset + bvec->bv_len >= PAGE_SIZE)
 248                 (*index)++;
 249         *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
 250 }
 251
 252 static int page_zero_filled(void *ptr)
 253 {
 254         unsigned int pos;
 255         unsigned long *page;
 256
 257         page = (unsigned long *)ptr;
 258
 259         for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
 260                 if (page[pos])
 261                         return 0;
 262         }
 263
 264         return 1;
 265 }
 266
 267 static void handle_zero_page(struct bio_vec *bvec)
 268 {
 269         struct page *page = bvec->bv_page;
 270         void *user_mem;
 271
 272         user_mem = kmap_atomic(page);
 273         if (is_partial_io(bvec))
 274                 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
 275         else
 276                 clear_page(user_mem);
 277         kunmap_atomic(user_mem);
 278
 279         flush_dcache_page(page);
 280 }
 281
 282 static void zram_free_page(struct zram *zram, size_t index)
 283 {
 284         struct zram_meta *meta = zram->meta;
 285         unsigned long handle = meta->table[index].handle;
 286         u16 size = meta->table[index].size;
 287
 288         if (unlikely(!handle)) {
 289                 /*
 290                  * No memory is allocated for zero filled pages.
 291                  * Simply clear zero page flag.
 292                  */
 293                 if (zram_test_flag(meta, index, ZRAM_ZERO)) {
 294                         zram_clear_flag(meta, index, ZRAM_ZERO);
 295                         zram->stats.pages_zero--;
 296                 }
 297                 return;
 298         }
 299
 300         if (unlikely(size > max_zpage_size))
 301                 zram->stats.bad_compress--;
 302
 303         zs_free(meta->mem_pool, handle);
 304
 305         if (size <= PAGE_SIZE / 2)
 306                 zram->stats.good_compress--;
 307
 308         atomic64_sub(meta->table[index].size, &zram->stats.compr_size);
 309         zram->stats.pages_stored--;
 310
 311         meta->table[index].handle = 0;
 312         meta->table[index].size = 0;
 313 }
 314
 315 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
 316 {
 317         int ret = LZO_E_OK;
 318         size_t clen = PAGE_SIZE;
 319         unsigned char *cmem;
 320         struct zram_meta *meta = zram->meta;
 321         unsigned long handle = meta->table[index].handle;
 322
 323         if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
 324                 clear_page(mem);
 325                 return 0;
 326         }
 327
 328         cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
 329         if (meta->table[index].size == PAGE_SIZE)
 330                 copy_page(mem, cmem);
 331         else
 332                 ret = lzo1x_decompress_safe(cmem, meta->table[index].size,
 333                                                 mem, &clen);
 334         zs_unmap_object(meta->mem_pool, handle);
 335
 336         /* Should NEVER happen. Return bio error if it does. */
 337         if (unlikely(ret != LZO_E_OK)) {
 338                 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
 339                 atomic64_inc(&zram->stats.failed_reads);
 340                 return ret;
 341         }
 342
 343         return 0;
 344 }
 345
 346 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 347                           u32 index, int offset, struct bio *bio)
 348 {
 349         int ret;
 350         struct page *page;
 351         unsigned char *user_mem, *uncmem = NULL;
 352         struct zram_meta *meta = zram->meta;
 353         page = bvec->bv_page;
 354
 355         if (unlikely(!meta->table[index].handle) ||
 356                         zram_test_flag(meta, index, ZRAM_ZERO)) {
 357                 handle_zero_page(bvec);
 358                 return 0;
 359         }
 360
 361         if (is_partial_io(bvec))
 362                 /* Use  a temporary buffer to decompress the page */
 363                 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
 364
 365         user_mem = kmap_atomic(page);
 366         if (!is_partial_io(bvec))
 367                 uncmem = user_mem;
 368
 369         if (!uncmem) {
 370                 pr_info("Unable to allocate temp memory\n");
 371                 ret = -ENOMEM;
 372                 goto out_cleanup;
 373         }
 374
 375         ret = zram_decompress_page(zram, uncmem, index);
 376         /* Should NEVER happen. Return bio error if it does. */
 377         if (unlikely(ret != LZO_E_OK))
 378                 goto out_cleanup;
 379
 380         if (is_partial_io(bvec))
 381                 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
 382                                 bvec->bv_len);
 383
 384         flush_dcache_page(page);
 385         ret = 0;
 386 out_cleanup:
 387         kunmap_atomic(user_mem);
 388         if (is_partial_io(bvec))
 389                 kfree(uncmem);
 390         return ret;
 391 }
 392
 393 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 394                            int offset)
 395 {
 396         int ret = 0;
 397         size_t clen;
 398         unsigned long handle;
 399         struct page *page;
 400         unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
 401         struct zram_meta *meta = zram->meta;
 402
 403         page = bvec->bv_page;
 404         src = meta->compress_buffer;
 405
 406         if (is_partial_io(bvec)) {
 407                 /*
 408                  * This is a partial IO. We need to read the full page
 409                  * before to write the changes.
