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 bucket *g = PTR_BUCKET(c, k, i);
  29
  30                 if (GC_MOVE(g))
  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, 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, 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->op.replace_collision)
  56                 trace_bcache_gc_copy_collision(&io->w->key);
  57
  58         bch_keybuf_del(&io->op.c->moving_gc_keys, io->w);
  59
  60         up(&io->op.c->moving_in_flight);
  61
  62         closure_return_with_destructor(cl, moving_io_destructor);
  63 }
  64
  65 static void read_moving_endio(struct bio *bio, int error)
  66 {
  67         struct bbio *b = container_of(bio, struct bbio, bio);
  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         else if (!KEY_DIRTY(&b->key) &&
  74                  ptr_stale(io->op.c, &b->key, 0)) {
  75                 io->op.error = -EINTR;
  76         }
  77
  78         bch_bbio_endio(io->op.c, bio, error, "reading data to move");
  79 }
  80
  81 static void moving_init(struct moving_io *io)
  82 {
  83         struct bio *bio = &io->bio.bio;
  84
  85         bio_init(bio);
  86         bio_get(bio);
  87         bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
  88
  89         bio->bi_size            = KEY_SIZE(&io->w->key) << 9;
  90         bio->bi_max_vecs        = DIV_ROUND_UP(KEY_SIZE(&io->w->key),
  91                                                PAGE_SECTORS);
  92         bio->bi_private         = &io->cl;
  93         bio->bi_io_vec          = bio->bi_inline_vecs;
  94         bch_bio_map(bio, NULL);
  95 }
  96
  97 static void write_moving(struct closure *cl)
  98 {
  99         struct moving_io *io = container_of(cl, struct moving_io, cl);
 100         struct data_insert_op *op = &io->op;
 101
 102         if (!op->error) {
 103                 moving_init(io);
 104
 105                 io->bio.bio.bi_sector = KEY_START(&io->w->key);
 106                 op->write_prio          = 1;
 107                 op->bio                 = &io->bio.bio;
 108
 109                 op->writeback           = KEY_DIRTY(&io->w->key);
 110                 op->csum                = KEY_CSUM(&io->w->key);
 111
 112                 bkey_copy(&op->replace_key, &io->w->key);
 113                 op->replace             = true;
 114
 115                 closure_call(&op->cl, bch_data_insert, NULL, cl);
 116         }
 117
 118         continue_at(cl, write_moving_finish, system_wq);
 119 }
 120
 121 static void read_moving_submit(struct closure *cl)
 122 {
 123         struct moving_io *io = container_of(cl, struct moving_io, cl);
 124         struct bio *bio = &io->bio.bio;
 125
 126         bch_submit_bbio(bio, io->op.c, &io->w->key, 0);
 127
 128         continue_at(cl, write_moving, system_wq);
 129 }
 130
 131 static void read_moving(struct cache_set *c)
 132 {
 133         struct keybuf_key *w;
 134         struct moving_io *io;
 135         struct bio *bio;
 136         struct closure cl;
 137
 138         closure_init_stack(&cl);
 139
 140         /* XXX: if we error, background writeback could stall indefinitely */
 141
 142         while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
 143                 w = bch_keybuf_next_rescan(c, &c->moving_gc_keys,
 144                                            &MAX_KEY, moving_pred);
 145                 if (!w)
 146                         break;
 147
 148                 if (ptr_stale(c, &w->key, 0)) {
 149                         bch_keybuf_del(&c->moving_gc_keys, w);
 150                         continue;
 151                 }
 152
 153                 io = kzalloc(sizeof(struct moving_io) + sizeof(struct bio_vec)
 154                              * DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
 155                              GFP_KERNEL);
 156                 if (!io)
 157                         goto err;
 158
 159                 w->private      = io;
 160                 io->w           = w;
 161                 io->op.inode    = KEY_INODE(&w->key);
 162                 io->op.c        = c;
 163
 164                 moving_init(io);
 165                 bio = &io->bio.bio;
 166
 167                 bio->bi_rw      = READ;
 168                 bio->bi_end_io  = read_moving_endio;
 169
 170                 if (bio_alloc_pages(bio, GFP_KERNEL))
 171                         goto err;
 172
 173                 trace_bcache_gc_copy(&w->key);
 174
 175                 down(&c->moving_in_flight);
 176                 closure_call(&io->cl, read_moving_submit, NULL, &cl);
 177         }
 178
 179         if (0) {
 180 err:            if (!IS_ERR_OR_NULL(w->private))
 181                         kfree(w->private);
 182
 183                 bch_keybuf_del(&c->moving_gc_keys, w);
 184         }
 185
 186         closure_sync(&cl);
 187 }
 188
 189 static bool bucket_cmp(struct bucket *l, struct bucket *r)
 190 {
 191         return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
 192 }
 193
 194 static unsigned bucket_heap_top(struct cache *ca)
 195 {
 196         struct bucket *b;
 197         return (b = heap_peek(&ca->heap)) ? GC_SECTORS_USED(b) : 0;
 198 }
 199
 200 void bch_moving_gc(struct cache_set *c)
 201 {
 202         struct cache *ca;
 203         struct bucket *b;
 204         unsigned i;
 205
 206         if (!c->copy_gc_enabled)
 207                 return;
 208
 209         mutex_lock(&c->bucket_lock);
 210
 211         for_each_cache(ca, c, i) {
 212                 unsigned sectors_to_move = 0;
 213                 unsigned reserve_sectors = ca->sb.bucket_size *
 214                         min(fifo_used(&ca->free), ca->free.size / 2);
 215
 216                 ca->heap.used = 0;
 217
 218                 for_each_bucket(b, ca) {
 219                         if (!GC_SECTORS_USED(b))
 220                                 continue;
 221
 222                         if (!heap_full(&ca->heap)) {
 223                                 sectors_to_move += GC_SECTORS_USED(b);
 224                                 heap_add(&ca->heap, b, bucket_cmp);
 225                         } else if (bucket_cmp(b, heap_peek(&ca->heap))) {
 226                                 sectors_to_move -= bucket_heap_top(ca);
 227                                 sectors_to_move += GC_SECTORS_USED(b);
 228
 229                                 ca->heap.data[0] = b;
 230                                 heap_sift(&ca->heap, 0, bucket_cmp);
 231                         }
 232                 }
 233
 234                 while (sectors_to_move > reserve_sectors) {
 235                         heap_pop(&ca->heap, b, bucket_cmp);
 236                         sectors_to_move -= GC_SECTORS_USED(b);
 237                 }
 238
 239                 while (heap_pop(&ca->heap, b, bucket_cmp))
 240                         SET_GC_MOVE(b, 1);
 241         }
 242
 243         mutex_unlock(&c->bucket_lock);
 244
 245         c->moving_gc_keys.last_scanned = ZERO_KEY;
 246
 247         read_moving(c);
 248 }
 249
 250 void bch_moving_init_cache_set(struct cache_set *c)
 251 {
 252         bch_keybuf_init(&c->moving_gc_keys);
 253         sema_init(&c->moving_in_flight, 64);
 254 }