[deliverable/linux.git] / drivers / md / bcache / writeback.c

/*
 * background writeback - scan btree for dirty data and write it to the backing
 * device
 *
 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
 * Copyright 2012 Google, Inc.
 */

#include "bcache.h"
#include "btree.h"
#include "debug.h"
#include "writeback.h"

#include <trace/events/bcache.h>

static struct workqueue_struct *dirty_wq;

static void read_dirty(struct closure *);

struct dirty_io {
	struct closure		cl;
	struct cached_dev	*dc;
	struct bio		bio;
};

/* Rate limiting */

static void __update_writeback_rate(struct cached_dev *dc)
{
	struct cache_set *c = dc->disk.c;
	uint64_t cache_sectors = c->nbuckets * c->sb.bucket_size;
	uint64_t cache_dirty_target =
		div_u64(cache_sectors * dc->writeback_percent, 100);

	int64_t target = div64_u64(cache_dirty_target * bdev_sectors(dc->bdev),
				   c->cached_dev_sectors);

	/* PD controller */

	int change = 0;
	int64_t error;
	int64_t dirty = bcache_dev_sectors_dirty(&dc->disk);
	int64_t derivative = dirty - dc->disk.sectors_dirty_last;

	dc->disk.sectors_dirty_last = dirty;

	derivative *= dc->writeback_rate_d_term;
	derivative = clamp(derivative, -dirty, dirty);

	derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative,
			      dc->writeback_rate_d_smooth, 0);

	/* Avoid divide by zero */
	if (!target)
		goto out;

	error = div64_s64((dirty + derivative - target) << 8, target);

	change = div_s64((dc->writeback_rate.rate * error) >> 8,
			 dc->writeback_rate_p_term_inverse);

	/* Don't increase writeback rate if the device isn't keeping up */
	if (change > 0 &&
	    time_after64(local_clock(),
			 dc->writeback_rate.next + 10 * NSEC_PER_MSEC))
		change = 0;

	dc->writeback_rate.rate =
		clamp_t(int64_t, dc->writeback_rate.rate + change,
			1, NSEC_PER_MSEC);
out:
	dc->writeback_rate_derivative = derivative;
	dc->writeback_rate_change = change;
	dc->writeback_rate_target = target;

	schedule_delayed_work(&dc->writeback_rate_update,
			      dc->writeback_rate_update_seconds * HZ);
}

static void update_writeback_rate(struct work_struct *work)
{
	struct cached_dev *dc = container_of(to_delayed_work(work),
					     struct cached_dev,
					     writeback_rate_update);

	down_read(&dc->writeback_lock);

	if (atomic_read(&dc->has_dirty) &&
	    dc->writeback_percent)
		__update_writeback_rate(dc);

	up_read(&dc->writeback_lock);
}

static unsigned writeback_delay(struct cached_dev *dc, unsigned sectors)
{
	uint64_t ret;

	if (atomic_read(&dc->disk.detaching) ||
	    !dc->writeback_percent)
		return 0;

	ret = bch_next_delay(&dc->writeback_rate, sectors * 10000000ULL);

	return min_t(uint64_t, ret, HZ);
}

/* Background writeback */

static bool dirty_pred(struct keybuf *buf, struct bkey *k)
{
	return KEY_DIRTY(k);
}

static bool dirty_full_stripe_pred(struct keybuf *buf, struct bkey *k)
{
	uint64_t stripe;
	unsigned nr_sectors = KEY_SIZE(k);
	struct cached_dev *dc = container_of(buf, struct cached_dev,
					     writeback_keys);
	unsigned stripe_size = 1 << dc->disk.stripe_size_bits;

	if (!KEY_DIRTY(k))
		return false;

	stripe = KEY_START(k) >> dc->disk.stripe_size_bits;
	while (1) {
		if (atomic_read(dc->disk.stripe_sectors_dirty + stripe) !=
		    stripe_size)
			return false;

		if (nr_sectors <= stripe_size)
			return true;

		nr_sectors -= stripe_size;
		stripe++;
	}
}

static void dirty_init(struct keybuf_key *w)
{
	struct dirty_io *io = w->private;
	struct bio *bio = &io->bio;

	bio_init(bio);
	if (!io->dc->writeback_percent)
		bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));

