drivers/md/bcache/movinggc.c

   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 closure          cl;
  16         struct keybuf_key       *w;
  17         struct data_insert_op   op;
  18         struct bbio             bio;
  19 };
  20
  21 static 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                 struct cache *ca = PTR_CACHE(c, k, i);
  29                 struct bucket *g = PTR_BUCKET(c, k, i);
  30
  31                 if (GC_SECTORS_USED(g) < ca->gc_move_threshold)
  32                         return true;
  33         }
  34
  35         return false;
  36 }
  37
  38 /* Moving GC - IO loop */
  39
  40 static void moving_io_destructor(struct closure *cl)
  41 {
  42         struct moving_io *io = container_of(cl, struct moving_io, cl);
  43         kfree(io);
  44 }
  45
  46 static void write_moving_finish(struct closure *cl)
  47 {
  48         struct moving_io *io = container_of(cl, struct moving_io, cl);
  49         struct bio *bio = &io->bio.bio;
  50         struct bio_vec *bv;
  51         int i;
  52
  53         bio_for_each_segment_all(bv, bio, i)
  54                 __free_page(bv->bv_page);
  55
  56         if (io->op.replace_collision)
  57                 trace_bcache_gc_copy_collision(&io->w->key);
  58
  59         bch_keybuf_del(&io->op.c->moving_gc_keys, io->w);
  60
  61         up(&io->op.c->moving_in_flight);
  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, cl);
  70
  71         if (error)
  72                 io->op.error = error;
  73
  74         bch_bbio_endio(io->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->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 moving_io *io = container_of(cl, struct moving_io, cl);
  96         struct data_insert_op *op = &io->op;
  97
  98         if (!op->error) {
  99                 moving_init(io);
 100
 101                 io->bio.bio.bi_sector = KEY_START(&io->w->key);
 102                 op->write_prio          = 1;
 103                 op->bio                 = &io->bio.bio;
 104
 105                 op->writeback           = KEY_DIRTY(&io->w->key);
 106                 op->csum                = KEY_CSUM(&io->w->key);
 107
 108                 bkey_copy(&op->replace_key, &io->w->key);
 109                 op->replace             = true;
 110
 111                 closure_call(&op->cl, bch_data_insert, NULL, cl);
 112         }
 113
 114         continue_at(cl, write_moving_finish, system_wq);
 115 }
 116
 117 static void read_moving_submit(struct closure *cl)
 118 {
 119         struct moving_io *io = container_of(cl, struct moving_io, cl);
 120         struct bio *bio = &io->bio.bio;
 121
 122         bch_submit_bbio(bio, io->op.c, &io->w->key, 0);
 123
 124         continue_at(cl, write_moving, system_wq);
 125 }
 126
 127 static void read_moving(struct cache_set *c)
 128 {
 129         struct keybuf_key *w;
 130         struct moving_io *io;
 131         struct bio *bio;
 132         struct closure cl;
 133
 134         closure_init_stack(&cl);
 135
 136         /* XXX: if we error, background writeback could stall indefinitely */
 137
 138         while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
 139                 w = bch_keybuf_next_rescan(c, &c->moving_gc_keys,
 140                                            &MAX_KEY, moving_pred);
 141                 if (!w)
 142                         break;
 143
 144                 io = kzalloc(sizeof(struct moving_io) + sizeof(struct bio_vec)
 145                              * DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
 146                              GFP_KERNEL);
 147                 if (!io)
 148                         goto err;
 149
 150                 w->private      = io;
 151                 io->w           = w;
 152                 io->op.inode    = KEY_INODE(&w->key);
 153                 io->op.c        = c;
 154
 155                 moving_init(io);
 156                 bio = &io->bio.bio;
 157
 158                 bio->bi_rw      = READ;
 159                 bio->bi_end_io  = read_moving_endio;
 160
 161                 if (bio_alloc_pages(bio, GFP_KERNEL))
 162                         goto err;
 163
 164                 trace_bcache_gc_copy(&w->key);
 165
 166                 down(&c->moving_in_flight);
 167                 closure_call(&io->cl, read_moving_submit, NULL, &cl);
 168         }
 169
 170         if (0) {
 171 err:            if (!IS_ERR_OR_NULL(w->private))
 172                         kfree(w->private);
 173
 174                 bch_keybuf_del(&c->moving_gc_keys, w);
 175         }
 176
 177         closure_sync(&cl);
 178 }
 179
 180 static bool bucket_cmp(struct bucket *l, struct bucket *r)
 181 {
 182         return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
 183 }
 184
 185 static unsigned bucket_heap_top(struct cache *ca)
 186 {
 187         return GC_SECTORS_USED(heap_peek(&ca->heap));
 188 }
 189
 190 void bch_moving_gc(struct cache_set *c)
 191 {
 192         struct cache *ca;
 193         struct bucket *b;
 194         unsigned i;
 195
 196         if (!c->copy_gc_enabled)
 197                 return;
 198
 199         mutex_lock(&c->bucket_lock);
 200
 201         for_each_cache(ca, c, i) {
 202                 unsigned sectors_to_move = 0;
 203                 unsigned reserve_sectors = ca->sb.bucket_size *
 204                         min(fifo_used(&ca->free), ca->free.size / 2);
 205
 206                 ca->heap.used = 0;
 207
 208                 for_each_bucket(b, ca) {
 209                         if (!GC_SECTORS_USED(b))
 210                                 continue;
 211
 212                         if (!heap_full(&ca->heap)) {
 213                                 sectors_to_move += GC_SECTORS_USED(b);
 214                                 heap_add(&ca->heap, b, bucket_cmp);
 215                         } else if (bucket_cmp(b, heap_peek(&ca->heap))) {
 216                                 sectors_to_move -= bucket_heap_top(ca);
 217                                 sectors_to_move += GC_SECTORS_USED(b);
 218
 219                                 ca->heap.data[0] = b;
 220                                 heap_sift(&ca->heap, 0, bucket_cmp);
 221                         }
 222                 }
 223
 224                 while (sectors_to_move > reserve_sectors) {
 225                         heap_pop(&ca->heap, b, bucket_cmp);
 226                         sectors_to_move -= GC_SECTORS_USED(b);
 227                 }
 228
 229                 ca->gc_move_threshold = bucket_heap_top(ca);
 230
 231                 pr_debug("threshold %u", ca->gc_move_threshold);
 232         }
 233
 234         mutex_unlock(&c->bucket_lock);
 235
 236         c->moving_gc_keys.last_scanned = ZERO_KEY;
 237
 238         read_moving(c);
 239 }
 240
 241 void bch_moving_init_cache_set(struct cache_set *c)
 242 {
 243         bch_keybuf_init(&c->moving_gc_keys);
 244         sema_init(&c->moving_in_flight, 64);
 245 }