1360 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * Main bcache entry point - handle a read or a write request and decide what to4 * 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 9524#define CUTOFF_CACHE_READA 9025 26struct kmem_cache *bch_search_cache;27 28static CLOSURE_CALLBACK(bch_data_insert_start);29 30static unsigned int cache_mode(struct cached_dev *dc)31{32 return BDEV_CACHE_MODE(&dc->sb);33}34 35static bool verify(struct cached_dev *dc)36{37 return dc->verify;38}39 40static 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 = bvec_kmap_local(&bv);48 49 csum = crc64_be(csum, d, bv.bv_len);50 kunmap_local(d);51 }52 53 k->ptr[KEY_PTRS(k)] = csum & (~0ULL >> 1);54}55 56/* Insert data into cache */57 58static CLOSURE_CALLBACK(bch_data_insert_keys)59{60 closure_type(op, struct data_insert_op, cl);61 atomic_t *journal_ref = NULL;62 struct bkey *replace_key = op->replace ? &op->replace_key : NULL;63 int ret;64 65 if (!op->replace)66 journal_ref = bch_journal(op->c, &op->insert_keys,67 op->flush_journal ? cl : NULL);68 69 ret = bch_btree_insert(op->c, &op->insert_keys,70 journal_ref, replace_key);71 if (ret == -ESRCH) {72 op->replace_collision = true;73 } else if (ret) {74 op->status = BLK_STS_RESOURCE;75 op->insert_data_done = true;76 }77 78 if (journal_ref)79 atomic_dec_bug(journal_ref);80 81 if (!op->insert_data_done) {82 continue_at(cl, bch_data_insert_start, op->wq);83 return;84 }85 86 bch_keylist_free(&op->insert_keys);87 closure_return(cl);88}89 90static int bch_keylist_realloc(struct keylist *l, unsigned int u64s,91 struct cache_set *c)92{93 size_t oldsize = bch_keylist_nkeys(l);94 size_t newsize = oldsize + u64s;95 96 /*97 * The journalling code doesn't handle the case where the keys to insert98 * is bigger than an empty write: If we just return -ENOMEM here,99 * bch_data_insert_keys() will insert the keys created so far100 * and finish the rest when the keylist is empty.101 */102 if (newsize * sizeof(uint64_t) > block_bytes(c->cache) - sizeof(struct jset))103 return -ENOMEM;104 105 return __bch_keylist_realloc(l, u64s);106}107 108static void bch_data_invalidate(struct closure *cl)109{110 struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);111 struct bio *bio = op->bio;112 113 pr_debug("invalidating %i sectors from %llu\n",114 bio_sectors(bio), (uint64_t) bio->bi_iter.bi_sector);115 116 while (bio_sectors(bio)) {117 unsigned int sectors = min(bio_sectors(bio),118 1U << (KEY_SIZE_BITS - 1));119 120 if (bch_keylist_realloc(&op->insert_keys, 2, op->c))121 goto out;122 123 bio->bi_iter.bi_sector += sectors;124 bio->bi_iter.bi_size -= sectors << 9;125 126 bch_keylist_add(&op->insert_keys,127 &KEY(op->inode,128 bio->bi_iter.bi_sector,129 sectors));130 }131 132 op->insert_data_done = true;133 /* get in bch_data_insert() */134 bio_put(bio);135out:136 continue_at(cl, bch_data_insert_keys, op->wq);137}138 139static CLOSURE_CALLBACK(bch_data_insert_error)140{141 closure_type(op, struct data_insert_op, cl);142 143 /*144 * Our data write just errored, which means we've got a bunch of keys to145 * insert that point to data that wasn't successfully written.146 *147 * We don't have to insert those keys but we still have to invalidate148 * that region of the cache - so, if we just strip off all the pointers149 * from the keys we'll accomplish just that.150 */151 152 struct bkey *src = op->insert_keys.keys, *dst = op->insert_keys.keys;153 154 while (src != op->insert_keys.top) {155 struct bkey *n = bkey_next(src);156 157 SET_KEY_PTRS(src, 0);158 memmove(dst, src, bkey_bytes(src));159 160 dst = bkey_next(dst);161 src = n;162 }163 164 op->insert_keys.top = dst;165 166 bch_data_insert_keys(&cl->work);167}168 169static void bch_data_insert_endio(struct bio *bio)170{171 struct closure *cl = bio->bi_private;172 struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);173 174 if (bio->bi_status) {175 /* TODO: We could try to recover from this. */176 if (op->writeback)177 op->status = bio->bi_status;178 else if (!op->replace)179 set_closure_fn(cl, bch_data_insert_error, op->wq);180 else181 set_closure_fn(cl, NULL, NULL);182 }183 184 bch_bbio_endio(op->c, bio, bio->bi_status, "writing data to cache");185}186 187static CLOSURE_CALLBACK(bch_data_insert_start)188{189 closure_type(op, struct data_insert_op, cl);190 struct bio *bio = op->bio, *n;191 192 if (op->bypass)193 return bch_data_invalidate(cl);194 195 if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0)196 wake_up_gc(op->c);197 198 /*199 * Journal writes are marked REQ_PREFLUSH; if the original write was a200 * flush, it'll wait on the journal write.201 */202 bio->bi_opf &= ~(REQ_PREFLUSH|REQ_FUA);203 204 do {205 unsigned int i;206 struct bkey *k;207 struct bio_set *split = &op->c->bio_split;208 209 /* 1 for the device pointer and 1 for the chksum */210 if (bch_keylist_realloc(&op->insert_keys,211 3 + (op->csum ? 