Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Primary bucket allocation code |
| 3 | * |
| 4 | * Copyright 2012 Google, Inc. |
| 5 | * |
| 6 | * Allocation in bcache is done in terms of buckets: |
| 7 | * |
| 8 | * Each bucket has associated an 8 bit gen; this gen corresponds to the gen in |
| 9 | * btree pointers - they must match for the pointer to be considered valid. |
| 10 | * |
| 11 | * Thus (assuming a bucket has no dirty data or metadata in it) we can reuse a |
| 12 | * bucket simply by incrementing its gen. |
| 13 | * |
| 14 | * The gens (along with the priorities; it's really the gens are important but |
| 15 | * the code is named as if it's the priorities) are written in an arbitrary list |
| 16 | * of buckets on disk, with a pointer to them in the journal header. |
| 17 | * |
| 18 | * When we invalidate a bucket, we have to write its new gen to disk and wait |
| 19 | * for that write to complete before we use it - otherwise after a crash we |
| 20 | * could have pointers that appeared to be good but pointed to data that had |
| 21 | * been overwritten. |
| 22 | * |
| 23 | * Since the gens and priorities are all stored contiguously on disk, we can |
| 24 | * batch this up: We fill up the free_inc list with freshly invalidated buckets, |
| 25 | * call prio_write(), and when prio_write() finishes we pull buckets off the |
| 26 | * free_inc list and optionally discard them. |
| 27 | * |
| 28 | * free_inc isn't the only freelist - if it was, we'd often to sleep while |
| 29 | * priorities and gens were being written before we could allocate. c->free is a |
| 30 | * smaller freelist, and buckets on that list are always ready to be used. |
| 31 | * |
| 32 | * If we've got discards enabled, that happens when a bucket moves from the |
| 33 | * free_inc list to the free list. |
| 34 | * |
| 35 | * There is another freelist, because sometimes we have buckets that we know |
| 36 | * have nothing pointing into them - these we can reuse without waiting for |
| 37 | * priorities to be rewritten. These come from freed btree nodes and buckets |
| 38 | * that garbage collection discovered no longer had valid keys pointing into |
| 39 | * them (because they were overwritten). That's the unused list - buckets on the |
| 40 | * unused list move to the free list, optionally being discarded in the process. |
| 41 | * |
| 42 | * It's also important to ensure that gens don't wrap around - with respect to |
| 43 | * either the oldest gen in the btree or the gen on disk. This is quite |
| 44 | * difficult to do in practice, but we explicitly guard against it anyways - if |
| 45 | * a bucket is in danger of wrapping around we simply skip invalidating it that |
| 46 | * time around, and we garbage collect or rewrite the priorities sooner than we |
| 47 | * would have otherwise. |
| 48 | * |
| 49 | * bch_bucket_alloc() allocates a single bucket from a specific cache. |
| 50 | * |
| 51 | * bch_bucket_alloc_set() allocates one or more buckets from different caches |
| 52 | * out of a cache set. |
| 53 | * |
| 54 | * free_some_buckets() drives all the processes described above. It's called |
| 55 | * from bch_bucket_alloc() and a few other places that need to make sure free |
| 56 | * buckets are ready. |
| 57 | * |
| 58 | * invalidate_buckets_(lru|fifo)() find buckets that are available to be |
| 59 | * invalidated, and then invalidate them and stick them on the free_inc list - |
| 60 | * in either lru or fifo order. |
| 61 | */ |
| 62 | |
| 63 | #include "bcache.h" |
| 64 | #include "btree.h" |
| 65 | |
Kent Overstreet | 49b1212 | 2013-07-24 17:16:09 -0700 | [diff] [blame] | 66 | #include <linux/blkdev.h> |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 67 | #include <linux/freezer.h> |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 68 | #include <linux/kthread.h> |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 69 | #include <linux/random.h> |
