1/* 2 * Compressed RAM block device 3 * 4 * Copyright (C) 2008, 2009, 2010 Nitin Gupta 5 * 2012, 2013 Minchan Kim 6 * 7 * This code is released using a dual license strategy: BSD/GPL 8 * You can choose the licence that better fits your requirements. 9 * 10 * Released under the terms of 3-clause BSD License 11 * Released under the terms of GNU General Public License Version 2.0 12 * 13 */ 14 15#define KMSG_COMPONENT "zram" 16#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 17 18#ifdef CONFIG_ZRAM_DEBUG 19#define DEBUG 20#endif 21 22#include <linux/module.h> 23#include <linux/kernel.h> 24#include <linux/bio.h> 25#include <linux/bitops.h> 26#include <linux/blkdev.h> 27#include <linux/buffer_head.h> 28#include <linux/device.h> 29#include <linux/genhd.h> 30#include <linux/highmem.h> 31#include <linux/slab.h> 32#include <linux/string.h> 33#include <linux/vmalloc.h> 34#include <linux/err.h> 35 36#include "zram_drv.h" 37 38/* Globals */ 39static int zram_major; 40static struct zram *zram_devices; 41static const char *default_compressor = "lzo"; 42 43/* Module params (documentation at end) */ 44static unsigned int num_devices = 1; 45 46static 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) \ 56static 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} \ 65static DEVICE_ATTR_RO(name); 66 67static inline bool init_done(struct zram *zram) 68{ 69 return zram->disksize; 70} 71 72static inline struct zram *dev_to_zram(struct device *dev) 73{ 74 return (struct zram *)dev_to_disk(dev)->private_data; 75} 76 77static ssize_t compact_store(struct device *dev, 78 struct device_attribute *attr, const char *buf, size_t len) 79{ 80 unsigned long nr_migrated; 81 struct zram *zram = dev_to_zram(dev); 82 struct zram_meta *meta; 83 84 down_read(&zram->init_lock); 85 if (!init_done(zram)) { 86 up_read(&zram->init_lock); 87 return -EINVAL; 88 } 89 90 meta = zram->meta; 91 nr_migrated = zs_compact(meta->mem_pool); 92 atomic64_add(nr_migrated, &zram->stats.num_migrated); 93 up_read(&zram->init_lock); 94 95 return len; 96} 97 98static ssize_t disksize_show(struct device *dev, 99 struct device_attribute *attr, char *buf) 100{ 101 struct zram *zram = dev_to_zram(dev); 102 103 return scnprintf(buf, PAGE_SIZE, "%llu\n", zram->disksize); 104} 105 106static ssize_t initstate_show(struct device *dev, 107 struct device_attribute *attr, char *buf) 108{ 109 u32 val; 110 struct zram *zram = dev_to_zram(dev); 111 112 down_read(&zram->init_lock); 113 val = init_done(zram); 114 up_read(&zram->init_lock); 115 116 return scnprintf(buf, PAGE_SIZE, "%u\n", val); 117} 118 119static ssize_t orig_data_size_show(struct device *dev, 120 struct device_attribute *attr, char *buf) 121{ 122 struct zram *zram = dev_to_zram(dev); 123 124 deprecated_attr_warn("orig_data_size"); 125 return scnprintf(buf, PAGE_SIZE, "%llu\n", 126 (u64)(atomic64_read(&zram->stats.pages_stored)) << PAGE_SHIFT); 127} 128 129static ssize_t mem_used_total_show(struct device *dev, 130 struct device_attribute *attr, char *buf) 131{ 132 u64 val = 0; 133 struct zram *zram = dev_to_zram(dev); 134 135 deprecated_attr_warn("mem_used_total"); 136 down_read(&zram->init_lock); 137 if (init_done(zram)) { 138 struct zram_meta *meta = zram->meta; 139 val = zs_get_total_pages(meta->mem_pool); 140 } 141 up_read(&zram->init_lock); 142 143 return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT); 144} 145 146static ssize_t max_comp_streams_show(struct device *dev, 147 struct device_attribute *attr, char *buf) 148{ 149 int val; 150 struct zram *zram = dev_to_zram(dev); 151 152 down_read(&zram->init_lock); 153 val = zram->max_comp_streams; 154 up_read(&zram->init_lock); 155 156 return scnprintf(buf, PAGE_SIZE, "%d\n", val); 157} 158 159static ssize_t mem_limit_show(struct device *dev, 160 struct device_attribute *attr, char *buf) 161{ 162 u64 val; 163 struct zram *zram = dev_to_zram(dev); 164 165 deprecated_attr_warn("mem_limit"); 166 down_read(&zram->init_lock); 167 val = zram->limit_pages; 168 up_read(&zram->init_lock); 169 170 return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT); 171} 172 173static ssize_t mem_limit_store(struct device *dev, 174 struct device_attribute *attr, const char *buf, size_t len) 175{ 176 u64 limit; 177 char *tmp; 178 struct zram *zram = dev_to_zram(dev); 179 180 limit = memparse(buf, &tmp); 181 if (buf == tmp) /* no chars parsed, invalid input */ 182 return -EINVAL; 183 184 down_write(&zram->init_lock); 185 zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT; 186 up_write(&zram->init_lock); 187 188 return len; 189} 190 191static ssize_t mem_used_max_show(struct device *dev, 192 struct device_attribute *attr, char *buf) 193{ 194 u64 val = 0; 195 struct zram *zram = dev_to_zram(dev); 196 197 deprecated_attr_warn("mem_used_max"); 198 down_read(&zram->init_lock); 199 if (init_done(zram)) 200 val = atomic_long_read(&zram->stats.max_used_pages); 201 up_read(&zram->init_lock); 202 203 return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT); 204} 205 206static ssize_t mem_used_max_store(struct device *dev, 207 struct device_attribute *attr, const char *buf, size_t len) 208{ 209 int err; 210 unsigned long val; 211 struct zram *zram = dev_to_zram(dev); 212 213 err = kstrtoul(buf, 10, &val); 214 if (err || val != 0) 215 return -EINVAL; 216 217 down_read(&zram->init_lock); 218 if (init_done(zram)) { 219 struct zram_meta *meta = zram->meta; 220 atomic_long_set(&zram->stats.max_used_pages, 221 zs_get_total_pages(meta->mem_pool)); 222 } 223 up_read(&zram->init_lock); 224 225 return len; 226} 227 228static ssize_t max_comp_streams_store(struct device *dev, 229 struct device_attribute *attr, const char *buf, size_t len) 230{ 231 int num; 232 struct zram *zram = dev_to_zram(dev); 233 int ret; 234 235 ret = kstrtoint(buf, 0, &num); 236 if (ret < 0) 237 return ret; 238 if (num < 1) 239 return -EINVAL; 240 241 down_write(&zram->init_lock); 242 if (init_done(zram)) { 243 if (!zcomp_set_max_streams(zram->comp, num)) { 244 pr_info("Cannot change max compression streams\n"); 245 ret = -EINVAL; 246 goto out; 247 } 248 } 249 250 zram->max_comp_streams = num; 251 ret = len; 252out: 253 up_write(&zram->init_lock); 254 return ret; 255} 256 257static ssize_t comp_algorithm_show(struct device *dev, 258 struct device_attribute *attr, char *buf) 259{ 260 size_t sz; 261 struct zram *zram = dev_to_zram(dev); 262 263 down_read(&zram->init_lock); 264 sz = zcomp_available_show(zram->compressor, buf); 265 up_read(&zram->init_lock); 266 267 return sz; 268} 269 270static ssize_t comp_algorithm_store(struct device *dev, 271 struct device_attribute *attr, const char *buf, size_t len) 272{ 273 struct zram *zram = dev_to_zram(dev); 274 down_write(&zram->init_lock); 275 if (init_done(zram)) { 276 up_write(&zram->init_lock); 277 pr_info("Can't change algorithm for initialized device\n"); 278 return -EBUSY; 279 } 280 strlcpy(zram->compressor, buf, sizeof(zram->compressor)); 281 up_write(&zram->init_lock); 282 return len; 283} 284 285/* flag operations needs meta->tb_lock */ 286static int zram_test_flag(struct zram_meta *meta, u32 index, 287 enum zram_pageflags flag) 288{ 289 return meta->table[index].value & BIT(flag); 290} 291 292static void zram_set_flag(struct zram_meta *meta, u32 index, 293 enum zram_pageflags flag) 294{ 295 meta->table[index].value |= BIT(flag); 296} 297 298static void zram_clear_flag(struct zram_meta *meta, u32 index, 299 enum zram_pageflags flag) 300{ 301 meta->table[index].value &= ~BIT(flag); 302} 303 304static size_t zram_get_obj_size(struct zram_meta *meta, u32 index) 305{ 306 return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1); 307} 308 309static void zram_set_obj_size(struct zram_meta *meta, 310 u32 index, size_t size) 311{ 312 unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT; 313 314 meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size; 315} 316 317static inline int is_partial_io(struct bio_vec *bvec) 318{ 319 return bvec->bv_len != PAGE_SIZE; 320} 321 322/* 323 * Check if request is within bounds and aligned on zram logical blocks. 324 */ 325static inline int valid_io_request(struct zram *zram, 326 sector_t start, unsigned int size) 327{ 328 u64 end, bound; 329 330 /* unaligned request */ 331 if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1))) 332 return 0; 333 if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1))) 334 return 0; 335 336 end = start + (size >> SECTOR_SHIFT); 337 bound = zram->disksize >> SECTOR_SHIFT; 338 /* out of range range */ 339 if (unlikely(start >= bound || end > bound || start > end)) 340 return 0; 341 342 /* I/O request is valid */ 343 return 1; 344} 345 346static void zram_meta_free(struct zram_meta *meta, u64 disksize) 347{ 348 size_t num_pages = disksize >> PAGE_SHIFT; 349 size_t index; 350 351 /* Free all pages