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         ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
 444                                meta->compress_workmem);
 445
 446         if (!is_partial_io(bvec)) {
 447                 kunmap_atomic(user_mem);
 448                 user_mem = NULL;
 449                 uncmem = NULL;
 450         }
 451
 452         if (unlikely(ret != LZO_E_OK)) {
 453                 pr_err("Compression failed! err=%d\n", ret);
 454                 goto out;
 455         }
 456
 457         if (unlikely(clen > max_zpage_size)) {
 458                 zram->stats.bad_compress++;
 459                 clen = PAGE_SIZE;
 460                 src = NULL;
 461                 if (is_partial_io(bvec))
 462                         src = uncmem;
 463         }
 464
 465         handle = zs_malloc(meta->mem_pool, clen);
 466         if (!handle) {
 467                 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
 468                         index, clen);
 469                 ret = -ENOMEM;
 470                 goto out;
 471         }
 472         cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
 473
 474         if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
 475                 src = kmap_atomic(page);
 476                 copy_page(cmem, src);
 477                 kunmap_atomic(src);
 478         } else {
 479                 memcpy(cmem, src, clen);
 480         }
 481
 482         zs_unmap_object(meta->mem_pool, handle);
 483
 484         /*
 485          * Free memory associated with this sector
 486          * before overwriting unused sectors.
 487          */
 488         zram_free_page(zram, index);
 489
 490         meta->table[index].handle = handle;
 491         meta->table[index].size = clen;
 492
 493         /* Update stats */
 494         atomic64_add(clen, &zram->stats.compr_size);
 495         zram->stats.pages_stored++;
 496         if (clen <= PAGE_SIZE / 2)
 497                 zram->stats.good_compress++;
 498
 499 out:
 500         if (is_partial_io(bvec))
 501                 kfree(uncmem);
 502
 503         if (ret)
 504                 atomic64_inc(&zram->stats.failed_writes);
 505         return ret;
 506 }
 507
 508 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 509                         int offset, struct bio *bio, int rw)
 510 {
 511         int ret;
 512
 513         if (rw == READ) {
 514                 down_read(&zram->lock);
 515                 ret = zram_bvec_read(zram, bvec, index, offset, bio);
 516                 up_read(&zram->lock);
 517         } else {
 518                 down_write(&zram->lock);
 519                 ret = zram_bvec_write(zram, bvec, index, offset);
 520                 up_write(&zram->lock);
 521         }
 522
 523         return ret;
 524 }
 525
 526 static void zram_reset_device(struct zram *zram, bool reset_capacity)
 527 {
 528         size_t index;
 529         struct zram_meta *meta;
 530
 531         down_write(&zram->init_lock);
 532         if (!zram->init_done) {
 533                 up_write(&zram->init_lock);
 534                 return;
 535         }
 536
 537         meta = zram->meta;
 538         zram->init_done = 0;
 539
 540         /* Free all pages that are still in this zram device */
 541         for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 542                 unsigned long handle = meta->table[index].handle;
 543                 if (!handle)
 544                         continue;
 545
 546                 zs_free(meta->mem_pool, handle);
 547         }
 548
 549         zram_meta_free(zram->meta);
 550         zram->meta = NULL;
 551         /* Reset stats */
 552         memset(&zram->stats, 0, sizeof(zram->stats));
 553
 554         zram->disksize = 0;
 555         if (reset_capacity)
 556                 set_capacity(zram->disk, 0);
 557         up_write(&zram->init_lock);
 558 }
 559
 560 static void zram_init_device(struct zram *zram, struct zram_meta *meta)
 561 {
 562         if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
 563                 pr_info(
 564                 "There is little point creating a zram of greater than "
 565                 "twice the size of memory since we expect a 2:1 compression "
 566                 "ratio. Note that zram uses about 0.1%% of the size of "
 567                 "the disk when not in use so a huge zram is "
 568                 "wasteful.\n"
 569                 "\tMemory Size: %lu kB\n"
 570                 "\tSize you selected: %llu kB\n"
 571                 "Continuing anyway ...\n",
 572                 (totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
 573                 );
 574         }
 575
 576         /* zram devices sort of resembles non-rotational disks */
 577         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 578
 579         zram->meta = meta;
 580         zram->init_done = 1;
 581
 582         pr_debug("Initialization done!\n");
 583 }
 584
 585 static ssize_t disksize_store(struct device *dev,
 586                 struct device_attribute *attr, const char *buf, size_t len)
 587 {
 588         u64 disksize;
 589         struct zram_meta *meta;
 590         struct zram *zram = dev_to_zram(dev);
 591
 592         disksize = memparse(buf, NULL);
 593         if (!disksize)
 594                 return -EINVAL;
 595
 596         disksize = PAGE_ALIGN(disksize);
 597         meta = zram_meta_alloc(disksize);
 598         down_write(&zram->init_lock);
 599         if (zram->init_done) {
 600                 up_write(&zram->init_lock);
 601                 zram_meta_free(meta);
 602                 pr_info("Cannot change disksize for initialized device\n");
 603                 return -EBUSY;
 604         }
 605
 606         zram->disksize = disksize;
 607         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
 608         zram_init_device(zram, meta);
 609         up_write(&zram->init_lock);
 610
 611         return len;
 612 }
 613
 614 static ssize_t reset_store(struct device *dev,
 615                 struct device_attribute *attr, const char *buf, size_t len)
 616 {
 617         int ret;
 618         unsigned short do_reset;
 619         struct zram *zram;
 620         struct block_device *bdev;
 621
 622         zram = dev_to_zram(dev);
 623         bdev = bdget_disk(zram->disk, 0);
 624
 625         /* Do not reset an active device! */
 626         if (bdev->bd_holders)
 627                 return -EBUSY;
 628
 629         ret = kstrtou16(buf, 10, &do_reset);