Kent Overstreet | c37511b | 2013-04-26 15:39:55 -0700 | [diff] [blame] | 70 | #include <trace/events/bcache.h> |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 71 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 72 | /* Bucket heap / gen */ |
| 73 | |
| 74 | uint8_t bch_inc_gen(struct cache *ca, struct bucket *b) |
| 75 | { |
| 76 | uint8_t ret = ++b->gen; |
| 77 | |
| 78 | ca->set->need_gc = max(ca->set->need_gc, bucket_gc_gen(b)); |
| 79 | WARN_ON_ONCE(ca->set->need_gc > BUCKET_GC_GEN_MAX); |
| 80 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 81 | return ret; |
| 82 | } |
| 83 | |
| 84 | void bch_rescale_priorities(struct cache_set *c, int sectors) |
| 85 | { |
| 86 | struct cache *ca; |
| 87 | struct bucket *b; |
| 88 | unsigned next = c->nbuckets * c->sb.bucket_size / 1024; |
| 89 | unsigned i; |
| 90 | int r; |
| 91 | |
| 92 | atomic_sub(sectors, &c->rescale); |
| 93 | |
| 94 | do { |
| 95 | r = atomic_read(&c->rescale); |
| 96 | |
| 97 | if (r >= 0) |
| 98 | return; |
| 99 | } while (atomic_cmpxchg(&c->rescale, r, r + next) != r); |
| 100 | |
| 101 | mutex_lock(&c->bucket_lock); |
| 102 | |
| 103 | c->min_prio = USHRT_MAX; |
| 104 | |
| 105 | for_each_cache(ca, c, i) |
| 106 | for_each_bucket(b, ca) |
| 107 | if (b->prio && |
| 108 | b->prio != BTREE_PRIO && |
| 109 | !atomic_read(&b->pin)) { |
| 110 | b->prio--; |
| 111 | c->min_prio = min(c->min_prio, b->prio); |
| 112 | } |
| 113 | |
| 114 | mutex_unlock(&c->bucket_lock); |
| 115 | } |
| 116 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 117 | /* |
| 118 | * Background allocation thread: scans for buckets to be invalidated, |
| 119 | * invalidates them, rewrites prios/gens (marking them as invalidated on disk), |
| 120 | * then optionally issues discard commands to the newly free buckets, then puts |
| 121 | * them on the various freelists. |
| 122 | */ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 123 | |
| 124 | static inline bool can_inc_bucket_gen(struct bucket *b) |
| 125 | { |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 126 | return bucket_gc_gen(b) < BUCKET_GC_GEN_MAX; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 127 | } |
| 128 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 129 | bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 130 | { |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 131 | BUG_ON(!ca->set->gc_mark_valid); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 132 | |
Kent Overstreet | 4fe6a81 | 2014-03-13 13:46:29 -0700 | [diff] [blame] | 133 | return (!GC_MARK(b) || |
| 134 | GC_MARK(b) == GC_MARK_RECLAIMABLE) && |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 135 | !atomic_read(&b->pin) && |
| 136 | can_inc_bucket_gen(b); |
| 137 | } |
| 138 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 139 | void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 140 | { |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 141 | lockdep_assert_held(&ca->set->bucket_lock); |
| 142 | BUG_ON(GC_MARK(b) && GC_MARK(b) != GC_MARK_RECLAIMABLE); |
Kent Overstreet | 7159b1a | 2014-02-12 18:43:32 -0800 | [diff] [blame] | 143 | |
| 144 | if (GC_SECTORS_USED(b)) |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 145 | trace_bcache_invalidate(ca, b - ca->buckets); |
Kent Overstreet | 7159b1a | 2014-02-12 18:43:32 -0800 | [diff] [blame] | 146 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 147 | bch_inc_gen(ca, b); |
| 148 | b->prio = INITIAL_PRIO; |
| 149 | atomic_inc(&b->pin); |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 150 | } |
| 151 | |
