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/backing-dev.h>
  29 #include <linux/string.h>
  30 #include <linux/vmalloc.h>
  31 #include <linux/err.h>
  32 #include <linux/idr.h>
  33 #include <linux/sysfs.h>
  34 #include <linux/cpuhotplug.h>
  35
  36 #include "zram_drv.h"
  37
  38 static DEFINE_IDR(zram_index_idr);
  39 /* idr index must be protected */
  40 static DEFINE_MUTEX(zram_index_mutex);
  41
  42 static int zram_major;
  43 static const char *default_compressor = "lzo";
  44
  45 /* Module params (documentation at end) */
  46 static unsigned int num_devices = 1;
  47
  48 static void zram_free_page(struct zram *zram, size_t index);
  49
  50 static inline bool init_done(struct zram *zram)
  51 {
  52         return zram->disksize;
  53 }
  54
  55 static inline struct zram *dev_to_zram(struct device *dev)
  56 {
  57         return (struct zram *)dev_to_disk(dev)->private_data;
  58 }
  59
  60 static unsigned long zram_get_handle(struct zram *zram, u32 index)
  61 {
  62         return zram->table[index].handle;
  63 }
  64
  65 static void zram_set_handle(struct zram *zram, u32 index, unsigned long handle)
  66 {
  67         zram->table[index].handle = handle;
  68 }
  69
  70 /* flag operations require table entry bit_spin_lock() being held */
  71 static int zram_test_flag(struct zram *zram, u32 index,
  72                         enum zram_pageflags flag)
  73 {
  74         return zram->table[index].value & BIT(flag);
  75 }
  76
  77 static void zram_set_flag(struct zram *zram, u32 index,
  78                         enum zram_pageflags flag)
  79 {
  80         zram->table[index].value |= BIT(flag);
  81 }
  82
  83 static void zram_clear_flag(struct zram *zram, u32 index,
  84                         enum zram_pageflags flag)
  85 {
  86         zram->table[index].value &= ~BIT(flag);
  87 }
  88
  89 static inline void zram_set_element(struct zram *zram, u32 index,
  90                         unsigned long element)
  91 {
  92         zram->table[index].element = element;
  93 }
  94
  95 static unsigned long zram_get_element(struct zram *zram, u32 index)
  96 {
  97         return zram->table[index].element;
  98 }
  99
 100 static size_t zram_get_obj_size(struct zram *zram, u32 index)
 101 {
 102         return zram->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
 103 }
 104
 105 static void zram_set_obj_size(struct zram *zram,
 106                                         u32 index, size_t size)
 107 {
 108         unsigned long flags = zram->table[index].value >> ZRAM_FLAG_SHIFT;
 109
 110         zram->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
 111 }
 112
 113 #if PAGE_SIZE != 4096
 114 static inline bool is_partial_io(struct bio_vec *bvec)
 115 {
 116         return bvec->bv_len != PAGE_SIZE;
 117 }
 118 #else
 119 static inline bool is_partial_io(struct bio_vec *bvec)
 120 {
 121         return false;
 122 }
 123 #endif
 124
 125 static void zram_revalidate_disk(struct zram *zram)
 126 {
 127         revalidate_disk(zram->disk);
 128         /* revalidate_disk reset the BDI_CAP_STABLE_WRITES so set again */
 129         zram->disk->queue->backing_dev_info->capabilities |=
 130                 BDI_CAP_STABLE_WRITES;
 131 }
 132
 133 /*
 134  * Check if request is within bounds and aligned on zram logical blocks.
 135  */
 136 static inline bool valid_io_request(struct zram *zram,
 137                 sector_t start, unsigned int size)
 138 {
 139         u64 end, bound;
 140
 141         /* unaligned request */
 142         if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
 143                 return false;
 144         if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
 145                 return false;
 146
 147         end = start + (size >> SECTOR_SHIFT);
 148         bound = zram->disksize >> SECTOR_SHIFT;
 149         /* out of range range */
 150         if (unlikely(start >= bound || end > bound || start > end))
 151                 return false;
 152
 153         /* I/O request is valid */
 154         return true;
 155 }
 156
 157 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
 158 {
 159         *index  += (*offset + bvec->bv_len) / PAGE_SIZE;
 160         *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
 161 }
 162
 163 static inline void update_used_max(struct zram *zram,
 164                                         const unsigned long pages)
 165 {
 166         unsigned long old_max, cur_max;
 167
 168         old_max = atomic_long_read(&zram->stats.max_used_pages);
 169
 170         do {
 171                 cur_max = old_max;
 172                 if (pages > cur_max)
 173                         old_max = atomic_long_cmpxchg(
 174                                 &zram->stats.max_used_pages, cur_max, pages);
 175         } while (old_max != cur_max);
 176 }
 177
 178 static inline void zram_fill_page(void *ptr, unsigned long len,
 179                                         unsigned long value)
 180 {
 181         WARN_ON_ONCE(!IS_ALIGNED(len, sizeof(unsigned long)));
 182         memset_l(ptr, value, len / sizeof(unsigned long));
 183 }
 184
 185 static bool page_same_filled(void *ptr, unsigned long *element)
 186 {
 187         unsigned int pos;
 188         unsigned long *page;
 189         unsigned long val;
 190
 191         page = (unsigned long *)ptr;
 192         val = page[0];
 193
 194         for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) {
 195                 if (val != page[pos])
 196                         return false;
 197         }
 198
 199         *element = val;
 200
 201         return true;
 202 }
 203
 204 static ssize_t initstate_show(struct device *dev,
 205                 struct device_attribute *attr, char *buf)
 206 {
 207         u32 val;
 208         struct zram *zram = dev_to_zram(dev);
 209
 210         down_read(&zram->init_lock);
 211         val = init_done(zram);
 212         up_read(&zram->init_lock);
 213
 214         return scnprintf(buf, PAGE_SIZE, "%u\n", val);
 215 }
 216
 217 static ssize_t disksize_show(struct device *dev,
 218                 struct device_attribute *attr, char *buf)
 219 {
 220         struct zram *zram = dev_to_zram(dev);
 221
 222         return scnprintf(buf, PAGE_SIZE, "%llu\n", zram->disksize);
 223 }
 224
 225 static ssize_t mem_limit_store(struct device *dev,
 226                 struct device_attribute *attr, const char *buf, size_t len)
 227 {
 228         u64 limit;
 229         char *tmp;
 230         struct zram *zram = dev_to_zram(dev);
 231
 232         limit = memparse(buf, &tmp);
 233         if (buf == tmp) /* no chars parsed, invalid input */
 234                 return -EINVAL;
 235
 236         down_write(&zram->init_lock);
 237         zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT;
 238         up_write(&zram->init_lock);
 239
 240         return len;
 241 }
 242
 243 static ssize_t mem_used_max_store(struct device *dev,
 244                 struct device_attribute *attr, const char *buf, size_t len)
 245 {
 246         int err;
 247         unsigned long val;
 248         struct zram *zram = dev_to_zram(dev);
 249
 250         err = kstrtoul(buf, 10, &val);
 251         if (err || val != 0)
 252                 return -EINVAL;
 253
 254         down_read(&zram->init_lock);
 255         if (init_done(zram)) {
 256                 atomic_long_set(&zram->stats.max_used_pages,
 257                                 zs_get_total_pages(zram->mem_pool));
 258         }
 259         up_read(&zram->init_lock);
 260
 261         return len;
 262 }
 263
