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 #include <linux/module.h>
  19 #include <linux/kernel.h>
  20 #include <linux/bio.h>
  21 #include <linux/bitops.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/buffer_head.h>
  24 #include <linux/device.h>
  25 #include <linux/genhd.h>
  26 #include <linux/highmem.h>
  27 #include <linux/slab.h>
  28 #include <linux/string.h>
  29 #include <linux/vmalloc.h>
  30 #include <linux/err.h>
  31 #include <linux/idr.h>
  32 #include <linux/sysfs.h>
  33
  34 #include "zram_drv.h"
  35
  36 static DEFINE_IDR(zram_index_idr);
  37 /* idr index must be protected */
  38 static DEFINE_MUTEX(zram_index_mutex);
  39
  40 static int zram_major;
  41 static const char *default_compressor = "lzo";
  42
  43 /* Module params (documentation at end) */
  44 static unsigned int num_devices = 1;
  45
  46 static inline void deprecated_attr_warn(const char *name)
  47 {
  48         pr_warn_once("%d (%s) Attribute %s (and others) will be removed. %s\n",
  49                         task_pid_nr(current),
  50                         current->comm,
  51                         name,
  52                         "See zram documentation.");
  53 }
  54
  55 #define ZRAM_ATTR_RO(name)                                              \
  56 static ssize_t name##_show(struct device *d,                            \
  57                                 struct device_attribute *attr, char *b) \
  58 {                                                                       \
  59         struct zram *zram = dev_to_zram(d);                             \
  60                                                                         \
  61         deprecated_attr_warn(__stringify(name));                        \
  62         return scnprintf(b, PAGE_SIZE, "%llu\n",                        \
  63                 (u64)atomic64_read(&zram->stats.name));                 \
  64 }                                                                       \
  65 static DEVICE_ATTR_RO(name);
  66
  67 static inline bool init_done(struct zram *zram)
  68 {
  69         return zram->disksize;
  70 }
  71
  72 static inline struct zram *dev_to_zram(struct device *dev)
  73 {
  74         return (struct zram *)dev_to_disk(dev)->private_data;
  75 }
  76
  77 /* flag operations require table entry bit_spin_lock() being held */
  78 static int zram_test_flag(struct zram_meta *meta, u32 index,
  79                         enum zram_pageflags flag)
  80 {
  81         return meta->table[index].value & BIT(flag);
  82 }
  83
  84 static void zram_set_flag(struct zram_meta *meta, u32 index,
  85                         enum zram_pageflags flag)
  86 {
  87         meta->table[index].value |= BIT(flag);
  88 }
  89
  90 static void zram_clear_flag(struct zram_meta *meta, u32 index,
  91                         enum zram_pageflags flag)
  92 {
  93         meta->table[index].value &= ~BIT(flag);
  94 }
  95
  96 static size_t zram_get_obj_size(struct zram_meta *meta, u32 index)
  97 {
  98         return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
  99 }
 100
 101 static void zram_set_obj_size(struct zram_meta *meta,
 102                                         u32 index, size_t size)
 103 {
 104         unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT;
 105
 106         meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
 107 }
 108
 109 static inline int is_partial_io(struct bio_vec *bvec)
 110 {
 111         return bvec->bv_len != PAGE_SIZE;
 112 }
 113
 114 /*
 115  * Check if request is within bounds and aligned on zram logical blocks.
 116  */
 117 static inline int valid_io_request(struct zram *zram,
 118                 sector_t start, unsigned int size)
 119 {
 120         u64 end, bound;
 121
 122         /* unaligned request */
 123         if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
 124                 return 0;
 125         if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
 126                 return 0;
 127
 128         end = start + (size >> SECTOR_SHIFT);
 129         bound = zram->disksize >> SECTOR_SHIFT;
 130         /* out of range range */
 131         if (unlikely(start >= bound || end > bound || start > end))
 132                 return 0;
 133
 134         /* I/O request is valid */
 135         return 1;
 136 }
 137
 138 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
 139 {
 140         if (*offset + bvec->bv_len >= PAGE_SIZE)
 141                 (*index)++;
 142         *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
 143 }
 144
 145 static inline void update_used_max(struct zram *zram,
 146                                         const unsigned long pages)
 147 {
 148         unsigned long old_max, cur_max;
 149
 150         old_max = atomic_long_read(&zram->stats.max_used_pages);
 151
 152         do {
 153                 cur_max = old_max;
 154                 if (pages > cur_max)
 155                         old_max = atomic_long_cmpxchg(
 156                                 &zram->stats.max_used_pages, cur_max, pages);
 157         } while (old_max != cur_max);
 158 }
 159
 160 static int page_zero_filled(void *ptr)
 161 {
 162         unsigned int pos;
 163         unsigned long *page;
 164
 165         page = (unsigned long *)ptr;
 166
 167         for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
 168                 if (page[pos])
 169                         return 0;
 170         }
 171
 172         return 1;
 173 }
 174
 175 static void handle_zero_page(struct bio_vec *bvec)
 176 {
 177         struct page *page = bvec->bv_page;
 178         void *user_mem;
 179
 180         user_mem = kmap_atomic(page);
 181         if (is_partial_io(bvec))
 182                 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
 183         else
 184                 clear_page(user_mem);
 185         kunmap_atomic(user_mem);
 186
 187         flush_dcache_page(page);
 188 }
 189
 190 static ssize_t initstate_show(struct device *dev,
