struct kmem_cache *bch_search_cache;
-static void check_should_skip(struct cached_dev *, struct search *);
-
/* Cgroup interface */
#ifdef CONFIG_CGROUP_BCACHE
struct search *s = container_of(op, struct search, op);
struct bio *bio = op->cache_bio, *n;
- if (op->skip)
+ if (op->bypass)
return bio_invalidate(cl);
if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
* we wait for buckets to be freed up, so just invalidate the
* rest of the write.
*/
- op->skip = true;
+ op->bypass = true;
return bio_invalidate(cl);
} else {
/*
* It inserts the data in op->cache_bio; bi_sector is used for the key offset,
* and op->inode is used for the key inode.
*
- * If op->skip is true, instead of inserting the data it invalidates the region
- * of the cache represented by op->cache_bio and op->inode.
+ * If op->bypass is true, instead of inserting the data it invalidates the
+ * region of the cache represented by op->cache_bio and op->inode.
*/
void bch_insert_data(struct closure *cl)
{
s->orig_bio = bio;
s->write = (bio->bi_rw & REQ_WRITE) != 0;
s->op.flush_journal = (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
- s->op.skip = (bio->bi_rw & REQ_DISCARD) != 0;
s->recoverable = 1;
s->start_time = jiffies;
do_bio_hook(s);
cached_dev_put(dc);
}
+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 search *s)
+{
+ struct cache_set *c = s->op.c;
+ struct bio *bio = &s->bio.bio;
+ unsigned mode = cache_mode(dc, bio);
+ unsigned sectors, congested = bch_get_congested(c);
+
+ if (atomic_read(&dc->disk.detaching) ||
+ 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_sector & (c->sb.block_size - 1) ||
+ bio_sectors(bio) & (c->sb.block_size - 1)) {
+ pr_debug("skipping unaligned io");
+ goto skip;
+ }
+
+ 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;
+
+ if (dc->sequential_merge) {
+ struct io *i;
+
+ spin_lock(&dc->io_lock);
+
+ hlist_for_each_entry(i, iohash(dc, bio->bi_sector), hash)
+ if (i->last == bio->bi_sector &&
+ time_before(jiffies, i->jiffies))
+ goto found;
+
+ i = list_first_entry(&dc->io_lru, struct io, lru);
+
+ add_sequential(s->task);
+ i->sequential = 0;
+found:
+ if (i->sequential + bio->bi_size > i->sequential)
+ i->sequential += bio->bi_size;
+
+ i->last = bio_end_sector(bio);
+ i->jiffies = jiffies + msecs_to_jiffies(5000);
+ s->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);
+ } else {
+ s->task->sequential_io = bio->bi_size;
+
+ add_sequential(s->task);
+ }
+
+ sectors = max(s->task->sequential_io,
+ s->task->sequential_io_avg) >> 9;
+
+ if (dc->sequential_cutoff &&
+ sectors >= dc->sequential_cutoff >> 9) {
+ trace_bcache_bypass_sequential(s->orig_bio);
+ goto skip;
+ }
+
+ if (congested && sectors >= congested) {
+ trace_bcache_bypass_congested(s->orig_bio);
+ goto skip;
+ }
+
+rescale:
+ bch_rescale_priorities(c, bio_sectors(bio));
+ return false;
+skip:
+ bch_mark_sectors_bypassed(s, bio_sectors(bio));
+ return true;
+}
+
/* Process reads */
static void cached_dev_read_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);
- bch_mark_cache_accounting(s, !s->cache_miss, s->op.skip);
- trace_bcache_read(s->orig_bio, !s->cache_miss, s->op.skip);
+ bch_mark_cache_accounting(s, !s->cache_miss, s->op.bypass);
+ trace_bcache_read(s->orig_bio, !s->cache_miss, s->op.bypass);
if (s->error)
continue_at_nobarrier(cl, request_read_error, bcache_wq);
struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
struct bio *miss;
- if (s->cache_miss || s->op.skip) {
+ if (s->cache_miss || s->op.bypass) {
miss = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
if (miss == bio)
s->op.lookup_done = true;
{
struct closure *cl = &s->cl;
- check_should_skip(dc, s);
closure_call(&s->op.cl, btree_read_async, NULL, cl);
-
continue_at(cl, request_read_done_bh, NULL);
}
{
struct closure *cl = &s->cl;
struct bio *bio = &s->bio.bio;
- struct bkey start, end;
- start = KEY(dc->disk.id, bio->bi_sector, 0);
- end = KEY(dc->disk.id, bio_end_sector(bio), 0);
+ struct bkey start = KEY(dc->disk.id, bio->bi_sector, 0);
+ struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0);
bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys, &start, &end);
- check_should_skip(dc, s);
down_read_non_owner(&dc->writeback_lock);
-
if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) {
- s->op.skip = false;
+ /*
+ * We overlap with some dirty data undergoing background
+ * writeback, force this write to writeback
+ */
+ s->op.bypass = false;
s->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)
- goto skip;
+ s->op.bypass = true;
if (should_writeback(dc, s->orig_bio,