 264 #ifdef CONFIG_ZRAM_WRITEBACK
 265 static bool zram_wb_enabled(struct zram *zram)
 266 {
 267         return zram->backing_dev;
 268 }
 269
 270 static void reset_bdev(struct zram *zram)
 271 {
 272         struct block_device *bdev;
 273
 274         if (!zram_wb_enabled(zram))
 275                 return;
 276
 277         bdev = zram->bdev;
 278         if (zram->old_block_size)
 279                 set_blocksize(bdev, zram->old_block_size);
 280         blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
 281         /* hope filp_close flush all of IO */
 282         filp_close(zram->backing_dev, NULL);
 283         zram->backing_dev = NULL;
 284         zram->old_block_size = 0;
 285         zram->bdev = NULL;
 286
 287         kvfree(zram->bitmap);
 288         zram->bitmap = NULL;
 289 }
 290
 291 static ssize_t backing_dev_show(struct device *dev,
 292                 struct device_attribute *attr, char *buf)
 293 {
 294         struct zram *zram = dev_to_zram(dev);
 295         struct file *file = zram->backing_dev;
 296         char *p;
 297         ssize_t ret;
 298
 299         down_read(&zram->init_lock);
 300         if (!zram_wb_enabled(zram)) {
 301                 memcpy(buf, "none\n", 5);
 302                 up_read(&zram->init_lock);
 303                 return 5;
 304         }
 305
 306         p = file_path(file, buf, PAGE_SIZE - 1);
 307         if (IS_ERR(p)) {
 308                 ret = PTR_ERR(p);
 309                 goto out;
 310         }
 311
 312         ret = strlen(p);
 313         memmove(buf, p, ret);
 314         buf[ret++] = '\n';
 315 out:
 316         up_read(&zram->init_lock);
 317         return ret;
 318 }
 319
 320 static ssize_t backing_dev_store(struct device *dev,
 321                 struct device_attribute *attr, const char *buf, size_t len)
 322 {
 323         char *file_name;
 324         struct file *backing_dev = NULL;
 325         struct inode *inode;
 326         struct address_space *mapping;
 327         unsigned int bitmap_sz, old_block_size = 0;
 328         unsigned long nr_pages, *bitmap = NULL;
 329         struct block_device *bdev = NULL;
 330         int err;
 331         struct zram *zram = dev_to_zram(dev);
 332
 333         file_name = kmalloc(PATH_MAX, GFP_KERNEL);
 334         if (!file_name)
 335                 return -ENOMEM;
 336
 337         down_write(&zram->init_lock);
 338         if (init_done(zram)) {
 339                 pr_info("Can't setup backing device for initialized device\n");
 340                 err = -EBUSY;
 341                 goto out;
 342         }
 343
 344         strlcpy(file_name, buf, len);
 345
 346         backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0);
 347         if (IS_ERR(backing_dev)) {
 348                 err = PTR_ERR(backing_dev);
 349                 backing_dev = NULL;
 350                 goto out;
 351         }
 352
 353         mapping = backing_dev->f_mapping;
 354         inode = mapping->host;
 355
 356         /* Support only block device in this moment */
 357         if (!S_ISBLK(inode->i_mode)) {
 358                 err = -ENOTBLK;
 359                 goto out;
 360         }
 361
 362         bdev = bdgrab(I_BDEV(inode));
 363         err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram);
 364         if (err < 0)
 365                 goto out;
 366
 367         nr_pages = i_size_read(inode) >> PAGE_SHIFT;
 368         bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long);
 369         bitmap = kvzalloc(bitmap_sz, GFP_KERNEL);
 370         if (!bitmap) {
 371                 err = -ENOMEM;
 372                 goto out;
 373         }
 374
 375         old_block_size = block_size(bdev);
 376         err = set_blocksize(bdev, PAGE_SIZE);
 377         if (err)
 378                 goto out;
 379
 380         reset_bdev(zram);
 381         spin_lock_init(&zram->bitmap_lock);
 382
 383         zram->old_block_size = old_block_size;
 384         zram->bdev = bdev;
 385         zram->backing_dev = backing_dev;
 386         zram->bitmap = bitmap;
 387         zram->nr_pages = nr_pages;
 388         up_write(&zram->init_lock);
 389
 390         pr_info("setup backing device %s\n", file_name);
 391         kfree(file_name);
 392
 393         return len;
 394 out:
 395         if (bitmap)
 396                 kvfree(bitmap);
 397
 398         if (bdev)
 399                 blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
 400
 401         if (backing_dev)
 402                 filp_close(backing_dev, NULL);
 403
 404         up_write(&zram->init_lock);
 405
 406         kfree(file_name);
 407
 408         return err;
 409 }
 410
 411 static unsigned long get_entry_bdev(struct zram *zram)
 412 {
 413         unsigned long entry;
 414
 415         spin_lock(&zram->bitmap_lock);
 416         /* skip 0 bit to confuse zram.handle = 0 */
 417         entry = find_next_zero_bit(zram->bitmap, zram->nr_pages, 1);
 418         if (entry == zram->nr_pages) {
 419                 spin_unlock(&zram->bitmap_lock);
 420                 return 0;
 421         }
 422
 423         set_bit(entry, zram->bitmap);
 424         spin_unlock(&zram->bitmap_lock);
 425
 426         return entry;
 427 }
 428
 429 static void put_entry_bdev(struct zram *zram, unsigned long entry)
 430 {
 431         int was_set;
 432
 433         spin_lock(&zram->bitmap_lock);
 434         was_set = test_and_clear_bit(entry, zram->bitmap);
 435         spin_unlock(&zram->bitmap_lock);
 436         WARN_ON_ONCE(!was_set);
 437 }
 438
 439 void zram_page_end_io(struct bio *bio)
 440 {
 441         struct page *page = bio->bi_io_vec[0].bv_page;
 442
 443         page_endio(page, op_is_write(bio_op(bio)),
 444                         blk_status_to_errno(bio->bi_status));
 445         bio_put(bio);
 446 }
 447
 448 /*
 449  * Returns 1 if the submission is successful.
 450  */
 451 static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec,
 452                         unsigned long entry, struct bio *parent)
 453 {
 454         struct bio *bio;
 455
 456         bio = bio_alloc(GFP_ATOMIC, 1);
 457         if (!bio)
 458                 return -ENOMEM;
 459
 460         bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9);
 461         bio_set_dev(bio, zram->bdev);
 462         if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len, bvec->bv_offset)) {
 463                 bio_put(bio);
 464                 return -EIO;
 465         }
 466
 467         if (!parent) {
 468                 bio->bi_opf = REQ_OP_READ;
 469                 bio->bi_end_io = zram_page_end_io;
 470         } else {
 471                 bio->bi_opf = parent->bi_opf;
 472                 bio_chain(bio, parent);
 473         }
 474
 475         submit_bio(bio);
 476         return 1;
 477 }
 478
 479 struct zram_work {
 480         struct work_struct work;
 481         struct zram *zram;
 482         unsigned long entry;
 483         struct bio *bio;
 484 };
 485
 486 #if PAGE_SIZE != 4096
 487 static void zram_sync_read(struct work_struct *work)
 488 {
 489         struct bio_vec bvec;
 490         struct zram_work *zw = container_of(work, struct zram_work, work);
 491         struct zram *zram = zw->zram;
 492         unsigned long entry = zw->entry;
 493         struct bio *bio = zw->bio;
 494
 495         read_from_bdev_async(zram, &bvec, entry, bio);
 496 }
 497
 498 /*
 499  * Block layer want one ->make_request_fn to be active at a time
 500  * so if we use chained IO with parent IO in same context,
 501  * it's a deadlock. To avoid, it, it uses worker thread context.