	bio->bi_size		= KEY_SIZE(&w->key) << 9;
	bio->bi_max_vecs	= DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS);
	bio->bi_private		= w;
	bio->bi_io_vec		= bio->bi_inline_vecs;
	bch_bio_map(bio, NULL);
}

static void refill_dirty(struct closure *cl)
{
	struct cached_dev *dc = container_of(cl, struct cached_dev,
					     writeback.cl);
	struct keybuf *buf = &dc->writeback_keys;
	bool searched_from_start = false;
	struct bkey end = MAX_KEY;
	SET_KEY_INODE(&end, dc->disk.id);

	if (!atomic_read(&dc->disk.detaching) &&
	    !dc->writeback_running)
		closure_return(cl);

	down_write(&dc->writeback_lock);

	if (!atomic_read(&dc->has_dirty)) {
		SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
		bch_write_bdev_super(dc, NULL);

		up_write(&dc->writeback_lock);
		closure_return(cl);
	}

	if (bkey_cmp(&buf->last_scanned, &end) >= 0) {
		buf->last_scanned = KEY(dc->disk.id, 0, 0);
		searched_from_start = true;
	}

	if (dc->partial_stripes_expensive) {
		uint64_t i;

		for (i = 0; i < dc->disk.nr_stripes; i++)
			if (atomic_read(dc->disk.stripe_sectors_dirty + i) ==
			    1 << dc->disk.stripe_size_bits)
				goto full_stripes;

		goto normal_refill;
full_stripes:
		bch_refill_keybuf(dc->disk.c, buf, &end,
				  dirty_full_stripe_pred);
	} else {
normal_refill:
		bch_refill_keybuf(dc->disk.c, buf, &end, dirty_pred);
	}

	if (bkey_cmp(&buf->last_scanned, &end) >= 0 && searched_from_start) {
		/* Searched the entire btree  - delay awhile */

		if (RB_EMPTY_ROOT(&buf->keys)) {
			atomic_set(&dc->has_dirty, 0);
			cached_dev_put(dc);
		}

		if (!atomic_read(&dc->disk.detaching))
			closure_delay(&dc->writeback, dc->writeback_delay * HZ);
	}

	up_write(&dc->writeback_lock);

	bch_ratelimit_reset(&dc->writeback_rate);

	/* Punt to workqueue only so we don't recurse and blow the stack */
	continue_at(cl, read_dirty, dirty_wq);
}

void bch_writeback_queue(struct cached_dev *dc)
{
	if (closure_trylock(&dc->writeback.cl, &dc->disk.cl)) {
		if (!atomic_read(&dc->disk.detaching))
			closure_delay(&dc->writeback, dc->writeback_delay * HZ);

		continue_at(&dc->writeback.cl, refill_dirty, dirty_wq);
	}
}

void bch_writeback_add(struct cached_dev *dc)
{
	if (!atomic_read(&dc->has_dirty) &&
	    !atomic_xchg(&dc->has_dirty, 1)) {
		atomic_inc(&dc->count);

		if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
			SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
			/* XXX: should do this synchronously */
			bch_write_bdev_super(dc, NULL);
		}

		bch_writeback_queue(dc);

		if (dc->writeback_percent)
			schedule_delayed_work(&dc->writeback_rate_update,
				      dc->writeback_rate_update_seconds * HZ);
	}
}

void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned inode,
				  uint64_t offset, int nr_sectors)
{
	struct bcache_device *d = c->devices[inode];
	unsigned stripe_size, stripe_offset;
	uint64_t stripe;

	if (!d)
		return;

	stripe_size = 1 << d->stripe_size_bits;
	stripe = offset >> d->stripe_size_bits;
	stripe_offset = offset & (stripe_size - 1);

	while (nr_sectors) {
		int s = min_t(unsigned, abs(nr_sectors),
			      stripe_size - stripe_offset);

		if (nr_sectors < 0)
			s = -s;

		atomic_add(s, d->stripe_sectors_dirty + stripe);
		nr_sectors -= s;
		stripe_offset = 0;
		stripe++;
	}
}

/* Background writeback - IO loop */

static void dirty_io_destructor(struct closure *cl)
{
	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
	kfree(io);
}

static void write_dirty_finish(struct closure *cl)
{
	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
	struct keybuf_key *w = io->bio.bi_private;
	struct cached_dev *dc = io->dc;
	struct bio_vec *bv;
	int i;

	bio_for_each_segment_all(bv, &io->bio, i)
		__free_page(bv->bv_page);

