1/*
2 * Moving/copying garbage collector
3 *
4 * Copyright 2012 Google, Inc.
5 */
6
7#include "bcache.h"
8#include "btree.h"
9#include "debug.h"
10#include "request.h"
11
12#include <trace/events/bcache.h>
13
14struct moving_io {
15	struct closure		cl;
16	struct keybuf_key	*w;
17	struct data_insert_op	op;
18	struct bbio		bio;
19};
20
21static bool moving_pred(struct keybuf *buf, struct bkey *k)
22{
23	struct cache_set *c = container_of(buf, struct cache_set,
24					   moving_gc_keys);
25	unsigned i;
26
27	for (i = 0; i < KEY_PTRS(k); i++)
28		if (ptr_available(c, k, i) &&
29		    GC_MOVE(PTR_BUCKET(c, k, i)))
30			return true;
31
32	return false;
33}
34
35/* Moving GC - IO loop */
36
37static void moving_io_destructor(struct closure *cl)
38{
39	struct moving_io *io = container_of(cl, struct moving_io, cl);
40	kfree(io);
41}
42
43static void write_moving_finish(struct closure *cl)
44{
45	struct moving_io *io = container_of(cl, struct moving_io, cl);
46	struct bio *bio = &io->bio.bio;
47	struct bio_vec *bv;
48	int i;
49
50	bio_for_each_segment_all(bv, bio, i)
51		__free_page(bv->bv_page);
52
53	if (io->op.replace_collision)
54		trace_bcache_gc_copy_collision(&io->w->key);
55
56	bch_keybuf_del(&io->op.c->moving_gc_keys, io->w);
57
58	up(&io->op.c->moving_in_flight);
59
60	closure_return_with_destructor(cl, moving_io_destructor);
61}
62
63static void read_moving_endio(struct bio *bio, int error)
64{
65	struct bbio *b = container_of(bio, struct bbio, bio);
66	struct moving_io *io = container_of(bio->bi_private,
67					    struct moving_io, cl);
68
69	if (error)
70		io->op.error = error;
71	else if (!KEY_DIRTY(&b->key) &&
72		 ptr_stale(io->op.c, &b->key, 0)) {
73		io->op.error = -EINTR;
74	}
75
76	bch_bbio_endio(io->op.c, bio, error, "reading data to move");
77}
78
79static void moving_init(struct moving_io *io)
80{
81	struct bio *bio = &io->bio.bio;
82
83	bio_init(bio);
84	bio_get(bio);
85	bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
86
87	bio->bi_iter.bi_size	= KEY_SIZE(&io->w->key) << 9;
88	bio->bi_max_vecs	= DIV_ROUND_UP(KEY_SIZE(&io->w->key),
89					       PAGE_SECTORS);
90	bio->bi_private		= &io->cl;
91	bio->bi_io_vec		= bio->bi_inline_vecs;
92	bch_bio_map(bio, NULL);
93}
94
95static void write_moving(struct closure *cl)
96{
97	struct moving_io *io = container_of(cl, struct moving_io, cl);
98	struct data_insert_op *op = &io->op;
99
100	if (!op->error) {
101		moving_init(io);
102
103		io->bio.bio.bi_iter.bi_sector = KEY_START(&io->w->key);
104		op->write_prio		= 1;
105		op->bio			= &io->bio.bio;
106
107		op->writeback		= KEY_DIRTY(&io->w->key);
108		op->csum		= KEY_CSUM(&io->w->key);
109
110		bkey_copy(&op->replace_key, &io->w->key);
111		op->replace		= true;
112
113		closure_call(&op->cl, bch_data_insert, NULL, cl);
114	}
115
116	continue_at(cl, write_moving_finish, op->wq);
117}
118
119static void read_moving_submit(struct closure *cl)
120{
121	struct moving_io *io = container_of(cl, struct moving_io, cl);
122	struct bio *bio = &io->bio.bio;
123
124	bch_submit_bbio(bio, io->op.c, &io->w->key, 0);
125
126	continue_at(cl, write_moving, io->op.wq);
127}
128