that are still in this zram device */ 352 for (index = 0; index < num_pages; index++) { 353 unsigned long handle = meta->table[index].handle; 354 355 if (!handle) 356 continue; 357 358 zs_free(meta->mem_pool, handle); 359 } 360 361 zs_destroy_pool(meta->mem_pool); 362 vfree(meta->table); 363 kfree(meta); 364} 365 366static struct zram_meta *zram_meta_alloc(int device_id, u64 disksize) 367{ 368 size_t num_pages; 369 char pool_name[8]; 370 struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL); 371 372 if (!meta) 373 return NULL; 374 375 num_pages = disksize >> PAGE_SHIFT; 376 meta->table = vzalloc(num_pages * sizeof(*meta->table)); 377 if (!meta->table) { 378 pr_err("Error allocating zram address table\n"); 379 goto out_error; 380 } 381 382 snprintf(pool_name, sizeof(pool_name), "zram%d", device_id); 383 meta->mem_pool = zs_create_pool(pool_name, GFP_NOIO | __GFP_HIGHMEM); 384 if (!meta->mem_pool) { 385 pr_err("Error creating memory pool\n"); 386 goto out_error; 387 } 388 389 return meta; 390 391out_error: 392 vfree(meta->table); 393 kfree(meta); 394 return NULL; 395} 396 397static inline bool zram_meta_get(struct zram *zram) 398{ 399 if (atomic_inc_not_zero(&zram->refcount)) 400 return true; 401 return false; 402} 403 404static inline void zram_meta_put(struct zram *zram) 405{ 406 atomic_dec(&zram->refcount); 407} 408 409static void update_position(u32 *index, int *offset, struct bio_vec *bvec) 410{ 411 if (*offset + bvec->bv_len >= PAGE_SIZE) 412 (*index)++; 413 *offset = (*offset + bvec->bv_len) % PAGE_SIZE; 414} 415 416static int page_zero_filled(void *ptr) 417{ 418 unsigned int pos; 419 unsigned long *page; 420 421 page = (unsigned long *)ptr; 422 423 for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) { 424 if (page[pos]) 425 return 0; 426 } 427 428 return 1; 429} 430 431static void handle_zero_page(struct bio_vec *bvec) 432{ 433 struct page *page = bvec->bv_page; 434 void *user_mem; 435 436 user_mem = kmap_atomic(page); 437 if (is_partial_io(bvec)) 438 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len); 439 else 440 clear_page(user_mem); 441 kunmap_atomic(user_mem); 442 443 flush_dcache_page(page); 444} 445 446 447/* 448 * To protect concurrent access to the same index entry, 449 * caller should hold this table index entry's bit_spinlock to 450 * indicate this index entry is accessing. 451 */ 452static void zram_free_page(struct zram *zram, size_t index) 453{ 454 struct zram_meta *meta = zram->meta; 455 unsigned long handle = meta->table[index].handle; 456 457 if (unlikely(!handle)) { 458 /* 459 * No memory is allocated for zero filled pages. 460 * Simply clear zero page flag. 461 */ 462 if (zram_test_flag(meta, index, ZRAM_ZERO)) { 463 zram_clear_flag(meta, index, ZRAM_ZERO); 464 atomic64_dec(&zram->stats.zero_pages); 465 } 466 return; 467 } 468 469 zs_free(meta->mem_pool, handle); 470 471 atomic64_sub(zram_get_obj_size(meta, index), 472 &zram->stats.compr_data_size); 473 atomic64_dec(&zram->stats.pages_stored); 474 475 meta->table[index].handle = 0; 476 zram_set_obj_size(meta, index, 0); 477} 478 479static int zram_decompress_page(struct zram *zram, char *mem, u32 index) 480{ 481 int ret = 0; 482 unsigned char *cmem; 483 struct zram_meta *meta = zram->meta; 484 unsigned long handle; 485 size_t size; 486 487 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); 488 handle = meta->table[index].handle; 489 size = zram_get_obj_size(meta, index); 490 491 if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) { 492 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); 493 clear_page(mem); 494 return 0; 495 } 496 497 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO); 498 if (size == PAGE_SIZE) 499 copy_page(mem, cmem); 500 else 501 ret = zcomp_decompress(zram->comp, cmem, size, mem); 502 zs_unmap_object(meta->mem_pool, handle); 503 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); 504 505 /* Should NEVER happen. Return bio error if it does. */ 506 if (unlikely(ret)) { 507 pr_err("Decompression failed! err=%d, page=%u\n", ret, index); 508 return ret; 509 } 510 511 return 0; 512} 513 514static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, 515 u32 index, int offset) 516{ 517 int ret; 518 struct page *page; 519 unsigned char *user_mem, *uncmem = NULL; 520 struct zram_meta *meta = zram->meta; 521 page = bvec->bv_page; 522 523 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); 