| 152 | static void bch_invalidate_one_bucket(struct cache *ca, struct bucket *b) |
| 153 | { |
| 154 | __bch_invalidate_one_bucket(ca, b); |
| 155 | |
| 156 | fifo_push(&ca->free_inc, b - ca->buckets); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 157 | } |
| 158 | |
Kent Overstreet | e0a985a | 2013-11-12 13:49:10 -0800 | [diff] [blame] | 159 | /* |
| 160 | * Determines what order we're going to reuse buckets, smallest bucket_prio() |
| 161 | * first: we also take into account the number of sectors of live data in that |
| 162 | * bucket, and in order for that multiply to make sense we have to scale bucket |
| 163 | * |
| 164 | * Thus, we scale the bucket priorities so that the bucket with the smallest |
| 165 | * prio is worth 1/8th of what INITIAL_PRIO is worth. |
| 166 | */ |
| 167 | |
| 168 | #define bucket_prio(b) \ |
| 169 | ({ \ |
| 170 | unsigned min_prio = (INITIAL_PRIO - ca->set->min_prio) / 8; \ |
| 171 | \ |
| 172 | (b->prio - ca->set->min_prio + min_prio) * GC_SECTORS_USED(b); \ |
| 173 | }) |
Kent Overstreet | b1a67b0 | 2013-03-25 11:46:44 -0700 | [diff] [blame] | 174 | |
| 175 | #define bucket_max_cmp(l, r) (bucket_prio(l) < bucket_prio(r)) |
| 176 | #define bucket_min_cmp(l, r) (bucket_prio(l) > bucket_prio(r)) |
| 177 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 178 | static void invalidate_buckets_lru(struct cache *ca) |
| 179 | { |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 180 | struct bucket *b; |
| 181 | ssize_t i; |
| 182 | |
| 183 | ca->heap.used = 0; |
| 184 | |
| 185 | for_each_bucket(b, ca) { |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 186 | if (!bch_can_invalidate_bucket(ca, b)) |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 187 | continue; |
| 188 | |
| 189 | if (!heap_full(&ca->heap)) |
| 190 | heap_add(&ca->heap, b, bucket_max_cmp); |
| 191 | else if (bucket_max_cmp(b, heap_peek(&ca->heap))) { |
| 192 | ca->heap.data[0] = b; |
| 193 | heap_sift(&ca->heap, 0, bucket_max_cmp); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 194 | } |
| 195 | } |
| 196 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 197 | for (i = ca->heap.used / 2 - 1; i >= 0; --i) |
| 198 | heap_sift(&ca->heap, i, bucket_min_cmp); |
| 199 | |
| 200 | while (!fifo_full(&ca->free_inc)) { |
| 201 | if (!heap_pop(&ca->heap, b, bucket_min_cmp)) { |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 202 | /* |
| 203 | * We don't want to be calling invalidate_buckets() |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 204 | * multiple times when it can't do anything |
| 205 | */ |
| 206 | ca->invalidate_needs_gc = 1; |
Kent Overstreet | 72a4451 | 2013-10-24 17:19:26 -0700 | [diff] [blame] | 207 | wake_up_gc(ca->set); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 208 | return; |
| 209 | } |
| 210 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 211 | bch_invalidate_one_bucket(ca, b); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 212 | } |
| 213 | } |
| 214 | |
| 215 | static void invalidate_buckets_fifo(struct cache *ca) |
| 216 | { |
| 217 | struct bucket *b; |
| 218 | size_t checked = 0; |
| 219 | |
| 220 | while (!fifo_full(&ca->free_inc)) { |
| 221 | if (ca->fifo_last_bucket < ca->sb.first_bucket || |
| 222 | ca->fifo_last_bucket >= ca->sb.nbuckets) |
| 223 | ca->fifo_last_bucket = ca->sb.first_bucket; |
| 224 | |
| 225 | b = ca->buckets + ca->fifo_last_bucket++; |
| 226 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 227 | if (bch_can_invalidate_bucket(ca, b)) |
| 228 | bch_invalidate_one_bucket(ca, b); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 229 | |
| 230 | if (++checked >= ca->sb.nbuckets) { |
| 231 | ca->invalidate_needs_gc = 1; |