 502  */
 503 static int read_from_bdev_sync(struct zram *zram, struct bio_vec *bvec,
 504                                 unsigned long entry, struct bio *bio)
 505 {
 506         struct zram_work work;
 507
 508         work.zram = zram;
 509         work.entry = entry;
 510         work.bio = bio;
 511
 512         INIT_WORK_ONSTACK(&work.work, zram_sync_read);
 513         queue_work(system_unbound_wq, &work.work);
 514         flush_work(&work.work);
 515         destroy_work_on_stack(&work.work);
 516
 517         return 1;
 518 }
 519 #else
 520 static int read_from_bdev_sync(struct zram *zram, struct bio_vec *bvec,
 521                                 unsigned long entry, struct bio *bio)
 522 {
 523         WARN_ON(1);
 524         return -EIO;
 525 }
 526 #endif
 527
 528 static int read_from_bdev(struct zram *zram, struct bio_vec *bvec,
 529                         unsigned long entry, struct bio *parent, bool sync)
 530 {
 531         if (sync)
 532                 return read_from_bdev_sync(zram, bvec, entry, parent);
 533         else
 534                 return read_from_bdev_async(zram, bvec, entry, parent);
 535 }
 536
 537 static int write_to_bdev(struct zram *zram, struct bio_vec *bvec,
 538                                         u32 index, struct bio *parent,
 539                                         unsigned long *pentry)
 540 {
 541         struct bio *bio;
 542         unsigned long entry;
 543
 544         bio = bio_alloc(GFP_ATOMIC, 1);
 545         if (!bio)
 546                 return -ENOMEM;
 547
 548         entry = get_entry_bdev(zram);
 549         if (!entry) {
 550                 bio_put(bio);
 551                 return -ENOSPC;
 552         }
 553
 554         bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9);
 555         bio_set_dev(bio, zram->bdev);
 556         if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len,
 557                                         bvec->bv_offset)) {
 558                 bio_put(bio);
 559                 put_entry_bdev(zram, entry);
 560                 return -EIO;
 561         }
 562
 563         if (!parent) {
 564                 bio->bi_opf = REQ_OP_WRITE | REQ_SYNC;
 565                 bio->bi_end_io = zram_page_end_io;
 566         } else {
 567                 bio->bi_opf = parent->bi_opf;
 568                 bio_chain(bio, parent);
 569         }
 570
 571         submit_bio(bio);
 572         *pentry = entry;
 573
 574         return 0;
 575 }
 576
 577 static void zram_wb_clear(struct zram *zram, u32 index)
 578 {
 579         unsigned long entry;
 580
 581         zram_clear_flag(zram, index, ZRAM_WB);
 582         entry = zram_get_element(zram, index);
 583         zram_set_element(zram, index, 0);
 584         put_entry_bdev(zram, entry);
 585 }
 586
 587 #else
 588 static bool zram_wb_enabled(struct zram *zram) { return false; }
 589 static inline void reset_bdev(struct zram *zram) {};
 590 static int write_to_bdev(struct zram *zram, struct bio_vec *bvec,
 591                                         u32 index, struct bio *parent,
 592                                         unsigned long *pentry)
 593
 594 {
 595         return -EIO;
 596 }
 597
 598 static int read_from_bdev(struct zram *zram, struct bio_vec *bvec,
 599                         unsigned long entry, struct bio *parent, bool sync)
 600 {
 601         return -EIO;
 602 }
 603 static void zram_wb_clear(struct zram *zram, u32 index) {}
 604 #endif
 605
 606
 607 /*
 608  * We switched to per-cpu streams and this attr is not needed anymore.
 609  * However, we will keep it around for some time, because:
 610  * a) we may revert per-cpu streams in the future
 611  * b) it's visible to user space and we need to follow our 2 years
 612  *    retirement rule; but we already have a number of 'soon to be
 613  *    altered' attrs, so max_comp_streams need to wait for the next
 614  *    layoff cycle.
 615  */
 616 static ssize_t max_comp_streams_show(struct device *dev,
 617                 struct device_attribute *attr, char *buf)
 618 {
 619         return scnprintf(buf, PAGE_SIZE, "%d\n", num_online_cpus());
 620 }
 621
 622 static ssize_t max_comp_streams_store(struct device *dev,
 623                 struct device_attribute *attr, const char *buf, size_t len)
 624 {
 625         return len;
 626 }
 627
 628 static ssize_t comp_algorithm_show(struct device *dev,
 629                 struct device_attribute *attr, char *buf)
 630 {
 631         size_t sz;
 632         struct zram *zram = dev_to_zram(dev);
 633
 634         down_read(&zram->init_lock);
 635         sz = zcomp_available_show(zram->compressor, buf);
 636         up_read(&zram->init_lock);
 637
 638         return sz;
 639 }
 640
 641 static ssize_t comp_algorithm_store(struct device *dev,
 642                 struct device_attribute *attr, const char *buf, size_t len)
 643 {
 644         struct zram *zram = dev_to_zram(dev);
 645         char compressor[ARRAY_SIZE(zram->compressor)];
 646         size_t sz;
 647
 648         strlcpy(compressor, buf, sizeof(compressor));
 649         /* ignore trailing newline */
 650         sz = strlen(compressor);
 651         if (sz > 0 && compressor[sz - 1] == '\n')
 652                 compressor[sz - 1] = 0x00;
 653
 654         if (!zcomp_available_algorithm(compressor))
 655                 return -EINVAL;
 656
 657         down_write(&zram->init_lock);
 658         if (init_done(zram)) {
 659                 up_write(&zram->init_lock);
 660                 pr_info("Can't change algorithm for initialized device\n");
 661                 return -EBUSY;
 662         }
 663
 664         strcpy(zram->compressor, compressor);
 665         up_write(&zram->init_lock);
 666         return len;
 667 }
 668
 669 static ssize_t compact_store(struct device *dev,
 670                 struct device_attribute *attr, const char *buf, size_t len)
 671 {
 672         struct zram *zram = dev_to_zram(dev);
 673
 674         down_read(&zram->init_lock);
 675         if (!init_done(zram)) {
 676                 up_read(&zram->init_lock);
 677                 return -EINVAL;
 678         }
 679
 680         zs_compact(zram->mem_pool);
 681         up_read(&zram->init_lock);
 682
 683         return len;
 684 }
 685
 686 static ssize_t io_stat_show(struct device *dev,
 687                 struct device_attribute *attr, char *buf)
 688 {
 689         struct zram *zram = dev_to_zram(dev);
 690         ssize_t ret;
 691
 692         down_read(&zram->init_lock);
 693         ret = scnprintf(buf, PAGE_SIZE,
 694                         "%8llu %8llu %8llu %8llu\n",
 695                         (u64)atomic64_read(&zram->stats.failed_reads),
 696                         (u64)atomic64_read(&zram->stats.failed_writes),
 697                         (u64)atomic64_read(&zram->stats.invalid_io),
 698                         (u64)atomic64_read(&zram->stats.notify_free));
 699         up_read(&zram->init_lock);
 700
 701         return ret;
 702 }
 703
 704 static ssize_t mm_stat_show(struct device *dev,
 705                 struct device_attribute *attr, char *buf)
 706 {
 707         struct zram *zram = dev_to_zram(dev);
 708         struct zs_pool_stats pool_stats;
 709         u64 orig_size, mem_used = 0;
 710         long max_used;
 711         ssize_t ret;
 712
 713         memset(&pool_stats, 0x00, sizeof(struct zs_pool_stats));
 714
 715         down_read(&zram->init_lock);
 716         if (init_done(zram)) {
 717                 mem_used = zs_get_total_pages(zram->mem_pool);
 718                 zs_pool_stats(zram->mem_pool, &pool_stats);
 719         }
 720
 721         orig_size = atomic64_read(&zram->stats.pages_stored);
 722         max_used = atomic_long_read(&zram->stats.max_used_pages);
 723
 724         ret = scnprintf(buf, PAGE_SIZE,