 191                 struct device_attribute *attr, char *buf)
 192 {
 193         u32 val;
 194         struct zram *zram = dev_to_zram(dev);
 195
 196         down_read(&zram->init_lock);
 197         val = init_done(zram);
 198         up_read(&zram->init_lock);
 199
 200         return scnprintf(buf, PAGE_SIZE, "%u\n", val);
 201 }
 202
 203 static ssize_t disksize_show(struct device *dev,
 204                 struct device_attribute *attr, char *buf)
 205 {
 206         struct zram *zram = dev_to_zram(dev);
 207
 208         return scnprintf(buf, PAGE_SIZE, "%llu\n", zram->disksize);
 209 }
 210
 211 static ssize_t orig_data_size_show(struct device *dev,
 212                 struct device_attribute *attr, char *buf)
 213 {
 214         struct zram *zram = dev_to_zram(dev);
 215
 216         deprecated_attr_warn("orig_data_size");
 217         return scnprintf(buf, PAGE_SIZE, "%llu\n",
 218                 (u64)(atomic64_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
 219 }
 220
 221 static ssize_t mem_used_total_show(struct device *dev,
 222                 struct device_attribute *attr, char *buf)
 223 {
 224         u64 val = 0;
 225         struct zram *zram = dev_to_zram(dev);
 226
 227         deprecated_attr_warn("mem_used_total");
 228         down_read(&zram->init_lock);
 229         if (init_done(zram)) {
 230                 struct zram_meta *meta = zram->meta;
 231                 val = zs_get_total_pages(meta->mem_pool);
 232         }
 233         up_read(&zram->init_lock);
 234
 235         return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
 236 }
 237
 238 static ssize_t mem_limit_show(struct device *dev,
 239                 struct device_attribute *attr, char *buf)
 240 {
 241         u64 val;
 242         struct zram *zram = dev_to_zram(dev);
 243
 244         deprecated_attr_warn("mem_limit");
 245         down_read(&zram->init_lock);
 246         val = zram->limit_pages;
 247         up_read(&zram->init_lock);
 248
 249         return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
 250 }
 251
 252 static ssize_t mem_limit_store(struct device *dev,
 253                 struct device_attribute *attr, const char *buf, size_t len)
 254 {
 255         u64 limit;
 256         char *tmp;
 257         struct zram *zram = dev_to_zram(dev);
 258
 259         limit = memparse(buf, &tmp);
 260         if (buf == tmp) /* no chars parsed, invalid input */
 261                 return -EINVAL;
 262
 263         down_write(&zram->init_lock);
 264         zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT;
 265         up_write(&zram->init_lock);
 266
 267         return len;
 268 }
 269
 270 static ssize_t mem_used_max_show(struct device *dev,
 271                 struct device_attribute *attr, char *buf)
 272 {
 273         u64 val = 0;
 274         struct zram *zram = dev_to_zram(dev);
 275
 276         deprecated_attr_warn("mem_used_max");
 277         down_read(&zram->init_lock);
 278         if (init_done(zram))
 279                 val = atomic_long_read(&zram->stats.max_used_pages);
 280         up_read(&zram->init_lock);
 281
 282         return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
 283 }
 284
 285 static ssize_t mem_used_max_store(struct device *dev,
 286                 struct device_attribute *attr, const char *buf, size_t len)
 287 {
 288         int err;
 289         unsigned long val;
 290         struct zram *zram = dev_to_zram(dev);
 291
 292         err = kstrtoul(buf, 10, &val);
 293         if (err || val != 0)
 294                 return -EINVAL;
 295
 296         down_read(&zram->init_lock);
 297         if (init_done(zram)) {
 298                 struct zram_meta *meta = zram->meta;
 299                 atomic_long_set(&zram->stats.max_used_pages,
 300                                 zs_get_total_pages(meta->mem_pool));
 301         }
 302         up_read(&zram->init_lock);
 303
 304         return len;
 305 }
 306
 307 static ssize_t max_comp_streams_show(struct device *dev,
 308                 struct device_attribute *attr, char *buf)
 309 {
 310         int val;
 311         struct zram *zram = dev_to_zram(dev);
 312
 313         down_read(&zram->init_lock);
 314         val = zram->max_comp_streams;
 315         up_read(&zram->init_lock);
 316
 317         return scnprintf(buf, PAGE_SIZE, "%d\n", val);
 318 }
 319
 320 static ssize_t max_comp_streams_store(struct device *dev,
 321                 struct device_attribute *attr, const char *buf, size_t len)
 322 {
 323         int num;
 324         struct zram *zram = dev_to_zram(dev);
 325         int ret;
 326
 327         ret = kstrtoint(buf, 0, &num);
 328         if (ret < 0)
 329                 return ret;
 330         if (num < 1)
 331                 return -EINVAL;
 332
 333         down_write(&zram->init_lock);
 334         if (init_done(zram)) {
 335                 if (!zcomp_set_max_streams(zram->comp, num)) {
 336                         pr_info("Cannot change max compression streams\n");
 337                         ret = -EINVAL;
 338                         goto out;
 339                 }
 340         }
 341
 342         zram->max_comp_streams = num;
 343         ret = len;
 344 out:
 345         up_write(&zram->init_lock);
 346         return ret;
 347 }
 348
 349 static ssize_t comp_algorithm_show(struct device *dev,
 350                 struct device_attribute *attr, char *buf)
 351 {
 352         size_t sz;
 353         struct zram *zram = dev_to_zram(dev);
 354
 355         down_read(&zram->init_lock);
 356         sz = zcomp_available_show(zram->compressor, buf);
 357         up_read(&zram->init_lock);
 358
 359         return sz;
 360 }
 361
 362 static ssize_t comp_algorithm_store(struct device *dev,
 363                 struct device_attribute *attr, const char *buf, size_t len)
 364 {
 365         struct zram *zram = dev_to_zram(dev);
 366         size_t sz;
 367
 368         down_write(&zram->init_lock);
 369         if (init_done(zram)) {
 370                 up_write(&zram->init_lock);
