1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Main bcache entry point - handle a read or a write request and decide what to 4 * do with it; the make_request functions are called by the block layer. 5 * 6 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com> 7 * Copyright 2012 Google, Inc. 8 */ 9 10 #include "bcache.h" 11 #include "btree.h" 12 #include "debug.h" 13 #include "request.h" 14 #include "writeback.h" 15 16 #include <linux/module.h> 17 #include <linux/hash.h> 18 #include <linux/random.h> 19 #include <linux/backing-dev.h> 20 21 #include <trace/events/bcache.h> 22 23 #define CUTOFF_CACHE_ADD 95 24 #define CUTOFF_CACHE_READA 90 25 26 struct kmem_cache *bch_search_cache; 27 28 static void bch_data_insert_start(struct closure *); 29 30 static unsigned cache_mode(struct cached_dev *dc) 31 { 32 return BDEV_CACHE_MODE(&dc->sb); 33 } 34 35 static bool verify(struct cached_dev *dc) 36 { 37 return dc->verify; 38 } 39 40 static void bio_csum(struct bio *bio, struct bkey *k) 41 { 42 struct bio_vec bv; 43 struct bvec_iter iter; 44 uint64_t csum = 0; 45 46 bio_for_each_segment(bv, bio, iter) { 47 void *d = kmap(bv.bv_page) + bv.bv_offset; 48 csum = bch_crc64_update(csum, d, bv.bv_len); 49 kunmap(bv.bv_page); 50 } 51 52 k->ptr[KEY_PTRS(k)] = csum & (~0ULL >> 1); 53 } 54 55 /* Insert data into cache */ 56 57 static void bch_data_insert_keys(struct closure *cl) 58 { 59 struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); 60 atomic_t *journal_ref = NULL; 61 struct bkey *replace_key = op->replace ? &op->replace_key : NULL; 62 int ret; 63 64 /* 65 * If we're looping, might already be waiting on 66 * another journal write - can't wait on more than one journal write at 67 * a time 68 * 69 * XXX: this looks wrong 70 */ 71 #if 0 72 while (atomic_read(&s->cl.remaining) & CLOSURE_WAITING) 73 closure_sync(&s->cl); 74 #endif 75 76 if (!op->replace) 77 journal_ref = bch_journal(op->c, &op->insert_keys, 78 op->flush_journal ? cl : NULL); 79 80 ret = bch_btree_insert(op->c, &op->insert_keys, 81 journal_ref, replace_key); 82 if (ret == -ESRCH) { 83 op->replace_collision = true; 84 } else if (ret) { 85 op->status = BLK_STS_RESOURCE; 86 op->insert_data_done = true; 87 } 88 89 if (journal_ref) 90 atomic_dec_bug(journal_ref); 91 92 if (!op->insert_data_done) { 93 continue_at(cl, bch_data_insert_start, op->wq); 94 return; 95 } 96 97 bch_keylist_free(&op->insert_keys); 98 closure_return(cl); 99 } 100 101 static int bch_keylist_realloc(struct keylist *l, unsigned u64s, 102 struct cache_set *c) 103 { 104 size_t oldsize = bch_keylist_nkeys(l); 105 size_t newsize = oldsize + u64s; 106 107 /* 108 * The journalling code doesn't handle the case where the keys to insert 109 * is bigger than an empty write: If we just return -ENOMEM here, 110 * bio_insert() and bio_invalidate() will insert the keys created so far 111 * and finish the rest when the keylist is empty. 112 */ 113 if (newsize * sizeof(uint64_t) > block_bytes(c) - sizeof(struct jset)) 114 return -ENOMEM; 115 116 return __bch_keylist_realloc(l, u64s); 117 } 118 119 static void bch_data_invalidate(struct closure *cl) 120 { 121 struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); 122 struct bio *bio = op->bio; 123 124 pr_debug("invalidating %i sectors from %llu", 125 bio_sectors(bio), (uint64_t) bio->bi_iter.bi_sector); 126 127 while (bio_sectors(bio)) { 128 unsigned sectors = min(bio_sectors(bio), 129 1U << (KEY_SIZE_BITS - 1)); 130 131 if (bch_keylist_realloc(&op->insert_keys, 2, op->c)) 132 goto out; 133 134 bio->bi_iter.bi_sector += sectors; 135 bio->bi_iter.bi_size -= sectors << 9; 136 137 bch_keylist_add(&op->insert_keys, 138 &KEY(op->inode, bio->bi_iter.bi_sector, sectors)); 139 } 140 141 op->insert_data_done = true; 142 /* get in bch_data_insert() */ 143 bio_put(bio); 144 out: 145 continue_at(cl, bch_data_insert_keys, op->wq); 146 } 147 148 static void bch_data_insert_error(struct closure *cl) 149 { 150 struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); 151 152 /* 153 * Our data write just errored, which means we've got a bunch of keys to 154 * insert that point to data that wasn't succesfully written. 