 725                         "%8llu %8llu %8llu %8lu %8ld %8llu %8lu\n",
 726                         orig_size << PAGE_SHIFT,
 727                         (u64)atomic64_read(&zram->stats.compr_data_size),
 728                         mem_used << PAGE_SHIFT,
 729                         zram->limit_pages << PAGE_SHIFT,
 730                         max_used << PAGE_SHIFT,
 731                         (u64)atomic64_read(&zram->stats.same_pages),
 732                         pool_stats.pages_compacted);
 733         up_read(&zram->init_lock);
 734
 735         return ret;
 736 }
 737
 738 static ssize_t debug_stat_show(struct device *dev,
 739                 struct device_attribute *attr, char *buf)
 740 {
 741         int version = 1;
 742         struct zram *zram = dev_to_zram(dev);
 743         ssize_t ret;
 744
 745         down_read(&zram->init_lock);
 746         ret = scnprintf(buf, PAGE_SIZE,
 747                         "version: %d\n%8llu\n",
 748                         version,
 749                         (u64)atomic64_read(&zram->stats.writestall));
 750         up_read(&zram->init_lock);
 751
 752         return ret;
 753 }
 754
 755 static DEVICE_ATTR_RO(io_stat);
 756 static DEVICE_ATTR_RO(mm_stat);
 757 static DEVICE_ATTR_RO(debug_stat);
 758
 759 static void zram_slot_lock(struct zram *zram, u32 index)
 760 {
 761         bit_spin_lock(ZRAM_ACCESS, &zram->table[index].value);
 762 }
 763
 764 static void zram_slot_unlock(struct zram *zram, u32 index)
 765 {
 766         bit_spin_unlock(ZRAM_ACCESS, &zram->table[index].value);
 767 }
 768
 769 static bool zram_same_page_read(struct zram *zram, u32 index,
 770                                 struct page *page,
 771                                 unsigned int offset, unsigned int len)
 772 {
 773         zram_slot_lock(zram, index);
 774         if (unlikely(!zram_get_handle(zram, index) ||
 775                         zram_test_flag(zram, index, ZRAM_SAME))) {
 776                 void *mem;
 777
 778                 zram_slot_unlock(zram, index);
 779                 mem = kmap_atomic(page);
 780                 zram_fill_page(mem + offset, len,
 781                                         zram_get_element(zram, index));
 782                 kunmap_atomic(mem);
 783                 return true;
 784         }
 785         zram_slot_unlock(zram, index);
 786
 787         return false;
 788 }
 789
 790 static void zram_meta_free(struct zram *zram, u64 disksize)
 791 {
 792         size_t num_pages = disksize >> PAGE_SHIFT;
 793         size_t index;
 794
 795         /* Free all pages that are still in this zram device */
 796         for (index = 0; index < num_pages; index++)
 797                 zram_free_page(zram, index);
 798
 799         zs_destroy_pool(zram->mem_pool);
 800         vfree(zram->table);
 801 }
 802
 803 static bool zram_meta_alloc(struct zram *zram, u64 disksize)
 804 {
 805         size_t num_pages;
 806
 807         num_pages = disksize >> PAGE_SHIFT;
 808         zram->table = vzalloc(num_pages * sizeof(*zram->table));
 809         if (!zram->table)
 810                 return false;
 811
 812         zram->mem_pool = zs_create_pool(zram->disk->disk_name);
 813         if (!zram->mem_pool) {
 814                 vfree(zram->table);
 815                 return false;
 816         }
 817
 818         return true;
 819 }
 820
 821 /*
 822  * To protect concurrent access to the same index entry,
 823  * caller should hold this table index entry's bit_spinlock to
 824  * indicate this index entry is accessing.
 825  */
 826 static void zram_free_page(struct zram *zram, size_t index)
 827 {
 828         unsigned long handle;
 829
 830         if (zram_wb_enabled(zram) && zram_test_flag(zram, index, ZRAM_WB)) {
 831                 zram_wb_clear(zram, index);
 832                 atomic64_dec(&zram->stats.pages_stored);
 833                 return;
 834         }
 835
 836         /*
 837          * No memory is allocated for same element filled pages.
 838          * Simply clear same page flag.
 839          */
 840         if (zram_test_flag(zram, index, ZRAM_SAME)) {
 841                 zram_clear_flag(zram, index, ZRAM_SAME);
 842                 zram_set_element(zram, index, 0);
 843                 atomic64_dec(&zram->stats.same_pages);
 844                 atomic64_dec(&zram->stats.pages_stored);
 845                 return;
 846         }
 847
 848         handle = zram_get_handle(zram, index);
 849         if (!handle)
 850                 return;
 851
 852         zs_free(zram->mem_pool, handle);
 853
 854         atomic64_sub(zram_get_obj_size(zram, index),
 855                         &zram->stats.compr_data_size);
 856         atomic64_dec(&zram->stats.pages_stored);
 857
 858         zram_set_handle(zram, index, 0);
 859         zram_set_obj_size(zram, index, 0);
 860 }
 861
 862 static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
 863                                 struct bio *bio, bool partial_io)
 864 {
 865         int ret;
 866         unsigned long handle;
 867         unsigned int size;
 868         void *src, *dst;
 869
 870         if (zram_wb_enabled(zram)) {
 871                 zram_slot_lock(zram, index);
 872                 if (zram_test_flag(zram, index, ZRAM_WB)) {
 873                         struct bio_vec bvec;
 874
 875                         zram_slot_unlock(zram, index);
 876
 877                         bvec.bv_page = page;
 878                         bvec.bv_len = PAGE_SIZE;
 879                         bvec.bv_offset = 0;
 880                         return read_from_bdev(zram, &bvec,
 881                                         zram_get_element(zram, index),
 882                                         bio, partial_io);
 883                 }
 884                 zram_slot_unlock(zram, index);
 885         }
 886
 887         if (zram_same_page_read(zram, index, page, 0, PAGE_SIZE))
 888                 return 0;
 889
 890         zram_slot_lock(zram, index);
 891         handle = zram_get_handle(zram, index);
 892         size = zram_get_obj_size(zram, index);
 893
 894         src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
 895         if (size == PAGE_SIZE) {
 896                 dst = kmap_atomic(page);
 897                 memcpy(dst, src, PAGE_SIZE);
 898                 kunmap_atomic(dst);
 899                 ret = 0;
 900         } else {
 901                 struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp);
 902
 903                 dst = kmap_atomic(page);
 904                 ret = zcomp_decompress(zstrm, src, size, dst);
 905                 kunmap_atomic(dst);
 906                 zcomp_stream_put(zram->comp);
 907         }
 908         zs_unmap_object(zram->mem_pool, handle);
 909         zram_slot_unlock(zram, index);
 910
 911         /* Should NEVER happen. Return bio error if it does. */
 912         if (unlikely(ret))
 913                 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
 914
 915         return ret;
 916 }
 917
 918 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 919                                 u32 index, int offset, struct bio *bio)
 920 {
 921         int ret;
 922         struct page *page;
 923
 924         page = bvec->bv_page;
 925         if (is_partial_io(bvec)) {
 926                 /* Use a temporary buffer to decompress the page */
 927                 page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
 928                 if (!page)
 929                         return -ENOMEM;
 930         }
 931
 932         ret = __zram_bvec_read(zram, page, index, bio, is_partial_io(bvec));
 933         if (unlikely(ret))
 934                 goto out;
 935
 936         if (is_partial_io(bvec)) {
 937                 void *dst = kmap_atomic(bvec->bv_page);
 938                 void *src = kmap_atomic(page);
 939
