--- /dev/null
+/*
+ * Main bcache entry point - handle a read or a write request and decide what to
+ * do with it; the make_request functions are called by the block layer.
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "request.h"
+#include "writeback.h"
+
+#include <linux/module.h>
+#include <linux/hash.h>
+#include <linux/random.h>
+
+#include <trace/events/bcache.h>
+
+#define CUTOFF_CACHE_ADD 95
+#define CUTOFF_CACHE_READA 90
+
+struct kmem_cache *bch_search_cache;
+
+static void bch_data_insert_start(struct closure *);
+
+static unsigned cache_mode(struct cached_dev *dc, struct bio *bio)
+{
+ return BDEV_CACHE_MODE(&dc->sb);
+}
+
+static bool verify(struct cached_dev *dc, struct bio *bio)
+{
+ return dc->verify;
+}
+
+static void bio_csum(struct bio *bio, struct bkey *k)
+{
+ struct bio_vec bv;
+ struct bvec_iter iter;
+ uint64_t csum = 0;
+
+ bio_for_each_segment(bv, bio, iter) {
+ void *d = kmap(bv.bv_page) + bv.bv_offset;
+ csum = bch_crc64_update(csum, d, bv.bv_len);
+ kunmap(bv.bv_page);
+ }
+
+ k->ptr[KEY_PTRS(k)] = csum & (~0ULL >> 1);
+}
+
+/* Insert data into cache */
+
+static void bch_data_insert_keys(struct closure *cl)
+{
+ struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
+ atomic_t *journal_ref = NULL;
+ struct bkey *replace_key = op->replace ? &op->replace_key : NULL;
+ int ret;
+
+ /*
+ * If we're looping, might already be waiting on
+ * another journal write - can't wait on more than one journal write at
+ * a time
+ *
+ * XXX: this looks wrong
+ */
+#if 0
+ while (atomic_read(&s->cl.remaining) & CLOSURE_WAITING)
+ closure_sync(&s->cl);
+#endif
+
+ if (!op->replace)
+ journal_ref = bch_journal(op->c, &op->insert_keys,
+ op->flush_journal ? cl : NULL);
+
+ ret = bch_btree_insert(op->c, &op->insert_keys,
+ journal_ref, replace_key);
+ if (ret == -ESRCH) {
+ op->replace_collision = true;
+ } else if (ret) {
+ op->error = -ENOMEM;
+ op->insert_data_done = true;
+ }
+
+ if (journal_ref)
+ atomic_dec_bug(journal_ref);
+
+ if (!op->insert_data_done)
+ continue_at(cl, bch_data_insert_start, op->wq);
+
+ bch_keylist_free(&op->insert_keys);
+ closure_return(cl);
+}
+
+static int bch_keylist_realloc(struct keylist *l, unsigned u64s,
+ struct cache_set *c)
+{
+ size_t oldsize = bch_keylist_nkeys(l);
+ size_t newsize = oldsize + u64s;
+
+ /*
+ * The journalling code doesn't handle the case where the keys to insert
+ * is bigger than an empty write: If we just return -ENOMEM here,
+ * bio_insert() and bio_invalidate() will insert the keys created so far
+ * and finish the rest when the keylist is empty.
+ */
+ if (newsize * sizeof(uint64_t) > block_bytes(c) - sizeof(struct jset))
+ return -ENOMEM;
+
+ return __bch_keylist_realloc(l, u64s);
+}
+
+static void bch_data_invalidate(struct closure *cl)
+{
+ struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
+ struct bio *bio = op->bio;
+
+ pr_debug("invalidating %i sectors from %llu",
+ bio_sectors(bio), (uint64_t) bio->bi_iter.bi_sector);
+
+ while (bio_sectors(bio)) {
+ unsigned sectors = min(bio_sectors(bio),
+ 1U << (KEY_SIZE_BITS - 1));
+
+ if (bch_keylist_realloc(&op->insert_keys, 2, op->c))
+ goto out;
+
+ bio->bi_iter.bi_sector += sectors;
+ bio->bi_iter.bi_size -= sectors << 9;
+
+ bch_keylist_add(&op->insert_keys,
+ &KEY(op->inode, bio->bi_iter.bi_sector, sectors));
+ }
+
+ op->insert_data_done = true;
+ bio_put(bio);
+out:
+ continue_at(cl, bch_data_insert_keys, op->wq);
+}
+
+static void bch_data_insert_error(struct closure *cl)
+{
+ struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
+
+ /*
+ * Our data write just errored, which means we've got a bunch of keys to
+ * insert that point to data that wasn't succesfully written.