155 * 156 * We don't have to insert those keys but we still have to invalidate 157 * that region of the cache - so, if we just strip off all the pointers 158 * from the keys we'll accomplish just that. 159 */ 160 161 struct bkey *src = op->insert_keys.keys, *dst = op->insert_keys.keys; 162 163 while (src != op->insert_keys.top) { 164 struct bkey *n = bkey_next(src); 165 166 SET_KEY_PTRS(src, 0); 167 memmove(dst, src, bkey_bytes(src)); 168 169 dst = bkey_next(dst); 170 src = n; 171 } 172 173 op->insert_keys.top = dst; 174 175 bch_data_insert_keys(cl); 176 } 177 178 static void bch_data_insert_endio(struct bio *bio) 179 { 180 struct closure *cl = bio->bi_private; 181 struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); 182 183 if (bio->bi_status) { 184 /* TODO: We could try to recover from this. */ 185 if (op->writeback) 186 op->status = bio->bi_status; 187 else if (!op->replace) 188 set_closure_fn(cl, bch_data_insert_error, op->wq); 189 else 190 set_closure_fn(cl, NULL, NULL); 191 } 192 193 bch_bbio_endio(op->c, bio, bio->bi_status, "writing data to cache"); 194 } 195 196 static void bch_data_insert_start(struct closure *cl) 197 { 198 struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); 199 struct bio *bio = op->bio, *n; 200 201 if (op->bypass) 202 return bch_data_invalidate(cl); 203 204 if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) 205 wake_up_gc(op->c); 206 207 /* 208 * Journal writes are marked REQ_PREFLUSH; if the original write was a 209 * flush, it'll wait on the journal write. 210 */ 211 bio->bi_opf &= ~(REQ_PREFLUSH|REQ_FUA); 212 213 do { 214 unsigned i; 215 struct bkey *k; 216 struct bio_set *split = &op->c->bio_split; 217 218 /* 1 for the device pointer and 1 for the chksum */ 219 if (bch_keylist_realloc(&op->insert_keys, 220 3 + (op->csum ? 1 : 0), 221 op->c)) { 222 continue_at(cl, bch_data_insert_keys, op->wq); 223 return; 224 } 225 226 k = op->insert_keys.top; 227 bkey_init(k); 228 SET_KEY_INODE(k, op->inode); 229 SET_KEY_OFFSET(k, bio->bi_iter.bi_sector); 230 231 if (!bch_alloc_sectors(op->c, k, bio_sectors(bio), 232 op->write_point, op->write_prio, 233 op->writeback)) 234 goto err; 235 236 n = bio_next_split(bio, KEY_SIZE(k), GFP_NOIO, split); 237 238 n->bi_end_io = bch_data_insert_endio; 239 n->bi_private = cl; 240 241 if (op->writeback) { 242 SET_KEY_DIRTY(k, true); 243 244 for (i = 0; i < KEY_PTRS(k); i++) 245 SET_GC_MARK(PTR_BUCKET(op->c, k, i), 246 GC_MARK_DIRTY); 247 } 248 249 SET_KEY_CSUM(k, op->csum); 250 if (KEY_CSUM(k)) 251 bio_csum(n, k); 252 253 trace_bcache_cache_insert(k); 254 bch_keylist_push(&op->insert_keys); 255 256 bio_set_op_attrs(n, REQ_OP_WRITE, 0); 257 bch_submit_bbio(n, op->c, k, 0); 258 } while (n != bio); 259 260 op->insert_data_done = true; 261 continue_at(cl, bch_data_insert_keys, op->wq); 262 return; 263 err: 264 /* bch_alloc_sectors() blocks if s->writeback = true */ 265 BUG_ON(op->writeback); 266 267 /* 268 * But if it's not a writeback write we'd rather just bail out if 269 * there aren't any buckets ready to write to - it might take awhile and 270 * we might be starving btree writes for gc or something. 271 */ 272 273 if (!op->replace) { 274 /* 275 * Writethrough write: We can't complete the write until we've 276 * updated the index. But we don't want to delay the write while 277 * we wait for buckets to be freed up, so just invalidate the 278 * rest of the write. 279 */ 280 op->bypass = true; 281 return bch_data_invalidate(cl); 282 } else { 283 /* 284 * From a cache miss, we can just insert the keys for the data 285 * we have written or bail out if we didn't do anything. 286 */ 287 op->insert_data_done = true; 288 bio_put(bio); 289 290 if (!bch_keylist_empty(&op->insert_keys)) 291 continue_at(cl, bch_data_insert_keys, op->wq); 292 else 293 closure_return(cl); 294 } 295 } 296 297 /** 298 * bch_data_insert - stick some data in the cache 299 * @cl: closure pointer. 300 * 301 * This is the starting point for any data to end up in a cache device; it could 302 * be from a normal write, or a writeback write, or a write to a flash only 303 * volume - it's also used by the moving garbage collector to compact data in 304 * mostly empty buckets. 305 * 306 * It first writes the data to the cache, creating a list of keys to be inserted 307 * (if the data had to be fragmented there will be multiple keys); after the 308 * data is written it calls bch_journal, and after the keys have been added to 309 * the next journal write they're inserted into the btree. 310 * 311 * It inserts the data in s->cache_bio; bi_sector is used for the key offset, 312 * and op->inode is used for the key inode. 313 * 314 * If s->bypass is true, instead of inserting the data it invalidates the 315 * region of the cache represented by s->cache_bio and op->inode. 