 940                 memcpy(dst + bvec->bv_offset, src + offset, bvec->bv_len);
 941                 kunmap_atomic(src);
 942                 kunmap_atomic(dst);
 943         }
 944 out:
 945         if (is_partial_io(bvec))
 946                 __free_page(page);
 947
 948         return ret;
 949 }
 950
 951 static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
 952                                 u32 index, struct bio *bio)
 953 {
 954         int ret = 0;
 955         unsigned long alloced_pages;
 956         unsigned long handle = 0;
 957         unsigned int comp_len = 0;
 958         void *src, *dst, *mem;
 959         struct zcomp_strm *zstrm;
 960         struct page *page = bvec->bv_page;
 961         unsigned long element = 0;
 962         enum zram_pageflags flags = 0;
 963         bool allow_wb = true;
 964
 965         mem = kmap_atomic(page);
 966         if (page_same_filled(mem, &element)) {
 967                 kunmap_atomic(mem);
 968                 /* Free memory associated with this sector now. */
 969                 flags = ZRAM_SAME;
 970                 atomic64_inc(&zram->stats.same_pages);
 971                 goto out;
 972         }
 973         kunmap_atomic(mem);
 974
 975 compress_again:
 976         zstrm = zcomp_stream_get(zram->comp);
 977         src = kmap_atomic(page);
 978         ret = zcomp_compress(zstrm, src, &comp_len);
 979         kunmap_atomic(src);
 980
 981         if (unlikely(ret)) {
 982                 zcomp_stream_put(zram->comp);
 983                 pr_err("Compression failed! err=%d\n", ret);
 984                 zs_free(zram->mem_pool, handle);
 985                 return ret;
 986         }
 987
 988         if (unlikely(comp_len > max_zpage_size)) {
 989                 if (zram_wb_enabled(zram) && allow_wb) {
 990                         zcomp_stream_put(zram->comp);
 991                         ret = write_to_bdev(zram, bvec, index, bio, &element);
 992                         if (!ret) {
 993                                 flags = ZRAM_WB;
 994                                 ret = 1;
 995                                 goto out;
 996                         }
 997                         allow_wb = false;
 998                         goto compress_again;
 999                 }
1000                 comp_len = PAGE_SIZE;
1001         }
1002
1003         /*
1004          * handle allocation has 2 paths:
1005          * a) fast path is executed with preemption disabled (for
1006          *  per-cpu streams) and has __GFP_DIRECT_RECLAIM bit clear,
1007          *  since we can't sleep;
1008          * b) slow path enables preemption and attempts to allocate
1009          *  the page with __GFP_DIRECT_RECLAIM bit set. we have to
1010          *  put per-cpu compression stream and, thus, to re-do
1011          *  the compression once handle is allocated.
1012          *
1013          * if we have a 'non-null' handle here then we are coming
1014          * from the slow path and handle has already been allocated.
1015          */
1016         if (!handle)
1017                 handle = zs_malloc(zram->mem_pool, comp_len,
1018                                 __GFP_KSWAPD_RECLAIM |
1019                                 __GFP_NOWARN |
1020                                 __GFP_HIGHMEM |
1021                                 __GFP_MOVABLE);
1022         if (!handle) {
1023                 zcomp_stream_put(zram->comp);
1024                 atomic64_inc(&zram->stats.writestall);
1025                 handle = zs_malloc(zram->mem_pool, comp_len,
1026                                 GFP_NOIO | __GFP_HIGHMEM |
1027                                 __GFP_MOVABLE);
1028                 if (handle)
1029                         goto compress_again;
1030                 return -ENOMEM;
1031         }
1032
1033         alloced_pages = zs_get_total_pages(zram->mem_pool);
1034         update_used_max(zram, alloced_pages);
1035
1036         if (zram->limit_pages && alloced_pages > zram->limit_pages) {
1037                 zcomp_stream_put(zram->comp);
1038                 zs_free(zram->mem_pool, handle);
1039                 return -ENOMEM;
1040         }
1041
1042         dst = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
1043
1044         src = zstrm->buffer;
1045         if (comp_len == PAGE_SIZE)
1046                 src = kmap_atomic(page);
1047         memcpy(dst, src, comp_len);
1048         if (comp_len == PAGE_SIZE)
1049                 kunmap_atomic(src);
1050
1051         zcomp_stream_put(zram->comp);
1052         zs_unmap_object(zram->mem_pool, handle);
1053         atomic64_add(comp_len, &zram->stats.compr_data_size);
1054 out:
1055         /*
1056          * Free memory associated with this sector
1057          * before overwriting unused sectors.
1058          */
1059         zram_slot_lock(zram, index);
1060         zram_free_page(zram, index);
1061
1062         if (flags) {
1063                 zram_set_flag(zram, index, flags);
1064                 zram_set_element(zram, index, element);
1065         }  else {
1066                 zram_set_handle(zram, index, handle);
1067                 zram_set_obj_size(zram, index, comp_len);
1068         }
1069         zram_slot_unlock(zram, index);
1070
1071         /* Update stats */
1072         atomic64_inc(&zram->stats.pages_stored);
1073         return ret;
1074 }
1075
1076 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
1077                                 u32 index, int offset, struct bio *bio)
1078 {
1079         int ret;
1080         struct page *page = NULL;
1081         void *src;
1082         struct bio_vec vec;
1083
1084         vec = *bvec;
1085         if (is_partial_io(bvec)) {
1086                 void *dst;
1087                 /*
1088                  * This is a partial IO. We need to read the full page
1089                  * before to write the changes.
1090                  */
1091                 page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
1092                 if (!page)
1093                         return -ENOMEM;
1094
1095                 ret = __zram_bvec_read(zram, page, index, bio, true);
1096                 if (ret)
1097                         goto out;
1098
1099                 src = kmap_atomic(bvec->bv_page);
1100                 dst = kmap_atomic(page);
1101                 memcpy(dst + offset, src + bvec->bv_offset, bvec->bv_len);
1102                 kunmap_atomic(dst);
1103                 kunmap_atomic(src);
1104
1105                 vec.bv_page = page;
1106                 vec.bv_len = PAGE_SIZE;
1107                 vec.bv_offset = 0;
1108         }
1109
1110         ret = __zram_bvec_write(zram, &vec, index, bio);
1111 out:
1112         if (is_partial_io(bvec))
1113                 __free_page(page);
1114         return ret;
1115 }
1116
1117 /*
1118  * zram_bio_discard - handler on discard request
1119  * @index: physical block index in PAGE_SIZE units
1120  * @offset: byte offset within physical block
1121  */
1122 static void zram_bio_discard(struct zram *zram, u32 index,
1123                              int offset, struct bio *bio)
1124 {
1125         size_t n = bio->bi_iter.bi_size;
1126
1127         /*
1128          * zram manages data in physical block size units. Because logical block
1129          * size isn't identical with physical block size on some arch, we
1130          * could get a discard request pointing to a specific offset within a
1131          * certain physical block.  Although we can handle this request by
1132          * reading that physiclal block and decompressing and partially zeroing
1133          * and re-compressing and then re-storing it, this isn't reasonable
1134          * because our intent with a discard request is to save memory.  So
1135          * skipping this logical block is appropriate here.