	/* This is kind of a dumb way of signalling errors. */
	if (KEY_DIRTY(&w->key)) {
		unsigned i;
		struct btree_op op;
		bch_btree_op_init_stack(&op);

		op.type = BTREE_REPLACE;
		bkey_copy(&op.replace, &w->key);

		SET_KEY_DIRTY(&w->key, false);
		bch_keylist_add(&op.keys, &w->key);

		for (i = 0; i < KEY_PTRS(&w->key); i++)
			atomic_inc(&PTR_BUCKET(dc->disk.c, &w->key, i)->pin);

		bch_btree_insert(&op, dc->disk.c);
		closure_sync(&op.cl);

		if (op.insert_collision)
			trace_bcache_writeback_collision(&w->key);

		atomic_long_inc(op.insert_collision
				? &dc->disk.c->writeback_keys_failed
				: &dc->disk.c->writeback_keys_done);
	}

	bch_keybuf_del(&dc->writeback_keys, w);
	up(&dc->in_flight);

	closure_return_with_destructor(cl, dirty_io_destructor);
}

static void dirty_endio(struct bio *bio, int error)
{
	struct keybuf_key *w = bio->bi_private;
	struct dirty_io *io = w->private;

	if (error)
		SET_KEY_DIRTY(&w->key, false);

	closure_put(&io->cl);
}

static void write_dirty(struct closure *cl)
{
	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
	struct keybuf_key *w = io->bio.bi_private;

	dirty_init(w);
	io->bio.bi_rw		= WRITE;
	io->bio.bi_sector	= KEY_START(&w->key);
	io->bio.bi_bdev		= io->dc->bdev;
	io->bio.bi_end_io	= dirty_endio;

	closure_bio_submit(&io->bio, cl, &io->dc->disk);

	continue_at(cl, write_dirty_finish, system_wq);
}

static void read_dirty_endio(struct bio *bio, int error)
{
	struct keybuf_key *w = bio->bi_private;
	struct dirty_io *io = w->private;

	bch_count_io_errors(PTR_CACHE(io->dc->disk.c, &w->key, 0),
			    error, "reading dirty data from cache");

	dirty_endio(bio, error);
}

static void read_dirty_submit(struct closure *cl)
{
	struct dirty_io *io = container_of(cl, struct dirty_io, cl);

	closure_bio_submit(&io->bio, cl, &io->dc->disk);

	continue_at(cl, write_dirty, system_wq);
}

static void read_dirty(struct closure *cl)
{
	struct cached_dev *dc = container_of(cl, struct cached_dev,
					     writeback.cl);
	unsigned delay = writeback_delay(dc, 0);
	struct keybuf_key *w;
	struct dirty_io *io;

	/*
	 * XXX: if we error, background writeback just spins. Should use some
	 * mempools.
	 */

	while (1) {
		w = bch_keybuf_next(&dc->writeback_keys);
		if (!w)
			break;

		BUG_ON(ptr_stale(dc->disk.c, &w->key, 0));

		if (delay > 0 &&
		    (KEY_START(&w->key) != dc->last_read ||
		     jiffies_to_msecs(delay) > 50))
			delay = schedule_timeout_uninterruptible(delay);

		dc->last_read	= KEY_OFFSET(&w->key);

		io = kzalloc(sizeof(struct dirty_io) + sizeof(struct bio_vec)
			     * DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
			     GFP_KERNEL);
		if (!io)
			goto err;

		w->private	= io;
		io->dc		= dc;

		dirty_init(w);
		io->bio.bi_sector	= PTR_OFFSET(&w->key, 0);
		io->bio.bi_bdev		= PTR_CACHE(dc->disk.c,
						    &w->key, 0)->bdev;
		io->bio.bi_rw		= READ;
		io->bio.bi_end_io	= read_dirty_endio;

		if (bio_alloc_pages(&io->bio, GFP_KERNEL))
			goto err_free;

		trace_bcache_writeback(&w->key);

		down(&dc->in_flight);
		closure_call(&io->cl, read_dirty_submit, NULL, cl);

		delay = writeback_delay(dc, KEY_SIZE(&w->key));
	}

	if (0) {
err_free:
		kfree(w->private);
err:
		bch_keybuf_del(&dc->writeback_keys, w);
	}

	/*
	 * Wait for outstanding writeback IOs to finish (and keybuf slots to be
	 * freed) before refilling again
	 */
	continue_at(cl, refill_dirty, dirty_wq);
}