316 */ 317 void bch_data_insert(struct closure *cl) 318 { 319 struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); 320 321 trace_bcache_write(op->c, op->inode, op->bio, 322 op->writeback, op->bypass); 323 324 bch_keylist_init(&op->insert_keys); 325 bio_get(op->bio); 326 bch_data_insert_start(cl); 327 } 328 329 /* Congested? */ 330 331 unsigned bch_get_congested(struct cache_set *c) 332 { 333 int i; 334 long rand; 335 336 if (!c->congested_read_threshold_us && 337 !c->congested_write_threshold_us) 338 return 0; 339 340 i = (local_clock_us() - c->congested_last_us) / 1024; 341 if (i < 0) 342 return 0; 343 344 i += atomic_read(&c->congested); 345 if (i >= 0) 346 return 0; 347 348 i += CONGESTED_MAX; 349 350 if (i > 0) 351 i = fract_exp_two(i, 6); 352 353 rand = get_random_int(); 354 i -= bitmap_weight(&rand, BITS_PER_LONG); 355 356 return i > 0 ? i : 1; 357 } 358 359 static void add_sequential(struct task_struct *t) 360 { 361 ewma_add(t->sequential_io_avg, 362 t->sequential_io, 8, 0); 363 364 t->sequential_io = 0; 365 } 366 367 static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k) 368 { 369 return &dc->io_hash[hash_64(k, RECENT_IO_BITS)]; 370 } 371 372 static bool check_should_bypass(struct cached_dev *dc, struct bio *bio) 373 { 374 struct cache_set *c = dc->disk.c; 375 unsigned mode = cache_mode(dc); 376 unsigned sectors, congested = bch_get_congested(c); 377 struct task_struct *task = current; 378 struct io *i; 379 380 if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) || 381 c->gc_stats.in_use > CUTOFF_CACHE_ADD || 382 (bio_op(bio) == REQ_OP_DISCARD)) 383 goto skip; 384 385 if (mode == CACHE_MODE_NONE || 386 (mode == CACHE_MODE_WRITEAROUND && 387 op_is_write(bio_op(bio)))) 388 goto skip; 389 390 /* 391 * Flag for bypass if the IO is for read-ahead or background, 392 * unless the read-ahead request is for metadata (eg, for gfs2). 393 */ 394 if (bio->bi_opf & (REQ_RAHEAD|REQ_BACKGROUND) && 395 !(bio->bi_opf & REQ_META)) 396 goto skip; 397 398 if (bio->bi_iter.bi_sector & (c->sb.block_size - 1) || 399 bio_sectors(bio) & (c->sb.block_size - 1)) { 400 pr_debug("skipping unaligned io"); 401 goto skip; 402 } 403 404 if (bypass_torture_test(dc)) { 405 if ((get_random_int() & 3) == 3) 406 goto skip; 407 else 408 goto rescale; 409 } 410 411 if (!congested && !dc->sequential_cutoff) 412 goto rescale; 413 414 spin_lock(&dc->io_lock); 415 416 hlist_for_each_entry(i, iohash(dc, bio->bi_iter.bi_sector), hash) 417 if (i->last == bio->bi_iter.bi_sector && 418 time_before(jiffies, i->jiffies)) 419 goto found; 420 421 i = list_first_entry(&dc->io_lru, struct io, lru); 422 423 add_sequential(task); 424 i->sequential = 0; 425 found: 426 if (i->sequential + bio->bi_iter.bi_size > i->sequential) 427 i->sequential += bio->bi_iter.bi_size; 428 429 i->last = bio_end_sector(bio); 430 i->jiffies = jiffies + msecs_to_jiffies(5000); 431 task->sequential_io = i->sequential; 432 433 hlist_del(&i->hash); 434 hlist_add_head(&i->hash, iohash(dc, i->last)); 435 list_move_tail(&i->lru, &dc->io_lru); 436 437 spin_unlock(&dc->io_lock); 438 439 sectors = max(task->sequential_io, 440 task->sequential_io_avg) >> 9; 441 442 if (dc->sequential_cutoff && 443 sectors >= dc->sequential_cutoff >> 9) { 444 trace_bcache_bypass_sequential(bio); 445 goto skip; 446 } 447 448 if (congested && sectors >= congested) { 449 trace_bcache_bypass_congested(bio); 450 goto skip; 451 } 452 453 rescale: 454 bch_rescale_priorities(c, bio_sectors(bio)); 455 return false; 456 skip: 457 bch_mark_sectors_bypassed(c, dc, bio_sectors(bio)); 458 return true; 459 } 460 461 /* Cache lookup */ 462 463 struct search { 464 /* Stack frame for bio_complete */ 465 struct closure cl; 466 467 struct bbio bio; 468 struct bio *orig_bio; 469 struct bio *cache_miss; 470 struct bcache_device *d; 471 472 unsigned insert_bio_sectors; 473 unsigned recoverable:1; 474 unsigned write:1; 475 unsigned read_dirty_data:1; 476 unsigned cache_missed:1; 477 478 unsigned long start_time; 479 480 struct btree_op op; 481 struct data_insert_op iop; 482 }; 483 484 static void bch_cache_read_endio(struct bio *bio) 485 { 486 struct bbio *b = container_of(bio, struct bbio, bio); 487 struct closure *cl = bio->bi_private; 488 struct search *s = container_of(cl, struct search, cl); 489 490 /* 491 * If the bucket was reused while our bio was in flight, we might have 492 * read the wrong data. Set s->error but not error so it doesn't get 493 * counted against the cache device, but we'll still reread the data 494 * from the backing device. 