524 if (unlikely(!meta->table[index].handle) || 525 zram_test_flag(meta, index, ZRAM_ZERO)) { 526 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); 527 handle_zero_page(bvec); 528 return 0; 529 } 530 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); 531 532 if (is_partial_io(bvec)) 533 /* Use a temporary buffer to decompress the page */ 534 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO); 535 536 user_mem = kmap_atomic(page); 537 if (!is_partial_io(bvec)) 538 uncmem = user_mem; 539 540 if (!uncmem) { 541 pr_info("Unable to allocate temp memory\n"); 542 ret = -ENOMEM; 543 goto out_cleanup; 544 } 545 546 ret = zram_decompress_page(zram, uncmem, index); 547 /* Should NEVER happen. Return bio error if it does. */ 548 if (unlikely(ret)) 549 goto out_cleanup; 550 551 if (is_partial_io(bvec)) 552 memcpy(user_mem + bvec->bv_offset, uncmem + offset, 553 bvec->bv_len); 554 555 flush_dcache_page(page); 556 ret = 0; 557out_cleanup: 558 kunmap_atomic(user_mem); 559 if (is_partial_io(bvec)) 560 kfree(uncmem); 561 return ret; 562} 563 564static inline void update_used_max(struct zram *zram, 565 const unsigned long pages) 566{ 567 unsigned long old_max, cur_max; 568 569 old_max = atomic_long_read(&zram->stats.max_used_pages); 570 571 do { 572 cur_max = old_max; 573 if (pages > cur_max) 574 old_max = atomic_long_cmpxchg( 575 &zram->stats.max_used_pages, cur_max, pages); 576 } while (old_max != cur_max); 577} 578 579static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, 580 int offset) 581{ 582 int ret = 0; 583 size_t clen; 584 unsigned long handle; 585 struct page *page; 586 unsigned char *user_mem, *cmem, *src, *uncmem = NULL; 587 struct zram_meta *meta = zram->meta; 588 struct zcomp_strm *zstrm; 589 bool locked = false; 590 unsigned long alloced_pages; 591 592 page = bvec->bv_page; 593 if (is_partial_io(bvec)) { 594 /* 595 * This is a partial IO. We need to read the full page 596 * before to write the changes. 597 */ 598 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO); 599 if (!uncmem) { 600 ret = -ENOMEM; 601 goto out; 602 } 603 ret = zram_decompress_page(zram, uncmem, index); 604 if (ret) 605 goto out; 606 } 607 608 zstrm = zcomp_strm_find(zram->comp); 609 locked = true; 610 user_mem = kmap_atomic(page); 611 612 if (is_partial_io(bvec)) { 613 memcpy(uncmem + offset, user_mem + bvec->bv_offset, 614 bvec->bv_len); 615 kunmap_atomic(user_mem); 616 user_mem = NULL; 617 } else { 618 uncmem = user_mem; 619 } 620 621 if (page_zero_filled(uncmem)) { 622 if (user_mem) 623 kunmap_atomic(user_mem); 624 /* Free memory associated with this sector now. */ 625 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); 626 zram_free_page(zram, index); 627 zram_set_flag(meta, index, ZRAM_ZERO); 628 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); 629 630 atomic64_inc(&zram->stats.zero_pages); 631 ret = 0; 632 goto out; 633 } 634 635 ret = zcomp_compress(zram->comp, zstrm, uncmem, &clen); 636 if (!is_partial_io(bvec)) { 637 kunmap_atomic(user_mem); 638 user_mem = NULL; 639 uncmem = NULL; 640 } 641 642 if (unlikely(ret)) { 643 pr_err("Compression failed! err=%d\n", ret); 644 goto out; 645 } 646 src = zstrm->buffer; 647 if (unlikely(clen > max_zpage_size)) { 648 clen = PAGE_SIZE; 649 if (is_partial_io(bvec)) 650 src = uncmem; 651 } 652 653 handle = zs_malloc(meta->mem_pool, clen); 654 if (!handle) { 655 pr_info("Error allocating memory for compressed page: %u, size=%zu\n", 656 index, clen); 657 ret = -ENOMEM; 658 goto out; 659 } 660 661 alloced_pages = zs_get_total_pages(meta->mem_pool); 662 if (zram->limit_pages && alloced_pages > zram->limit_pages) { 663 zs_free(meta->mem_pool, handle); 664 ret = -ENOMEM; 665 goto out; 666 } 667 668 update_used_max(zram, alloced_pages); 669 670 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO); 671 672 if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) { 673 src = kmap_atomic(page); 674 copy_page(cmem, src); 675 kunmap_atomic(src); 676 } else { 677 memcpy(cmem, src, clen); 678 } 679 680 zcomp_strm_release(zram->comp, zstrm); 681 locked = false; 682 zs_unmap_object(meta->mem_pool, handle); 683 684 /* 685 * Free memory associated with this sector 686 * before overwriting unused sectors. 