 410                  */
 411                 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
 412                 if (!uncmem) {
 413                         ret = -ENOMEM;
 414                         goto out;
 415                 }
 416                 ret = zram_decompress_page(zram, uncmem, index);
 417                 if (ret)
 418                         goto out;
 419         }
 420
 421         user_mem = kmap_atomic(page);
 422
 423         if (is_partial_io(bvec)) {
 424                 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
 425                        bvec->bv_len);
 426                 kunmap_atomic(user_mem);
 427                 user_mem = NULL;
 428         } else {
 429                 uncmem = user_mem;
 430         }
 431
 432         if (page_zero_filled(uncmem)) {
 433                 kunmap_atomic(user_mem);
 434                 /* Free memory associated with this sector now. */
 435                 zram_free_page(zram, index);
 436
 437                 zram->stats.pages_zero++;
 438                 zram_set_flag(meta, index, ZRAM_ZERO);
 439                 ret = 0;
 440                 goto out;
 441         }
 442
 443         /*
 444          * zram_slot_free_notify could miss free so that let's
 445          * double check.
 446          */
 447         if (unlikely(meta->table[index].handle ||
 448                         zram_test_flag(meta, index, ZRAM_ZERO)))
 449                 zram_free_page(zram, index);
 450
 451         ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
 452                                meta->compress_workmem);
 453
 454         if (!is_partial_io(bvec)) {
 455                 kunmap_atomic(user_mem);
 456                 user_mem = NULL;
 457                 uncmem = NULL;
 458         }
 459
 460         if (unlikely(ret != LZO_E_OK)) {
 461                 pr_err("Compression failed! err=%d\n", ret);
 462                 goto out;
 463         }
 464
 465         if (unlikely(clen > max_zpage_size)) {
 466                 zram->stats.bad_compress++;
 467                 clen = PAGE_SIZE;
 468                 src = NULL;
 469                 if (is_partial_io(bvec))
 470                         src = uncmem;
 471         }
 472
 473         handle = zs_malloc(meta->mem_pool, clen);
 474         if (!handle) {
 475                 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
 476                         index, clen);
 477                 ret = -ENOMEM;
 478                 goto out;
 479         }
 480         cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
 481
 482         if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
 483                 src = kmap_atomic(page);
 484                 copy_page(cmem, src);
 485                 kunmap_atomic(src);
 486         } else {
 487                 memcpy(cmem, src, clen);
 488         }
 489
 490         zs_unmap_object(meta->mem_pool, handle);
 491
 492         /*
 493          * Free memory associated with this sector
 494          * before overwriting unused sectors.
 495          */
 496         zram_free_page(zram, index);
 497
 498         meta->table[index].handle = handle;
 499         meta->table[index].size = clen;
 500
 501         /* Update stats */
 502         atomic64_add(clen, &zram->stats.compr_size);
 503         zram->stats.pages_stored++;
 504         if (clen <= PAGE_SIZE / 2)
 505                 zram->stats.good_compress++;
 506
 507 out:
 508         if (is_partial_io(bvec))
 509                 kfree(uncmem);
 510
 511         if (ret)
 512                 atomic64_inc(&zram->stats.failed_writes);
 513         return ret;
 514 }
 515
 516 static void handle_pending_slot_free(struct zram *zram)
 517 {
 518         struct zram_slot_free *free_rq;
 519
 520         spin_lock(&zram->slot_free_lock);
 521         while (zram->slot_free_rq) {
 522                 free_rq = zram->slot_free_rq;
 523                 zram->slot_free_rq = free_rq->next;
 524                 zram_free_page(zram, free_rq->index);
 525                 kfree(free_rq);
 526         }
 527         spin_unlock(&zram->slot_free_lock);
 528 }
 529
 530 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 531                         int offset, struct bio *bio, int rw)
 532 {
 533         int ret;
 534
 535         if (rw == READ) {
 536                 down_read(&zram->lock);
 537                 handle_pending_slot_free(zram);
 538                 ret = zram_bvec_read(zram, bvec, index, offset, bio);
 539                 up_read(&zram->lock);
 540         } else {
 541                 down_write(&zram->lock);
 542                 handle_pending_slot_free(zram);
 543                 ret = zram_bvec_write(zram, bvec, index, offset);
 544                 up_write(&zram->lock);
 545         }
 546
 547         return ret;
 548 }
 549
 550 static void zram_reset_device(struct zram *zram, bool reset_capacity)
 551 {
 552         size_t index;