1136          */
1137         if (offset) {
1138                 if (n <= (PAGE_SIZE - offset))
1139                         return;
1140
1141                 n -= (PAGE_SIZE - offset);
1142                 index++;
1143         }
1144
1145         while (n >= PAGE_SIZE) {
1146                 zram_slot_lock(zram, index);
1147                 zram_free_page(zram, index);
1148                 zram_slot_unlock(zram, index);
1149                 atomic64_inc(&zram->stats.notify_free);
1150                 index++;
1151                 n -= PAGE_SIZE;
1152         }
1153 }
1154
1155 /*
1156  * Returns errno if it has some problem. Otherwise return 0 or 1.
1157  * Returns 0 if IO request was done synchronously
1158  * Returns 1 if IO request was successfully submitted.
1159  */
1160 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
1161                         int offset, bool is_write, struct bio *bio)
1162 {
1163         unsigned long start_time = jiffies;
1164         int rw_acct = is_write ? REQ_OP_WRITE : REQ_OP_READ;
1165         struct request_queue *q = zram->disk->queue;
1166         int ret;
1167
1168         generic_start_io_acct(q, rw_acct, bvec->bv_len >> SECTOR_SHIFT,
1169                         &zram->disk->part0);
1170
1171         if (!is_write) {
1172                 atomic64_inc(&zram->stats.num_reads);
1173                 ret = zram_bvec_read(zram, bvec, index, offset, bio);
1174                 flush_dcache_page(bvec->bv_page);
1175         } else {
1176                 atomic64_inc(&zram->stats.num_writes);
1177                 ret = zram_bvec_write(zram, bvec, index, offset, bio);
1178         }
1179
1180         generic_end_io_acct(q, rw_acct, &zram->disk->part0, start_time);
1181
1182         if (unlikely(ret < 0)) {
1183                 if (!is_write)
1184                         atomic64_inc(&zram->stats.failed_reads);
1185                 else
1186                         atomic64_inc(&zram->stats.failed_writes);
1187         }
1188
1189         return ret;
1190 }
1191
1192 static void __zram_make_request(struct zram *zram, struct bio *bio)
1193 {
1194         int offset;
1195         u32 index;
1196         struct bio_vec bvec;
1197         struct bvec_iter iter;
1198
1199         index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
1200         offset = (bio->bi_iter.bi_sector &
1201                   (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
1202
1203         switch (bio_op(bio)) {
1204         case REQ_OP_DISCARD:
1205         case REQ_OP_WRITE_ZEROES:
1206                 zram_bio_discard(zram, index, offset, bio);
1207                 bio_endio(bio);
1208                 return;
1209         default:
1210                 break;
1211         }
1212
1213         bio_for_each_segment(bvec, bio, iter) {
1214                 struct bio_vec bv = bvec;
1215                 unsigned int unwritten = bvec.bv_len;
1216
1217                 do {
1218                         bv.bv_len = min_t(unsigned int, PAGE_SIZE - offset,
1219                                                         unwritten);
1220                         if (zram_bvec_rw(zram, &bv, index, offset,
1221                                         op_is_write(bio_op(bio)), bio) < 0)
1222                                 goto out;
1223
1224                         bv.bv_offset += bv.bv_len;
1225                         unwritten -= bv.bv_len;
1226
1227                         update_position(&index, &offset, &bv);
1228                 } while (unwritten);
1229         }
1230
1231         bio_endio(bio);
1232         return;
1233
1234 out:
1235         bio_io_error(bio);
1236 }
1237
1238 /*
1239  * Handler function for all zram I/O requests.
1240  */
1241 static blk_qc_t zram_make_request(struct request_queue *queue, struct bio *bio)
1242 {
1243         struct zram *zram = queue->queuedata;
1244
1245         if (!valid_io_request(zram, bio->bi_iter.bi_sector,
1246                                         bio->bi_iter.bi_size)) {
1247                 atomic64_inc(&zram->stats.invalid_io);
1248                 goto error;
1249         }
1250
1251         __zram_make_request(zram, bio);
1252         return BLK_QC_T_NONE;
1253
1254 error:
1255         bio_io_error(bio);
1256         return BLK_QC_T_NONE;
1257 }
1258
1259 static void zram_slot_free_notify(struct block_device *bdev,
1260                                 unsigned long index)
1261 {
1262         struct zram *zram;
1263
1264         zram = bdev->bd_disk->private_data;
1265
1266         zram_slot_lock(zram, index);
1267         zram_free_page(zram, index);
1268         zram_slot_unlock(zram, index);
1269         atomic64_inc(&zram->stats.notify_free);
1270 }
1271
1272 static int zram_rw_page(struct block_device *bdev, sector_t sector,
1273                        struct page *page, bool is_write)
1274 {
1275         int offset, ret;
1276         u32 index;
1277         struct zram *zram;
1278         struct bio_vec bv;
1279
1280         if (PageTransHuge(page))
1281                 return -ENOTSUPP;
1282         zram = bdev->bd_disk->private_data;
1283
1284         if (!valid_io_request(zram, sector, PAGE_SIZE)) {
1285                 atomic64_inc(&zram->stats.invalid_io);
1286                 ret = -EINVAL;
1287                 goto out;
1288         }
1289
1290         index = sector >> SECTORS_PER_PAGE_SHIFT;
1291         offset = (sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
1292
1293         bv.bv_page = page;
1294         bv.bv_len = PAGE_SIZE;
1295         bv.bv_offset = 0;
1296
1297         ret = zram_bvec_rw(zram, &bv, index, offset, is_write, NULL);
1298 out:
1299         /*
1300          * If I/O fails, just return error(ie, non-zero) without
1301          * calling page_endio.
1302          * It causes resubmit the I/O with bio request by upper functions
1303          * of rw_page(e.g., swap_readpage, __swap_writepage) and
1304          * bio->bi_end_io does things to handle the error
1305          * (e.g., SetPageError, set_page_dirty and extra works).