+ *
+ * We don't have to insert those keys but we still have to invalidate
+ * that region of the cache - so, if we just strip off all the pointers
+ * from the keys we'll accomplish just that.
+ */
+
+ struct bkey *src = op->insert_keys.keys, *dst = op->insert_keys.keys;
+
+ while (src != op->insert_keys.top) {
+ struct bkey *n = bkey_next(src);
+
+ SET_KEY_PTRS(src, 0);
+ memmove(dst, src, bkey_bytes(src));
+
+ dst = bkey_next(dst);
+ src = n;
+ }
+
+ op->insert_keys.top = dst;
+
+ bch_data_insert_keys(cl);
+}
+
+static void bch_data_insert_endio(struct bio *bio, int error)
+{
+ struct closure *cl = bio->bi_private;
+ struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
+
+ if (error) {
+ /* TODO: We could try to recover from this. */
+ if (op->writeback)
+ op->error = error;
+ else if (!op->replace)
+ set_closure_fn(cl, bch_data_insert_error, op->wq);
+ else
+ set_closure_fn(cl, NULL, NULL);
+ }
+
+ bch_bbio_endio(op->c, bio, error, "writing data to cache");
+}
+
+static void bch_data_insert_start(struct closure *cl)
+{
+ struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
+ struct bio *bio = op->bio, *n;
+
+ if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
+ set_gc_sectors(op->c);
+ wake_up_gc(op->c);
+ }
+
+ if (op->bypass)
+ return bch_data_invalidate(cl);
+
+ /*
+ * Journal writes are marked REQ_FLUSH; if the original write was a
+ * flush, it'll wait on the journal write.
+ */
+ bio->bi_rw &= ~(REQ_FLUSH|REQ_FUA);
+
+ do {
+ unsigned i;
+ struct bkey *k;
+ struct bio_set *split = op->c->bio_split;
+
+ /* 1 for the device pointer and 1 for the chksum */
+ if (bch_keylist_realloc(&op->insert_keys,
+ 3 + (op->csum ? 1 : 0),
+ op->c))
+ continue_at(cl, bch_data_insert_keys, op->wq);
+
+ k = op->insert_keys.top;
+ bkey_init(k);
+ SET_KEY_INODE(k, op->inode);
+ SET_KEY_OFFSET(k, bio->bi_iter.bi_sector);
+
+ if (!bch_alloc_sectors(op->c, k, bio_sectors(bio),
+ op->write_point, op->write_prio,
+ op->writeback))
+ goto err;
+
+ n = bio_next_split(bio, KEY_SIZE(k), GFP_NOIO, split);
+
+ n->bi_end_io = bch_data_insert_endio;
+ n->bi_private = cl;
+
+ if (op->writeback) {
+ SET_KEY_DIRTY(k, true);
+
+ for (i = 0; i < KEY_PTRS(k); i++)
+ SET_GC_MARK(PTR_BUCKET(op->c, k, i),
+ GC_MARK_DIRTY);
+ }
+
+ SET_KEY_CSUM(k, op->csum);
+ if (KEY_CSUM(k))
+ bio_csum(n, k);
+
+ trace_bcache_cache_insert(k);
+ bch_keylist_push(&op->insert_keys);
+
+ n->bi_rw |= REQ_WRITE;
+ bch_submit_bbio(n, op->c, k, 0);
+ } while (n != bio);
+
+ op->insert_data_done = true;
+ continue_at(cl, bch_data_insert_keys, op->wq);
+err:
+ /* bch_alloc_sectors() blocks if s->writeback = true */
+ BUG_ON(op->writeback);
+
+ /*
+ * But if it's not a writeback write we'd rather just bail out if
+ * there aren't any buckets ready to write to - it might take awhile and
+ * we might be starving btree writes for gc or something.
+ */
+
+ if (!op->replace) {
+ /*
+ * Writethrough write: We can't complete the write until we've
+ * updated the index. But we don't want to delay the write while
+ * we wait for buckets to be freed up, so just invalidate the
+ * rest of the write.
+ */
+ op->bypass = true;
+ return bch_data_invalidate(cl);
+ } else {
+ /*
+ * From a cache miss, we can just insert the keys for the data
+ * we have written or bail out if we didn't do anything.
+ */
+ op->insert_data_done = true;
+ bio_put(bio);
+
+ if (!bch_keylist_empty(&op->insert_keys))
+ continue_at(cl, bch_data_insert_keys, op->wq);
+ else
+ closure_return(cl);
+ }
+}
+
+/**
+ * bch_data_insert - stick some data in the cache
+ *
+ * This is the starting point for any data to end up in a cache device; it could
+ * be from a normal write, or a writeback write, or a write to a flash only
+ * volume - it's also used by the moving garbage collector to compact data in
+ * mostly empty buckets.