/* Init */

static int bch_btree_sectors_dirty_init(struct btree *b, struct btree_op *op,
					struct cached_dev *dc)
{
	struct bkey *k;
	struct btree_iter iter;

	bch_btree_iter_init(b, &iter, &KEY(dc->disk.id, 0, 0));
	while ((k = bch_btree_iter_next_filter(&iter, b, bch_ptr_bad)))
		if (!b->level) {
			if (KEY_INODE(k) > dc->disk.id)
				break;

			if (KEY_DIRTY(k))
				bcache_dev_sectors_dirty_add(b->c, dc->disk.id,
							     KEY_START(k),
							     KEY_SIZE(k));
		} else {
			btree(sectors_dirty_init, k, b, op, dc);
			if (KEY_INODE(k) > dc->disk.id)
				break;

			cond_resched();
		}

	return 0;
}

void bch_sectors_dirty_init(struct cached_dev *dc)
{
	struct btree_op op;

	bch_btree_op_init_stack(&op);
	btree_root(sectors_dirty_init, dc->disk.c, &op, dc);
}

void bch_cached_dev_writeback_init(struct cached_dev *dc)
{
	sema_init(&dc->in_flight, 64);
	closure_init_unlocked(&dc->writeback);
	init_rwsem(&dc->writeback_lock);

	bch_keybuf_init(&dc->writeback_keys);

	dc->writeback_metadata		= true;
	dc->writeback_running		= true;
	dc->writeback_percent		= 10;
	dc->writeback_delay		= 30;
	dc->writeback_rate.rate		= 1024;

	dc->writeback_rate_update_seconds = 30;
	dc->writeback_rate_d_term	= 16;
	dc->writeback_rate_p_term_inverse = 64;
	dc->writeback_rate_d_smooth	= 8;

	INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
	schedule_delayed_work(&dc->writeback_rate_update,
			      dc->writeback_rate_update_seconds * HZ);
}

void bch_writeback_exit(void)
{
	if (dirty_wq)
		destroy_workqueue(dirty_wq);
}

int __init bch_writeback_init(void)
{
	dirty_wq = create_workqueue("bcache_writeback");
	if (!dirty_wq)
		return -ENOMEM;