495 */ 496 497 if (bio->bi_status) 498 s->iop.status = bio->bi_status; 499 else if (!KEY_DIRTY(&b->key) && 500 ptr_stale(s->iop.c, &b->key, 0)) { 501 atomic_long_inc(&s->iop.c->cache_read_races); 502 s->iop.status = BLK_STS_IOERR; 503 } 504 505 bch_bbio_endio(s->iop.c, bio, bio->bi_status, "reading from cache"); 506 } 507 508 /* 509 * Read from a single key, handling the initial cache miss if the key starts in 510 * the middle of the bio 511 */ 512 static int cache_lookup_fn(struct btree_op *op, struct btree *b, struct bkey *k) 513 { 514 struct search *s = container_of(op, struct search, op); 515 struct bio *n, *bio = &s->bio.bio; 516 struct bkey *bio_key; 517 unsigned ptr; 518 519 if (bkey_cmp(k, &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0)) <= 0) 520 return MAP_CONTINUE; 521 522 if (KEY_INODE(k) != s->iop.inode || 523 KEY_START(k) > bio->bi_iter.bi_sector) { 524 unsigned bio_sectors = bio_sectors(bio); 525 unsigned sectors = KEY_INODE(k) == s->iop.inode 526 ? min_t(uint64_t, INT_MAX, 527 KEY_START(k) - bio->bi_iter.bi_sector) 528 : INT_MAX; 529 530 int ret = s->d->cache_miss(b, s, bio, sectors); 531 if (ret != MAP_CONTINUE) 532 return ret; 533 534 /* if this was a complete miss we shouldn't get here */ 535 BUG_ON(bio_sectors <= sectors); 536 } 537 538 if (!KEY_SIZE(k)) 539 return MAP_CONTINUE; 540 541 /* XXX: figure out best pointer - for multiple cache devices */ 542 ptr = 0; 543 544 PTR_BUCKET(b->c, k, ptr)->prio = INITIAL_PRIO; 545 546 if (KEY_DIRTY(k)) 547 s->read_dirty_data = true; 548 549 n = bio_next_split(bio, min_t(uint64_t, INT_MAX, 550 KEY_OFFSET(k) - bio->bi_iter.bi_sector), 551 GFP_NOIO, &s->d->bio_split); 552 553 bio_key = &container_of(n, struct bbio, bio)->key; 554 bch_bkey_copy_single_ptr(bio_key, k, ptr); 555 556 bch_cut_front(&KEY(s->iop.inode, n->bi_iter.bi_sector, 0), bio_key); 557 bch_cut_back(&KEY(s->iop.inode, bio_end_sector(n), 0), bio_key); 558 559 n->bi_end_io = bch_cache_read_endio; 560 n->bi_private = &s->cl; 561 562 /* 563 * The bucket we're reading from might be reused while our bio 564 * is in flight, and we could then end up reading the wrong 565 * data. 566 * 567 * We guard against this by checking (in cache_read_endio()) if 568 * the pointer is stale again; if so, we treat it as an error 569 * and reread from the backing device (but we don't pass that 570 * error up anywhere). 571 */ 572 573 __bch_submit_bbio(n, b->c); 574 return n == bio ? MAP_DONE : MAP_CONTINUE; 575 } 576 577 static void cache_lookup(struct closure *cl) 578 { 579 struct search *s = container_of(cl, struct search, iop.cl); 580 struct bio *bio = &s->bio.bio; 581 struct cached_dev *dc; 582 int ret; 583 584 bch_btree_op_init(&s->op, -1); 585 586 ret = bch_btree_map_keys(&s->op, s->iop.c, 587 &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0), 588 cache_lookup_fn, MAP_END_KEY); 589 if (ret == -EAGAIN) { 590 continue_at(cl, cache_lookup, bcache_wq); 591 return; 592 } 593 594 /* 595 * We might meet err when searching the btree, If that happens, we will 596 * get negative ret, in this scenario we should not recover data from 597 * backing device (when cache device is dirty) because we don't know 598 * whether bkeys the read request covered are all clean. 599 * 600 * And after that happened, s->iop.status is still its initial value 601 * before we submit s->bio.bio 602 */ 603 if (ret < 0) { 604 BUG_ON(ret == -EINTR); 605 if (s->d && s->d->c && 606 !UUID_FLASH_ONLY(&s->d->c->uuids[s->d->id])) { 607 dc = container_of(s->d, struct cached_dev, disk); 608 if (dc && atomic_read(&dc->has_dirty)) 609 s->recoverable = false; 610 } 611 if (!s->iop.status) 612 s->iop.status = BLK_STS_IOERR; 613 } 614 615 closure_return(cl); 616 } 617 618 /* Common code for the make_request functions */ 619 620 static void request_endio(struct bio *bio) 621 { 622 struct closure *cl = bio->bi_private; 623 624 if (bio->bi_status) { 625 struct search *s = container_of(cl, struct search, cl); 626 s->iop.status = bio->bi_status; 627 /* Only cache read errors are recoverable */ 628 s->recoverable = false; 629 } 630 631 bio_put(bio); 632 closure_put(cl); 633 } 634 635 static void backing_request_endio(struct bio *bio) 636 { 637 struct closure *cl = bio->bi_private; 638 639 if (bio->bi_status) { 640 struct search *s = container_of(cl, struct search, cl); 641 struct cached_dev *dc = container_of(s->d, 642 struct cached_dev, disk); 643 /* 644 * If a bio has REQ_PREFLUSH for writeback mode, it is 645 * speically assembled in cached_dev_write() for a non-zero 646 * write request which has REQ_PREFLUSH. we don't set 647 * s->iop.status by this failure, the status will be decided 648 * by result of bch_data_insert() operation. 