 371                 pr_info("Can't change algorithm for initialized device\n");
 372                 return -EBUSY;
 373         }
 374         strlcpy(zram->compressor, buf, sizeof(zram->compressor));
 375
 376         /* ignore trailing newline */
 377         sz = strlen(zram->compressor);
 378         if (sz > 0 && zram->compressor[sz - 1] == '\n')
 379                 zram->compressor[sz - 1] = 0x00;
 380
 381         up_write(&zram->init_lock);
 382         return len;
 383 }
 384
 385 static ssize_t compact_store(struct device *dev,
 386                 struct device_attribute *attr, const char *buf, size_t len)
 387 {
 388         unsigned long nr_migrated;
 389         struct zram *zram = dev_to_zram(dev);
 390         struct zram_meta *meta;
 391
 392         down_read(&zram->init_lock);
 393         if (!init_done(zram)) {
 394                 up_read(&zram->init_lock);
 395                 return -EINVAL;
 396         }
 397
 398         meta = zram->meta;
 399         nr_migrated = zs_compact(meta->mem_pool);
 400         atomic64_add(nr_migrated, &zram->stats.num_migrated);
 401         up_read(&zram->init_lock);
 402
 403         return len;
 404 }
 405
 406 static ssize_t io_stat_show(struct device *dev,
 407                 struct device_attribute *attr, char *buf)
 408 {
 409         struct zram *zram = dev_to_zram(dev);
 410         ssize_t ret;
 411
 412         down_read(&zram->init_lock);
 413         ret = scnprintf(buf, PAGE_SIZE,
 414                         "%8llu %8llu %8llu %8llu\n",
 415                         (u64)atomic64_read(&zram->stats.failed_reads),
 416                         (u64)atomic64_read(&zram->stats.failed_writes),
 417                         (u64)atomic64_read(&zram->stats.invalid_io),
 418                         (u64)atomic64_read(&zram->stats.notify_free));
 419         up_read(&zram->init_lock);
 420
 421         return ret;
 422 }
 423
 424 static ssize_t mm_stat_show(struct device *dev,
 425                 struct device_attribute *attr, char *buf)
 426 {
 427         struct zram *zram = dev_to_zram(dev);
 428         u64 orig_size, mem_used = 0;
 429         long max_used;
 430         ssize_t ret;
 431
 432         down_read(&zram->init_lock);
 433         if (init_done(zram))
 434                 mem_used = zs_get_total_pages(zram->meta->mem_pool);
 435
 436         orig_size = atomic64_read(&zram->stats.pages_stored);
 437         max_used = atomic_long_read(&zram->stats.max_used_pages);
 438
 439         ret = scnprintf(buf, PAGE_SIZE,
 440                         "%8llu %8llu %8llu %8lu %8ld %8llu %8llu\n",
 441                         orig_size << PAGE_SHIFT,
 442                         (u64)atomic64_read(&zram->stats.compr_data_size),
 443                         mem_used << PAGE_SHIFT,
 444                         zram->limit_pages << PAGE_SHIFT,
 445                         max_used << PAGE_SHIFT,
 446                         (u64)atomic64_read(&zram->stats.zero_pages),
 447                         (u64)atomic64_read(&zram->stats.num_migrated));
 448         up_read(&zram->init_lock);
 449
 450         return ret;
 451 }
 452
 453 static DEVICE_ATTR_RO(io_stat);
 454 static DEVICE_ATTR_RO(mm_stat);
 455 ZRAM_ATTR_RO(num_reads);
 456 ZRAM_ATTR_RO(num_writes);
 457 ZRAM_ATTR_RO(failed_reads);
 458 ZRAM_ATTR_RO(failed_writes);
 459 ZRAM_ATTR_RO(invalid_io);
 460 ZRAM_ATTR_RO(notify_free);
 461 ZRAM_ATTR_RO(zero_pages);
 462 ZRAM_ATTR_RO(compr_data_size);
 463
 464 static inline bool zram_meta_get(struct zram *zram)
 465 {
 466         if (atomic_inc_not_zero(&zram->refcount))
 467                 return true;
 468         return false;
 469 }
 470
 471 static inline void zram_meta_put(struct zram *zram)
 472 {
 473         atomic_dec(&zram->refcount);
 474 }
 475
 476 static void zram_meta_free(struct zram_meta *meta, u64 disksize)
 477 {
 478         size_t num_pages = disksize >> PAGE_SHIFT;
 479         size_t index;
 480
 481         /* Free all pages that are still in this zram device */
 482         for (index = 0; index < num_pages; index++) {
 483                 unsigned long handle = meta->table[index].handle;
 484
 485                 if (!handle)
 486                         continue;
 487
 488                 zs_free(meta->mem_pool, handle);
 489         }
 490
 491         zs_destroy_pool(meta->mem_pool);
 492         vfree(meta->table);
 493         kfree(meta);
 494 }
 495
 496 static struct zram_meta *zram_meta_alloc(int device_id, u64 disksize)
 497 {
 498         size_t num_pages;
 499         char pool_name[8];
 500         struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
 501
 502         if (!meta)
 503                 return NULL;
 504
 505         num_pages = disksize >> PAGE_SHIFT;
 506         meta->table = vzalloc(num_pages * sizeof(*meta->table));
 507         if (!meta->table) {
 508                 pr_err("Error allocating zram address table\n");
 509                 goto out_error;
 510         }
 511
 512         snprintf(pool_name, sizeof(pool_name), "zram%d", device_id);
 513         meta->mem_pool = zs_create_pool(pool_name, GFP_NOIO | __GFP_HIGHMEM);
 514         if (!meta->mem_pool) {
 515                 pr_err("Error creating memory pool\n");
 516                 goto out_error;
 517         }
 518
 519         return meta;
 520
 521 out_error:
 522         vfree(meta->table);
 523         kfree(meta);
 524         return NULL;
 525 }
 526
 527 /*
 528  * To protect concurrent access to the same index entry,
 529  * caller should hold this table index entry's bit_spinlock to
 530  * indicate this index entry is accessing.
 531  */
 532 static void zram_free_page(struct zram *zram, size_t index)
 533 {
 534         struct zram_meta *meta = zram->meta;
 535         unsigned long handle = meta->table[index].handle;
 536
 537         if (unlikely(!handle)) {
 538                 /*
 539                  * No memory is allocated for zero filled pages.
 540                  * Simply clear zero page flag.