1306          */
1307         if (unlikely(ret < 0))
1308                 return ret;
1309
1310         switch (ret) {
1311         case 0:
1312                 page_endio(page, is_write, 0);
1313                 break;
1314         case 1:
1315                 ret = 0;
1316                 break;
1317         default:
1318                 WARN_ON(1);
1319         }
1320         return ret;
1321 }
1322
1323 static void zram_reset_device(struct zram *zram)
1324 {
1325         struct zcomp *comp;
1326         u64 disksize;
1327
1328         down_write(&zram->init_lock);
1329
1330         zram->limit_pages = 0;
1331
1332         if (!init_done(zram)) {
1333                 up_write(&zram->init_lock);
1334                 return;
1335         }
1336
1337         comp = zram->comp;
1338         disksize = zram->disksize;
1339         zram->disksize = 0;
1340
1341         set_capacity(zram->disk, 0);
1342         part_stat_set_all(&zram->disk->part0, 0);
1343
1344         up_write(&zram->init_lock);
1345         /* I/O operation under all of CPU are done so let's free */
1346         zram_meta_free(zram, disksize);
1347         memset(&zram->stats, 0, sizeof(zram->stats));
1348         zcomp_destroy(comp);
1349         reset_bdev(zram);
1350 }
1351
1352 static ssize_t disksize_store(struct device *dev,
1353                 struct device_attribute *attr, const char *buf, size_t len)
1354 {
1355         u64 disksize;
1356         struct zcomp *comp;
1357         struct zram *zram = dev_to_zram(dev);
1358         int err;
1359
1360         disksize = memparse(buf, NULL);
1361         if (!disksize)
1362                 return -EINVAL;
1363
1364         down_write(&zram->init_lock);
1365         if (init_done(zram)) {
1366                 pr_info("Cannot change disksize for initialized device\n");
1367                 err = -EBUSY;
1368                 goto out_unlock;
1369         }
1370
1371         disksize = PAGE_ALIGN(disksize);
1372         if (!zram_meta_alloc(zram, disksize)) {
1373                 err = -ENOMEM;
1374                 goto out_unlock;
1375         }
1376
1377         comp = zcomp_create(zram->compressor);
1378         if (IS_ERR(comp)) {
1379                 pr_err("Cannot initialise %s compressing backend\n",
1380                                 zram->compressor);
1381                 err = PTR_ERR(comp);
1382                 goto out_free_meta;
1383         }
1384
1385         zram->comp = comp;
1386         zram->disksize = disksize;
1387         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
1388         zram_revalidate_disk(zram);
1389         up_write(&zram->init_lock);
1390
1391         return len;
1392
1393 out_free_meta:
1394         zram_meta_free(zram, disksize);
1395 out_unlock:
1396         up_write(&zram->init_lock);
1397         return err;
1398 }
1399
1400 static ssize_t reset_store(struct device *dev,
1401                 struct device_attribute *attr, const char *buf, size_t len)
1402 {
1403         int ret;
1404         unsigned short do_reset;
1405         struct zram *zram;
1406         struct block_device *bdev;
1407
1408         ret = kstrtou16(buf, 10, &do_reset);
1409         if (ret)
1410                 return ret;
1411
1412         if (!do_reset)
1413                 return -EINVAL;
1414
1415         zram = dev_to_zram(dev);
1416         bdev = bdget_disk(zram->disk, 0);
1417         if (!bdev)
1418                 return -ENOMEM;
1419
1420         mutex_lock(&bdev->bd_mutex);
1421         /* Do not reset an active device or claimed device */
1422         if (bdev->bd_openers || zram->claim) {
1423                 mutex_unlock(&bdev->bd_mutex);
1424                 bdput(bdev);
1425                 return -EBUSY;
1426         }
1427
1428         /* From now on, anyone can't open /dev/zram[0-9] */
1429         zram->claim = true;
1430         mutex_unlock(&bdev->bd_mutex);
1431
1432         /* Make sure all the pending I/O are finished */
1433         fsync_bdev(bdev);
1434         zram_reset_device(zram);
1435         zram_revalidate_disk(zram);
1436         bdput(bdev);
1437
1438         mutex_lock(&bdev->bd_mutex);
1439         zram->claim = false;
1440         mutex_unlock(&bdev->bd_mutex);
1441
1442         return len;
1443 }
1444
1445 static int zram_open(struct block_device *bdev, fmode_t mode)
1446 {
1447         int ret = 0;
1448         struct zram *zram;
1449
1450         WARN_ON(!mutex_is_locked(&bdev->bd_mutex));
1451
1452         zram = bdev->bd_disk->private_data;
1453         /* zram was claimed to reset so open request fails */
1454         if (zram->claim)
1455                 ret = -EBUSY;
1456
1457         return ret;
1458 }
1459
1460 static const struct block_device_operations zram_devops = {
1461         .open = zram_open,
1462         .swap_slot_free_notify = zram_slot_free_notify,
1463         .rw_page = zram_rw_page,
1464         .owner = THIS_MODULE
1465 };
1466
1467 static DEVICE_ATTR_WO(compact);
1468 static DEVICE_ATTR_RW(disksize);
1469 static DEVICE_ATTR_RO(initstate);
1470 static DEVICE_ATTR_WO(reset);
1471 static DEVICE_ATTR_WO(mem_limit);
1472 static DEVICE_ATTR_WO(mem_used_max);
1473 static DEVICE_ATTR_RW(max_comp_streams);
1474 static DEVICE_ATTR_RW(comp_algorithm);
1475 #ifdef CONFIG_ZRAM_WRITEBACK
1476 static DEVICE_ATTR_RW(backing_dev);
1477 #endif
1478
1479 static struct attribute *zram_disk_attrs[] = {
1480         &dev_attr_disksize.attr,
1481         &dev_attr_initstate.attr,
1482         &dev_attr_reset.attr,
1483         &dev_attr_compact.attr,
1484         &dev_attr_mem_limit.attr,
1485         &dev_attr_mem_used_max.attr,
1486         &dev_attr_max_comp_streams.attr,
1487         &dev_attr_comp_algorithm.attr,
1488 #ifdef CONFIG_ZRAM_WRITEBACK
1489         &dev_attr_backing_dev.attr,
1490 #endif
1491         &dev_attr_io_stat.attr,
1492         &dev_attr_mm_stat.attr,
1493         &dev_attr_debug_stat.attr,
1494         NULL,
1495 };
1496
1497 static const struct attribute_group zram_disk_attr_group = {
1498         .attrs = zram_disk_attrs,
1499 };
1500
1501 /*
1502  * Allocate and initialize new zram device. the function returns
1503  * '>= 0' device_id upon success, and negative value otherwise.
1504  */
1505 static int zram_add(void)
1506 {
1507         struct zram *zram;
1508         struct request_queue *queue;
1509         int ret, device_id;
1510
1511         zram = kzalloc(sizeof(struct zram), GFP_KERNEL);
1512         if (!zram)
1513                 return -ENOMEM;
1514
1515         ret = idr_alloc(&zram_index_idr, zram, 0, 0, GFP_KERNEL);
1516         if (ret < 0)
1517                 goto out_free_dev;
1518         device_id = ret;
1519
1520         init_rwsem(&zram->init_lock);
1521
1522         queue = blk_alloc_queue(GFP_KERNEL);
1523         if (!queue) {
1524                 pr_err("Error allocating disk queue for device %d\n",
1525                         device_id);
1526                 ret = -ENOMEM;
1527                 goto out_free_idr;
1528         }
1529
1530         blk_queue_make_request(queue, zram_make_request);
1531
1532         /* gendisk structure */
1533         zram->disk = alloc_disk(1);
1534         if (!zram->disk) {
1535                 pr_err("Error allocating disk structure for device %d\n",
1536                         device_id);
1537                 ret = -ENOMEM;
1538                 goto out_free_queue;
1539         }
1540
1541         zram->disk->major = zram_major;
1542         zram->disk->first_minor = device_id;
1543         zram->disk->fops = &zram_devops;
1544         zram->disk->queue = queue;
1545         zram->disk->queue->queuedata = zram;
1546         zram->disk->private_data = zram;
1547         snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
1548
1549         /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
1550         set_capacity(zram->disk, 0);
1551         /* zram devices sort of resembles non-rotational disks */
1552         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
1553         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
1554         /*
1555          * To ensure that we always get PAGE_SIZE aligned
1556          * and n*PAGE_SIZED sized I/O requests.