649 */ 650 if (unlikely(s->iop.writeback && 651 bio->bi_opf & REQ_PREFLUSH)) { 652 pr_err("Can't flush %s: returned bi_status %i", 653 dc->backing_dev_name, bio->bi_status); 654 } else { 655 /* set to orig_bio->bi_status in bio_complete() */ 656 s->iop.status = bio->bi_status; 657 } 658 s->recoverable = false; 659 /* should count I/O error for backing device here */ 660 bch_count_backing_io_errors(dc, bio); 661 } 662 663 bio_put(bio); 664 closure_put(cl); 665 } 666 667 static void bio_complete(struct search *s) 668 { 669 if (s->orig_bio) { 670 generic_end_io_acct(s->d->disk->queue, bio_op(s->orig_bio), 671 &s->d->disk->part0, s->start_time); 672 673 trace_bcache_request_end(s->d, s->orig_bio); 674 s->orig_bio->bi_status = s->iop.status; 675 bio_endio(s->orig_bio); 676 s->orig_bio = NULL; 677 } 678 } 679 680 static void do_bio_hook(struct search *s, 681 struct bio *orig_bio, 682 bio_end_io_t *end_io_fn) 683 { 684 struct bio *bio = &s->bio.bio; 685 686 bio_init(bio, NULL, 0); 687 __bio_clone_fast(bio, orig_bio); 688 /* 689 * bi_end_io can be set separately somewhere else, e.g. the 690 * variants in, 691 * - cache_bio->bi_end_io from cached_dev_cache_miss() 692 * - n->bi_end_io from cache_lookup_fn() 693 */ 694 bio->bi_end_io = end_io_fn; 695 bio->bi_private = &s->cl; 696 697 bio_cnt_set(bio, 3); 698 } 699 700 static void search_free(struct closure *cl) 701 { 702 struct search *s = container_of(cl, struct search, cl); 703 704 if (s->iop.bio) 705 bio_put(s->iop.bio); 706 707 bio_complete(s); 708 closure_debug_destroy(cl); 709 mempool_free(s, &s->d->c->search); 710 } 711 712 static inline struct search *search_alloc(struct bio *bio, 713 struct bcache_device *d) 714 { 715 struct search *s; 716 717 s = mempool_alloc(&d->c->search, GFP_NOIO); 718 719 closure_init(&s->cl, NULL); 720 do_bio_hook(s, bio, request_endio); 721 722 s->orig_bio = bio; 723 s->cache_miss = NULL; 724 s->cache_missed = 0; 725 s->d = d; 726 s->recoverable = 1; 727 s->write = op_is_write(bio_op(bio)); 728 s->read_dirty_data = 0; 729 s->start_time = jiffies; 730 731 s->iop.c = d->c; 732 s->iop.bio = NULL; 733 s->iop.inode = d->id; 734 s->iop.write_point = hash_long((unsigned long) current, 16); 735 s->iop.write_prio = 0; 736 s->iop.status = 0; 737 s->iop.flags = 0; 738 s->iop.flush_journal = op_is_flush(bio->bi_opf); 739 s->iop.wq = bcache_wq; 740 741 return s; 742 } 743 744 /* Cached devices */ 745 746 static void cached_dev_bio_complete(struct closure *cl) 747 { 748 struct search *s = container_of(cl, struct search, cl); 749 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); 750 751 search_free(cl); 752 cached_dev_put(dc); 753 } 754 755 /* Process reads */ 756 757 static void cached_dev_cache_miss_done(struct closure *cl) 758 { 759 struct search *s = container_of(cl, struct search, cl); 760 761 if (s->iop.replace_collision) 762 bch_mark_cache_miss_collision(s->iop.c, s->d); 763 764 if (s->iop.bio) 765 bio_free_pages(s->iop.bio); 766 767 cached_dev_bio_complete(cl); 768 } 769 770 static void cached_dev_read_error(struct closure *cl) 771 { 772 struct search *s = container_of(cl, struct search, cl); 773 struct bio *bio = &s->bio.bio; 774 775 /* 776 * If read request hit dirty data (s->read_dirty_data is true), 777 * then recovery a failed read request from cached device may 778 * get a stale data back. So read failure recovery is only 779 * permitted when read request hit clean data in cache device, 780 * or when cache read race happened. 781 */ 782 if (s->recoverable && !s->read_dirty_data) { 783 /* Retry from the backing device: */ 784 trace_bcache_read_retry(s->orig_bio); 785 786 s->iop.status = 0; 787 do_bio_hook(s, s->orig_bio, backing_request_endio); 788 789 /* XXX: invalidate cache */ 790 791 /* I/O request sent to backing device */ 792 closure_bio_submit(s->iop.c, bio, cl); 793 } 794 795 continue_at(cl, cached_dev_cache_miss_done, NULL); 796 } 797 798 static void cached_dev_read_done(struct closure *cl) 799 { 800 struct search *s = container_of(cl, struct search, cl); 801 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); 802 803 /* 804 * We had a cache miss; cache_bio now contains data ready to be inserted 805 * into the cache. 806 * 807 * First, we copy the data we just read from cache_bio's bounce buffers 808 * to the buffers the original bio pointed to: 809 */ 810 811 if (s->iop.bio) { 812 bio_reset(s->iop.bio); 813 s->iop.bio->bi_iter.bi_sector = s->cache_miss->bi_iter.bi_sector; 814 bio_copy_dev(s->iop.bio, s->cache_miss); 815 s->iop.bio->bi_iter.bi_size = s->insert_bio_sectors << 9; 816 bch_bio_map(s->iop.bio, NULL); 817 818 bio_copy_data(s->cache_miss, s->iop.bio); 819 820 bio_put(s->cache_miss); 821 s->cache_miss = NULL; 822 } 823 824 if (verify(dc) && s->recoverable && !s->read_dirty_data) 825 bch_data_verify(dc, s->orig_bio); 826 827 bio_complete(s); 828 829 if (s->iop.bio && 830 !test_bit(CACHE_SET_STOPPING, &s->iop.c->flags)) { 831 BUG_ON(!s->iop.replace); 832 closure_call(&s->iop.cl, bch_data_insert, NULL, cl); 