 541                  */
 542                 if (zram_test_flag(meta, index, ZRAM_ZERO)) {
 543                         zram_clear_flag(meta, index, ZRAM_ZERO);
 544                         atomic64_dec(&zram->stats.zero_pages);
 545                 }
 546                 return;
 547         }
 548
 549         zs_free(meta->mem_pool, handle);
 550
 551         atomic64_sub(zram_get_obj_size(meta, index),
 552                         &zram->stats.compr_data_size);
 553         atomic64_dec(&zram->stats.pages_stored);
 554
 555         meta->table[index].handle = 0;
 556         zram_set_obj_size(meta, index, 0);
 557 }
 558
 559 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
 560 {
 561         int ret = 0;
 562         unsigned char *cmem;
 563         struct zram_meta *meta = zram->meta;
 564         unsigned long handle;
 565         size_t size;
 566
 567         bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
 568         handle = meta->table[index].handle;
 569         size = zram_get_obj_size(meta, index);
 570
 571         if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
 572                 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
 573                 clear_page(mem);
 574                 return 0;
 575         }
 576
 577         cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
 578         if (size == PAGE_SIZE)
 579                 copy_page(mem, cmem);
 580         else
 581                 ret = zcomp_decompress(zram->comp, cmem, size, mem);
 582         zs_unmap_object(meta->mem_pool, handle);
 583         bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
 584
 585         /* Should NEVER happen. Return bio error if it does. */
 586         if (unlikely(ret)) {
 587                 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
 588                 return ret;
 589         }
 590
 591         return 0;
 592 }
 593
 594 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 595                           u32 index, int offset)
 596 {
 597         int ret;
 598         struct page *page;
 599         unsigned char *user_mem, *uncmem = NULL;
 600         struct zram_meta *meta = zram->meta;
 601         page = bvec->bv_page;
 602
 603         bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
 604         if (unlikely(!meta->table[index].handle) ||
 605                         zram_test_flag(meta, index, ZRAM_ZERO)) {
 606                 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
 607                 handle_zero_page(bvec);
 608                 return 0;
 609         }
 610         bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
 611
 612         if (is_partial_io(bvec))
 613                 /* Use  a temporary buffer to decompress the page */
 614                 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
 615
 616         user_mem = kmap_atomic(page);
 617         if (!is_partial_io(bvec))
 618                 uncmem = user_mem;
 619
 620         if (!uncmem) {
 621                 pr_info("Unable to allocate temp memory\n");
 622                 ret = -ENOMEM;
 623                 goto out_cleanup;
 624         }
 625
 626         ret = zram_decompress_page(zram, uncmem, index);
 627         /* Should NEVER happen. Return bio error if it does. */
 628         if (unlikely(ret))
 629                 goto out_cleanup;
 630
 631         if (is_partial_io(bvec))
 632                 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
 633                                 bvec->bv_len);
 634
 635         flush_dcache_page(page);
 636         ret = 0;
 637 out_cleanup:
 638         kunmap_atomic(user_mem);
 639         if (is_partial_io(bvec))
 640                 kfree(uncmem);
 641         return ret;
 642 }
 643
 644 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 645                            int offset)
 646 {
 647         int ret = 0;
 648         size_t clen;
 649         unsigned long handle;
 650         struct page *page;
 651         unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
 652         struct zram_meta *meta = zram->meta;
 653         struct zcomp_strm *zstrm = NULL;
 654         unsigned long alloced_pages;
 655
 656         page = bvec->bv_page;
 657         if (is_partial_io(bvec)) {
 658                 /*
 659                  * This is a partial IO. We need to read the full page
 660                  * before to write the changes.
 661                  */
 662                 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
 663                 if (!uncmem) {
 664                         ret = -ENOMEM;
 665                         goto out;
 666                 }
 667                 ret = zram_decompress_page(zram, uncmem, index);
 668                 if (ret)
 669                         goto out;
 670         }
 671
 672         zstrm = zcomp_strm_find(zram->comp);
 673         user_mem = kmap_atomic(page);
 674
 675         if (is_partial_io(bvec)) {
 676                 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
 677                        bvec->bv_len);
 678                 kunmap_atomic(user_mem);
 679                 user_mem = NULL;
 680         } else {
 681                 uncmem = user_mem;
 682         }
 683
 684         if (page_zero_filled(uncmem)) {
 685                 if (user_mem)
 686                         kunmap_atomic(user_mem);
 687                 /* Free memory associated with this sector now. */
 688                 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
 689                 zram_free_page(zram, index);
 690                 zram_set_flag(meta, index, ZRAM_ZERO);
 691                 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
 692
 693                 atomic64_inc(&zram->stats.zero_pages);
 694                 ret = 0;
 695                 goto out;
 696         }
 697
 698         ret = zcomp_compress(zram->comp, zstrm, uncmem, &clen);
 699         if (!is_partial_io(bvec)) {
 700                 kunmap_atomic(user_mem);
 701                 user_mem = NULL;
 702                 uncmem = NULL;
 703         }
 704
 705         if (unlikely(ret)) {
 706                 pr_err("Compression failed! err=%d\n", ret);
 707                 goto out;
 708         }
 709         src = zstrm->buffer;
 710         if (unlikely(clen > max_zpage_size)) {
 711                 clen = PAGE_SIZE;
 712                 if (is_partial_io(bvec))
 713                         src = uncmem;
 714         }
 715
 716         handle = zs_malloc(meta->mem_pool, clen);
 717         if (!handle) {
 718                 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
 719                         index, clen);
 720                 ret = -ENOMEM;
 721                 goto out;
 722         }
 723
 724         alloced_pages = zs_get_total_pages(meta->mem_pool);
 725         if (zram->limit_pages && alloced_pages > zram->limit_pages) {
 726                 zs_free(meta->mem_pool, handle);
 727                 ret = -ENOMEM;
 728                 goto out;
 729         }
 730
 731         update_used_max(zram, alloced_pages);
 732
 733         cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
 734
 735         if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
 736                 src = kmap_atomic(page);
 737                 copy_page(cmem, src);
 738                 kunmap_atomic(src);
 739         } else {
 740                 memcpy(cmem, src, clen);
 741         }
 742
 743         zcomp_strm_release(zram->comp, zstrm);
 744         zstrm = NULL;
 745         zs_unmap_object(meta->mem_pool, handle);
 746
 747         /*
 748          * Free memory associated with this sector
 749          * before overwriting unused sectors.