+ *
+ * It first writes the data to the cache, creating a list of keys to be inserted
+ * (if the data had to be fragmented there will be multiple keys); after the
+ * data is written it calls bch_journal, and after the keys have been added to
+ * the next journal write they're inserted into the btree.
+ *
+ * It inserts the data in s->cache_bio; bi_sector is used for the key offset,
+ * and op->inode is used for the key inode.
+ *
+ * If s->bypass is true, instead of inserting the data it invalidates the
+ * region of the cache represented by s->cache_bio and op->inode.
+ */
+void bch_data_insert(struct closure *cl)
+{
+ struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
+
+ trace_bcache_write(op->c, op->inode, op->bio,
+ op->writeback, op->bypass);
+
+ bch_keylist_init(&op->insert_keys);
+ bio_get(op->bio);
+ bch_data_insert_start(cl);
+}
+
+/* Congested? */
+
+unsigned bch_get_congested(struct cache_set *c)
+{
+ int i;
+ long rand;
+
+ if (!c->congested_read_threshold_us &&
+ !c->congested_write_threshold_us)
+ return 0;
+
+ i = (local_clock_us() - c->congested_last_us) / 1024;
+ if (i < 0)
+ return 0;
+
+ i += atomic_read(&c->congested);
+ if (i >= 0)
+ return 0;
+
+ i += CONGESTED_MAX;
+
+ if (i > 0)
+ i = fract_exp_two(i, 6);
+
+ rand = get_random_int();
+ i -= bitmap_weight(&rand, BITS_PER_LONG);
+
+ return i > 0 ? i : 1;
+}
+
+static void add_sequential(struct task_struct *t)
+{
+ ewma_add(t->sequential_io_avg,
+ t->sequential_io, 8, 0);
+
+ t->sequential_io = 0;
+}
+
+static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
+{
+ return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
+}
+
+static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
+{
+ struct cache_set *c = dc->disk.c;
+ unsigned mode = cache_mode(dc, bio);
+ unsigned sectors, congested = bch_get_congested(c);
+ struct task_struct *task = current;
+ struct io *i;
+
+ if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
+ c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
+ (bio->bi_rw & REQ_DISCARD))
+ goto skip;
+
+ if (mode == CACHE_MODE_NONE ||
+ (mode == CACHE_MODE_WRITEAROUND &&
+ (bio->bi_rw & REQ_WRITE)))
+ goto skip;
+
+ if (bio->bi_iter.bi_sector & (c->sb.block_size - 1) ||
+ bio_sectors(bio) & (c->sb.block_size - 1)) {
+ pr_debug("skipping unaligned io");
+ goto skip;
+ }
+
+ if (bypass_torture_test(dc)) {
+ if ((get_random_int() & 3) == 3)
+ goto skip;
+ else
+ goto rescale;
+ }
+
+ if (!congested && !dc->sequential_cutoff)
+ goto rescale;
+
+ if (!congested &&
+ mode == CACHE_MODE_WRITEBACK &&
+ (bio->bi_rw & REQ_WRITE) &&
+ (bio->bi_rw & REQ_SYNC))
+ goto rescale;
+
+ spin_lock(&dc->io_lock);
+
+ hlist_for_each_entry(i, iohash(dc, bio->bi_iter.bi_sector), hash)
+ if (i->last == bio->bi_iter.bi_sector &&
+ time_before(jiffies, i->jiffies))
+ goto found;
+
+ i = list_first_entry(&dc->io_lru, struct io, lru);
+
+ add_sequential(task);
+ i->sequential = 0;
+found:
+ if (i->sequential + bio->bi_iter.bi_size > i->sequential)
+ i->sequential += bio->bi_iter.bi_size;
+
+ i->last = bio_end_sector(bio);
+ i->jiffies = jiffies + msecs_to_jiffies(5000);
+ task->sequential_io = i->sequential;
+
+ hlist_del(&i->hash);
+ hlist_add_head(&i->hash, iohash(dc, i->last));
+ list_move_tail(&i->lru, &dc->io_lru);
+
+ spin_unlock(&dc->io_lock);
+
+ sectors = max(task->sequential_io,
+ task->sequential_io_avg) >> 9;
+
+ if (dc->sequential_cutoff &&
+ sectors >= dc->sequential_cutoff >> 9) {
+ trace_bcache_bypass_sequential(bio);
+ goto skip;
+ }
+
+ if (congested && sectors >= congested) {
+ trace_bcache_bypass_congested(bio);
+ goto skip;
+ }
+
+rescale:
+ bch_rescale_priorities(c, bio_sectors(bio));
+ return false;
+skip:
+ bch_mark_sectors_bypassed(c, dc, bio_sectors(bio));
+ return true;
+}
+
+/* Cache lookup */
+
+struct search {
+ /* Stack frame for bio_complete */
+ struct closure cl;
+
+ struct bbio bio;
+ struct bio *orig_bio;
+ struct bio *cache_miss;
+ struct bcache_device *d;
+
+ unsigned insert_bio_sectors;
+ unsigned recoverable:1;
+ unsigned write:1;
+ unsigned read_dirty_data:1;
+
+ unsigned long start_time;
+
+ struct btree_op op;
+ struct data_insert_op iop;
+};
+
+static void bch_cache_read_endio(struct bio *bio, int error)
+{
+ struct bbio *b = container_of(bio, struct bbio, bio);
+ struct closure *cl = bio->bi_private;
+ struct search *s = container_of(cl, struct search, cl);
+
+ /*
+ * If the bucket was reused while our bio was in flight, we might have
+ * read the wrong data. Set s->error but not error so it doesn't get
+ * counted against the cache device, but we'll still reread the data
+ * from the backing device.