	return 0;
}
Commit	Line	Data
cafe5635 KO	1	/*
	2	* background writeback - scan btree for dirty data and write it to the backing
	3	* device
	4	*
	5	* Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
	6	* Copyright 2012 Google, Inc.
	7	*/
	8
	9	#include "bcache.h"
	10	#include "btree.h"
	11	#include "debug.h"
279afbad	12	#include "writeback.h"
cafe5635	13
c37511b8 KO	14	#include <trace/events/bcache.h>
c37511b8 KO	15
cafe5635 KO	16	static struct workqueue_struct *dirty_wq;
	17
	18	static void read_dirty(struct closure *);
	19
	20	struct dirty_io {
	21	struct closure cl;
	22	struct cached_dev *dc;
	23	struct bio bio;
	24	};
	25
	26	/* Rate limiting */
	27
	28	static void __update_writeback_rate(struct cached_dev *dc)
	29	{
	30	struct cache_set *c = dc->disk.c;
	31	uint64_t cache_sectors = c->nbuckets * c->sb.bucket_size;
	32	uint64_t cache_dirty_target =
	33	div_u64(cache_sectors * dc->writeback_percent, 100);
	34
	35	int64_t target = div64_u64(cache_dirty_target * bdev_sectors(dc->bdev),
	36	c->cached_dev_sectors);
	37
	38	/* PD controller */
	39
	40	int change = 0;
	41	int64_t error;
279afbad	42	int64_t dirty = bcache_dev_sectors_dirty(&dc->disk);
cafe5635 KO	43	int64_t derivative = dirty - dc->disk.sectors_dirty_last;
	44
	45	dc->disk.sectors_dirty_last = dirty;
	46
	47	derivative *= dc->writeback_rate_d_term;
	48	derivative = clamp(derivative, -dirty, dirty);
	49
	50	derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative,
	51	dc->writeback_rate_d_smooth, 0);
	52
	53	/* Avoid divide by zero */
	54	if (!target)
	55	goto out;
	56
	57	error = div64_s64((dirty + derivative - target) << 8, target);
	58
	59	change = div_s64((dc->writeback_rate.rate * error) >> 8,
	60	dc->writeback_rate_p_term_inverse);
	61
	62	/* Don't increase writeback rate if the device isn't keeping up */
	63	if (change > 0 &&
	64	time_after64(local_clock(),
	65	dc->writeback_rate.next + 10 * NSEC_PER_MSEC))
	66	change = 0;
	67
	68	dc->writeback_rate.rate =
	69	clamp_t(int64_t, dc->writeback_rate.rate + change,
	70	1, NSEC_PER_MSEC);
	71	out:
	72	dc->writeback_rate_derivative = derivative;
	73	dc->writeback_rate_change = change;
	74	dc->writeback_rate_target = target;
	75
	76	schedule_delayed_work(&dc->writeback_rate_update,
	77	dc->writeback_rate_update_seconds * HZ);
	78	}
	79
	80	static void update_writeback_rate(struct work_struct *work)
	81	{
	82	struct cached_dev *dc = container_of(to_delayed_work(work),
	83	struct cached_dev,
	84	writeback_rate_update);
	85
	86	down_read(&dc->writeback_lock);
	87
	88	if (atomic_read(&dc->has_dirty) &&
	89	dc->writeback_percent)
	90	__update_writeback_rate(dc);
	91
	92	up_read(&dc->writeback_lock);
	93	}
	94
	95	static unsigned writeback_delay(struct cached_dev *dc, unsigned sectors)
	96	{
c2a4f318 KO	97	uint64_t ret;
c2a4f318 KO	98
cafe5635 KO	99	if (atomic_read(&dc->disk.detaching) \|\|
	100	!dc->writeback_percent)
	101	return 0;
	102
c2a4f318 KO	103	ret = bch_next_delay(&dc->writeback_rate, sectors * 10000000ULL);
	104
	105	return min_t(uint64_t, ret, HZ);
cafe5635 KO	106	}
	107
	108	/* Background writeback */
	109
	110	static bool dirty_pred(struct keybuf buf, struct bkey k)
	111	{
	112	return KEY_DIRTY(k);
	113	}
	114
72c27061 KO	115	static bool dirty_full_stripe_pred(struct keybuf buf, struct bkey k)
	116	{
	117	uint64_t stripe;
	118	unsigned nr_sectors = KEY_SIZE(k);
	119	struct cached_dev *dc = container_of(buf, struct cached_dev,
	120	writeback_keys);
	121	unsigned stripe_size = 1 << dc->disk.stripe_size_bits;
	122
	123	if (!KEY_DIRTY(k))
	124	return false;
	125
	126	stripe = KEY_START(k) >> dc->disk.stripe_size_bits;
	127	while (1) {
	128	if (atomic_read(dc->disk.stripe_sectors_dirty + stripe) !=