 750          */
 751         bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
 752         zram_free_page(zram, index);
 753
 754         meta->table[index].handle = handle;
 755         zram_set_obj_size(meta, index, clen);
 756         bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
 757
 758         /* Update stats */
 759         atomic64_add(clen, &zram->stats.compr_data_size);
 760         atomic64_inc(&zram->stats.pages_stored);
 761 out:
 762         if (zstrm)
 763                 zcomp_strm_release(zram->comp, zstrm);
 764         if (is_partial_io(bvec))
 765                 kfree(uncmem);
 766         return ret;
 767 }
 768
 769 /*
 770  * zram_bio_discard - handler on discard request
 771  * @index: physical block index in PAGE_SIZE units
 772  * @offset: byte offset within physical block
 773  */
 774 static void zram_bio_discard(struct zram *zram, u32 index,
 775                              int offset, struct bio *bio)
 776 {
 777         size_t n = bio->bi_iter.bi_size;
 778         struct zram_meta *meta = zram->meta;
 779
 780         /*
 781          * zram manages data in physical block size units. Because logical block
 782          * size isn't identical with physical block size on some arch, we
 783          * could get a discard request pointing to a specific offset within a
 784          * certain physical block.  Although we can handle this request by
 785          * reading that physiclal block and decompressing and partially zeroing
 786          * and re-compressing and then re-storing it, this isn't reasonable
 787          * because our intent with a discard request is to save memory.  So
 788          * skipping this logical block is appropriate here.
 789          */
 790         if (offset) {
 791                 if (n <= (PAGE_SIZE - offset))
 792                         return;
 793
 794                 n -= (PAGE_SIZE - offset);
 795                 index++;
 796         }
 797
 798         while (n >= PAGE_SIZE) {
 799                 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
 800                 zram_free_page(zram, index);
 801                 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
 802                 atomic64_inc(&zram->stats.notify_free);
 803                 index++;
 804                 n -= PAGE_SIZE;
 805         }
 806 }
 807
 808 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 809                         int offset, int rw)
 810 {
 811         unsigned long start_time = jiffies;
 812         int ret;
 813
 814         generic_start_io_acct(rw, bvec->bv_len >> SECTOR_SHIFT,
 815                         &zram->disk->part0);
 816
 817         if (rw == READ) {
 818                 atomic64_inc(&zram->stats.num_reads);
 819                 ret = zram_bvec_read(zram, bvec, index, offset);
 820         } else {
 821                 atomic64_inc(&zram->stats.num_writes);
 822                 ret = zram_bvec_write(zram, bvec, index, offset);
 823         }
 824
 825         generic_end_io_acct(rw, &zram->disk->part0, start_time);
 826
 827         if (unlikely(ret)) {
 828                 if (rw == READ)
 829                         atomic64_inc(&zram->stats.failed_reads);
 830                 else
 831                         atomic64_inc(&zram->stats.failed_writes);
 832         }
 833
 834         return ret;
 835 }
 836
 837 static void __zram_make_request(struct zram *zram, struct bio *bio)
 838 {
 839         int offset, rw;
 840         u32 index;
 841         struct bio_vec bvec;
 842         struct bvec_iter iter;
 843
 844         index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
 845         offset = (bio->bi_iter.bi_sector &
 846                   (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
 847
 848         if (unlikely(bio->bi_rw & REQ_DISCARD)) {
 849                 zram_bio_discard(zram, index, offset, bio);
 850                 bio_endio(bio, 0);
 851                 return;
 852         }
 853
 854         rw = bio_data_dir(bio);
 855         bio_for_each_segment(bvec, bio, iter) {
 856                 int max_transfer_size = PAGE_SIZE - offset;
 857
 858                 if (bvec.bv_len > max_transfer_size) {
 859                         /*
 860                          * zram_bvec_rw() can only make operation on a single
 861                          * zram page. Split the bio vector.
 862                          */
 863                         struct bio_vec bv;
 864
 865                         bv.bv_page = bvec.bv_page;
 866                         bv.bv_len = max_transfer_size;
 867                         bv.bv_offset = bvec.bv_offset;
 868
 869                         if (zram_bvec_rw(zram, &bv, index, offset, rw) < 0)
 870                                 goto out;
 871
 872                         bv.bv_len = bvec.bv_len - max_transfer_size;
 873                         bv.bv_offset += max_transfer_size;
 874                         if (zram_bvec_rw(zram, &bv, index + 1, 0, rw) < 0)
 875                                 goto out;
 876                 } else
 877                         if (zram_bvec_rw(zram, &bvec, index, offset, rw) < 0)
 878                                 goto out;
 879
 880                 update_position(&index, &offset, &bvec);
 881         }
 882
 883         set_bit(BIO_UPTODATE, &bio->bi_flags);
 884         bio_endio(bio, 0);
 885         return;
 886
 887 out:
 888         bio_io_error(bio);
 889 }
 890
 891 /*
 892  * Handler function for all zram I/O requests.
