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