687 */ 688 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); 689 zram_free_page(zram, index); 690 691 meta->table[index].handle = handle; 692 zram_set_obj_size(meta, index, clen); 693 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); 694 695 /* Update stats */ 696 atomic64_add(clen, &zram->stats.compr_data_size); 697 atomic64_inc(&zram->stats.pages_stored); 698out: 699 if (locked) 700 zcomp_strm_release(zram->comp, zstrm); 701 if (is_partial_io(bvec)) 702 kfree(uncmem); 703 return ret; 704} 705 706static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, 707 int offset, int rw) 708{ 709 unsigned long start_time = jiffies; 710 int ret; 711 712 generic_start_io_acct(rw, bvec->bv_len >> SECTOR_SHIFT, 713 &zram->disk->part0); 714 715 if (rw == READ) { 716 atomic64_inc(&zram->stats.num_reads); 717 ret = zram_bvec_read(zram, bvec, index, offset); 718 } else { 719 atomic64_inc(&zram->stats.num_writes); 720 ret = zram_bvec_write(zram, bvec, index, offset); 721 } 722 723 generic_end_io_acct(rw, &zram->disk->part0, start_time); 724 725 if (unlikely(ret)) { 726 if (rw == READ) 727 atomic64_inc(&zram->stats.failed_reads); 728 else 729 atomic64_inc(&zram->stats.failed_writes); 730 } 731 732 return ret; 733} 734 735/* 736 * zram_bio_discard - handler on discard request 737 * @index: physical block index in PAGE_SIZE units 738 * @offset: byte offset within physical block 739 */ 740static void zram_bio_discard(struct zram *zram, u32 index, 741 int offset, struct bio *bio) 742{ 743 size_t n = bio->bi_iter.bi_size; 744 struct zram_meta *meta = zram->meta; 745 746 /* 747 * zram manages data in physical block size units. Because logical block 748 * size isn't identical with physical block size on some arch, we 749 * could get a discard request pointing to a specific offset within a 750 * certain physical block. Although we can handle this request by 751 * reading that physiclal block and decompressing and partially zeroing 752 * and re-compressing and then re-storing it, this isn't reasonable 753 * because our intent with a discard request is to save memory. So 754 * skipping this logical block is appropriate here. 755 */ 756 if (offset) { 757 if (n <= (PAGE_SIZE - offset)) 758 return; 759 760 n -= (PAGE_SIZE - offset); 761 index++; 762 } 763 764 while (n >= PAGE_SIZE) { 765 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); 766 zram_free_page(zram, index); 767 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); 768 atomic64_inc(&zram->stats.notify_free); 769 index++; 770 n -= PAGE_SIZE; 771 } 772} 773 774static void zram_reset_device(struct zram *zram) 775{ 776 struct zram_meta *meta; 777 struct zcomp *comp; 778 u64 disksize; 779 780 down_write(&zram->init_lock); 781 782 zram->limit_pages = 0; 783 784 if (!init_done(zram)) { 785 up_write(&zram->init_lock); 786 return; 787 } 788 789 meta = zram->meta; 790 comp = zram->comp; 791 disksize = zram->disksize; 792 /* 793 * Refcount will go down to 0 eventually and r/w handler 794 * cannot handle further I/O so it will bail out by 795 * check zram_meta_get. 796 */ 797 zram_meta_put(zram); 798 /* 799 * We want to free zram_meta in process context to avoid 800 * deadlock between reclaim path and any other locks. 801 */ 802 wait_event(zram->io_done, atomic_read(&zram->refcount) == 0); 803 804 /* Reset stats */ 805 memset(&zram->stats, 0, sizeof(zram->stats)); 806 zram->disksize = 0; 807 zram->max_comp_streams = 1; 808 809 set_capacity(zram->disk, 0); 810 part_stat_set_all(&zram->disk->part0, 0); 811 812 up_write(&zram->init_lock); 813 /* I/O operation under all of CPU are done so let's free */ 814 zram_meta_free(meta, disksize); 815 zcomp_destroy(comp); 816} 817 818static ssize_t disksize_store(struct device *dev, 819 struct device_attribute *attr, const char *buf, size_t len) 820{ 821 u64 disksize; 822 struct zcomp *comp; 823 struct zram_meta *meta; 824 struct zram *zram = dev_to_zram(dev); 825 int err; 826 827 disksize = memparse(buf, NULL); 828 if (!disksize) 829 return -EINVAL; 830 831 disksize = PAGE_ALIGN(disksize); 832 meta = zram_meta_alloc(zram->disk->first_minor, disksize); 833 if (!meta) 834 return -ENOMEM; 835 836 comp = zcomp_create(zram->compressor, zram->max_comp_streams); 837 if (IS_ERR(comp)) { 838 pr_info("Cannot initialise %s compressing backend\n", 839 zram->compressor); 840 err = PTR_ERR(comp); 841 goto out_free_meta; 842 } 843 844 down_write(&zram->init_lock); 845 if (init_done(zram)) { 846 pr_info("Cannot change disksize for initialized device\n"); 847 err = -EBUSY; 848 goto out_destroy_comp; 849 } 850 851 init_waitqueue_head(&zram->io_done); 852 atomic_set(&zram->refcount, 1); 853 zram->meta = meta; 854 zram->comp = comp; 855 zram->disksize = disksize; 856 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT); 857 up_write(&zram->init_lock); 858 859 /* 860 * Revalidate disk out of the init_lock to avoid lockdep splat. 