833 } 834 835 continue_at(cl, cached_dev_cache_miss_done, NULL); 836 } 837 838 static void cached_dev_read_done_bh(struct closure *cl) 839 { 840 struct search *s = container_of(cl, struct search, cl); 841 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); 842 843 bch_mark_cache_accounting(s->iop.c, s->d, 844 !s->cache_missed, s->iop.bypass); 845 trace_bcache_read(s->orig_bio, !s->cache_miss, s->iop.bypass); 846 847 if (s->iop.status) 848 continue_at_nobarrier(cl, cached_dev_read_error, bcache_wq); 849 else if (s->iop.bio || verify(dc)) 850 continue_at_nobarrier(cl, cached_dev_read_done, bcache_wq); 851 else 852 continue_at_nobarrier(cl, cached_dev_bio_complete, NULL); 853 } 854 855 static int cached_dev_cache_miss(struct btree *b, struct search *s, 856 struct bio *bio, unsigned sectors) 857 { 858 int ret = MAP_CONTINUE; 859 unsigned reada = 0; 860 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); 861 struct bio *miss, *cache_bio; 862 863 s->cache_missed = 1; 864 865 if (s->cache_miss || s->iop.bypass) { 866 miss = bio_next_split(bio, sectors, GFP_NOIO, &s->d->bio_split); 867 ret = miss == bio ? MAP_DONE : MAP_CONTINUE; 868 goto out_submit; 869 } 870 871 if (!(bio->bi_opf & REQ_RAHEAD) && 872 !(bio->bi_opf & REQ_META) && 873 s->iop.c->gc_stats.in_use < CUTOFF_CACHE_READA) 874 reada = min_t(sector_t, dc->readahead >> 9, 875 get_capacity(bio->bi_disk) - bio_end_sector(bio)); 876 877 s->insert_bio_sectors = min(sectors, bio_sectors(bio) + reada); 878 879 s->iop.replace_key = KEY(s->iop.inode, 880 bio->bi_iter.bi_sector + s->insert_bio_sectors, 881 s->insert_bio_sectors); 882 883 ret = bch_btree_insert_check_key(b, &s->op, &s->iop.replace_key); 884 if (ret) 885 return ret; 886 887 s->iop.replace = true; 888 889 miss = bio_next_split(bio, sectors, GFP_NOIO, &s->d->bio_split); 890 891 /* btree_search_recurse()'s btree iterator is no good anymore */ 892 ret = miss == bio ? MAP_DONE : -EINTR; 893 894 cache_bio = bio_alloc_bioset(GFP_NOWAIT, 895 DIV_ROUND_UP(s->insert_bio_sectors, PAGE_SECTORS), 896 &dc->disk.bio_split); 897 if (!cache_bio) 898 goto out_submit; 899 900 cache_bio->bi_iter.bi_sector = miss->bi_iter.bi_sector; 901 bio_copy_dev(cache_bio, miss); 902 cache_bio->bi_iter.bi_size = s->insert_bio_sectors << 9; 903 904 cache_bio->bi_end_io = backing_request_endio; 905 cache_bio->bi_private = &s->cl; 906 907 bch_bio_map(cache_bio, NULL); 908 if (bch_bio_alloc_pages(cache_bio, __GFP_NOWARN|GFP_NOIO)) 909 goto out_put; 910 911 if (reada) 912 bch_mark_cache_readahead(s->iop.c, s->d); 913 914 s->cache_miss = miss; 915 s->iop.bio = cache_bio; 916 bio_get(cache_bio); 917 /* I/O request sent to backing device */ 918 closure_bio_submit(s->iop.c, cache_bio, &s->cl); 919 920 return ret; 921 out_put: 922 bio_put(cache_bio); 923 out_submit: 924 miss->bi_end_io = backing_request_endio; 925 miss->bi_private = &s->cl; 926 /* I/O request sent to backing device */ 927 closure_bio_submit(s->iop.c, miss, &s->cl); 928 return ret; 929 } 930 931 static void cached_dev_read(struct cached_dev *dc, struct search *s) 932 { 933 struct closure *cl = &s->cl; 934 935 closure_call(&s->iop.cl, cache_lookup, NULL, cl); 936 continue_at(cl, cached_dev_read_done_bh, NULL); 937 } 938 939 /* Process writes */ 940 941 static void cached_dev_write_complete(struct closure *cl) 942 { 943 struct search *s = container_of(cl, struct search, cl); 944 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); 945 946 up_read_non_owner(&dc->writeback_lock); 947 cached_dev_bio_complete(cl); 948 } 949 950 static void cached_dev_write(struct cached_dev *dc, struct search *s) 951 { 952 struct closure *cl = &s->cl; 953 struct bio *bio = &s->bio.bio; 954 struct bkey start = KEY(dc->disk.id, bio->bi_iter.bi_sector, 0); 955 struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0); 956 957 bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys, &start, &end); 958 959 down_read_non_owner(&dc->writeback_lock); 960 if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) { 961 /* 962 * We overlap with some dirty data undergoing background 963 * writeback, force this write to writeback 964 */ 965 s->iop.bypass = false; 966 s->iop.writeback = true; 967 } 968 969 /* 970 * Discards aren't _required_ to do anything, so skipping if 971 * check_overlapping returned true is ok 972 * 973 * But check_overlapping drops dirty keys for which io hasn't started, 974 * so we still want to call it. 975 */ 976 if (bio_op(bio) == REQ_OP_DISCARD) 977 s->iop.bypass = true; 978 979 if (should_writeback(dc, s->orig_bio, 980 cache_mode(dc), 981 s->iop.bypass)) { 982 s->iop.bypass = false; 983 s->iop.writeback = true; 984 } 985 986 if (s->iop.bypass) { 987 s->iop.bio = s->orig_bio; 988 bio_get(s->iop.bio); 989 990 if (bio_op(bio) == REQ_OP_DISCARD && 991 !blk_queue_discard(bdev_get_queue(dc->bdev))) 992 goto insert_data; 993 994 /* I/O request sent to backing device */ 995 bio->bi_end_io = backing_request_endio; 996 closure_bio_submit(s->iop.c, bio, cl); 997 998 } else if (s->iop.writeback) { 999 bch_writeback_add(dc); 1000 s->iop.bio = bio; 1001 1002 if (bio->bi_opf & REQ_PREFLUSH) { 1003 /* 1004 * Also need to send a flush to the backing 1005 * device. 