1 : 0),212 op->c)) {213 continue_at(cl, bch_data_insert_keys, op->wq);214 return;215 }216 217 k = op->insert_keys.top;218 bkey_init(k);219 SET_KEY_INODE(k, op->inode);220 SET_KEY_OFFSET(k, bio->bi_iter.bi_sector);221 222 if (!bch_alloc_sectors(op->c, k, bio_sectors(bio),223 op->write_point, op->write_prio,224 op->writeback))225 goto err;226 227 n = bio_next_split(bio, KEY_SIZE(k), GFP_NOIO, split);228 229 n->bi_end_io = bch_data_insert_endio;230 n->bi_private = cl;231 232 if (op->writeback) {233 SET_KEY_DIRTY(k, true);234 235 for (i = 0; i < KEY_PTRS(k); i++)236 SET_GC_MARK(PTR_BUCKET(op->c, k, i),237 GC_MARK_DIRTY);238 }239 240 SET_KEY_CSUM(k, op->csum);241 if (KEY_CSUM(k))242 bio_csum(n, k);243 244 trace_bcache_cache_insert(k);245 bch_keylist_push(&op->insert_keys);246 247 n->bi_opf = REQ_OP_WRITE;248 bch_submit_bbio(n, op->c, k, 0);249 } while (n != bio);250 251 op->insert_data_done = true;252 continue_at(cl, bch_data_insert_keys, op->wq);253 return;254err:255 /* bch_alloc_sectors() blocks if s->writeback = true */256 BUG_ON(op->writeback);257 258 /*259 * But if it's not a writeback write we'd rather just bail out if260 * there aren't any buckets ready to write to - it might take awhile and261 * we might be starving btree writes for gc or something.262 */263 264 if (!op->replace) {265 /*266 * Writethrough write: We can't complete the write until we've267 * updated the index. But we don't want to delay the write while268 * we wait for buckets to be freed up, so just invalidate the269 * rest of the write.270 */271 op->bypass = true;272 return bch_data_invalidate(cl);273 } else {274 /*275 * From a cache miss, we can just insert the keys for the data276 * we have written or bail out if we didn't do anything.277 */278 op->insert_data_done = true;279 bio_put(bio);280 281 if (!bch_keylist_empty(&op->insert_keys))282 continue_at(cl, bch_data_insert_keys, op->wq);283 else284 closure_return(cl);285 }286}287 288/**289 * bch_data_insert - stick some data in the cache290 * @cl: closure pointer.291 *292 * This is the starting point for any data to end up in a cache device; it could293 * be from a normal write, or a writeback write, or a write to a flash only294 * volume - it's also used by the moving garbage collector to compact data in295 * mostly empty buckets.296 *297 * It first writes the data to the cache, creating a list of keys to be inserted298 * (if the data had to be fragmented there will be multiple keys); after the299 * data is written it calls bch_journal, and after the keys have been added to300 * the next journal write they're inserted into the btree.301 *302 * It inserts the data in op->bio; bi_sector is used for the key offset,303 * and op->inode is used for the key inode.304 *305 * If op->bypass is true, instead of inserting the data it invalidates the306 * region of the cache represented by op->bio and op->inode.307 */308CLOSURE_CALLBACK(bch_data_insert)309{310 closure_type(op, struct data_insert_op, cl);311 312 trace_bcache_write(op->c, op->inode, op->bio,313 op->writeback, op->bypass);314 315 bch_keylist_init(&op->insert_keys);316 bio_get(op->bio);317 bch_data_insert_start(&cl->work);318}319 320/*321 * Congested? Return 0 (not congested) or the limit (in sectors)322 * beyond which we should bypass the cache due to congestion.323 */324unsigned int bch_get_congested(const struct cache_set *c)325{326 int i;327 328 if (!c->congested_read_threshold_us &&329 !c->congested_write_threshold_us)330 return 0;331 332 i = (local_clock_us() - c->congested_last_us) / 1024;333 if (i < 0)334 return 0;335 336 i += atomic_read(&c->congested);337 if (i >= 0)338 return 0;339 340 i += CONGESTED_MAX;341 342 if (i > 0)343 i = fract_exp_two(i, 6);344 345 i -= hweight32(get_random_u32());346 347 return i > 0 ? i : 1;348}349 350static void add_sequential(struct task_struct *t)351{352 ewma_add(t->sequential_io_avg,353 t->sequential_io, 8, 0);354 355 t->sequential_io = 0;356}357 358static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)359{360 return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];361}362 363static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)364{365 struct cache_set *c = dc->disk.c;366 unsigned int mode = cache_mode(dc);367 unsigned int sectors, congested;368 struct task_struct *task = current;369 struct io *i;370 