861 * It's okay because disk's capacity is protected by init_lock 862 * so that revalidate_disk always sees up-to-date capacity. 863 */ 864 revalidate_disk(zram->disk); 865 866 return len; 867 868out_destroy_comp: 869 up_write(&zram->init_lock); 870 zcomp_destroy(comp); 871out_free_meta: 872 zram_meta_free(meta, disksize); 873 return err; 874} 875 876static ssize_t reset_store(struct device *dev, 877 struct device_attribute *attr, const char *buf, size_t len) 878{ 879 int ret; 880 unsigned short do_reset; 881 struct zram *zram; 882 struct block_device *bdev; 883 884 zram = dev_to_zram(dev); 885 bdev = bdget_disk(zram->disk, 0); 886 887 if (!bdev) 888 return -ENOMEM; 889 890 mutex_lock(&bdev->bd_mutex); 891 /* Do not reset an active device! */ 892 if (bdev->bd_openers) { 893 ret = -EBUSY; 894 goto out; 895 } 896 897 ret = kstrtou16(buf, 10, &do_reset); 898 if (ret) 899 goto out; 900 901 if (!do_reset) { 902 ret = -EINVAL; 903 goto out; 904 } 905 906 /* Make sure all pending I/O is finished */ 907 fsync_bdev(bdev); 908 zram_reset_device(zram); 909 910 mutex_unlock(&bdev->bd_mutex); 911 revalidate_disk(zram->disk); 912 bdput(bdev); 913 914 return len; 915 916out: 917 mutex_unlock(&bdev->bd_mutex); 918 bdput(bdev); 919 return ret; 920} 921 922static void __zram_make_request(struct zram *zram, struct bio *bio) 923{ 924 int offset, rw; 925 u32 index; 926 struct bio_vec bvec; 927 struct bvec_iter iter; 928 929 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT; 930 offset = (bio->bi_iter.bi_sector & 931 (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT; 932 933 if (unlikely(bio->bi_rw & REQ_DISCARD)) { 934 zram_bio_discard(zram, index, offset, bio); 935 bio_endio(bio, 0); 936 return; 937 } 938 939 rw = bio_data_dir(bio); 940 bio_for_each_segment(bvec, bio, iter) { 941 int max_transfer_size = PAGE_SIZE - offset; 942 943 if (bvec.bv_len > max_transfer_size) { 944 /* 945 * zram_bvec_rw() can only make operation on a single 946 * zram page. Split the bio vector. 947 */ 948 struct bio_vec bv; 949 950 bv.bv_page = bvec.bv_page; 951 bv.bv_len = max_transfer_size; 952 bv.bv_offset = bvec.bv_offset; 953 954 if (zram_bvec_rw(zram, &bv, index, offset, rw) < 0) 955 goto out; 956 957 bv.bv_len = bvec.bv_len - max_transfer_size; 958 bv.bv_offset += max_transfer_size; 959 if (zram_bvec_rw(zram, &bv, index + 1, 0, rw) < 0) 960 goto out; 961 } else 962 if (zram_bvec_rw(zram, &bvec, index, offset, rw) < 0) 963 goto out; 964 965 update_position(&index, &offset, &bvec); 966 } 967 968 set_bit(BIO_UPTODATE, &bio->bi_flags); 969 bio_endio(bio, 0); 970 return; 971 972out: 973 bio_io_error(bio); 974} 975 976/* 977 * Handler function for all zram I/O requests. 978 */ 979static void zram_make_request(struct request_queue *queue, struct bio *bio) 980{ 981 struct zram *zram = queue->queuedata; 982 983 if (unlikely(!zram_meta_get(zram))) 984 goto error; 985 986 if (!valid_io_request(zram, bio->bi_iter.bi_sector, 987 bio->bi_iter.bi_size)) { 988 atomic64_inc(&zram->stats.invalid_io); 989 goto put_zram; 990 } 991 992 __zram_make_request(zram, bio); 993 zram_meta_put(zram); 994 return; 995put_zram: 996 zram_meta_put(zram); 997error: 998 bio_io_error(bio); 999} 1000 1001static void zram_slot_free_notify(struct block_device *bdev, 1002 unsigned long index) 1003{ 1004 struct zram *zram; 1005 struct zram_meta *meta; 1006 1007 zram = bdev->bd_disk->private_data; 1008 meta = zram->meta; 1009 1010 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); 1011 zram_free_page(zram, index); 1012 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); 1013 atomic64_inc(&zram->stats.notify_free); 1014} 1015 1016static int zram_rw_page(struct block_device *bdev, sector_t sector, 1017 struct page *page, int rw) 1018{ 1019 int offset, err = -EIO; 1020 u32 index; 1021 struct zram *zram; 1022 struct bio_vec bv; 1023 1024 zram = bdev->bd_disk->private_data; 1025 if (unlikely(!zram_meta_get(zram))) 1026 goto out; 1027 1028 if (!valid_io_request(zram, sector, PAGE_SIZE)) { 1029 atomic64_inc(&zram->stats.invalid_io); 1030 err = -EINVAL; 1031 goto put_zram; 1032 } 1033 1034 index = sector >> SECTORS_PER_PAGE_SHIFT; 1035 offset = sector & (SECTORS_PER_PAGE - 1) << SECTOR_SHIFT; 1036 1037 bv.bv_page = page; 1038 bv.bv_len = PAGE_SIZE; 1039 bv.bv_offset = 0; 1040 1041 err = zram_bvec_rw(zram, &bv, index, offset, rw); 1042put_zram: 1043 zram_meta_put(zram); 1044out: 1045 /* 1046 * If I/O fails, just return error(ie, non-zero) without 1047 * calling page_endio. 