	129	stripe_size)
	130	return false;
	131
	132	if (nr_sectors <= stripe_size)
	133	return true;
	134
	135	nr_sectors -= stripe_size;
	136	stripe++;
	137	}
	138	}
	139
cafe5635 KO	140	static void dirty_init(struct keybuf_key *w)
	141	{
	142	struct dirty_io *io = w->private;
	143	struct bio *bio = &io->bio;
	144
	145	bio_init(bio);
	146	if (!io->dc->writeback_percent)
	147	bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
	148
	149	bio->bi_size = KEY_SIZE(&w->key) << 9;
	150	bio->bi_max_vecs = DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS);
	151	bio->bi_private = w;
	152	bio->bi_io_vec = bio->bi_inline_vecs;
169ef1cf	153	bch_bio_map(bio, NULL);
cafe5635 KO	154	}
	155
	156	static void refill_dirty(struct closure *cl)
	157	{
	158	struct cached_dev *dc = container_of(cl, struct cached_dev,
	159	writeback.cl);
	160	struct keybuf *buf = &dc->writeback_keys;
	161	bool searched_from_start = false;
	162	struct bkey end = MAX_KEY;
	163	SET_KEY_INODE(&end, dc->disk.id);
	164
	165	if (!atomic_read(&dc->disk.detaching) &&
	166	!dc->writeback_running)
	167	closure_return(cl);
	168
	169	down_write(&dc->writeback_lock);
	170
	171	if (!atomic_read(&dc->has_dirty)) {
	172	SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
	173	bch_write_bdev_super(dc, NULL);
	174
	175	up_write(&dc->writeback_lock);
	176	closure_return(cl);
	177	}
	178
	179	if (bkey_cmp(&buf->last_scanned, &end) >= 0) {
	180	buf->last_scanned = KEY(dc->disk.id, 0, 0);
	181	searched_from_start = true;
	182	}
	183
72c27061 KO	184	if (dc->partial_stripes_expensive) {
	185	uint64_t i;
	186
	187	for (i = 0; i < dc->disk.nr_stripes; i++)
	188	if (atomic_read(dc->disk.stripe_sectors_dirty + i) ==
	189	1 << dc->disk.stripe_size_bits)
	190	goto full_stripes;
	191
	192	goto normal_refill;
	193	full_stripes:
	194	bch_refill_keybuf(dc->disk.c, buf, &end,
	195	dirty_full_stripe_pred);
	196	} else {
	197	normal_refill:
	198	bch_refill_keybuf(dc->disk.c, buf, &end, dirty_pred);
	199	}
cafe5635 KO	200
	201	if (bkey_cmp(&buf->last_scanned, &end) >= 0 && searched_from_start) {
	202	/* Searched the entire btree - delay awhile */
	203
	204	if (RB_EMPTY_ROOT(&buf->keys)) {
	205	atomic_set(&dc->has_dirty, 0);
	206	cached_dev_put(dc);
	207	}
	208
	209	if (!atomic_read(&dc->disk.detaching))
	210	closure_delay(&dc->writeback, dc->writeback_delay * HZ);
	211	}
	212
	213	up_write(&dc->writeback_lock);
	214
c2a4f318	215	bch_ratelimit_reset(&dc->writeback_rate);
cafe5635 KO	216
	217	/* Punt to workqueue only so we don't recurse and blow the stack */
	218	continue_at(cl, read_dirty, dirty_wq);
	219	}
	220
	221	void bch_writeback_queue(struct cached_dev *dc)
	222	{
	223	if (closure_trylock(&dc->writeback.cl, &dc->disk.cl)) {
	224	if (!atomic_read(&dc->disk.detaching))
	225	closure_delay(&dc->writeback, dc->writeback_delay * HZ);
	226
	227	continue_at(&dc->writeback.cl, refill_dirty, dirty_wq);
	228	}
	229	}
	230
279afbad	231	void bch_writeback_add(struct cached_dev *dc)
cafe5635	232	{
cafe5635 KO	233	if (!atomic_read(&dc->has_dirty) &&
	234	!atomic_xchg(&dc->has_dirty, 1)) {
	235	atomic_inc(&dc->count);
	236
	237	if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
	238	SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
	239	/* XXX: should do this synchronously */
	240	bch_write_bdev_super(dc, NULL);
	241	}
	242
	243	bch_writeback_queue(dc);
	244
	245	if (dc->writeback_percent)
	246	schedule_delayed_work(&dc->writeback_rate_update,
	247	dc->writeback_rate_update_seconds * HZ);
	248	}
	249	}
	250
279afbad KO	251	void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned inode,
	252	uint64_t offset, int nr_sectors)
	253	{
	254	struct bcache_device *d = c->devices[inode];