+ */
+
+ if (error)
+ s->iop.error = error;
+ else if (!KEY_DIRTY(&b->key) &&
+ ptr_stale(s->iop.c, &b->key, 0)) {
+ atomic_long_inc(&s->iop.c->cache_read_races);
+ s->iop.error = -EINTR;
+ }
+
+ bch_bbio_endio(s->iop.c, bio, error, "reading from cache");
+}
+
+/*
+ * Read from a single key, handling the initial cache miss if the key starts in
+ * the middle of the bio
+ */
+static int cache_lookup_fn(struct btree_op *op, struct btree *b, struct bkey *k)
+{
+ struct search *s = container_of(op, struct search, op);
+ struct bio *n, *bio = &s->bio.bio;
+ struct bkey *bio_key;
+ unsigned ptr;
+
+ if (bkey_cmp(k, &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0)) <= 0)
+ return MAP_CONTINUE;
+
+ if (KEY_INODE(k) != s->iop.inode ||
+ KEY_START(k) > bio->bi_iter.bi_sector) {
+ unsigned bio_sectors = bio_sectors(bio);
+ unsigned sectors = KEY_INODE(k) == s->iop.inode
+ ? min_t(uint64_t, INT_MAX,
+ KEY_START(k) - bio->bi_iter.bi_sector)
+ : INT_MAX;
+
+ int ret = s->d->cache_miss(b, s, bio, sectors);
+ if (ret != MAP_CONTINUE)
+ return ret;
+
+ /* if this was a complete miss we shouldn't get here */
+ BUG_ON(bio_sectors <= sectors);
+ }
+
+ if (!KEY_SIZE(k))
+ return MAP_CONTINUE;
+
+ /* XXX: figure out best pointer - for multiple cache devices */
+ ptr = 0;
+
+ PTR_BUCKET(b->c, k, ptr)->prio = INITIAL_PRIO;
+
+ if (KEY_DIRTY(k))
+ s->read_dirty_data = true;
+
+ n = bio_next_split(bio, min_t(uint64_t, INT_MAX,
+ KEY_OFFSET(k) - bio->bi_iter.bi_sector),
+ GFP_NOIO, s->d->bio_split);
+
+ bio_key = &container_of(n, struct bbio, bio)->key;
+ bch_bkey_copy_single_ptr(bio_key, k, ptr);
+
+ bch_cut_front(&KEY(s->iop.inode, n->bi_iter.bi_sector, 0), bio_key);
+ bch_cut_back(&KEY(s->iop.inode, bio_end_sector(n), 0), bio_key);
+
+ n->bi_end_io = bch_cache_read_endio;
+ n->bi_private = &s->cl;
+
+ /*
+ * The bucket we're reading from might be reused while our bio
+ * is in flight, and we could then end up reading the wrong
+ * data.
+ *
+ * We guard against this by checking (in cache_read_endio()) if
+ * the pointer is stale again; if so, we treat it as an error
+ * and reread from the backing device (but we don't pass that
+ * error up anywhere).