1048 * It causes resubmit the I/O with bio request by upper functions 1049 * of rw_page(e.g., swap_readpage, __swap_writepage) and 1050 * bio->bi_end_io does things to handle the error 1051 * (e.g., SetPageError, set_page_dirty and extra works). 1052 */ 1053 if (err == 0) 1054 page_endio(page, rw, 0); 1055 return err; 1056} 1057 1058static const struct block_device_operations zram_devops = { 1059 .swap_slot_free_notify = zram_slot_free_notify, 1060 .rw_page = zram_rw_page, 1061 .owner = THIS_MODULE 1062}; 1063 1064static DEVICE_ATTR_WO(compact); 1065static DEVICE_ATTR_RW(disksize); 1066static DEVICE_ATTR_RO(initstate); 1067static DEVICE_ATTR_WO(reset); 1068static DEVICE_ATTR_RO(orig_data_size); 1069static DEVICE_ATTR_RO(mem_used_total); 1070static DEVICE_ATTR_RW(mem_limit); 1071static DEVICE_ATTR_RW(mem_used_max); 1072static DEVICE_ATTR_RW(max_comp_streams); 1073static DEVICE_ATTR_RW(comp_algorithm); 1074 1075static ssize_t io_stat_show(struct device *dev, 1076 struct device_attribute *attr, char *buf) 1077{ 1078 struct zram *zram = dev_to_zram(dev); 1079 ssize_t ret; 1080 1081 down_read(&zram->init_lock); 1082 ret = scnprintf(buf, PAGE_SIZE, 1083 "%8llu %8llu %8llu %8llu\n", 1084 (u64)atomic64_read(&zram->stats.failed_reads), 1085 (u64)atomic64_read(&zram->stats.failed_writes), 1086 (u64)atomic64_read(&zram->stats.invalid_io), 1087 (u64)atomic64_read(&zram->stats.notify_free)); 1088 up_read(&zram->init_lock); 1089 1090 return ret; 1091} 1092 1093static ssize_t mm_stat_show(struct device *dev, 1094 struct device_attribute *attr, char *buf) 1095{ 1096 struct zram *zram = dev_to_zram(dev); 1097 u64 orig_size, mem_used = 0; 1098 long max_used; 1099 ssize_t ret; 1100 1101 down_read(&zram->init_lock); 1102 if (init_done(zram)) 1103 mem_used = zs_get_total_pages(zram->meta->mem_pool); 1104 1105 orig_size = atomic64_read(&zram->stats.pages_stored); 1106 max_used = atomic_long_read(&zram->stats.max_used_pages); 1107 1108 ret = scnprintf(buf, PAGE_SIZE, 1109 "%8llu %8llu %8llu %8lu %8ld %8llu %8llu\n", 1110 orig_size << PAGE_SHIFT, 1111 (u64)atomic64_read(&zram->stats.compr_data_size), 1112 mem_used << PAGE_SHIFT, 1113 zram->limit_pages << PAGE_SHIFT, 1114 max_used << PAGE_SHIFT, 1115 (u64)atomic64_read(&zram->stats.zero_pages), 1116 (u64)atomic64_read(&zram->stats.num_migrated)); 1117 up_read(&zram->init_lock); 1118 1119 return ret; 1120} 1121 1122static DEVICE_ATTR_RO(io_stat); 1123static DEVICE_ATTR_RO(mm_stat); 1124ZRAM_ATTR_RO(num_reads); 1125ZRAM_ATTR_RO(num_writes); 1126ZRAM_ATTR_RO(failed_reads); 1127ZRAM_ATTR_RO(failed_writes); 1128ZRAM_ATTR_RO(invalid_io); 1129ZRAM_ATTR_RO(notify_free); 1130ZRAM_ATTR_RO(zero_pages); 1131ZRAM_ATTR_RO(compr_data_size); 1132 1133static struct attribute *zram_disk_attrs[] = { 1134 &dev_attr_disksize.attr, 1135 &dev_attr_initstate.attr, 1136 &dev_attr_reset.attr, 1137 &dev_attr_num_reads.attr, 1138 &dev_attr_num_writes.attr, 1139 &dev_attr_failed_reads.attr, 1140 &dev_attr_failed_writes.attr, 1141 &dev_attr_compact.attr, 1142 &dev_attr_invalid_io.attr, 1143 &dev_attr_notify_free.attr, 1144 &dev_attr_zero_pages.attr, 1145 &dev_attr_orig_data_size.attr, 1146 &dev_attr_compr_data_size.attr, 1147 &dev_attr_mem_used_total.attr, 1148 &dev_attr_mem_limit.attr, 1149 &dev_attr_mem_used_max.attr, 1150 &dev_attr_max_comp_streams.attr, 1151 &dev_attr_comp_algorithm.attr, 1152 &dev_attr_io_stat.attr, 1153 &dev_attr_mm_stat.attr, 1154 NULL, 1155}; 1156 1157static struct attribute_group zram_disk_attr_group = { 1158 .attrs = zram_disk_attrs, 1159}; 1160 1161static int create_device(struct zram *zram, int device_id) 1162{ 1163 struct request_queue *queue; 1164 int ret = -ENOMEM; 1165 1166 init_rwsem(&zram->init_lock); 1167 1168 queue = blk_alloc_queue(GFP_KERNEL); 1169 if (!queue) { 1170 pr_err("Error allocating disk queue for device %d\n", 1171 device_id); 1172 goto out; 1173 } 1174 1175 blk_queue_make_request(queue, zram_make_request); 1176 1177 /* gendisk structure */ 1178 zram->disk = alloc_disk(1); 