	255	unsigned stripe_size, stripe_offset;
	256	uint64_t stripe;
	257
	258	if (!d)
	259	return;
	260
	261	stripe_size = 1 << d->stripe_size_bits;
	262	stripe = offset >> d->stripe_size_bits;
	263	stripe_offset = offset & (stripe_size - 1);
	264
	265	while (nr_sectors) {
	266	int s = min_t(unsigned, abs(nr_sectors),
	267	stripe_size - stripe_offset);
	268
	269	if (nr_sectors < 0)
	270	s = -s;
	271
	272	atomic_add(s, d->stripe_sectors_dirty + stripe);
	273	nr_sectors -= s;
	274	stripe_offset = 0;
	275	stripe++;
	276	}
	277	}
	278
cafe5635 KO	279	/* Background writeback - IO loop */
	280
	281	static void dirty_io_destructor(struct closure *cl)
	282	{
	283	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
	284	kfree(io);
	285	}
	286
	287	static void write_dirty_finish(struct closure *cl)
	288	{
	289	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
	290	struct keybuf_key *w = io->bio.bi_private;
	291	struct cached_dev *dc = io->dc;
8e51e414 KO	292	struct bio_vec *bv;
8e51e414 KO	293	int i;
cafe5635	294
8e51e414	295	bio_for_each_segment_all(bv, &io->bio, i)
cafe5635 KO	296	__free_page(bv->bv_page);
	297
	298	/* This is kind of a dumb way of signalling errors. */
	299	if (KEY_DIRTY(&w->key)) {
	300	unsigned i;
	301	struct btree_op op;
	302	bch_btree_op_init_stack(&op);
	303
	304	op.type = BTREE_REPLACE;
	305	bkey_copy(&op.replace, &w->key);
	306
	307	SET_KEY_DIRTY(&w->key, false);
	308	bch_keylist_add(&op.keys, &w->key);
	309
	310	for (i = 0; i < KEY_PTRS(&w->key); i++)
	311	atomic_inc(&PTR_BUCKET(dc->disk.c, &w->key, i)->pin);
	312
cafe5635 KO	313	bch_btree_insert(&op, dc->disk.c);
	314	closure_sync(&op.cl);
	315
c37511b8 KO	316	if (op.insert_collision)
	317	trace_bcache_writeback_collision(&w->key);
	318
cafe5635 KO	319	atomic_long_inc(op.insert_collision
	320	? &dc->disk.c->writeback_keys_failed
	321	: &dc->disk.c->writeback_keys_done);
	322	}
	323
	324	bch_keybuf_del(&dc->writeback_keys, w);
c2a4f318	325	up(&dc->in_flight);
cafe5635 KO	326
	327	closure_return_with_destructor(cl, dirty_io_destructor);
	328	}
	329
	330	static void dirty_endio(struct bio *bio, int error)
	331	{
	332	struct keybuf_key *w = bio->bi_private;
	333	struct dirty_io *io = w->private;
	334
	335	if (error)
	336	SET_KEY_DIRTY(&w->key, false);
	337
	338	closure_put(&io->cl);
	339	}
	340
	341	static void write_dirty(struct closure *cl)
	342	{
	343	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
	344	struct keybuf_key *w = io->bio.bi_private;
	345
	346	dirty_init(w);
	347	io->bio.bi_rw = WRITE;
	348	io->bio.bi_sector = KEY_START(&w->key);
	349	io->bio.bi_bdev = io->dc->bdev;
	350	io->bio.bi_end_io = dirty_endio;
	351
cafe5635 KO	352	closure_bio_submit(&io->bio, cl, &io->dc->disk);
cafe5635 KO	353
c2a4f318	354	continue_at(cl, write_dirty_finish, system_wq);
cafe5635 KO	355	}
	356
	357	static void read_dirty_endio(struct bio *bio, int error)
	358	{
	359	struct keybuf_key *w = bio->bi_private;
	360	struct dirty_io *io = w->private;
	361
	362	bch_count_io_errors(PTR_CACHE(io->dc->disk.c, &w->key, 0),
	363	error, "reading dirty data from cache");
	364
	365	dirty_endio(bio, error);
	366	}
	367
	368	static void read_dirty_submit(struct closure *cl)
	369	{
	370	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
	371
cafe5635 KO	372	closure_bio_submit(&io->bio, cl, &io->dc->disk);
cafe5635 KO	373
c2a4f318	374	continue_at(cl, write_dirty, system_wq);
cafe5635 KO	375	}
	376
	377	static void read_dirty(struct closure *cl)
	378	{
	379	struct cached_dev *dc = container_of(cl, struct cached_dev,
	380	writeback.cl);
	381	unsigned delay = writeback_delay(dc, 0);
	382	struct keybuf_key *w;
	383	struct dirty_io *io;
	384