+ */
+
+ __bch_submit_bbio(n, b->c);
+ return n == bio ? MAP_DONE : MAP_CONTINUE;
+}
+
+static void cache_lookup(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, iop.cl);
+ struct bio *bio = &s->bio.bio;
+ int ret;
+
+ bch_btree_op_init(&s->op, -1);
+
+ ret = bch_btree_map_keys(&s->op, s->iop.c,
+ &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0),
+ cache_lookup_fn, MAP_END_KEY);
+ if (ret == -EAGAIN)
+ continue_at(cl, cache_lookup, bcache_wq);
+
+ closure_return(cl);
+}
+
+/* Common code for the make_request functions */
+
+static void request_endio(struct bio *bio, int error)
+{
+ struct closure *cl = bio->bi_private;
+
+ if (error) {
+ struct search *s = container_of(cl, struct search, cl);
+ s->iop.error = error;
+ /* Only cache read errors are recoverable */
+ s->recoverable = false;
+ }
+
+ bio_put(bio);
+ closure_put(cl);
+}
+
+static void bio_complete(struct search *s)
+{
+ if (s->orig_bio) {
+ generic_end_io_acct(bio_data_dir(s->orig_bio),
+ &s->d->disk->part0, s->start_time);
+
+ trace_bcache_request_end(s->d, s->orig_bio);
+ bio_endio(s->orig_bio, s->iop.error);
+ s->orig_bio = NULL;
+ }
+}
+
+static void do_bio_hook(struct search *s, struct bio *orig_bio)
+{
+ struct bio *bio = &s->bio.bio;
+
+ bio_init(bio);
+ __bio_clone_fast(bio, orig_bio);
+ bio->bi_end_io = request_endio;
+ bio->bi_private = &s->cl;
+
+ atomic_set(&bio->bi_cnt, 3);
+}
+
+static void search_free(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ bio_complete(s);
+
+ if (s->iop.bio)
+ bio_put(s->iop.bio);
+
+ closure_debug_destroy(cl);
+ mempool_free(s, s->d->c->search);
+}
+
+static inline struct search *search_alloc(struct bio *bio,
+ struct bcache_device *d)
+{
+ struct search *s;
+
+ s = mempool_alloc(d->c->search, GFP_NOIO);
+
+ closure_init(&s->cl, NULL);
+ do_bio_hook(s, bio);
+
+ s->orig_bio = bio;
+ s->cache_miss = NULL;
+ s->d = d;
+ s->recoverable = 1;
+ s->write = (bio->bi_rw & REQ_WRITE) != 0;
+ s->read_dirty_data = 0;
+ s->start_time = jiffies;
+
+ s->iop.c = d->c;
+ s->iop.bio = NULL;
+ s->iop.inode = d->id;
+ s->iop.write_point = hash_long((unsigned long) current, 16);
+ s->iop.write_prio = 0;
+ s->iop.error = 0;
+ s->iop.flags = 0;
+ s->iop.flush_journal = (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
+ s->iop.wq = bcache_wq;
+
+ return s;
+}
+
+/* Cached devices */
+
+static void cached_dev_bio_complete(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+
+ search_free(cl);
+ cached_dev_put(dc);
+}
+
+/* Process reads */
+
+static void cached_dev_cache_miss_done(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+
+ if (s->iop.replace_collision)
+ bch_mark_cache_miss_collision(s->iop.c, s->d);
+
+ if (s->iop.bio) {
+ int i;
+ struct bio_vec *bv;
+
+ bio_for_each_segment_all(bv, s->iop.bio, i)
+ __free_page(bv->bv_page);
+ }
+
+ cached_dev_bio_complete(cl);
+}
+
+static void cached_dev_read_error(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct bio *bio = &s->bio.bio;
+
+ if (s->recoverable) {
+ /* Retry from the backing device: */
+ trace_bcache_read_retry(s->orig_bio);
+
+ s->iop.error = 0;
+ do_bio_hook(s, s->orig_bio);
+
+ /* XXX: invalidate cache */
+
+ closure_bio_submit(bio, cl, s->d);
+ }
+
+ continue_at(cl, cached_dev_cache_miss_done, NULL);
+}
+
+static void cached_dev_read_done(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+
+ /*
+ * We had a cache miss; cache_bio now contains data ready to be inserted
+ * into the cache.