371 if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||372 (bio_op(bio) == REQ_OP_DISCARD))373 goto skip;374 375 if (c->gc_stats.in_use > CUTOFF_CACHE_ADD) {376 /*377 * If cached buckets are all clean now, 'true' will be378 * returned and all requests will bypass the cache device.379 * Then c->sectors_to_gc has no chance to be negative, and380 * gc thread won't wake up and caching won't work forever.381 * Here call force_wake_up_gc() to avoid such aftermath.382 */383 if (BDEV_STATE(&dc->sb) == BDEV_STATE_CLEAN &&384 c->gc_mark_valid)385 force_wake_up_gc(c);386 387 goto skip;388 }389 390 if (mode == CACHE_MODE_NONE ||391 (mode == CACHE_MODE_WRITEAROUND &&392 op_is_write(bio_op(bio))))393 goto skip;394 395 /*396 * If the bio is for read-ahead or background IO, bypass it or397 * not depends on the following situations,398 * - If the IO is for meta data, always cache it and no bypass399 * - If the IO is not meta data, check dc->cache_reada_policy,400 * BCH_CACHE_READA_ALL: cache it and not bypass401 * BCH_CACHE_READA_META_ONLY: not cache it and bypass402 * That is, read-ahead request for metadata always get cached403 * (eg, for gfs2 or xfs).404 */405 if ((bio->bi_opf & (REQ_RAHEAD|REQ_BACKGROUND))) {406 if (!(bio->bi_opf & (REQ_META|REQ_PRIO)) &&407 (dc->cache_readahead_policy != BCH_CACHE_READA_ALL))408 goto skip;409 }410 411 if (bio->bi_iter.bi_sector & (c->cache->sb.block_size - 1) ||412 bio_sectors(bio) & (c->cache->sb.block_size - 1)) {413 pr_debug("skipping unaligned io\n");414 goto skip;415 }416 417 if (bypass_torture_test(dc)) {418 if (get_random_u32_below(4) == 3)419 goto skip;420 else421 goto rescale;422 }423 424 congested = bch_get_congested(c);425 if (!congested && !dc->sequential_cutoff)426 goto rescale;427 428 spin_lock(&dc->io_lock);429 430 hlist_for_each_entry(i, iohash(dc, bio->bi_iter.bi_sector), hash)431 if (i->last == bio->bi_iter.bi_sector &&432 time_before(jiffies, i->jiffies))433 goto found;434 435 i = list_first_entry(&dc->io_lru, struct io, lru);436 437 add_sequential(task);438 i->sequential = 0;439found:440 if (i->sequential + bio->bi_iter.bi_size > i->sequential)441 i->sequential += bio->bi_iter.bi_size;442 443 i->last = bio_end_sector(bio);444 i->jiffies = jiffies + msecs_to_jiffies(5000);445 task->sequential_io = i->sequential;446 447 hlist_del(&i->hash);448 hlist_add_head(&i->hash, iohash(dc, i->last));449 list_move_tail(&i->lru, &dc->io_lru);450 451 spin_unlock(&dc->io_lock);452 453 sectors = max(task->sequential_io,454 task->sequential_io_avg) >> 9;455 456 if (dc->sequential_cutoff &&457 sectors >= dc->sequential_cutoff >> 9) {458 trace_bcache_bypass_sequential(bio);459 goto skip;460 }461 462 if (congested && sectors >= congested) {463 trace_bcache_bypass_congested(bio);464 goto skip;465 }466 467rescale:468 bch_rescale_priorities(c, bio_sectors(bio));469 return false;470skip:471 bch_mark_sectors_bypassed(c, dc, bio_sectors(bio));472 return true;473}474 475/* Cache lookup */476 477struct search {478 /* Stack frame for bio_complete */479 struct closure cl;480 481 struct bbio bio;482 struct bio *orig_bio;483 struct bio *cache_miss;484 struct bcache_device *d;485 486 unsigned int insert_bio_sectors;487 unsigned int recoverable:1;488 unsigned int write:1;489 unsigned int read_dirty_data:1;490 unsigned int cache_missed:1;491 492 struct block_device *orig_bdev;493 unsigned long start_time;494 495 struct btree_op op;496 struct data_insert_op iop;497};498 499static void bch_cache_read_endio(struct bio *bio)500{501 struct bbio *b = container_of(bio, struct bbio, bio);502 struct closure *cl = bio->bi_private;503 struct search *s = container_of(cl, struct search, cl);504 505 /*506 * If the bucket was reused while our bio was in flight, we might have507 * read the wrong data. Set s->error but not error so it doesn't get508 * counted against the cache device, but we'll still reread the data509 * from the backing device.510 */511 512 if (bio->bi_status)513 s->iop.status = bio->bi_status;514 else if (!KEY_DIRTY(&b->key) &&515 ptr_stale(s->iop.c, &b->key, 0)) {516 atomic_long_inc(&s->iop.c->cache_read_races);517 s->iop.status = BLK_STS_IOERR;518 }519 520 bch_bbio_endio(s->iop.c, bio, bio->bi_status, "reading from cache");521}522 523/*524 * Read from a single key, handling the initial cache miss if the key starts in525 * the middle of the bio526 */527static int cache_lookup_fn(struct btree_op *op, struct btree *b, struct bkey *k)528{529 struct search *s = container_of(op, struct search, op);530 struct bio *n, *bio = &s->bio.bio;531 struct bkey *bio_key;532 unsigned int ptr;533 534 if (bkey_cmp(k, &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0)) <= 0)535 return MAP_CONTINUE;536 537 if (KEY_INODE(k) != s->iop.inode ||538 KEY_START(k) > bio->bi_iter.bi_sector) {539 unsigned int bio_sectors = bio_sectors(bio);540 unsigned int sectors = KEY_INODE(k) == s->iop.inode541 ? min_t(uint64_t, INT_MAX,542 KEY_START(k) - bio->bi_iter.bi_sector)543 : INT_MAX;544 int ret = s->d->cache_miss(b, s, bio, sectors);545 546 if (ret != MAP_CONTINUE)547 return ret;548 549 /* if this was a complete miss we shouldn't get here */550 BUG_ON(bio_sectors <= sectors);551 }552 553 if (!KEY_SIZE(k))554 return MAP_CONTINUE;555 556 /* XXX: figure out best pointer - for multiple cache devices */557 ptr = 0;558 559 PTR_BUCKET(b->c, k, ptr)->prio = INITIAL_PRIO;560 561 if (KEY_DIRTY(k))562 s->read_dirty_data = true;563 564 n = bio_next_split(bio, min_t(uint64_t, INT_MAX,565 KEY_OFFSET(k) - bio->bi_iter.bi_sector),566 GFP_NOIO, &s->d->bio_split);567 568 bio_key = &container_of(n, struct bbio, bio)->key;569 bch_bkey_copy_single_ptr(bio_key, k, ptr);570 571 bch_cut_front(&KEY(s->iop.inode, n->bi_iter.bi_sector, 0), bio_key);572 bch_cut_back(&KEY(s->iop.inode, bio_end_sector(n), 0), bio_key);573 574 n->bi_end_io = bch_cache_read_endio;575 n->bi_private = &s->cl;576 577 /*578 * The bucket we're reading from might be reused while our bio579 * is in flight, and we could then end up reading the wrong580 * data.581 *582 * We guard against this by checking (in cache_read_endio()) if583 * the pointer is stale again; if so, we treat it as an error584 * and reread from the backing device (but we don't pass that585 * error up anywhere).586 */587 588 __bch_submit_bbio(n, b->c);589 return n == bio ? MAP_DONE : MAP_CONTINUE;590}591 592static CLOSURE_CALLBACK(cache_lookup)593{594 closure_type(s, struct search, iop.cl);595 struct bio *bio = &s->bio.bio;596 struct cached_dev *dc;597 int ret;598 599 bch_btree_op_init(&s->op, -1);600 601 ret = bch_btree_map_keys(&s->op, s->iop.c,602 &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0),603 cache_lookup_fn, MAP_END_KEY);604 if (ret == -EAGAIN) {605 continue_at(cl, cache_lookup, bcache_wq);606 return;607 }608 609 /*610 * We might meet err when searching the btree, If that happens, we will611 * get negative ret, in this scenario we should not recover data from612 * backing device (when cache device is dirty) because we don't know613 * whether bkeys the read request covered are all clean.614 *615 * And after that happened, s->iop.status is still its initial value616 * before we submit s->bio.bio617 */618 if (ret < 0) {619 BUG_ON(ret == -EINTR);620 if (s->d && s->d->c &&621 !UUID_FLASH_ONLY(&s->d->c->uuids[s->d->id])) {622 dc = container_of(s->d, struct cached_dev, disk);623 if (dc && atomic_read(&dc->has_dirty))624 s->recoverable = false;625 }626 if (!s->iop.status)627 s->iop.status = BLK_STS_IOERR;628 }629 630 closure_return(cl);631}632 633/* Common code for the make_request functions */634 635static void 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);641 642 s->iop.status = bio->bi_status;643 /* Only cache read errors are recoverable */644 s->recoverable = false;645 }646 647 bio_put(bio);648 closure_put(cl);649}650 651static void backing_request_endio(struct bio *bio)652{653 struct closure *cl = bio->bi_private;654 655 if (bio->bi_status) {656 struct search *s = container_of(cl, struct search, cl);657 struct cached_dev *dc = container_of(s->d,658 struct cached_dev, disk);659 /*660 * If a bio has REQ_PREFLUSH for writeback mode, it is661 * speically assembled in cached_dev_write() for a non-zero662 * write request which has REQ_PREFLUSH. we don't set663 * s->iop.status by this failure, the status will be decided664 * by result of bch_data_insert() operation.665 */666 if (unlikely(s->iop.writeback &&667 bio->bi_opf & REQ_PREFLUSH)) {668 pr_err("Can't flush %pg: returned bi_status %i\n",669 dc->bdev, bio->bi_status);670 } else {671 /* set to orig_bio->bi_status in bio_complete() */672 s->iop.status = bio->bi_status;673 }674 s->recoverable = false;675 /* should count I/O error for backing device here */676 bch_count_backing_io_errors(dc, bio);677 }678 679 bio_put(bio);680 closure_put(cl);681}682 683static void bio_complete(struct search *s)684{685 if (s->orig_bio) {686 /* Count on bcache device */687 bio_end_io_acct_remapped(s->orig_bio, s->start_time,688 s->orig_bdev);689 trace_bcache_request_end(s->d, s->orig_bio);690 s->orig_bio->bi_status = s->iop.status;691 bio_endio(s->orig_bio);692 s->orig_bio = NULL;693 }694}695 696static void do_bio_hook(struct search *s,697 struct bio *orig_bio,698 