 553         struct zram_meta *meta;
 554
 555         flush_work(&zram->free_work);
 556
 557         down_write(&zram->init_lock);
 558         if (!zram->init_done) {
 559                 up_write(&zram->init_lock);
 560                 return;
 561         }
 562
 563         meta = zram->meta;
 564         zram->init_done = 0;
 565
 566         /* Free all pages that are still in this zram device */
 567         for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 568                 unsigned long handle = meta->table[index].handle;
 569                 if (!handle)
 570                         continue;
 571
 572                 zs_free(meta->mem_pool, handle);
 573         }
 574
 575         zram_meta_free(zram->meta);
 576         zram->meta = NULL;
 577         /* Reset stats */
 578         memset(&zram->stats, 0, sizeof(zram->stats));
 579
 580         zram->disksize = 0;
 581         if (reset_capacity)
 582                 set_capacity(zram->disk, 0);
 583         up_write(&zram->init_lock);
 584 }
 585
 586 static void zram_init_device(struct zram *zram, struct zram_meta *meta)
 587 {
 588         if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
 589                 pr_info(
 590                 "There is little point creating a zram of greater than "
 591                 "twice the size of memory since we expect a 2:1 compression "
 592                 "ratio. Note that zram uses about 0.1%% of the size of "
 593                 "the disk when not in use so a huge zram is "
 594                 "wasteful.\n"
 595                 "\tMemory Size: %lu kB\n"
 596                 "\tSize you selected: %llu kB\n"
 597                 "Continuing anyway ...\n",
 598                 (totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
 599                 );
 600         }
 601
 602         /* zram devices sort of resembles non-rotational disks */
 603         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 604
 605         zram->meta = meta;
 606         zram->init_done = 1;
 607
 608         pr_debug("Initialization done!\n");
 609 }
 610
 611 static ssize_t disksize_store(struct device *dev,
 612                 struct device_attribute *attr, const char *buf, size_t len)
 613 {
 614         u64 disksize;
 615         struct zram_meta *meta;
 616         struct zram *zram = dev_to_zram(dev);
 617
 618         disksize = memparse(buf, NULL);
 619         if (!disksize)
 620                 return -EINVAL;
 621
 622         disksize = PAGE_ALIGN(disksize);
 623         meta = zram_meta_alloc(disksize);
 624         down_write(&zram->init_lock);
 625         if (zram->init_done) {
 626                 up_write(&zram->init_lock);
 627                 zram_meta_free(meta);
 628                 pr_info("Cannot change disksize for initialized device\n");
 629                 return -EBUSY;
 630         }
 631
 632         zram->disksize = disksize;
 633         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
 634         zram_init_device(zram, meta);
 635         up_write(&zram->init_lock);
 636
 637         return len;
 638 }
 639
 640 static ssize_t reset_store(struct device *dev,
 641                 struct device_attribute *attr, const char *buf, size_t len)
 642 {
 643         int ret;
 644         unsigned short do_reset;
 645         struct zram *zram;
 646         struct block_device *bdev;
 647
 648         zram = dev_to_zram(dev);
 649         bdev = bdget_disk(zram->disk, 0);
 650
 651         if (!bdev)
 652                 return -ENOMEM;
 653
 654         /* Do not reset an active device! */
 655         if (bdev->bd_holders)
 656                 return -EBUSY;
 657
 658         ret = kstrtou16(buf, 10, &do_reset);
 659         if (ret)
 660                 return ret;
 661
 662         if (!do_reset)
 663                 return -EINVAL;
 664
 665         /* Make sure all pending I/O is finished */
 666         fsync_bdev(bdev);
 667
 668         zram_reset_device(zram, true);
 669         return len;
 670 }
 671
 672 static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
 673 {
 674         int i, offset;
 675         u32 index;
 676         struct bio_vec *bvec;
 677
 678         switch (rw) {
 679         case READ:
 680                 atomic64_inc(&zram->stats.num_reads);
 681                 break;
 682         case WRITE:
 683                 atomic64_inc(&zram->stats.num_writes);
 684                 break;
 685         }
 686
 687         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 688         offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
 689
 690         bio_for_each_segment(bvec, bio, i) {
 691                 int max_transfer_size = PAGE_SIZE - offset;
 692
 693                 if (bvec->bv_len > max_transfer_size) {
 694                         /*
 695                          * zram_bvec_rw() can only make operation on a single
 696                          * zram page. Split the bio vector.