 893  */
 894 static void zram_make_request(struct request_queue *queue, struct bio *bio)
 895 {
 896         struct zram *zram = queue->queuedata;
 897
 898         if (unlikely(!zram_meta_get(zram)))
 899                 goto error;
 900
 901         if (!valid_io_request(zram, bio->bi_iter.bi_sector,
 902                                         bio->bi_iter.bi_size)) {
 903                 atomic64_inc(&zram->stats.invalid_io);
 904                 goto put_zram;
 905         }
 906
 907         __zram_make_request(zram, bio);
 908         zram_meta_put(zram);
 909         return;
 910 put_zram:
 911         zram_meta_put(zram);
 912 error:
 913         bio_io_error(bio);
 914 }
 915
 916 static void zram_slot_free_notify(struct block_device *bdev,
 917                                 unsigned long index)
 918 {
 919         struct zram *zram;
 920         struct zram_meta *meta;
 921
 922         zram = bdev->bd_disk->private_data;
 923         meta = zram->meta;
 924
 925         bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
 926         zram_free_page(zram, index);
 927         bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
 928         atomic64_inc(&zram->stats.notify_free);
 929 }
 930
 931 static int zram_rw_page(struct block_device *bdev, sector_t sector,
 932                        struct page *page, int rw)
 933 {
 934         int offset, err = -EIO;
 935         u32 index;
 936         struct zram *zram;
 937         struct bio_vec bv;
 938
 939         zram = bdev->bd_disk->private_data;
 940         if (unlikely(!zram_meta_get(zram)))
 941                 goto out;
 942
 943         if (!valid_io_request(zram, sector, PAGE_SIZE)) {
 944                 atomic64_inc(&zram->stats.invalid_io);
 945                 err = -EINVAL;
 946                 goto put_zram;
 947         }
 948
 949         index = sector >> SECTORS_PER_PAGE_SHIFT;
 950         offset = sector & (SECTORS_PER_PAGE - 1) << SECTOR_SHIFT;
 951
 952         bv.bv_page = page;
 953         bv.bv_len = PAGE_SIZE;
 954         bv.bv_offset = 0;
 955
 956         err = zram_bvec_rw(zram, &bv, index, offset, rw);
 957 put_zram:
 958         zram_meta_put(zram);
 959 out:
 960         /*
 961          * If I/O fails, just return error(ie, non-zero) without
 962          * calling page_endio.
 963          * It causes resubmit the I/O with bio request by upper functions
 964          * of rw_page(e.g., swap_readpage, __swap_writepage) and
 965          * bio->bi_end_io does things to handle the error
 966          * (e.g., SetPageError, set_page_dirty and extra works).
 967          */
 968         if (err == 0)
 969                 page_endio(page, rw, 0);
 970         return err;
 971 }
 972
 973 static void zram_reset_device(struct zram *zram)
 974 {
 975         struct zram_meta *meta;
 976         struct zcomp *comp;
 977         u64 disksize;
 978
 979         down_write(&zram->init_lock);
 980
 981         zram->limit_pages = 0;
 982
 983         if (!init_done(zram)) {
 984                 up_write(&zram->init_lock);
 985                 return;
 986         }
 987
 988         meta = zram->meta;
 989         comp = zram->comp;
 990         disksize = zram->disksize;
 991         /*
 992          * Refcount will go down to 0 eventually and r/w handler
 993          * cannot handle further I/O so it will bail out by
 994          * check zram_meta_get.
 995          */
 996         zram_meta_put(zram);
 997         /*
 998          * We want to free zram_meta in process context to avoid
 999          * deadlock between reclaim path and any other locks.
1000          */
1001         wait_event(zram->io_done, atomic_read(&zram->refcount) == 0);
1002
1003         /* Reset stats */
1004         memset(&zram->stats, 0, sizeof(zram->stats));
1005         zram->disksize = 0;
1006         zram->max_comp_streams = 1;
1007
1008         set_capacity(zram->disk, 0);
1009         part_stat_set_all(&zram->disk->part0, 0);
1010
1011         up_write(&zram->init_lock);
1012         /* I/O operation under all of CPU are done so let's free */
1013         zram_meta_free(meta, disksize);
1014         zcomp_destroy(comp);
1015 }
1016
1017 static ssize_t disksize_store(struct device *dev,
1018                 struct device_attribute *attr, const char *buf, size_t len)
1019 {
1020         u64 disksize;
1021         struct zcomp *comp;
1022         struct zram_meta *meta;
1023         struct zram *zram = dev_to_zram(dev);
1024         int err;
1025
1026         disksize = memparse(buf, NULL);
1027         if (!disksize)
1028                 return -EINVAL;
1029
1030         disksize = PAGE_ALIGN(disksize);
1031         meta = zram_meta_alloc(zram->disk->first_minor, disksize);
1032         if (!meta)
1033                 return -ENOMEM;
1034
1035         comp = zcomp_create(zram->compressor, zram->max_comp_streams);
1036         if (IS_ERR(comp)) {
1037                 pr_info("Cannot initialise %s compressing backend\n",
1038                                 zram->compressor);
1039                 err = PTR_ERR(comp);
1040                 goto out_free_meta;
1041         }
1042
1043         down_write(&zram->init_lock);
1044         if (init_done(zram)) {
1045                 pr_info("Cannot change disksize for initialized device\n");
1046                 err = -EBUSY;
1047                 goto out_destroy_comp;
1048         }
1049
1050         init_waitqueue_head(&zram->io_done);
1051         atomic_set(&zram->refcount, 1);
1052         zram->meta = meta;
1053         zram->comp = comp;
1054         zram->disksize = disksize;
1055         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
1056         up_write(&zram->init_lock);
1057
1058         /*
1059          * Revalidate disk out of the init_lock to avoid lockdep splat.
1060          * It's okay because disk's capacity is protected by init_lock
1061          * so that revalidate_disk always sees up-to-date capacity.