bio_end_io_t *end_io_fn)699{700 struct bio *bio = &s->bio.bio;701 702 bio_init_clone(orig_bio->bi_bdev, bio, orig_bio, GFP_NOIO);703 /*704 * bi_end_io can be set separately somewhere else, e.g. the705 * variants in,706 * - cache_bio->bi_end_io from cached_dev_cache_miss()707 * - n->bi_end_io from cache_lookup_fn()708 */709 bio->bi_end_io = end_io_fn;710 bio->bi_private = &s->cl;711 712 bio_cnt_set(bio, 3);713}714 715static CLOSURE_CALLBACK(search_free)716{717 closure_type(s, struct search, cl);718 719 atomic_dec(&s->iop.c->search_inflight);720 721 if (s->iop.bio)722 bio_put(s->iop.bio);723 724 bio_complete(s);725 closure_debug_destroy(cl);726 mempool_free(s, &s->iop.c->search);727}728 729static inline struct search *search_alloc(struct bio *bio,730 struct bcache_device *d, struct block_device *orig_bdev,731 unsigned long start_time)732{733 struct search *s;734 735 s = mempool_alloc(&d->c->search, GFP_NOIO);736 737 closure_init(&s->cl, NULL);738 do_bio_hook(s, bio, request_endio);739 atomic_inc(&d->c->search_inflight);740 741 s->orig_bio = bio;742 s->cache_miss = NULL;743 s->cache_missed = 0;744 s->d = d;745 s->recoverable = 1;746 s->write = op_is_write(bio_op(bio));747 s->read_dirty_data = 0;748 /* Count on the bcache device */749 s->orig_bdev = orig_bdev;750 s->start_time = start_time;751 s->iop.c = d->c;752 s->iop.bio = NULL;753 s->iop.inode = d->id;754 s->iop.write_point = hash_long((unsigned long) current, 16);755 s->iop.write_prio = 0;756 s->iop.status = 0;757 s->iop.flags = 0;758 s->iop.flush_journal = op_is_flush(bio->bi_opf);759 s->iop.wq = bcache_wq;760 761 return s;762}763 764/* Cached devices */765 766static CLOSURE_CALLBACK(cached_dev_bio_complete)767{768 closure_type(s, struct search, cl);769 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);770 771 cached_dev_put(dc);772 search_free(&cl->work);773}774 775/* Process reads */776 777static CLOSURE_CALLBACK(cached_dev_read_error_done)778{779 closure_type(s, struct search, cl);780 781 if (s->iop.replace_collision)782 bch_mark_cache_miss_collision(s->iop.c, s->d);783 784 if (s->iop.bio)785 bio_free_pages(s->iop.bio);786 787 cached_dev_bio_complete(&cl->work);788}789 790static CLOSURE_CALLBACK(cached_dev_read_error)791{792 closure_type(s, struct search, cl);793 struct bio *bio = &s->bio.bio;794 795 /*796 * If read request hit dirty data (s->read_dirty_data is true),797 * then recovery a failed read request from cached device may798 * get a stale data back. So read failure recovery is only799 * permitted when read request hit clean data in cache device,800 * or when cache read race happened.801 */802 if (s->recoverable && !s->read_dirty_data) {803 /* Retry from the backing device: */804 trace_bcache_read_retry(s->orig_bio);805 806 s->iop.status = 0;807 do_bio_hook(s, s->orig_bio, backing_request_endio);808 809 /* XXX: invalidate cache */810 811 /* I/O request sent to backing device */812 closure_bio_submit(s->iop.c, bio, cl);813 }814 815 continue_at(cl, cached_dev_read_error_done, NULL);816}817 818static CLOSURE_CALLBACK(cached_dev_cache_miss_done)819{820 closure_type(s, struct search, cl);821 struct bcache_device *d = s->d;822 823 if (s->iop.replace_collision)824 bch_mark_cache_miss_collision(s->iop.c, s->d);825 826 if (s->iop.bio)827 bio_free_pages(s->iop.bio);828 829 cached_dev_bio_complete(&cl->work);830 closure_put(&d->cl);831}832 833static CLOSURE_CALLBACK(cached_dev_read_done)834{835 closure_type(s, struct search, cl);836 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);837 838 /*839 * We had a cache miss; cache_bio now contains data ready to be inserted840 * into the cache.841 *842 * First, we copy the data we just read from cache_bio's bounce buffers843 * to the buffers the original bio pointed to:844 */845 846 if (s->iop.bio) {847 bio_reset(s->iop.bio, s->cache_miss->bi_bdev, REQ_OP_READ);848 s->iop.bio->bi_iter.bi_sector =849 s->cache_miss->bi_iter.bi_sector;850 s->iop.bio->bi_iter.bi_size = s->insert_bio_sectors << 9;851 bio_clone_blkg_association(s->iop.bio, s->cache_miss);852 bch_bio_map(s->iop.bio, NULL);853 854 bio_copy_data(s->cache_miss, s->iop.bio);855 856 bio_put(s->cache_miss);857 s->cache_miss = NULL;858 }859 860 if (verify(dc) && s->recoverable && !s->read_dirty_data)861 bch_data_verify(dc, s->orig_bio);862 863 closure_get(&dc->disk.cl);864 bio_complete(s);865 866 if (s->iop.bio &&867 !test_bit(CACHE_SET_STOPPING, &s->iop.c->flags)) {868 BUG_ON(!s->iop.replace);869 closure_call(&s->iop.cl, bch_data_insert, NULL, cl);870 }871 872 continue_at(cl, cached_dev_cache_miss_done, NULL);873}874 875static