 697                          */
 698                         struct bio_vec bv;
 699
 700                         bv.bv_page = bvec->bv_page;
 701                         bv.bv_len = max_transfer_size;
 702                         bv.bv_offset = bvec->bv_offset;
 703
 704                         if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
 705                                 goto out;
 706
 707                         bv.bv_len = bvec->bv_len - max_transfer_size;
 708                         bv.bv_offset += max_transfer_size;
 709                         if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
 710                                 goto out;
 711                 } else
 712                         if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
 713                             < 0)
 714                                 goto out;
 715
 716                 update_position(&index, &offset, bvec);
 717         }
 718
 719         set_bit(BIO_UPTODATE, &bio->bi_flags);
 720         bio_endio(bio, 0);
 721         return;
 722
 723 out:
 724         bio_io_error(bio);
 725 }
 726
 727 /*
 728  * Handler function for all zram I/O requests.
 729  */
 730 static void zram_make_request(struct request_queue *queue, struct bio *bio)
 731 {
 732         struct zram *zram = queue->queuedata;
 733
 734         down_read(&zram->init_lock);
 735         if (unlikely(!zram->init_done))
 736                 goto error;
 737
 738         if (!valid_io_request(zram, bio)) {
 739                 atomic64_inc(&zram->stats.invalid_io);
 740                 goto error;
 741         }
 742
 743         __zram_make_request(zram, bio, bio_data_dir(bio));
 744         up_read(&zram->init_lock);
 745
 746         return;
 747
 748 error:
 749         up_read(&zram->init_lock);
 750         bio_io_error(bio);
 751 }
 752
 753 static void zram_slot_free(struct work_struct *work)
 754 {
 755         struct zram *zram;
 756
 757         zram = container_of(work, struct zram, free_work);
 758         down_write(&zram->lock);
 759         handle_pending_slot_free(zram);
 760         up_write(&zram->lock);
 761 }
 762
 763 static void add_slot_free(struct zram *zram, struct zram_slot_free *free_rq)
 764 {
 765         spin_lock(&zram->slot_free_lock);
 766         free_rq->next = zram->slot_free_rq;
 767         zram->slot_free_rq = free_rq;
 768         spin_unlock(&zram->slot_free_lock);
 769 }
 770
 771 static void zram_slot_free_notify(struct block_device *bdev,
 772                                 unsigned long index)
 773 {
 774         struct zram *zram;
 775         struct zram_slot_free *free_rq;
 776
 777         zram = bdev->bd_disk->private_data;
 778         atomic64_inc(&zram->stats.notify_free);
 779
 780         free_rq = kmalloc(sizeof(struct zram_slot_free), GFP_ATOMIC);
 781         if (!free_rq)
 782                 return;
 783
 784         free_rq->index = index;
 785         add_slot_free(zram, free_rq);
 786         schedule_work(&zram->free_work);
 787 }
 788
 789 static const struct block_device_operations zram_devops = {
 790         .swap_slot_free_notify = zram_slot_free_notify,
 791         .owner = THIS_MODULE
 792 };
 793
 794 static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
 795                 disksize_show, disksize_store);
 796 static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
 797 static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
 798 static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
 799 static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);
 800 static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
 801 static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
 802 static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
 803 static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
 804 static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
 805 static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
 806
 807 static struct attribute *zram_disk_attrs[] = {
 808         &dev_attr_disksize.attr,
 809         &dev_attr_initstate.attr,
 810         &dev_attr_reset.attr,
 811         &dev_attr_num_reads.attr,
 812         &dev_attr_num_writes.attr,
 813         &dev_attr_invalid_io.attr,
 814         &dev_attr_notify_free.attr,
 815         &dev_attr_zero_pages.attr,
 816         &dev_attr_orig_data_size.attr,
 817         &dev_attr_compr_data_size.attr,
 818         &dev_attr_mem_used_total.attr,
 819         NULL,
 820 };
 821
 822 static struct attribute_group zram_disk_attr_group = {
 823         .attrs = zram_disk_attrs,
 824 };
 825
 826 static int create_device(struct zram *zram, int device_id)
 827 {
 828         int ret = -ENOMEM;
 829
 830         init_rwsem(&zram->lock);
 831         init_rwsem(&zram->init_lock);
 832
 833         INIT_WORK(&zram->free_work, zram_slot_free);
 834         spin_lock_init(&zram->slot_free_lock);
 835         zram->slot_free_rq = NULL;
 836
 837         zram->queue = blk_alloc_queue(GFP_KERNEL);
 838         if (!zram->queue) {
 839                 pr_err("Error allocating disk queue for device %d\n",
 840                         device_id);
 841                 goto out;
 842         }
 843
 844         blk_queue_make_request(zram->queue, zram_make_request);
 845         zram->queue->queuedata = zram;
 846
 847          /* gendisk structure */
 848         zram->disk = alloc_disk(1);
 849         if (!zram->disk) {
 850                 pr_warn("Error allocating disk structure for device %d\n",
 851                         device_id);
 852                 goto out_free_queue;
 853         }
 854
 855         zram->disk->major = zram_major;
 856         zram->disk->first_minor = device_id;
 857         zram->disk->fops = &zram_devops;
 858         zram->disk->queue = zram->queue;
 859         zram->disk->private_data = zram;
 860         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 861
 862         /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
 863         set_capacity(zram->disk, 0);
 864
 865         /*
 866          * To ensure that we always get PAGE_SIZE aligned
 867          * and n*PAGE_SIZED sized I/O requests.
