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