+ *
+ * First, we copy the data we just read from cache_bio's bounce buffers
+ * to the buffers the original bio pointed to:
+ */
+
+ if (s->iop.bio) {
+ bio_reset(s->iop.bio);
+ s->iop.bio->bi_iter.bi_sector = s->cache_miss->bi_iter.bi_sector;
+ s->iop.bio->bi_bdev = s->cache_miss->bi_bdev;
+ s->iop.bio->bi_iter.bi_size = s->insert_bio_sectors << 9;
+ bch_bio_map(s->iop.bio, NULL);
+
+ bio_copy_data(s->cache_miss, s->iop.bio);
+
+ bio_put(s->cache_miss);
+ s->cache_miss = NULL;
+ }
+
+ if (verify(dc, &s->bio.bio) && s->recoverable && !s->read_dirty_data)
+ bch_data_verify(dc, s->orig_bio);
+
+ bio_complete(s);
+
+ if (s->iop.bio &&
+ !test_bit(CACHE_SET_STOPPING, &s->iop.c->flags)) {
+ BUG_ON(!s->iop.replace);
+ closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
+ }
+
+ continue_at(cl, cached_dev_cache_miss_done, NULL);
+}
+
+static void cached_dev_read_done_bh(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+
+ bch_mark_cache_accounting(s->iop.c, s->d,
+ !s->cache_miss, s->iop.bypass);
+ trace_bcache_read(s->orig_bio, !s->cache_miss, s->iop.bypass);
+
+ if (s->iop.error)
+ continue_at_nobarrier(cl, cached_dev_read_error, bcache_wq);
+ else if (s->iop.bio || verify(dc, &s->bio.bio))
+ continue_at_nobarrier(cl, cached_dev_read_done, bcache_wq);
+ else
+ continue_at_nobarrier(cl, cached_dev_bio_complete, NULL);
+}
+
+static int cached_dev_cache_miss(struct btree *b, struct search *s,
+ struct bio *bio, unsigned sectors)
+{
+ int ret = MAP_CONTINUE;
+ unsigned reada = 0;
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+ struct bio *miss, *cache_bio;
+
+ if (s->cache_miss || s->iop.bypass) {
+ miss = bio_next_split(bio, sectors, GFP_NOIO, s->d->bio_split);
+ ret = miss == bio ? MAP_DONE : MAP_CONTINUE;
+ goto out_submit;
+ }
+
+ if (!(bio->bi_rw & REQ_RAHEAD) &&
+ !(bio->bi_rw & REQ_META) &&
+ s->iop.c->gc_stats.in_use < CUTOFF_CACHE_READA)
+ reada = min_t(sector_t, dc->readahead >> 9,
+ bdev_sectors(bio->bi_bdev) - bio_end_sector(bio));
+
+ s->insert_bio_sectors = min(sectors, bio_sectors(bio) + reada);
+
+ s->iop.replace_key = KEY(s->iop.inode,
+ bio->bi_iter.bi_sector + s->insert_bio_sectors,
+ s->insert_bio_sectors);
+
+ ret = bch_btree_insert_check_key(b, &s->op, &s->iop.replace_key);
+ if (ret)
+ return ret;
+
+ s->iop.replace = true;
+
+ miss = bio_next_split(bio, sectors, GFP_NOIO, s->d->bio_split);
+
+ /* btree_search_recurse()'s btree iterator is no good anymore */
+ ret = miss == bio ? MAP_DONE : -EINTR;
+
+ cache_bio = bio_alloc_bioset(GFP_NOWAIT,
+ DIV_ROUND_UP(s->insert_bio_sectors, PAGE_SECTORS),
+ dc->disk.bio_split);
+ if (!cache_bio)
+ goto out_submit;
+
+ cache_bio->bi_iter.bi_sector = miss->bi_iter.bi_sector;
+ cache_bio->bi_bdev = miss->bi_bdev;
+ cache_bio->bi_iter.bi_size = s->insert_bio_sectors << 9;
+
+ cache_bio->bi_end_io = request_endio;
+ cache_bio->bi_private = &s->cl;
+
+ bch_bio_map(cache_bio, NULL);
+ if (bio_alloc_pages(cache_bio, __GFP_NOWARN|GFP_NOIO))
+ goto out_put;
+
+ if (reada)
+ bch_mark_cache_readahead(s->iop.c, s->d);
+
+ s->cache_miss = miss;
+ s->iop.bio = cache_bio;
+ bio_get(cache_bio);
+ closure_bio_submit(cache_bio, &s->cl, s->d);
+
+ return ret;
+out_put:
+ bio_put(cache_bio);
+out_submit:
+ miss->bi_end_io = request_endio;
+ miss->bi_private = &s->cl;
+ closure_bio_submit(miss, &s->cl, s->d);
+ return ret;
+}
+
+static void cached_dev_read(struct cached_dev *dc, struct search *s)
+{
+ struct closure *cl = &s->cl;
+
+ closure_call(&s->iop.cl, cache_lookup, NULL, cl);
+ continue_at(cl, cached_dev_read_done_bh, NULL);
+}
+
+/* Process writes */
+
+static void cached_dev_write_complete(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+
+ up_read_non_owner(&dc->writeback_lock);
+ cached_dev_bio_complete(cl);
+}
+
+static void cached_dev_write(struct cached_dev *dc, struct search *s)
+{
+ struct closure *cl = &s->cl;
+ struct bio *bio = &s->bio.bio;
+ struct bkey start = KEY(dc->disk.id, bio->bi_iter.bi_sector, 0);
+ struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0);
+
+ bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys, &start, &end);
+
+ down_read_non_owner(&dc->writeback_lock);
+ if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) {
+ /*
+ * We overlap with some dirty data undergoing background
+ * writeback, force this write to writeback
+ */
+ s->iop.bypass = false;
+ s->iop.writeback = true;
+ }
+
+ /*
+ * Discards aren't _required_ to do anything, so skipping if
+ * check_overlapping returned true is ok
+ *
+ * But check_overlapping drops dirty keys for which io hasn't started,
+ * so we still want to call it.