CLOSURE_CALLBACK(cached_dev_read_done_bh)876{877 closure_type(s, struct search, cl);878 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);879 880 bch_mark_cache_accounting(s->iop.c, s->d,881 !s->cache_missed, s->iop.bypass);882 trace_bcache_read(s->orig_bio, !s->cache_missed, s->iop.bypass);883 884 if (s->iop.status)885 continue_at_nobarrier(cl, cached_dev_read_error, bcache_wq);886 else if (s->iop.bio || verify(dc))887 continue_at_nobarrier(cl, cached_dev_read_done, bcache_wq);888 else889 continue_at_nobarrier(cl, cached_dev_bio_complete, NULL);890}891 892static int cached_dev_cache_miss(struct btree *b, struct search *s,893 struct bio *bio, unsigned int sectors)894{895 int ret = MAP_CONTINUE;896 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);897 struct bio *miss, *cache_bio;898 unsigned int size_limit;899 900 s->cache_missed = 1;901 902 if (s->cache_miss || s->iop.bypass) {903 miss = bio_next_split(bio, sectors, GFP_NOIO, &s->d->bio_split);904 ret = miss == bio ? MAP_DONE : MAP_CONTINUE;905 goto out_submit;906 }907 908 /* Limitation for valid replace key size and cache_bio bvecs number */909 size_limit = min_t(unsigned int, BIO_MAX_VECS * PAGE_SECTORS,910 (1 << KEY_SIZE_BITS) - 1);911 s->insert_bio_sectors = min3(size_limit, sectors, bio_sectors(bio));912 913 s->iop.replace_key = KEY(s->iop.inode,914 bio->bi_iter.bi_sector + s->insert_bio_sectors,915 s->insert_bio_sectors);916 917 ret = bch_btree_insert_check_key(b, &s->op, &s->iop.replace_key);918 if (ret)919 return ret;920 921 s->iop.replace = true;922 923 miss = bio_next_split(bio, s->insert_bio_sectors, GFP_NOIO,924 &s->d->bio_split);925 926 /* btree_search_recurse()'s btree iterator is no good anymore */927 ret = miss == bio ? MAP_DONE : -EINTR;928 929 cache_bio = bio_alloc_bioset(miss->bi_bdev,930 DIV_ROUND_UP(s->insert_bio_sectors, PAGE_SECTORS),931 0, GFP_NOWAIT, &dc->disk.bio_split);932 if (!cache_bio)933 goto out_submit;934 935 cache_bio->bi_iter.bi_sector = miss->bi_iter.bi_sector;936 cache_bio->bi_iter.bi_size = s->insert_bio_sectors << 9;937 938 cache_bio->bi_end_io = backing_request_endio;939 cache_bio->bi_private = &s->cl;940 941 bch_bio_map(cache_bio, NULL);942 if (bch_bio_alloc_pages(cache_bio, __GFP_NOWARN|GFP_NOIO))943 goto out_put;944 945 s->cache_miss = miss;946 s->iop.bio = cache_bio;947 bio_get(cache_bio);948 /* I/O request sent to backing device */949 closure_bio_submit(s->iop.c, cache_bio, &s->cl);950 951 return ret;952out_put:953 bio_put(cache_bio);954out_submit:955 miss->bi_end_io = backing_request_endio;956 miss->bi_private = &s->cl;957 /* I/O request sent to backing device */958 closure_bio_submit(s->iop.c, miss, &s->cl);959 return ret;960}961 962static void cached_dev_read(struct cached_dev *dc, struct search *s)963{964 struct closure *cl = &s->cl;965 966 closure_call(&s->iop.cl, cache_lookup, NULL, cl);967 continue_at(cl, cached_dev_read_done_bh, NULL);968}969 970/* Process writes */971 972static CLOSURE_CALLBACK(cached_dev_write_complete)973{974 closure_type(s, struct search, cl);975 struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);976 977 up_read_non_owner(&dc->writeback_lock);978 cached_dev_bio_complete(&cl->work);979}980 981static void cached_dev_write(struct cached_dev *dc, struct search *s)982{983 struct closure *cl = &s->cl;984 struct bio *bio = &s->bio.bio;985 struct bkey start = KEY(dc->disk.id, bio->bi_iter.bi_sector, 0);986 struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0);987 988 bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys, &start, &end);989 990 down_read_non_owner(&dc->writeback_lock);991 if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) {992 /*993 * We overlap with some dirty data undergoing background994 * writeback, force this write to writeback995 */996 s->iop.bypass = false;997 s->iop.writeback = true;998 }999 1000 /*1001 * Discards aren't _required_ to do anything, so skipping if1002 * check_overlapping returned true is ok1003 *1004 * But check_overlapping drops dirty keys for which io hasn't started,1005 * so we still want to call it.1006 */1007 if (bio_op(bio) == REQ_OP_DISCARD)1008 s->iop.bypass = true;1009 1010 if (should_writeback(dc, s->orig_bio,1011 cache_mode(dc),1012 s->iop.bypass)) {1013 s->iop.bypass = false;1014 s->iop.writeback = true;1015 }1016 1017 if (s->iop.bypass) {1018 s->iop.bio = s->orig_bio;1019 bio_get(s->iop.bio);1020 1021 if (bio_op(bio) == REQ_OP_DISCARD &&1022 !bdev_max_discard_sectors(dc->bdev))1023 goto insert_data;1024 1025 /* I/O request sent to backing device */1026 bio->bi_end_io = backing_request_endio;1027 closure_bio_submit(s->iop.c, bio, cl);1028 