 630         if (ret)
 631                 return ret;
 632
 633         if (!do_reset)
 634                 return -EINVAL;
 635
 636         /* Make sure all pending I/O is finished */
 637         if (bdev)
 638                 fsync_bdev(bdev);
 639
 640         zram_reset_device(zram, true);
 641         return len;
 642 }
 643
 644 static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
 645 {
 646         int i, offset;
 647         u32 index;
 648         struct bio_vec *bvec;
 649
 650         switch (rw) {
 651         case READ:
 652                 atomic64_inc(&zram->stats.num_reads);
 653                 break;
 654         case WRITE:
 655                 atomic64_inc(&zram->stats.num_writes);
 656                 break;
 657         }
 658
 659         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 660         offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
 661
 662         bio_for_each_segment(bvec, bio, i) {
 663                 int max_transfer_size = PAGE_SIZE - offset;
 664
 665                 if (bvec->bv_len > max_transfer_size) {
 666                         /*
 667                          * zram_bvec_rw() can only make operation on a single
 668                          * zram page. Split the bio vector.
 669                          */
 670                         struct bio_vec bv;
 671
 672                         bv.bv_page = bvec->bv_page;
 673                         bv.bv_len = max_transfer_size;
 674                         bv.bv_offset = bvec->bv_offset;
 675
 676                         if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
 677                                 goto out;
 678
 679                         bv.bv_len = bvec->bv_len - max_transfer_size;
 680                         bv.bv_offset += max_transfer_size;
 681                         if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
 682                                 goto out;
 683                 } else
 684                         if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
 685                             < 0)
 686                                 goto out;
 687
 688                 update_position(&index, &offset, bvec);
 689         }
 690
 691         set_bit(BIO_UPTODATE, &bio->bi_flags);
 692         bio_endio(bio, 0);
 693         return;
 694
 695 out:
 696         bio_io_error(bio);
 697 }
 698
 699 /*
 700  * Handler function for all zram I/O requests.
 701  */
 702 static void zram_make_request(struct request_queue *queue, struct bio *bio)
 703 {
 704         struct zram *zram = queue->queuedata;
 705
 706         down_read(&zram->init_lock);
 707         if (unlikely(!zram->init_done))
 708                 goto error;
 709
 710         if (!valid_io_request(zram, bio)) {
 711                 atomic64_inc(&zram->stats.invalid_io);
 712                 goto error;
 713         }
 714
 715         __zram_make_request(zram, bio, bio_data_dir(bio));
 716         up_read(&zram->init_lock);
 717
 718         return;
 719
 720 error:
 721         up_read(&zram->init_lock);
 722         bio_io_error(bio);
 723 }
 724
 725 static void zram_slot_free_notify(struct block_device *bdev,
 726                                 unsigned long index)
 727 {
 728         struct zram *zram;
 729
 730         zram = bdev->bd_disk->private_data;
 731         down_write(&zram->lock);
 732         zram_free_page(zram, index);
 733         up_write(&zram->lock);
 734         atomic64_inc(&zram->stats.notify_free);
 735 }
 736
 737 static const struct block_device_operations zram_devops = {
 738         .swap_slot_free_notify = zram_slot_free_notify,
 739         .owner = THIS_MODULE
 740 };
 741
 742 static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
 743                 disksize_show, disksize_store);
 744 static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
 745 static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
 746 static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
 747 static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);
 748 static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
 749 static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
 750 static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
 751 static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
 752 static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
 753 static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
 754
 755 static struct attribute *zram_disk_attrs[] = {
 756         &dev_attr_disksize.attr,
 757         &dev_attr_initstate.attr,
 758         &dev_attr_reset.attr,
 759         &dev_attr_num_reads.attr,
 760         &dev_attr_num_writes.attr,
 761         &dev_attr_invalid_io.attr,
 762         &dev_attr_notify_free.attr,
 763         &dev_attr_zero_pages.attr,
 764         &dev_attr_orig_data_size.attr,
 765         &dev_attr_compr_data_size.attr,
 766         &dev_attr_mem_used_total.attr,
 767         NULL,
 768 };
 769
 770 static struct attribute_group zram_disk_attr_group = {
 771         .attrs = zram_disk_attrs,
 772 };
 773
 774 static int create_device(struct zram *zram, int device_id)
 775 {
 776         int ret = -ENOMEM;
 777
 778         init_rwsem(&zram->lock);
 779         init_rwsem(&zram->init_lock);
 780
 781         zram->queue = blk_alloc_queue(GFP_KERNEL);
 782         if (!zram->queue) {
 783                 pr_err("Error allocating disk queue for device %d\n",
 784                         device_id);
 785                 goto out;
 786         }
 787
 788         blk_queue_make_request(zram->queue, zram_make_request);
 789         zram->queue->queuedata = zram;
 790
 791          /* gendisk structure */
 792         zram->disk = alloc_disk(1);
 793         if (!zram->disk) {
 794                 pr_warn("Error allocating disk structure for device %d\n",
 795                         device_id);
 796                 goto out_free_queue;
 797         }
 798
 799         zram->disk->major = zram_major;
 800         zram->disk->first_minor = device_id;
 801         zram->disk->fops = &zram_devops;
 802         zram->disk->queue = zram->queue;
 803         zram->disk->private_data = zram;
 804         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 805
 806         /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
 807         set_capacity(zram->disk, 0);
 808
 809         /*
 810          * To ensure that we always get PAGE_SIZE aligned
 811          * and n*PAGE_SIZED sized I/O requests.