1179 if (!zram->disk) { 1180 pr_warn("Error allocating disk structure for device %d\n", 1181 device_id); 1182 ret = -ENOMEM; 1183 goto out_free_queue; 1184 } 1185 1186 zram->disk->major = zram_major; 1187 zram->disk->first_minor = device_id; 1188 zram->disk->fops = &zram_devops; 1189 zram->disk->queue = queue; 1190 zram->disk->queue->queuedata = zram; 1191 zram->disk->private_data = zram; 1192 snprintf(zram->disk->disk_name, 16, "zram%d", device_id); 1193 1194 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */ 1195 set_capacity(zram->disk, 0); 1196 /* zram devices sort of resembles non-rotational disks */ 1197 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue); 1198 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue); 1199 /* 1200 * To ensure that we always get PAGE_SIZE aligned 1201 * and n*PAGE_SIZED sized I/O requests. 1202 */ 1203 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE); 1204 blk_queue_logical_block_size(zram->disk->queue, 1205 ZRAM_LOGICAL_BLOCK_SIZE); 1206 blk_queue_io_min(zram->disk->queue, PAGE_SIZE); 1207 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE); 1208 zram->disk->queue->limits.discard_granularity = PAGE_SIZE; 1209 zram->disk->queue->limits.max_discard_sectors = UINT_MAX; 1210 /* 1211 * zram_bio_discard() will clear all logical blocks if logical block 1212 * size is identical with physical block size(PAGE_SIZE). But if it is 1213 * different, we will skip discarding some parts of logical blocks in 1214 * the part of the request range which isn't aligned to physical block 1215 * size. So we can't ensure that all discarded logical blocks are 1216 * zeroed. 1217 */ 1218 if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE) 1219 zram->disk->queue->limits.discard_zeroes_data = 1; 1220 else 1221 zram->disk->queue->limits.discard_zeroes_data = 0; 1222 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue); 1223 1224 add_disk(zram->disk); 1225 1226 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj, 1227 &zram_disk_attr_group); 1228 if (ret < 0) { 1229 pr_warn("Error creating sysfs group"); 1230 goto out_free_disk; 1231 } 1232 strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor)); 1233 zram->meta = NULL; 1234 zram->max_comp_streams = 1; 1235 return 0; 1236 1237out_free_disk: 1238 del_gendisk(zram->disk); 1239 put_disk(zram->disk); 1240out_free_queue: 1241 blk_cleanup_queue(queue); 1242out: 1243 return ret; 1244} 1245 1246static void destroy_devices(unsigned int nr) 1247{ 1248 struct zram *zram; 1249 unsigned int i; 1250 1251 for (i = 0; i < nr; i++) { 1252 zram = &zram_devices[i]; 1253 /* 1254 * Remove sysfs first, so no one will perform a disksize 1255 * store while we destroy the devices 1256 */ 1257 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj, 1258 &zram_disk_attr_group); 1259 1260 zram_reset_device(zram); 1261 1262 blk_cleanup_queue(zram->disk->queue); 1263 del_gendisk(zram->disk); 1264 put_disk(zram->disk); 1265 } 1266 1267 kfree(zram_devices); 1268 unregister_blkdev(zram_major, "zram"); 1269 pr_info("Destroyed %u device(s)\n", nr); 1270} 1271 1272static int __init zram_init(void) 1273{ 1274 int ret, dev_id; 1275 1276 if (num_devices > max_num_devices) { 1277 pr_warn("Invalid value for num_devices: %u\n", 1278 num_devices); 1279 return -EINVAL; 1280 } 1281 1282 zram_major = register_blkdev(0, "zram"); 1283 if (zram_major <= 0) { 1284 pr_warn("Unable to get major number\n"); 1285 return -EBUSY; 1286 } 1287 1288 /* Allocate the device array and initialize each one */ 1289 zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL); 1290 if (!zram_devices) { 1291 unregister_blkdev(zram_major, "zram"); 1292 return -ENOMEM; 1293 } 1294 1295 for (dev_id = 0; dev_id < num_devices; dev_id++) { 1296 ret = create_device(&zram_devices[dev_id], dev_id); 1297 if (ret) 1298 goto out_error; 1299 } 1300 1301 pr_info("Created %u device(s)\n", num_devices); 1302 return 0; 1303 1304out_error: 1305 destroy_devices(dev_id); 1306 return ret; 1307} 1308 1309static void __exit zram_exit(void) 1310{ 1311 destroy_devices(num_devices); 1312} 1313 1314module_init(zram_init); 1315module_exit(zram_exit); 1316 1317module_param(num_devices, uint, 0); 1318MODULE_PARM_DESC(num_devices, "Number of zram devices"); 1319 1320MODULE_LICENSE("Dual BSD/GPL"); 1321MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>"); 1322MODULE_DESCRIPTION("Compressed RAM Block Device"); 1323