1029 } else if (s->iop.writeback) {1030 bch_writeback_add(dc);1031 s->iop.bio = bio;1032 1033 if (bio->bi_opf & REQ_PREFLUSH) {1034 /*1035 * Also need to send a flush to the backing1036 * device.1037 */1038 struct bio *flush;1039 1040 flush = bio_alloc_bioset(bio->bi_bdev, 0,1041 REQ_OP_WRITE | REQ_PREFLUSH,1042 GFP_NOIO, &dc->disk.bio_split);1043 if (!flush) {1044 s->iop.status = BLK_STS_RESOURCE;1045 goto insert_data;1046 }1047 flush->bi_end_io = backing_request_endio;1048 flush->bi_private = cl;1049 /* I/O request sent to backing device */1050 closure_bio_submit(s->iop.c, flush, cl);1051 }1052 } else {1053 s->iop.bio = bio_alloc_clone(bio->bi_bdev, bio, GFP_NOIO,1054 &dc->disk.bio_split);1055 /* I/O request sent to backing device */1056 bio->bi_end_io = backing_request_endio;1057 closure_bio_submit(s->iop.c, bio, cl);1058 }1059 1060insert_data:1061 closure_call(&s->iop.cl, bch_data_insert, NULL, cl);1062 continue_at(cl, cached_dev_write_complete, NULL);1063}1064 1065static CLOSURE_CALLBACK(cached_dev_nodata)1066{1067 closure_type(s, struct search, cl);1068 struct bio *bio = &s->bio.bio;1069 1070 if (s->iop.flush_journal)1071 bch_journal_meta(s->iop.c, cl);1072 1073 /* If it's a flush, we send the flush to the backing device too */1074 bio->bi_end_io = backing_request_endio;1075 closure_bio_submit(s->iop.c, bio, cl);1076 1077 continue_at(cl, cached_dev_bio_complete, NULL);1078}1079 1080struct detached_dev_io_private {1081 struct bcache_device *d;1082 unsigned long start_time;1083 bio_end_io_t *bi_end_io;1084 void *bi_private;1085 struct block_device *orig_bdev;1086};1087 1088static void detached_dev_end_io(struct bio *bio)1089{1090 struct detached_dev_io_private *ddip;1091 1092 ddip = bio->bi_private;1093 bio->bi_end_io = ddip->bi_end_io;1094 bio->bi_private = ddip->bi_private;1095 1096 /* Count on the bcache device */1097 bio_end_io_acct_remapped(bio, ddip->start_time, ddip->orig_bdev);1098 1099 if (bio->bi_status) {1100 struct cached_dev *dc = container_of(ddip->d,1101 struct cached_dev, disk);1102 /* should count I/O error for backing device here */1103 bch_count_backing_io_errors(dc, bio);1104 }1105 1106 kfree(ddip);1107 bio->bi_end_io(bio);1108}1109 1110static void detached_dev_do_request(struct bcache_device *d, struct bio *bio,1111 struct block_device *orig_bdev, unsigned long start_time)1112{1113 struct detached_dev_io_private *ddip;1114 struct cached_dev *dc = container_of(d, struct cached_dev, disk);1115 1116 /*1117 * no need to call closure_get(&dc->disk.cl),1118 * because upper layer had already opened bcache device,1119 * which would call closure_get(&dc->disk.cl)1120 */1121 ddip = kzalloc(sizeof(struct detached_dev_io_private), GFP_NOIO);1122 if (!ddip) {1123 bio->bi_status = BLK_STS_RESOURCE;1124 bio->bi_end_io(bio);1125 return;1126 }1127 1128 ddip->d = d;1129 /* Count on the bcache device */1130 ddip->orig_bdev = orig_bdev;1131 ddip->start_time = start_time;1132 ddip->bi_end_io = bio->bi_end_io;1133 ddip->bi_private = bio->bi_private;1134 bio->bi_end_io = detached_dev_end_io;1135 bio->bi_private = ddip;1136 1137 if ((bio_op(bio) == REQ_OP_DISCARD) &&1138 !bdev_max_discard_sectors(dc->bdev))1139 bio->bi_end_io(bio);1140 else1141 submit_bio_noacct(bio);1142}1143 1144static void quit_max_writeback_rate(struct cache_set *c,1145 struct cached_dev *this_dc)1146{1147 int i;1148 struct bcache_device *d;1149 struct cached_dev *dc;1150 1151 /*1152 * mutex bch_register_lock may compete with other parallel requesters,1153 * or attach/detach operations on other backing device. Waiting to1154 * the mutex lock may increase I/O request latency for seconds or more.1155 * To avoid such situation, if mutext_trylock() failed, only writeback1156 * rate of current cached device is set to 1, and __update_write_back()1157 * will decide writeback rate of other cached devices (remember now1158 * c->idle_counter is 0 already).1159 */1160 if (mutex_trylock(&bch_register_lock)) {1161 for (i = 0; i < c->devices_max_used; i++) {1162 if (!c->devices[i])1163 continue;1164 1165 if (UUID_FLASH_ONLY(&c->uuids[i]))1166 continue;1167 1168 d = c->devices[i];1169 dc = container_of(d, struct cached_dev, disk);1170 /*1171 * set writeback rate to default minimum value,1172 * then let update_writeback_rate() to decide the1173 * upcoming rate.1174 */1175 atomic_long_set(&dc->writeback_rate.rate, 1);1176 }1177 mutex_unlock(&bch_register_lock);1178 } else1179 atomic_long_set(&this_dc->writeback_rate.rate, 1);1180}1181 1182/* Cached devices - read & write stuff */1183 1184void cached_dev_submit_bio(struct bio *bio)1185{1186 