 812          */
 813         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
 814         blk_queue_logical_block_size(zram->disk->queue,
 815                                         ZRAM_LOGICAL_BLOCK_SIZE);
 816         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
 817         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 818
 819         add_disk(zram->disk);
 820
 821         ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
 822                                 &zram_disk_attr_group);
 823         if (ret < 0) {
 824                 pr_warn("Error creating sysfs group");
 825                 goto out_free_disk;
 826         }
 827
 828         zram->init_done = 0;
 829         return 0;
 830
 831 out_free_disk:
 832         del_gendisk(zram->disk);
 833         put_disk(zram->disk);
 834 out_free_queue:
 835         blk_cleanup_queue(zram->queue);
 836 out:
 837         return ret;
 838 }
 839
 840 static void destroy_device(struct zram *zram)
 841 {
 842         sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
 843                         &zram_disk_attr_group);
 844
 845         if (zram->disk) {
 846                 del_gendisk(zram->disk);
 847                 put_disk(zram->disk);
 848         }
 849
 850         if (zram->queue)
 851                 blk_cleanup_queue(zram->queue);
 852 }
 853
 854 static int __init zram_init(void)
 855 {
 856         int ret, dev_id;
 857
 858         if (num_devices > max_num_devices) {
 859                 pr_warn("Invalid value for num_devices: %u\n",
 860                                 num_devices);
 861                 ret = -EINVAL;
 862                 goto out;
 863         }
 864
 865         zram_major = register_blkdev(0, "zram");
 866         if (zram_major <= 0) {
 867                 pr_warn("Unable to get major number\n");
 868                 ret = -EBUSY;
 869                 goto out;
 870         }
 871
 872         /* Allocate the device array and initialize each one */
 873         zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
 874         if (!zram_devices) {
 875                 ret = -ENOMEM;
 876                 goto unregister;
 877         }
 878
 879         for (dev_id = 0; dev_id < num_devices; dev_id++) {
 880                 ret = create_device(&zram_devices[dev_id], dev_id);
 881                 if (ret)
 882                         goto free_devices;
 883         }
 884
 885         pr_info("Created %u device(s) ...\n", num_devices);
 886
 887         return 0;
 888
 889 free_devices:
 890         while (dev_id)
 891                 destroy_device(&zram_devices[--dev_id]);
 892         kfree(zram_devices);
 893 unregister:
 894         unregister_blkdev(zram_major, "zram");
 895 out:
 896         return ret;
 897 }
 898
 899 static void __exit zram_exit(void)
 900 {
 901         int i;
 902         struct zram *zram;
 903
 904         for (i = 0; i < num_devices; i++) {
 905                 zram = &zram_devices[i];
 906
 907                 destroy_device(zram);
 908                 /*
 909                  * Shouldn't access zram->disk after destroy_device
 910                  * because destroy_device already released zram->disk.
 911                  */
 912                 zram_reset_device(zram, false);
 913         }
 914
 915         unregister_blkdev(zram_major, "zram");
 916
 917         kfree(zram_devices);
 918         pr_debug("Cleanup done!\n");
 919 }
 920
 921 module_init(zram_init);
 922 module_exit(zram_exit);
 923
 924 module_param(num_devices, uint, 0);
 925 MODULE_PARM_DESC(num_devices, "Number of zram devices");
 926
 927 MODULE_LICENSE("Dual BSD/GPL");
 928 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 929 MODULE_DESCRIPTION("Compressed RAM Block Device");
 930 MODULE_ALIAS("devname:zram");