1006 */ 1007 struct bio *flush; 1008 1009 flush = bio_alloc_bioset(GFP_NOIO, 0, 1010 &dc->disk.bio_split); 1011 if (!flush) { 1012 s->iop.status = BLK_STS_RESOURCE; 1013 goto insert_data; 1014 } 1015 bio_copy_dev(flush, bio); 1016 flush->bi_end_io = backing_request_endio; 1017 flush->bi_private = cl; 1018 flush->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH; 1019 /* I/O request sent to backing device */ 1020 closure_bio_submit(s->iop.c, flush, cl); 1021 } 1022 } else { 1023 s->iop.bio = bio_clone_fast(bio, GFP_NOIO, &dc->disk.bio_split); 1024 /* I/O request sent to backing device */ 1025 bio->bi_end_io = backing_request_endio; 1026 closure_bio_submit(s->iop.c, bio, cl); 1027 } 1028 1029 insert_data: 1030 closure_call(&s->iop.cl, bch_data_insert, NULL, cl); 1031 continue_at(cl, cached_dev_write_complete, NULL); 1032 } 1033 1034 static void cached_dev_nodata(struct closure *cl) 1035 { 1036 struct search *s = container_of(cl, struct search, cl); 1037 struct bio *bio = &s->bio.bio; 1038 1039 if (s->iop.flush_journal) 1040 bch_journal_meta(s->iop.c, cl); 1041 1042 /* If it's a flush, we send the flush to the backing device too */ 1043 bio->bi_end_io = backing_request_endio; 1044 closure_bio_submit(s->iop.c, bio, cl); 1045 1046 continue_at(cl, cached_dev_bio_complete, NULL); 1047 } 1048 1049 struct detached_dev_io_private { 1050 struct bcache_device *d; 1051 unsigned long start_time; 1052 bio_end_io_t *bi_end_io; 1053 void *bi_private; 1054 }; 1055 1056 static void detached_dev_end_io(struct bio *bio) 1057 { 1058 struct detached_dev_io_private *ddip; 1059 1060 ddip = bio->bi_private; 1061 bio->bi_end_io = ddip->bi_end_io; 1062 bio->bi_private = ddip->bi_private; 1063 1064 generic_end_io_acct(ddip->d->disk->queue, bio_op(bio), 1065 &ddip->d->disk->part0, ddip->start_time); 1066 1067 if (bio->bi_status) { 1068 struct cached_dev *dc = container_of(ddip->d, 1069 struct cached_dev, disk); 1070 /* should count I/O error for backing device here */ 1071 bch_count_backing_io_errors(dc, bio); 1072 } 1073 1074 kfree(ddip); 1075 bio->bi_end_io(bio); 1076 } 1077 1078 static void detached_dev_do_request(struct bcache_device *d, struct bio *bio) 1079 { 1080 struct detached_dev_io_private *ddip; 1081 struct cached_dev *dc = container_of(d, struct cached_dev, disk); 1082 1083 /* 1084 * no need to call closure_get(&dc->disk.cl), 1085 * because upper layer had already opened bcache device, 1086 * which would call closure_get(&dc->disk.cl) 1087 */ 1088 ddip = kzalloc(sizeof(struct detached_dev_io_private), GFP_NOIO); 1089 ddip->d = d; 1090 ddip->start_time = jiffies; 1091 ddip->bi_end_io = bio->bi_end_io; 1092 ddip->bi_private = bio->bi_private; 1093 bio->bi_end_io = detached_dev_end_io; 1094 bio->bi_private = ddip; 1095 1096 if ((bio_op(bio) == REQ_OP_DISCARD) && 1097 !blk_queue_discard(bdev_get_queue(dc->bdev))) 1098 bio->bi_end_io(bio); 1099 else 1100 generic_make_request(bio); 1101 } 1102 1103 /* Cached devices - read & write stuff */ 1104 1105 static blk_qc_t cached_dev_make_request(struct request_queue *q, 1106 struct bio *bio) 1107 { 1108 struct search *s; 1109 struct bcache_device *d = bio->bi_disk->private_data; 1110 struct cached_dev *dc = container_of(d, struct cached_dev, disk); 1111 int rw = bio_data_dir(bio); 1112 1113 if (unlikely((d->c && test_bit(CACHE_SET_IO_DISABLE, &d->c->flags)) || 1114 dc->io_disable)) { 1115 bio->bi_status = BLK_STS_IOERR; 1116 bio_endio(bio); 1117 return BLK_QC_T_NONE; 1118 } 1119 1120 atomic_set(&dc->backing_idle, 0); 1121 generic_start_io_acct(q, bio_op(bio), bio_sectors(bio), &d->disk->part0); 1122 1123 bio_set_dev(bio, dc->bdev); 1124 bio->bi_iter.bi_sector += dc->sb.data_offset; 1125 1126 if (cached_dev_get(dc)) { 1127 s = search_alloc(bio, d); 1128 trace_bcache_request_start(s->d, bio); 1129 1130 if (!bio->bi_iter.bi_size) { 1131 /* 1132 * can't call bch_journal_meta from under 1133 * generic_make_request 1134 */ 1135 continue_at_nobarrier(&s->cl, 1136 cached_dev_nodata, 1137 bcache_wq); 1138 } else { 1139 s->iop.bypass = check_should_bypass(dc, bio); 1140 1141 