struct search *s;1187 struct block_device *orig_bdev = bio->bi_bdev;1188 struct bcache_device *d = orig_bdev->bd_disk->private_data;1189 struct cached_dev *dc = container_of(d, struct cached_dev, disk);1190 unsigned long start_time;1191 int rw = bio_data_dir(bio);1192 1193 if (unlikely((d->c && test_bit(CACHE_SET_IO_DISABLE, &d->c->flags)) ||1194 dc->io_disable)) {1195 bio->bi_status = BLK_STS_IOERR;1196 bio_endio(bio);1197 return;1198 }1199 1200 if (likely(d->c)) {1201 if (atomic_read(&d->c->idle_counter))1202 atomic_set(&d->c->idle_counter, 0);1203 /*1204 * If at_max_writeback_rate of cache set is true and new I/O1205 * comes, quit max writeback rate of all cached devices1206 * attached to this cache set, and set at_max_writeback_rate1207 * to false.1208 */1209 if (unlikely(atomic_read(&d->c->at_max_writeback_rate) == 1)) {1210 atomic_set(&d->c->at_max_writeback_rate, 0);1211 quit_max_writeback_rate(d->c, dc);1212 }1213 }1214 1215 start_time = bio_start_io_acct(bio);1216 1217 bio_set_dev(bio, dc->bdev);1218 bio->bi_iter.bi_sector += dc->sb.data_offset;1219 1220 if (cached_dev_get(dc)) {1221 s = search_alloc(bio, d, orig_bdev, start_time);1222 trace_bcache_request_start(s->d, bio);1223 1224 if (!bio->bi_iter.bi_size) {1225 /*1226 * can't call bch_journal_meta from under1227 * submit_bio_noacct1228 */1229 continue_at_nobarrier(&s->cl,1230 cached_dev_nodata,1231 bcache_wq);1232 } else {1233 s->iop.bypass = check_should_bypass(dc, bio);1234 1235 if (rw)1236 cached_dev_write(dc, s);1237 else1238 cached_dev_read(dc, s);1239 }1240 } else1241 /* I/O request sent to backing device */1242 detached_dev_do_request(d, bio, orig_bdev, start_time);1243}1244 1245static int cached_dev_ioctl(struct bcache_device *d, blk_mode_t mode,1246 unsigned int cmd, unsigned long arg)1247{1248 struct cached_dev *dc = container_of(d, struct cached_dev, disk);1249 1250 if (dc->io_disable)1251 return -EIO;1252 if (!dc->bdev->bd_disk->fops->ioctl)1253 return -ENOTTY;1254 return dc->bdev->bd_disk->fops->ioctl(dc->bdev, mode, cmd, arg);1255}1256 1257void bch_cached_dev_request_init(struct cached_dev *dc)1258{1259 dc->disk.cache_miss = cached_dev_cache_miss;1260 dc->disk.ioctl = cached_dev_ioctl;1261}1262 1263/* Flash backed devices */1264 1265static int flash_dev_cache_miss(struct btree *b, struct search *s,1266 struct bio *bio, unsigned int sectors)1267{1268 unsigned int bytes = min(sectors, bio_sectors(bio)) << 9;1269 1270 swap(bio->bi_iter.bi_size, bytes);1271 zero_fill_bio(bio);1272 swap(bio->bi_iter.bi_size, bytes);1273 1274 bio_advance(bio, bytes);1275 1276 if (!bio->bi_iter.bi_size)1277 return MAP_DONE;1278 1279 return MAP_CONTINUE;1280}1281 1282static CLOSURE_CALLBACK(flash_dev_nodata)1283{1284 closure_type(s, struct search, cl);1285 1286 if (s->iop.flush_journal)1287 bch_journal_meta(s->iop.c, cl);1288 1289 continue_at(cl, search_free, NULL);1290}1291 1292void flash_dev_submit_bio(struct bio *bio)1293{1294 struct search *s;1295 struct closure *cl;1296 struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;1297 1298 if (unlikely(d->c && test_bit(CACHE_SET_IO_DISABLE, &d->c->flags))) {1299 bio->bi_status = BLK_STS_IOERR;1300 bio_endio(bio);1301 return;1302 }1303 1304 s = search_alloc(bio, d, bio->bi_bdev, bio_start_io_acct(bio));1305 cl = &s->cl;1306 bio = &s->bio.bio;1307 1308 trace_bcache_request_start(s->d, bio);1309 1310 if (!bio->bi_iter.bi_size) {1311 /*1312 * can't call bch_journal_meta from under submit_bio_noacct1313 */1314 continue_at_nobarrier(&s->cl,1315 flash_dev_nodata,1316 bcache_wq);1317 return;1318 } else if (bio_data_dir(bio)) {1319 bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys,1320 &KEY(d->id, bio->bi_iter.bi_sector, 0),1321 &KEY(d->id, bio_end_sector(bio), 0));1322 1323 s->iop.bypass = (bio_op(bio) == REQ_OP_DISCARD) != 0;1324 s->iop.writeback = true;1325 s->iop.bio = bio;1326 1327 closure_call(&s->iop.cl, bch_data_insert, NULL, cl);1328 } else {1329 closure_call(&s->iop.cl, cache_lookup, NULL, cl);1330 }1331 1332 continue_at(cl, search_free, NULL);1333}1334 1335static int flash_dev_ioctl(struct bcache_device *d, blk_mode_t mode,1336 unsigned int cmd, unsigned long arg)1337{1338 return -ENOTTY;1339}1340 1341void bch_flash_dev_request_init(struct bcache_device *d)1342{1343 d->cache_miss = flash_dev_cache_miss;1344 d->ioctl = flash_dev_ioctl;1345}1346 1347void bch_request_exit(void)1348{1349 kmem_cache_destroy(bch_search_cache);1350}1351 1352int __init bch_request_init(void)1353{1354 bch_search_cache = KMEM_CACHE(search, 0);1355 if (!bch_search_cache)1356 return -ENOMEM;1357 1358 return 0;1359}1360