cache_mode(dc, bio),
- s->op.skip)) {
- s->op.skip = false;
+ s->op.bypass)) {
+ s->op.bypass = false;
s->writeback = true;
}
- if (s->op.skip)
- goto skip;
-
- trace_bcache_write(s->orig_bio, s->writeback, s->op.skip);
+ trace_bcache_write(s->orig_bio, s->writeback, s->op.bypass);
- if (!s->writeback) {
- s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
- dc->disk.bio_split);
+ if (s->op.bypass) {
+ s->op.cache_bio = s->orig_bio;
+ bio_get(s->op.cache_bio);
- closure_bio_submit(bio, cl, s->d);
- } else {
+ if (!(bio->bi_rw & REQ_DISCARD) ||
+ blk_queue_discard(bdev_get_queue(dc->bdev)))
+ closure_bio_submit(bio, cl, s->d);
+ } else if (s->writeback) {
bch_writeback_add(dc);
s->op.cache_bio = bio;
closure_bio_submit(flush, cl, s->d);
}
+ } else {
+ s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
+ dc->disk.bio_split);
+
+ closure_bio_submit(bio, cl, s->d);
}
-out:
+
closure_call(&s->op.cl, bch_insert_data, NULL, cl);
continue_at(cl, cached_dev_write_complete, NULL);
-skip:
- s->op.skip = true;
- s->op.cache_bio = s->orig_bio;
- bio_get(s->op.cache_bio);
-
- if ((bio->bi_rw & REQ_DISCARD) &&
- !blk_queue_discard(bdev_get_queue(dc->bdev)))
- goto out;
-
- closure_bio_submit(bio, cl, s->d);
- goto out;
}
static void request_nodata(struct cached_dev *dc, struct search *s)
struct closure *cl = &s->cl;
struct bio *bio = &s->bio.bio;
- if (bio->bi_rw & REQ_DISCARD) {
- request_write(dc, s);
- return;
- }
-
if (s->op.flush_journal)
bch_journal_meta(s->op.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 */
-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 void check_should_skip(struct cached_dev *dc, struct search *s)
-{
- struct cache_set *c = s->op.c;
- struct bio *bio = &s->bio.bio;
- unsigned mode = cache_mode(dc, bio);
- unsigned sectors, congested = bch_get_congested(c);
-
- if (atomic_read(&dc->disk.detaching) ||
- 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_sector & (c->sb.block_size - 1) ||
- bio_sectors(bio) & (c->sb.block_size - 1)) {
- pr_debug("skipping unaligned io");
- goto skip;
- }
-
- 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;
-
- if (dc->sequential_merge) {
- struct io *i;
-
- spin_lock(&dc->io_lock);
-
- hlist_for_each_entry(i, iohash(dc, bio->bi_sector), hash)
- if (i->last == bio->bi_sector &&
- time_before(jiffies, i->jiffies))
- goto found;
-
- i = list_first_entry(&dc->io_lru, struct io, lru);
-
- add_sequential(s->task);
- i->sequential = 0;
-found:
- if (i->sequential + bio->bi_size > i->sequential)
- i->sequential += bio->bi_size;
-
- i->last = bio_end_sector(bio);
- i->jiffies = jiffies + msecs_to_jiffies(5000);
- s->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);
- } else {
- s->task->sequential_io = bio->bi_size;
-
- add_sequential(s->task);
- }
-
- sectors = max(s->task->sequential_io,
- s->task->sequential_io_avg) >> 9;
-
- if (dc->sequential_cutoff &&
- sectors >= dc->sequential_cutoff >> 9) {
- trace_bcache_bypass_sequential(s->orig_bio);
- goto skip;
- }
-
- if (congested && sectors >= congested) {
- trace_bcache_bypass_congested(s->orig_bio);
- goto skip;
- }
-
-rescale:
- bch_rescale_priorities(c, bio_sectors(bio));
- return;
-skip:
- bch_mark_sectors_bypassed(s, bio_sectors(bio));
- s->op.skip = true;
-}
-
static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
{
struct search *s;
s = search_alloc(bio, d);
trace_bcache_request_start(s, bio);
- if (!bio_has_data(bio))
+ if (!bio->bi_size)
request_nodata(dc, s);
- else if (rw)
- request_write(dc, s);
- else
- request_read(dc, s);
+ else {
+ s->op.bypass = check_should_bypass(dc, s);
+
+ if (rw)
+ request_write(dc, s);
+ else
+ request_read(dc, s);
+ }
} else {
if ((bio->bi_rw & REQ_DISCARD) &&
!blk_queue_discard(bdev_get_queue(dc->bdev)))
trace_bcache_request_start(s, bio);
- if (bio_has_data(bio) && !rw) {
- closure_call(&s->op.cl, btree_read_async, NULL, cl);
- } else if (bio_has_data(bio) || s->op.skip) {
+ if (!bio->bi_size) {
+ if (s->op.flush_journal)
+ bch_journal_meta(s->op.c, cl);
+ } else if (rw) {
bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys,
&KEY(d->id, bio->bi_sector, 0),
&KEY(d->id, bio_end_sector(bio), 0));
+ s->op.bypass = (bio->bi_rw & REQ_DISCARD) != 0;
s->writeback = true;
s->op.cache_bio = bio;
closure_call(&s->op.cl, bch_insert_data, NULL, cl);
} else {
- /* No data - probably a cache flush */
- if (s->op.flush_journal)
- bch_journal_meta(s->op.c, cl);
+ closure_call(&s->op.cl, btree_read_async, NULL, cl);
}
continue_at(cl, search_free, NULL);
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