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                 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
  37 static 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
  43 static 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
  48         bio_free_pages(bio);
  49
  50         if (io->op.replace_collision)
  51                 trace_bcache_gc_copy_collision(&io->w->key);
  52
  53         bch_keybuf_del(&io->op.c->moving_gc_keys, io->w);
  54
  55         up(&io->op.c->moving_in_flight);
  56
  57         closure_return_with_destructor(cl, moving_io_destructor);
  58 }
  59
  60 static void read_moving_endio(struct bio *bio)
  61 {
  62         struct bbio *b = container_of(bio, struct bbio, bio);
  63         struct moving_io *io = container_of(bio->bi_private,
  64                                             struct moving_io, cl);
  65
  66         if (bio->bi_error)
  67                 io->op.error = bio->bi_error;
  68         else if (!KEY_DIRTY(&b->key) &&
  69                  ptr_stale(io->op.c, &b->key, 0)) {
  70                 io->op.error = -EINTR;
  71         }
  72
  73         bch_bbio_endio(io->op.c, bio, bio->bi_error, "reading data to move");
  74 }
  75
  76 static void moving_init(struct moving_io *io)
  77 {
  78         struct bio *bio = &io->bio.bio;
  79
  80         bio_init(bio, bio->bi_inline_vecs,
  81                  DIV_ROUND_UP(KEY_SIZE(&io->w->key), PAGE_SECTORS));
  82         bio_get(bio);
  83         bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
  84
  85         bio->bi_iter.bi_size    = KEY_SIZE(&io->w->key) << 9;
  86         bio->bi_private         = &io->cl;
  87         bch_bio_map(bio, NULL);
  88 }
  89
  90 static void write_moving(struct closure *cl)
  91 {
  92         struct moving_io *io = container_of(cl, struct moving_io, cl);
  93         struct data_insert_op *op = &io->op;
  94
  95         if (!op->error) {
  96                 moving_init(io);
  97
  98                 io->bio.bio.bi_iter.bi_sector = KEY_START(&io->w->key);
  99                 op->write_prio          = 1;
 100                 op->bio                 = &io->bio.bio;
 101
 102                 op->writeback           = KEY_DIRTY(&io->w->key);
 103                 op->csum                = KEY_CSUM(&io->w->key);
 104
 105                 bkey_copy(&op->replace_key, &io->w->key);
 106                 op->replace             = true;
 107
 108                 closure_call(&op->cl, bch_data_insert, NULL, cl);
 109         }
 110
 111         continue_at(cl, write_moving_finish, op->wq);
 112 }
 113
 114 static void read_moving_submit(struct closure *cl)
 115 {
 116         struct moving_io *io = container_of(cl, struct moving_io, cl);
 117         struct bio *bio = &io->bio.bio;
 118
 119         bch_submit_bbio(bio, io->op.c, &io->w->key, 0);
 120
 121         continue_at(cl, write_moving, io->op.wq);
 122 }
 123
 124 static void read_moving(struct cache_set *c)
 125 {
 126         struct keybuf_key *w;
 127         struct moving_io *io;
 128         struct bio *bio;
 129         struct closure cl;
 130
 131         closure_init_stack(&cl);
 132
 133         /* XXX: if we error, background writeback could stall indefinitely */
 134
 135         while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
 136                 w = bch_keybuf_next_rescan(c, &c->moving_gc_keys,
 137                                            &MAX_KEY, moving_pred);
 138                 if (!w)
 139                         break;
 140
 141                 if (ptr_stale(c, &w->key, 0)) {
 142                         bch_keybuf_del(&c->moving_gc_keys, w);
 143                         continue;
 144                 }
 145
 146                 io = kzalloc(sizeof(struct moving_io) + sizeof(struct bio_vec)
 147                              * DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
 148                              GFP_KERNEL);
 149                 if (!io)
 150                         goto err;
 151
 152                 w->private      = io;
 153                 io->w           = w;
 154                 io->op.inode    = KEY_INODE(&w->key);
 155                 io->op.c        = c;
 156                 io->op.wq       = c->moving_gc_wq;
 157
 158                 moving_init(io);
 159                 bio = &io->bio.bio;
 160
 161                 bio_set_op_attrs(bio, REQ_OP_READ, 0);
 162                 bio->bi_end_io  = read_moving_endio;
 163
 164                 if (bio_alloc_pages(bio, GFP_KERNEL))
 165                         goto err;
 166
 167                 trace_bcache_gc_copy(&w->key);
 168
 169                 down(&c->moving_in_flight);
 170                 closure_call(&io->cl, read_moving_submit, NULL, &cl);
 171         }
 172
 173         if (0) {
 174 err:            if (!IS_ERR_OR_NULL(w->private))
 175                         kfree(w->private);
 176
 177                 bch_keybuf_del(&c->moving_gc_keys, w);
 178         }
 179
 180         closure_sync(&cl);
 181 }
 182
 183 static bool bucket_cmp(struct bucket *l, struct bucket *r)
 184 {
 185         return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
 186 }
 187
 188 static unsigned bucket_heap_top(struct cache *ca)
 189 {
 190         struct bucket *b;
 191         return (b = heap_peek(&ca->heap)) ? GC_SECTORS_USED(b) : 0;
 192 }
 193
 194 void bch_moving_gc(struct cache_set *c)
 195 {
 196         struct cache *ca;
 197         struct bucket *b;
 198         unsigned i;
 199
 200         if (!c->copy_gc_enabled)
 201                 return;
 202
 203         mutex_lock(&c->bucket_lock);
 204
 205         for_each_cache(ca, c, i) {
 206                 unsigned sectors_to_move = 0;
 207                 unsigned reserve_sectors = ca->sb.bucket_size *
 208                         fifo_used(&ca->free[RESERVE_MOVINGGC]);
 209
 210                 ca->heap.used = 0;
 211
 212                 for_each_bucket(b, ca) {
 213                         if (GC_MARK(b) == GC_MARK_METADATA ||
 214                             !GC_SECTORS_USED(b) ||
 215                             GC_SECTORS_USED(b) == ca->sb.bucket_size ||
 216                             atomic_read(&b->pin))
 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                 while (heap_pop(&ca->heap, b, bucket_cmp))
 237                         SET_GC_MOVE(b, 1);
 238         }
 239
 240         mutex_unlock(&c->bucket_lock);
 241
 242         c->moving_gc_keys.last_scanned = ZERO_KEY;
 243
 244         read_moving(c);
 245 }
 246
 247 void bch_moving_init_cache_set(struct cache_set *c)
 248 {
 249         bch_keybuf_init(&c->moving_gc_keys);
 250         sema_init(&c->moving_in_flight, 64);
 251 }