+ */
+ if (bio->bi_rw & REQ_DISCARD)
+ s->iop.bypass = true;
+
+ if (should_writeback(dc, s->orig_bio,
+ cache_mode(dc, bio),
+ s->iop.bypass)) {
+ s->iop.bypass = false;
+ s->iop.writeback = true;
+ }
+
+ if (s->iop.bypass) {
+ s->iop.bio = s->orig_bio;
+ bio_get(s->iop.bio);
+
+ if (!(bio->bi_rw & REQ_DISCARD) ||
+ blk_queue_discard(bdev_get_queue(dc->bdev)))
+ closure_bio_submit(bio, cl, s->d);
+ } else if (s->iop.writeback) {
+ bch_writeback_add(dc);
+ s->iop.bio = bio;
+
+ if (bio->bi_rw & REQ_FLUSH) {
+ /* Also need to send a flush to the backing device */
+ struct bio *flush = bio_alloc_bioset(GFP_NOIO, 0,
+ dc->disk.bio_split);
+
+ flush->bi_rw = WRITE_FLUSH;
+ flush->bi_bdev = bio->bi_bdev;
+ flush->bi_end_io = request_endio;
+ flush->bi_private = cl;
+
+ closure_bio_submit(flush, cl, s->d);
+ }
+ } else {
+ s->iop.bio = bio_clone_fast(bio, GFP_NOIO, dc->disk.bio_split);
+
+ closure_bio_submit(bio, cl, s->d);
+ }
+
+ closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
+ continue_at(cl, cached_dev_write_complete, NULL);
+}
+
+static void cached_dev_nodata(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct bio *bio = &s->bio.bio;
+
+ if (s->iop.flush_journal)
+ bch_journal_meta(s->iop.c, cl);
+
+ /* If it's a flush, we send the flush to the backing device too */
+ closure_bio_submit(bio, cl, s->d);
+
+ continue_at(cl, cached_dev_bio_complete, NULL);
+}
+
+/* Cached devices - read & write stuff */
+
+static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
+{
+ struct search *s;
+ struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
+ struct cached_dev *dc = container_of(d, struct cached_dev, disk);
+ int rw = bio_data_dir(bio);
+
+ generic_start_io_acct(rw, bio_sectors(bio), &d->disk->part0);
+
+ bio->bi_bdev = dc->bdev;
+ bio->bi_iter.bi_sector += dc->sb.data_offset;
+
+ if (cached_dev_get(dc)) {
+ s = search_alloc(bio, d);
+ trace_bcache_request_start(s->d, bio);
+
+ if (!bio->bi_iter.bi_size) {
+ /*
+ * can't call bch_journal_meta from under
+ * generic_make_request
+ */
+ continue_at_nobarrier(&s->cl,
+ cached_dev_nodata,
+ bcache_wq);
+ } else {
+ s->iop.bypass = check_should_bypass(dc, bio);
+
+ if (rw)
+ cached_dev_write(dc, s);
+ else
+ cached_dev_read(dc, s);
+ }
+ } else {
+ if ((bio->bi_rw & REQ_DISCARD) &&
+ !blk_queue_discard(bdev_get_queue(dc->bdev)))
+ bio_endio(bio, 0);
+ else
+ bch_generic_make_request(bio, &d->bio_split_hook);
+ }
+}
+
+static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode,
+ unsigned int cmd, unsigned long arg)
+{
+ struct cached_dev *dc = container_of(d, struct cached_dev, disk);
+ return __blkdev_driver_ioctl(dc->bdev, mode, cmd, arg);
+}
+
+static int cached_dev_congested(void *data, int bits)
+{
+ struct bcache_device *d = data;
+ struct cached_dev *dc = container_of(d, struct cached_dev, disk);
+ struct request_queue *q = bdev_get_queue(dc->bdev);
+ int ret = 0;
+
+ if (bdi_congested(&q->backing_dev_info, bits))
+ return 1;
+
+ if (cached_dev_get(dc)) {
+ unsigned i;
+ struct cache *ca;
+
+ for_each_cache(ca, d->c, i) {