	385	/*
	386	* XXX: if we error, background writeback just spins. Should use some
	387	* mempools.
	388	*/
	389
	390	while (1) {
	391	w = bch_keybuf_next(&dc->writeback_keys);
	392	if (!w)
	393	break;
	394
	395	BUG_ON(ptr_stale(dc->disk.c, &w->key, 0));
	396
	397	if (delay > 0 &&
	398	(KEY_START(&w->key) != dc->last_read \|\|
c2a4f318	399	jiffies_to_msecs(delay) > 50))
79e3dab9	400	delay = schedule_timeout_uninterruptible(delay);
cafe5635 KO	401
	402	dc->last_read = KEY_OFFSET(&w->key);
	403
	404	io = kzalloc(sizeof(struct dirty_io) + sizeof(struct bio_vec)
	405	* DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
	406	GFP_KERNEL);
	407	if (!io)
	408	goto err;
	409
	410	w->private = io;
	411	io->dc = dc;
	412
	413	dirty_init(w);
	414	io->bio.bi_sector = PTR_OFFSET(&w->key, 0);
	415	io->bio.bi_bdev = PTR_CACHE(dc->disk.c,
	416	&w->key, 0)->bdev;
	417	io->bio.bi_rw = READ;
	418	io->bio.bi_end_io = read_dirty_endio;
	419
8e51e414	420	if (bio_alloc_pages(&io->bio, GFP_KERNEL))
cafe5635 KO	421	goto err_free;
cafe5635 KO	422
c37511b8	423	trace_bcache_writeback(&w->key);
cafe5635	424
c2a4f318 KO	425	down(&dc->in_flight);
c2a4f318 KO	426	closure_call(&io->cl, read_dirty_submit, NULL, cl);
cafe5635 KO	427
cafe5635 KO	428	delay = writeback_delay(dc, KEY_SIZE(&w->key));
cafe5635 KO	429	}
	430
	431	if (0) {
	432	err_free:
	433	kfree(w->private);
	434	err:
	435	bch_keybuf_del(&dc->writeback_keys, w);
	436	}
	437
c2a4f318 KO	438	/*
	439	* Wait for outstanding writeback IOs to finish (and keybuf slots to be
	440	* freed) before refilling again
	441	*/
	442	continue_at(cl, refill_dirty, dirty_wq);
cafe5635 KO	443	}
cafe5635 KO	444
444fc0b6 KO	445	/* Init */
	446
	447	static int bch_btree_sectors_dirty_init(struct btree b, struct btree_op op,
	448	struct cached_dev *dc)
	449	{
	450	struct bkey *k;
	451	struct btree_iter iter;
	452
	453	bch_btree_iter_init(b, &iter, &KEY(dc->disk.id, 0, 0));
	454	while ((k = bch_btree_iter_next_filter(&iter, b, bch_ptr_bad)))
	455	if (!b->level) {
	456	if (KEY_INODE(k) > dc->disk.id)
	457	break;
	458
	459	if (KEY_DIRTY(k))
279afbad KO	460	bcache_dev_sectors_dirty_add(b->c, dc->disk.id,
	461	KEY_START(k),
	462	KEY_SIZE(k));
444fc0b6 KO	463	} else {
	464	btree(sectors_dirty_init, k, b, op, dc);
	465	if (KEY_INODE(k) > dc->disk.id)
	466	break;
	467
	468	cond_resched();
	469	}
	470
	471	return 0;
	472	}
	473
	474	void bch_sectors_dirty_init(struct cached_dev *dc)
	475	{
	476	struct btree_op op;
	477
	478	bch_btree_op_init_stack(&op);
	479	btree_root(sectors_dirty_init, dc->disk.c, &op, dc);
	480	}
	481
f59fce84	482	void bch_cached_dev_writeback_init(struct cached_dev *dc)
cafe5635	483	{
c2a4f318	484	sema_init(&dc->in_flight, 64);
cafe5635 KO	485	closure_init_unlocked(&dc->writeback);
	486	init_rwsem(&dc->writeback_lock);
	487
72c27061	488	bch_keybuf_init(&dc->writeback_keys);
cafe5635 KO	489
	490	dc->writeback_metadata = true;
	491	dc->writeback_running = true;
	492	dc->writeback_percent = 10;
	493	dc->writeback_delay = 30;
	494	dc->writeback_rate.rate = 1024;
	495
	496	dc->writeback_rate_update_seconds = 30;
	497	dc->writeback_rate_d_term = 16;
	498	dc->writeback_rate_p_term_inverse = 64;
	499	dc->writeback_rate_d_smooth = 8;
	500
	501	INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
	502	schedule_delayed_work(&dc->writeback_rate_update,
	503	dc->writeback_rate_update_seconds * HZ);
	504	}
	505
	506	void bch_writeback_exit(void)
	507	{
	508	if (dirty_wq)
	509	destroy_workqueue(dirty_wq);
	510	}
	511
	512	int __init bch_writeback_init(void)
	513	{
c2a4f318	514	dirty_wq = create_workqueue("bcache_writeback");
cafe5635 KO	515	if (!dirty_wq)
	516	return -ENOMEM;
	517
	518	return 0;
	519	}