if (rw) 1142 cached_dev_write(dc, s); 1143 else 1144 cached_dev_read(dc, s); 1145 } 1146 } else 1147 /* I/O request sent to backing device */ 1148 detached_dev_do_request(d, bio); 1149 1150 return BLK_QC_T_NONE; 1151 } 1152 1153 static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode, 1154 unsigned int cmd, unsigned long arg) 1155 { 1156 struct cached_dev *dc = container_of(d, struct cached_dev, disk); 1157 return __blkdev_driver_ioctl(dc->bdev, mode, cmd, arg); 1158 } 1159 1160 static int cached_dev_congested(void *data, int bits) 1161 { 1162 struct bcache_device *d = data; 1163 struct cached_dev *dc = container_of(d, struct cached_dev, disk); 1164 struct request_queue *q = bdev_get_queue(dc->bdev); 1165 int ret = 0; 1166 1167 if (bdi_congested(q->backing_dev_info, bits)) 1168 return 1; 1169 1170 if (cached_dev_get(dc)) { 1171 unsigned i; 1172 struct cache *ca; 1173 1174 for_each_cache(ca, d->c, i) { 1175 q = bdev_get_queue(ca->bdev); 1176 ret |= bdi_congested(q->backing_dev_info, bits); 1177 } 1178 1179 cached_dev_put(dc); 1180 } 1181 1182 return ret; 1183 } 1184 1185 void bch_cached_dev_request_init(struct cached_dev *dc) 1186 { 1187 struct gendisk *g = dc->disk.disk; 1188 1189 g->queue->make_request_fn = cached_dev_make_request; 1190 g->queue->backing_dev_info->congested_fn = cached_dev_congested; 1191 dc->disk.cache_miss = cached_dev_cache_miss; 1192 dc->disk.ioctl = cached_dev_ioctl; 1193 } 1194 1195 /* Flash backed devices */ 1196 1197 static int flash_dev_cache_miss(struct btree *b, struct search *s, 1198 struct bio *bio, unsigned sectors) 1199 { 1200 unsigned bytes = min(sectors, bio_sectors(bio)) << 9; 1201 1202 swap(bio->bi_iter.bi_size, bytes); 1203 zero_fill_bio(bio); 1204 swap(bio->bi_iter.bi_size, bytes); 1205 1206 bio_advance(bio, bytes); 1207 1208 if (!bio->bi_iter.bi_size) 1209 return MAP_DONE; 1210 1211 return MAP_CONTINUE; 1212 } 1213 1214 static void flash_dev_nodata(struct closure *cl) 1215 { 1216 struct search *s = container_of(cl, struct search, cl); 1217 1218 if (s->iop.flush_journal) 1219 bch_journal_meta(s->iop.c, cl); 1220 1221 continue_at(cl, search_free, NULL); 1222 } 1223 1224 static blk_qc_t flash_dev_make_request(struct request_queue *q, 1225 struct bio *bio) 1226 { 1227 struct search *s; 1228 struct closure *cl; 1229 struct bcache_device *d = bio->bi_disk->private_data; 1230 1231 if (unlikely(d->c && test_bit(CACHE_SET_IO_DISABLE, &d->c->flags))) { 1232 bio->bi_status = BLK_STS_IOERR; 1233 bio_endio(bio); 1234 return BLK_QC_T_NONE; 1235 } 1236 1237 generic_start_io_acct(q, bio_op(bio), bio_sectors(bio), &d->disk->part0); 1238 1239 s = search_alloc(bio, d); 1240 cl = &s->cl; 1241 bio = &s->bio.bio; 1242 1243 trace_bcache_request_start(s->d, bio); 1244 1245 if (!bio->bi_iter.bi_size) { 1246 /* 1247 * can't call bch_journal_meta from under 1248 * generic_make_request 1249 */ 1250 continue_at_nobarrier(&s->cl, 1251 flash_dev_nodata, 1252 bcache_wq); 1253 return BLK_QC_T_NONE; 1254 } else if (bio_data_dir(bio)) { 1255 bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys, 1256 &KEY(d->id, bio->bi_iter.bi_sector, 0), 1257 &KEY(d->id, bio_end_sector(bio), 0)); 1258 1259 s->iop.bypass = (bio_op(bio) == REQ_OP_DISCARD) != 0; 1260 s->iop.writeback = true; 1261 s->iop.bio = bio; 1262 1263 closure_call(&s->iop.cl, bch_data_insert, NULL, cl); 1264 } else { 1265 closure_call(&s->iop.cl, cache_lookup, NULL, cl); 1266 } 1267 1268 continue_at(cl, search_free, NULL); 1269 return BLK_QC_T_NONE; 1270 } 1271 1272 static int flash_dev_ioctl(struct bcache_device *d, fmode_t mode, 1273 unsigned int cmd, unsigned long arg) 1274 { 1275 return -ENOTTY; 1276 } 1277 1278 static int flash_dev_congested(void *data, int bits) 1279 { 1280 struct bcache_device *d = data; 1281 struct request_queue *q; 1282 struct cache *ca; 1283 unsigned i; 1284 int ret = 0; 1285 1286 for_each_cache(ca, d->c, i) { 1287 q = bdev_get_queue(ca->bdev); 1288 ret |= bdi_congested(q->backing_dev_info, bits); 1289 } 1290 1291 return ret; 1292 } 1293 1294 void bch_flash_dev_request_init(struct bcache_device *d) 1295 { 1296 struct gendisk *g = d->disk; 1297 1298 g->queue->make_request_fn = flash_dev_make_request; 1299 g->queue->backing_dev_info->congested_fn = flash_dev_congested; 1300 d->cache_miss = flash_dev_cache_miss; 1301 d->ioctl = flash_dev_ioctl; 1302 } 1303 1304 void bch_request_exit(void) 1305 { 1306 if (bch_search_cache) 1307 kmem_cache_destroy(bch_search_cache); 1308 } 1309 1310 int __init bch_request_init(void) 1311 { 1312 bch_search_cache = KMEM_CACHE(search, 0); 1313 if (!bch_search_cache) 1314 return -ENOMEM; 1315 1316 return 0; 1317 } 1318