129static void read_moving(struct cache_set *c)
130{
131	struct keybuf_key *w;
132	struct moving_io *io;
133	struct bio *bio;
134	struct closure cl;
135
136	closure_init_stack(&cl);
137
138	/* XXX: if we error, background writeback could stall indefinitely */
139
140	while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
141		w = bch_keybuf_next_rescan(c, &c->moving_gc_keys,
142					   &MAX_KEY, moving_pred);
143		if (!w)
144			break;
145
146		if (ptr_stale(c, &w->key, 0)) {
147			bch_keybuf_del(&c->moving_gc_keys, w);
148			continue;
149		}
150
151		io = kzalloc(sizeof(struct moving_io) + sizeof(struct bio_vec)
152			     * DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
153			     GFP_KERNEL);
154		if (!io)
155			goto err;
156
157		w->private	= io;
158		io->w		= w;
159		io->op.inode	= KEY_INODE(&w->key);
160		io->op.c	= c;
161		io->op.wq	= c->moving_gc_wq;
162
163		moving_init(io);
164		bio = &io->bio.bio;
165
166		bio->bi_rw	= READ;
167		bio->bi_end_io	= read_moving_endio;
168
169		if (bio_alloc_pages(bio, GFP_KERNEL))
170			goto err;
171
172		trace_bcache_gc_copy(&w->key);
173
174		down(&c->moving_in_flight);
175		closure_call(&io->cl, read_moving_submit, NULL, &cl);
176	}
177
178	if (0) {
179err:		if (!IS_ERR_OR_NULL(w->private))
180			kfree(w->private);
181
182		bch_keybuf_del(&c->moving_gc_keys, w);
183	}
184
185	closure_sync(&cl);
186}
187
188static bool bucket_cmp(struct bucket *l, struct bucket *r)
189{
190	return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
191}
192
193static unsigned bucket_heap_top(struct cache *ca)
194{
195	struct bucket *b;
196	return (b = heap_peek(&ca->heap)) ? GC_SECTORS_USED(b) : 0;
197}
198
199void bch_moving_gc(struct cache_set *c)
200{
201	struct cache *ca;
202	struct bucket *b;
203	unsigned i;
204
205	if (!c->copy_gc_enabled)
206		return;
207
208	mutex_lock(&c->bucket_lock);
209
210	for_each_cache(ca, c, i) {
211		unsigned sectors_to_move = 0;
212		unsigned reserve_sectors = ca->sb.bucket_size *
213			fifo_used(&ca->free[RESERVE_MOVINGGC]);
214
215		ca->heap.used = 0;
216
217		for_each_bucket(b, ca) {
218			if (GC_MARK(b) == GC_MARK_METADATA ||
219			    !GC_SECTORS_USED(b) ||
220			    GC_SECTORS_USED(b) == ca->sb.bucket_size ||
221			    atomic_read(&b->pin))
222				continue;
223
224			if (!heap_full(&ca->heap)) {
225				sectors_to_move += GC_SECTORS_USED(b);
226				heap_add(&ca->heap, b, bucket_cmp);
227			} else if (bucket_cmp(b, heap_peek(&ca->heap))) {
228				sectors_to_move -= bucket_heap_top(ca);
229				sectors_to_move += GC_SECTORS_USED(b);
230
231				ca->heap.data[0] = b;
232				heap_sift(&ca->heap, 0, bucket_cmp);
233			}
234		}
235
236		while (sectors_to_move > reserve_sectors) {
237			heap_pop(&ca->heap, b, bucket_cmp);
238			sectors_to_move -= GC_SECTORS_USED(b);
239		}
240
241		while (heap_pop(&ca->heap, b, bucket_cmp))
242			SET_GC_MOVE(b, 1);
243	}
244
245	mutex_unlock(&c->bucket_lock);
246
247	c->moving_gc_keys.last_scanned = ZERO_KEY;
248
249	read_moving(c);
250}
251
252void bch_moving_init_cache_set(struct cache_set *c)
253{
254	bch_keybuf_init(&c->moving_gc_keys);
255	sema_init(&c->moving_in_flight, 64);
256}
257