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