1062          */
1063         revalidate_disk(zram->disk);
1064
1065         return len;
1066
1067 out_destroy_comp:
1068         up_write(&zram->init_lock);
1069         zcomp_destroy(comp);
1070 out_free_meta:
1071         zram_meta_free(meta, disksize);
1072         return err;
1073 }
1074
1075 static ssize_t reset_store(struct device *dev,
1076                 struct device_attribute *attr, const char *buf, size_t len)
1077 {
1078         int ret;
1079         unsigned short do_reset;
1080         struct zram *zram;
1081         struct block_device *bdev;
1082
1083         ret = kstrtou16(buf, 10, &do_reset);
1084         if (ret)
1085                 return ret;
1086
1087         if (!do_reset)
1088                 return -EINVAL;
1089
1090         zram = dev_to_zram(dev);
1091         bdev = bdget_disk(zram->disk, 0);
1092         if (!bdev)
1093                 return -ENOMEM;
1094
1095         mutex_lock(&bdev->bd_mutex);
1096         /* Do not reset an active device or claimed device */
1097         if (bdev->bd_openers || zram->claim) {
1098                 mutex_unlock(&bdev->bd_mutex);
1099                 bdput(bdev);
1100                 return -EBUSY;
1101         }
1102
1103         /* From now on, anyone can't open /dev/zram[0-9] */
1104         zram->claim = true;
1105         mutex_unlock(&bdev->bd_mutex);
1106
1107         /* Make sure all the pending I/O are finished */
1108         fsync_bdev(bdev);
1109         zram_reset_device(zram);
1110         revalidate_disk(zram->disk);
1111         bdput(bdev);
1112
1113         mutex_lock(&bdev->bd_mutex);
1114         zram->claim = false;
1115         mutex_unlock(&bdev->bd_mutex);
1116
1117         return len;
1118 }
1119
1120 static int zram_open(struct block_device *bdev, fmode_t mode)
1121 {
1122         int ret = 0;
1123         struct zram *zram;
1124
1125         WARN_ON(!mutex_is_locked(&bdev->bd_mutex));
1126
1127         zram = bdev->bd_disk->private_data;
1128         /* zram was claimed to reset so open request fails */
1129         if (zram->claim)
1130                 ret = -EBUSY;
1131
1132         return ret;
1133 }
1134
1135 static const struct block_device_operations zram_devops = {
1136         .open = zram_open,
1137         .swap_slot_free_notify = zram_slot_free_notify,
1138         .rw_page = zram_rw_page,
1139         .owner = THIS_MODULE
1140 };
1141
1142 static DEVICE_ATTR_WO(compact);
1143 static DEVICE_ATTR_RW(disksize);
1144 static DEVICE_ATTR_RO(initstate);
1145 static DEVICE_ATTR_WO(reset);
1146 static DEVICE_ATTR_RO(orig_data_size);
1147 static DEVICE_ATTR_RO(mem_used_total);
1148 static DEVICE_ATTR_RW(mem_limit);
1149 static DEVICE_ATTR_RW(mem_used_max);
1150 static DEVICE_ATTR_RW(max_comp_streams);
1151 static DEVICE_ATTR_RW(comp_algorithm);
1152
1153 static struct attribute *zram_disk_attrs[] = {
1154         &dev_attr_disksize.attr,
1155         &dev_attr_initstate.attr,
1156         &dev_attr_reset.attr,
1157         &dev_attr_num_reads.attr,
1158         &dev_attr_num_writes.attr,
1159         &dev_attr_failed_reads.attr,
1160         &dev_attr_failed_writes.attr,
1161         &dev_attr_compact.attr,
1162         &dev_attr_invalid_io.attr,
1163         &dev_attr_notify_free.attr,
1164         &dev_attr_zero_pages.attr,
1165         &dev_attr_orig_data_size.attr,
1166         &dev_attr_compr_data_size.attr,
1167         &dev_attr_mem_used_total.attr,
1168         &dev_attr_mem_limit.attr,
1169         &dev_attr_mem_used_max.attr,
1170         &dev_attr_max_comp_streams.attr,
1171         &dev_attr_comp_algorithm.attr,
1172         &dev_attr_io_stat.attr,
1173         &dev_attr_mm_stat.attr,
1174         NULL,
1175 };
1176
1177 static struct attribute_group zram_disk_attr_group = {
1178         .attrs = zram_disk_attrs,
1179 };
1180
1181 /*
1182  * Allocate and initialize new zram device. the function returns
1183  * '>= 0' device_id upon success, and negative value otherwise.
1184  */
1185 static int zram_add(void)
1186 {
1187         struct zram *zram;
1188         struct request_queue *queue;
1189         int ret, device_id;
1190
1191         zram = kzalloc(sizeof(struct zram), GFP_KERNEL);
1192         if (!zram)
1193                 return -ENOMEM;
1194
1195         ret = idr_alloc(&zram_index_idr, zram, 0, 0, GFP_KERNEL);
1196         if (ret < 0)
1197                 goto out_free_dev;
1198         device_id = ret;
1199
1200         init_rwsem(&zram->init_lock);
1201
1202         queue = blk_alloc_queue(GFP_KERNEL);
1203         if (!queue) {
1204                 pr_err("Error allocating disk queue for device %d\n",
1205                         device_id);
1206                 ret = -ENOMEM;
1207                 goto out_free_idr;
1208         }
1209
1210         blk_queue_make_request(queue, zram_make_request);
1211
1212         /* gendisk structure */
1213         zram->disk = alloc_disk(1);
1214         if (!zram->disk) {
1215                 pr_warn("Error allocating disk structure for device %d\n",
1216                         device_id);
1217                 ret = -ENOMEM;
1218                 goto out_free_queue;
1219         }
1220
1221         zram->disk->major = zram_major;
1222         zram->disk->first_minor = device_id;
1223         zram->disk->fops = &zram_devops;
1224         zram->disk->queue = queue;
1225         zram->disk->queue->queuedata = zram;
1226         zram->disk->private_data = zram;
1227         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
1228
1229         /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
1230         set_capacity(zram->disk, 0);
1231         /* zram devices sort of resembles non-rotational disks */
1232         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
1233         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
1234         /*
1235          * To ensure that we always get PAGE_SIZE aligned
1236          * and n*PAGE_SIZED sized I/O requests.
1237          */
1238         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
1239         blk_queue_logical_block_size(zram->disk->queue,
1240                                         ZRAM_LOGICAL_BLOCK_SIZE);
1241         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
1242         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
1243         zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
1244         zram->disk->queue->limits.max_discard_sectors = UINT_MAX;
1245         /*
1246          * zram_bio_discard() will clear all logical blocks if logical block
1247          * size is identical with physical block size(PAGE_SIZE). But if it is
1248          * different, we will skip discarding some parts of logical blocks in
1249          * the part of the request range which isn't aligned to physical block
1250          * size.  So we can't ensure that all discarded logical blocks are
1251          * zeroed.