 868          */
 869         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
 870         blk_queue_logical_block_size(zram->disk->queue,
 871                                         ZRAM_LOGICAL_BLOCK_SIZE);
 872         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
 873         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 874
 875         add_disk(zram->disk);
 876
 877         ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
 878                                 &zram_disk_attr_group);
 879         if (ret < 0) {
 880                 pr_warn("Error creating sysfs group");
 881                 goto out_free_disk;
 882         }
 883
 884         zram->init_done = 0;
 885         return 0;
 886
 887 out_free_disk:
 888         del_gendisk(zram->disk);
 889         put_disk(zram->disk);
 890 out_free_queue:
 891         blk_cleanup_queue(zram->queue);
 892 out:
 893         return ret;
 894 }
 895
 896 static void destroy_device(struct zram *zram)
 897 {
 898         sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
 899                         &zram_disk_attr_group);
 900
 901         del_gendisk(zram->disk);
 902         put_disk(zram->disk);
 903
 904         blk_cleanup_queue(zram->queue);
 905 }
 906
 907 static int __init zram_init(void)
 908 {
 909         int ret, dev_id;
 910
 911         if (num_devices > max_num_devices) {
 912                 pr_warn("Invalid value for num_devices: %u\n",
 913                                 num_devices);
 914                 ret = -EINVAL;
 915                 goto out;
 916         }
 917
 918         zram_major = register_blkdev(0, "zram");
 919         if (zram_major <= 0) {
 920                 pr_warn("Unable to get major number\n");
 921                 ret = -EBUSY;
 922                 goto out;
 923         }
 924
 925         /* Allocate the device array and initialize each one */
 926         zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
 927         if (!zram_devices) {
 928                 ret = -ENOMEM;
 929                 goto unregister;
 930         }
 931
 932         for (dev_id = 0; dev_id < num_devices; dev_id++) {
 933                 ret = create_device(&zram_devices[dev_id], dev_id);
 934                 if (ret)
 935                         goto free_devices;
 936         }
 937
 938         pr_info("Created %u device(s) ...\n", num_devices);
 939
 940         return 0;
 941
 942 free_devices:
 943         while (dev_id)
 944                 destroy_device(&zram_devices[--dev_id]);
 945         kfree(zram_devices);
 946 unregister:
 947         unregister_blkdev(zram_major, "zram");
 948 out:
 949         return ret;
 950 }
 951
 952 static void __exit zram_exit(void)
 953 {
 954         int i;
 955         struct zram *zram;
 956
 957         for (i = 0; i < num_devices; i++) {
 958                 zram = &zram_devices[i];
 959
 960                 destroy_device(zram);
 961                 /*
 962                  * Shouldn't access zram->disk after destroy_device
 963                  * because destroy_device already released zram->disk.
 964                  */
 965                 zram_reset_device(zram, false);
 966         }
 967
 968         unregister_blkdev(zram_major, "zram");
 969
 970         kfree(zram_devices);
 971         pr_debug("Cleanup done!\n");
 972 }
 973
 974 module_init(zram_init);
 975 module_exit(zram_exit);
 976
 977 module_param(num_devices, uint, 0);
 978 MODULE_PARM_DESC(num_devices, "Number of zram devices");
 979
 980 MODULE_LICENSE("Dual BSD/GPL");
 981 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 982 MODULE_DESCRIPTION("Compressed RAM Block Device");