1557          */
1558         blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
1559         blk_queue_logical_block_size(zram->disk->queue,
1560                                         ZRAM_LOGICAL_BLOCK_SIZE);
1561         blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
1562         blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
1563         zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
1564         blk_queue_max_discard_sectors(zram->disk->queue, UINT_MAX);
1565         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
1566
1567         /*
1568          * zram_bio_discard() will clear all logical blocks if logical block
1569          * size is identical with physical block size(PAGE_SIZE). But if it is
1570          * different, we will skip discarding some parts of logical blocks in
1571          * the part of the request range which isn't aligned to physical block
1572          * size.  So we can't ensure that all discarded logical blocks are
1573          * zeroed.
1574          */
1575         if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
1576                 blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
1577
1578         add_disk(zram->disk);
1579
1580         ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
1581                                 &zram_disk_attr_group);
1582         if (ret < 0) {
1583                 pr_err("Error creating sysfs group for device %d\n",
1584                                 device_id);
1585                 goto out_free_disk;
1586         }
1587         strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
1588
1589         pr_info("Added device: %s\n", zram->disk->disk_name);
1590         return device_id;
1591
1592 out_free_disk:
1593         del_gendisk(zram->disk);
1594         put_disk(zram->disk);
1595 out_free_queue:
1596         blk_cleanup_queue(queue);
1597 out_free_idr:
1598         idr_remove(&zram_index_idr, device_id);
1599 out_free_dev:
1600         kfree(zram);
1601         return ret;
1602 }
1603
1604 static int zram_remove(struct zram *zram)
1605 {
1606         struct block_device *bdev;
1607
1608         bdev = bdget_disk(zram->disk, 0);
1609         if (!bdev)
1610                 return -ENOMEM;
1611
1612         mutex_lock(&bdev->bd_mutex);
1613         if (bdev->bd_openers || zram->claim) {
1614                 mutex_unlock(&bdev->bd_mutex);
1615                 bdput(bdev);
1616                 return -EBUSY;
1617         }
1618
1619         zram->claim = true;
1620         mutex_unlock(&bdev->bd_mutex);
1621
1622         /*
1623          * Remove sysfs first, so no one will perform a disksize
1624          * store while we destroy the devices. This also helps during
1625          * hot_remove -- zram_reset_device() is the last holder of
1626          * ->init_lock, no later/concurrent disksize_store() or any
1627          * other sysfs handlers are possible.
1628          */
1629         sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
1630                         &zram_disk_attr_group);
1631
1632         /* Make sure all the pending I/O are finished */
1633         fsync_bdev(bdev);
1634         zram_reset_device(zram);
1635         bdput(bdev);
1636
1637         pr_info("Removed device: %s\n", zram->disk->disk_name);
1638
1639         blk_cleanup_queue(zram->disk->queue);
1640         del_gendisk(zram->disk);
1641         put_disk(zram->disk);
1642         kfree(zram);
1643         return 0;
1644 }
1645
1646 /* zram-control sysfs attributes */
1647
1648 /*
1649  * NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a
1650  * sense that reading from this file does alter the state of your system -- it
1651  * creates a new un-initialized zram device and returns back this device's
1652  * device_id (or an error code if it fails to create a new device).
1653  */
1654 static ssize_t hot_add_show(struct class *class,
1655                         struct class_attribute *attr,
1656                         char *buf)
1657 {
1658         int ret;
1659
1660         mutex_lock(&zram_index_mutex);
1661         ret = zram_add();
1662         mutex_unlock(&zram_index_mutex);
1663
1664         if (ret < 0)
1665                 return ret;
1666         return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
1667 }
1668 static CLASS_ATTR_RO(hot_add);
1669
1670 static ssize_t hot_remove_store(struct class *class,
1671                         struct class_attribute *attr,
1672                         const char *buf,
1673                         size_t count)
1674 {
1675         struct zram *zram;
1676         int ret, dev_id;
1677
1678         /* dev_id is gendisk->first_minor, which is `int' */
1679         ret = kstrtoint(buf, 10, &dev_id);
1680         if (ret)
1681                 return ret;
1682         if (dev_id < 0)
1683                 return -EINVAL;
1684
1685         mutex_lock(&zram_index_mutex);
1686
1687         zram = idr_find(&zram_index_idr, dev_id);
1688         if (zram) {
1689                 ret = zram_remove(zram);
1690                 if (!ret)
1691                         idr_remove(&zram_index_idr, dev_id);
1692         } else {
1693                 ret = -ENODEV;
1694         }
1695
1696         mutex_unlock(&zram_index_mutex);
1697         return ret ? ret : count;
1698 }
1699 static CLASS_ATTR_WO(hot_remove);
1700
1701 static struct attribute *zram_control_class_attrs[] = {
1702         &class_attr_hot_add.attr,
1703         &class_attr_hot_remove.attr,
1704         NULL,
1705 };
1706 ATTRIBUTE_GROUPS(zram_control_class);
1707
1708 static struct class zram_control_class = {
1709         .name           = "zram-control",
1710         .owner          = THIS_MODULE,
1711         .class_groups   = zram_control_class_groups,
1712 };
1713
1714 static int zram_remove_cb(int id, void *ptr, void *data)
1715 {
1716         zram_remove(ptr);
1717         return 0;
1718 }
1719
1720 static void destroy_devices(void)
1721 {
1722         class_unregister(&zram_control_class);
1723         idr_for_each(&zram_index_idr, &zram_remove_cb, NULL);
1724         idr_destroy(&zram_index_idr);
1725         unregister_blkdev(zram_major, "zram");
1726         cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
1727 }
1728
1729 static int __init zram_init(void)
1730 {
1731         int ret;
1732
1733         ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare",
1734                                       zcomp_cpu_up_prepare, zcomp_cpu_dead);
1735         if (ret < 0)
1736                 return ret;
1737
1738         ret = class_register(&zram_control_class);
1739         if (ret) {
1740                 pr_err("Unable to register zram-control class\n");
1741                 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
1742                 return ret;
1743         }
1744
1745         zram_major = register_blkdev(0, "zram");
1746         if (zram_major <= 0) {
1747                 pr_err("Unable to get major number\n");
1748                 class_unregister(&zram_control_class);
1749                 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
1750                 return -EBUSY;
1751         }
1752
1753         while (num_devices != 0) {
1754                 mutex_lock(&zram_index_mutex);
1755                 ret = zram_add();
1756                 mutex_unlock(&zram_index_mutex);
1757                 if (ret < 0)
1758                         goto out_error;
1759                 num_devices--;
1760         }
1761
1762         return 0;
1763
1764 out_error:
1765         destroy_devices();
1766         return ret;
1767 }
1768
1769 static void __exit zram_exit(void)
1770 {
1771         destroy_devices();
1772 }
1773
1774 module_init(zram_init);
1775 module_exit(zram_exit);
1776
1777 module_param(num_devices, uint, 0);
1778 MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices");
1779
1780 MODULE_LICENSE("Dual BSD/GPL");
1781 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1782 MODULE_DESCRIPTION("Compressed RAM Block Device");