Commit 84f0db03 authored by Kent Overstreet's avatar Kent Overstreet

bcache: Refactor request_write()

Try to improve some of the naming a bit to be more consistent, and also
improve the flow of control in request_write() a bit.
Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
parent c2f95ae2
......@@ -260,7 +260,7 @@ struct btree_op {
} type:8;
unsigned csum:1;
unsigned skip:1;
unsigned bypass:1;
unsigned flush_journal:1;
unsigned insert_data_done:1;
......
......@@ -25,8 +25,6 @@
struct kmem_cache *bch_search_cache;
static void check_should_skip(struct cached_dev *, struct search *);
/* Cgroup interface */
#ifdef CONFIG_CGROUP_BCACHE
......@@ -480,7 +478,7 @@ static void bch_insert_data_loop(struct closure *cl)
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) {
......@@ -557,7 +555,7 @@ static void bch_insert_data_loop(struct closure *cl)
* 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 {
/*
......@@ -590,8 +588,8 @@ static void bch_insert_data_loop(struct closure *cl)
* 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)
{
......@@ -717,7 +715,6 @@ static struct search *search_alloc(struct bio *bio, struct bcache_device *d)
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);
......@@ -757,6 +754,134 @@ static void cached_dev_bio_complete(struct closure *cl)
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)
......@@ -854,8 +979,8 @@ static void request_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, !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);
......@@ -873,7 +998,7 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
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;
......@@ -940,9 +1065,7 @@ static void request_read(struct cached_dev *dc, struct search *s)
{
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);
}
......@@ -961,41 +1084,48 @@ static void request_write(struct cached_dev *dc, struct search *s)
{
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);
if (!(bio->bi_rw & REQ_DISCARD) ||
blk_queue_discard(bdev_get_queue(dc->bdev)))
closure_bio_submit(bio, cl, s->d);
} else {
} else if (s->writeback) {
bch_writeback_add(dc);
s->op.cache_bio = bio;
......@@ -1011,21 +1141,15 @@ static void request_write(struct cached_dev *dc, struct search *s)
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)
......@@ -1033,14 +1157,10 @@ 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);
......@@ -1048,134 +1168,6 @@ static void request_nodata(struct cached_dev *dc, struct search *s)
/* 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;
......@@ -1195,12 +1187,16 @@ static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
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)
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)))
......@@ -1298,21 +1294,21 @@ static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
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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