1252          */
1253         if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
1254                 zram->disk->queue->limits.discard_zeroes_data = 1;
1255         else
1256                 zram->disk->queue->limits.discard_zeroes_data = 0;
1257         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
1258
1259         add_disk(zram->disk);
1260
1261         ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
1262                                 &zram_disk_attr_group);
1263         if (ret < 0) {
1264                 pr_warn("Error creating sysfs group");
1265                 goto out_free_disk;
1266         }
1267         strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
1268         zram->meta = NULL;
1269         zram->max_comp_streams = 1;
1270
1271         pr_info("Added device: %s\n", zram->disk->disk_name);
1272         return device_id;
1273
1274 out_free_disk:
1275         del_gendisk(zram->disk);
1276         put_disk(zram->disk);
1277 out_free_queue:
1278         blk_cleanup_queue(queue);
1279 out_free_idr:
1280         idr_remove(&zram_index_idr, device_id);
1281 out_free_dev:
1282         kfree(zram);
1283         return ret;
1284 }
1285
1286 static int zram_remove(struct zram *zram)
1287 {
1288         struct block_device *bdev;
1289
1290         bdev = bdget_disk(zram->disk, 0);
1291         if (!bdev)
1292                 return -ENOMEM;
1293
1294         mutex_lock(&bdev->bd_mutex);
1295         if (bdev->bd_openers || zram->claim) {
1296                 mutex_unlock(&bdev->bd_mutex);
1297                 bdput(bdev);
1298                 return -EBUSY;
1299         }
1300
1301         zram->claim = true;
1302         mutex_unlock(&bdev->bd_mutex);
1303
1304         /*
1305          * Remove sysfs first, so no one will perform a disksize
1306          * store while we destroy the devices. This also helps during
1307          * hot_remove -- zram_reset_device() is the last holder of
1308          * ->init_lock, no later/concurrent disksize_store() or any
1309          * other sysfs handlers are possible.
1310          */
1311         sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
1312                         &zram_disk_attr_group);
1313
1314         /* Make sure all the pending I/O are finished */
1315         fsync_bdev(bdev);
1316         zram_reset_device(zram);
1317         bdput(bdev);
1318
1319         pr_info("Removed device: %s\n", zram->disk->disk_name);
1320
1321         idr_remove(&zram_index_idr, zram->disk->first_minor);
1322         blk_cleanup_queue(zram->disk->queue);
1323         del_gendisk(zram->disk);
1324         put_disk(zram->disk);
1325         kfree(zram);
1326         return 0;
1327 }
1328
1329 /* zram-control sysfs attributes */
1330 static ssize_t hot_add_show(struct class *class,
1331                         struct class_attribute *attr,
1332                         char *buf)
1333 {
1334         int ret;
1335
1336         mutex_lock(&zram_index_mutex);
1337         ret = zram_add();
1338         mutex_unlock(&zram_index_mutex);
1339
1340         if (ret < 0)
1341                 return ret;
1342         return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
1343 }
1344
1345 static ssize_t hot_remove_store(struct class *class,
1346                         struct class_attribute *attr,
1347                         const char *buf,
1348                         size_t count)
1349 {
1350         struct zram *zram;
1351         int ret, dev_id;
1352
1353         /* dev_id is gendisk->first_minor, which is `int' */
1354         ret = kstrtoint(buf, 10, &dev_id);
1355         if (ret)
1356                 return ret;
1357         if (dev_id < 0)
1358                 return -EINVAL;
1359
1360         mutex_lock(&zram_index_mutex);
1361
1362         zram = idr_find(&zram_index_idr, dev_id);
1363         if (zram)
1364                 ret = zram_remove(zram);
1365         else
1366                 ret = -ENODEV;
1367
1368         mutex_unlock(&zram_index_mutex);
1369         return ret ? ret : count;
1370 }
1371
1372 static struct class_attribute zram_control_class_attrs[] = {
1373         __ATTR_RO(hot_add),
1374         __ATTR_WO(hot_remove),
1375         __ATTR_NULL,
1376 };
1377
1378 static struct class zram_control_class = {
1379         .name           = "zram-control",
1380         .owner          = THIS_MODULE,
1381         .class_attrs    = zram_control_class_attrs,
1382 };
1383
1384 static int zram_remove_cb(int id, void *ptr, void *data)
1385 {
1386         zram_remove(ptr);
1387         return 0;
1388 }
1389
1390 static void destroy_devices(void)
1391 {
1392         class_unregister(&zram_control_class);
1393         idr_for_each(&zram_index_idr, &zram_remove_cb, NULL);
1394         idr_destroy(&zram_index_idr);
1395         unregister_blkdev(zram_major, "zram");
1396 }
1397
1398 static int __init zram_init(void)
1399 {
1400         int ret;
1401
1402         ret = class_register(&zram_control_class);
1403         if (ret) {
1404                 pr_warn("Unable to register zram-control class\n");
1405                 return ret;
1406         }
1407
1408         zram_major = register_blkdev(0, "zram");
1409         if (zram_major <= 0) {
1410                 pr_warn("Unable to get major number\n");
1411                 class_unregister(&zram_control_class);
1412                 return -EBUSY;
1413         }
1414
1415         while (num_devices != 0) {
1416                 mutex_lock(&zram_index_mutex);
1417                 ret = zram_add();
1418                 mutex_unlock(&zram_index_mutex);
1419                 if (ret < 0)
1420                         goto out_error;
1421                 num_devices--;
1422         }
1423
1424         return 0;
1425
1426 out_error:
1427         destroy_devices();
1428         return ret;
1429 }
1430
1431 static void __exit zram_exit(void)
1432 {
1433         destroy_devices();
1434 }
1435
1436 module_init(zram_init);
1437 module_exit(zram_exit);
1438
1439 module_param(num_devices, uint, 0);
1440 MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices");
1441
1442 MODULE_LICENSE("Dual BSD/GPL");
1443 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1444 MODULE_DESCRIPTION("Compressed RAM Block Device");