+ q = bdev_get_queue(ca->bdev);
+ ret |= bdi_congested(&q->backing_dev_info, bits);
+ }
+
+ cached_dev_put(dc);
+ }
+
+ return ret;
+}
+
+void bch_cached_dev_request_init(struct cached_dev *dc)
+{
+ struct gendisk *g = dc->disk.disk;
+
+ g->queue->make_request_fn = cached_dev_make_request;
+ g->queue->backing_dev_info.congested_fn = cached_dev_congested;
+ dc->disk.cache_miss = cached_dev_cache_miss;
+ dc->disk.ioctl = cached_dev_ioctl;
+}
+
+/* Flash backed devices */
+
+static int flash_dev_cache_miss(struct btree *b, struct search *s,
+ struct bio *bio, unsigned sectors)
+{
+ unsigned bytes = min(sectors, bio_sectors(bio)) << 9;
+
+ swap(bio->bi_iter.bi_size, bytes);
+ zero_fill_bio(bio);
+ swap(bio->bi_iter.bi_size, bytes);
+
+ bio_advance(bio, bytes);
+
+ if (!bio->bi_iter.bi_size)
+ return MAP_DONE;
+
+ return MAP_CONTINUE;
+}
+
+static void flash_dev_nodata(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+
+ if (s->iop.flush_journal)
+ bch_journal_meta(s->iop.c, cl);
+
+ continue_at(cl, search_free, NULL);
+}
+
+static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
+{
+ struct search *s;
+ struct closure *cl;
+ struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
+ int rw = bio_data_dir(bio);
+
+ generic_start_io_acct(rw, bio_sectors(bio), &d->disk->part0);
+
+ s = search_alloc(bio, d);
+ cl = &s->cl;
+ bio = &s->bio.bio;
+
+ trace_bcache_request_start(s->d, bio);
+
+ if (!bio->bi_iter.bi_size) {
+ /*
+ * can't call bch_journal_meta from under
+ * generic_make_request
+ */
+ continue_at_nobarrier(&s->cl,
+ flash_dev_nodata,
+ bcache_wq);
+ } else if (rw) {
+ bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys,
+ &KEY(d->id, bio->bi_iter.bi_sector, 0),
+ &KEY(d->id, bio_end_sector(bio), 0));
+
+ s->iop.bypass = (bio->bi_rw & REQ_DISCARD) != 0;
+ s->iop.writeback = true;
+ s->iop.bio = bio;
+
+ closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
+ } else {
+ closure_call(&s->iop.cl, cache_lookup, NULL, cl);
+ }
+
+ continue_at(cl, search_free, NULL);
+}
+
+static int flash_dev_ioctl(struct bcache_device *d, fmode_t mode,
+ unsigned int cmd, unsigned long arg)
+{
+ return -ENOTTY;
+}
+
+static int flash_dev_congested(void *data, int bits)
+{
+ struct bcache_device *d = data;
+ struct request_queue *q;
+ struct cache *ca;
+ unsigned i;
+ int ret = 0;
+
+ for_each_cache(ca, d->c, i) {
+ q = bdev_get_queue(ca->bdev);
+ ret |= bdi_congested(&q->backing_dev_info, bits);
+ }
+
+ return ret;
+}
+
+void bch_flash_dev_request_init(struct bcache_device *d)
+{
+ struct gendisk *g = d->disk;
+
+ g->queue->make_request_fn = flash_dev_make_request;
+ g->queue->backing_dev_info.congested_fn = flash_dev_congested;
+ d->cache_miss = flash_dev_cache_miss;
+ d->ioctl = flash_dev_ioctl;
+}
+
+void bch_request_exit(void)
+{
+ if (bch_search_cache)
+ kmem_cache_destroy(bch_search_cache);
+}
+
+int __init bch_request_init(void)
+{
+ bch_search_cache = KMEM_CACHE(search, 0);
+ if (!bch_search_cache)
+ return -ENOMEM;
+
+ return 0;
+}
Code Review / kvmfornfv.git / blobdiff