Kent Overstreet | 72a4451 | 2013-10-24 17:19:26 -0700 | [diff] [blame] | 232 | wake_up_gc(ca->set); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 233 | return; |
| 234 | } |
| 235 | } |
| 236 | } |
| 237 | |
| 238 | static void invalidate_buckets_random(struct cache *ca) |
| 239 | { |
| 240 | struct bucket *b; |
| 241 | size_t checked = 0; |
| 242 | |
| 243 | while (!fifo_full(&ca->free_inc)) { |
| 244 | size_t n; |
| 245 | get_random_bytes(&n, sizeof(n)); |
| 246 | |
| 247 | n %= (size_t) (ca->sb.nbuckets - ca->sb.first_bucket); |
| 248 | n += ca->sb.first_bucket; |
| 249 | |
| 250 | b = ca->buckets + n; |
| 251 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 252 | if (bch_can_invalidate_bucket(ca, b)) |
| 253 | bch_invalidate_one_bucket(ca, b); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 254 | |
| 255 | if (++checked >= ca->sb.nbuckets / 2) { |
| 256 | ca->invalidate_needs_gc = 1; |
Kent Overstreet | 72a4451 | 2013-10-24 17:19:26 -0700 | [diff] [blame] | 257 | wake_up_gc(ca->set); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 258 | return; |
| 259 | } |
| 260 | } |
| 261 | } |
| 262 | |
| 263 | static void invalidate_buckets(struct cache *ca) |
| 264 | { |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 265 | BUG_ON(ca->invalidate_needs_gc); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 266 | |
| 267 | switch (CACHE_REPLACEMENT(&ca->sb)) { |
| 268 | case CACHE_REPLACEMENT_LRU: |
| 269 | invalidate_buckets_lru(ca); |
| 270 | break; |
| 271 | case CACHE_REPLACEMENT_FIFO: |
| 272 | invalidate_buckets_fifo(ca); |
| 273 | break; |
| 274 | case CACHE_REPLACEMENT_RANDOM: |
| 275 | invalidate_buckets_random(ca); |
| 276 | break; |
| 277 | } |
| 278 | } |
| 279 | |
| 280 | #define allocator_wait(ca, cond) \ |
| 281 | do { \ |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 282 | while (1) { \ |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 283 | set_current_state(TASK_INTERRUPTIBLE); \ |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 284 | if (cond) \ |
| 285 | break; \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 286 | \ |
| 287 | mutex_unlock(&(ca)->set->bucket_lock); \ |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 288 | if (kthread_should_stop()) \ |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 289 | return 0; \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 290 | \ |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 291 | try_to_freeze(); \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 292 | schedule(); \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 293 | mutex_lock(&(ca)->set->bucket_lock); \ |
| 294 | } \ |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 295 | __set_current_state(TASK_RUNNING); \ |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 296 | } while (0) |
| 297 | |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 298 | static int bch_allocator_push(struct cache *ca, long bucket) |
| 299 | { |
| 300 | unsigned i; |
| 301 | |
| 302 | /* Prios/gens are actually the most important reserve */ |
| 303 | if (fifo_push(&ca->free[RESERVE_PRIO], bucket)) |
| 304 | return true; |
| 305 | |
| 306 | for (i = 0; i < RESERVE_NR; i++) |
| 307 | if (fifo_push(&ca->free[i], bucket)) |
| 308 | return true; |
| 309 | |
| 310 | return false; |
| 311 | } |
| 312 | |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 313 | static int bch_allocator_thread(void *arg) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 314 | { |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 315 | struct cache *ca = arg; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 316 | |
| 317 | mutex_lock(&ca->set->bucket_lock); |
| 318 | |
| 319 | while (1) { |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 320 | /* |
| 321 | * First, we pull buckets off of the unused and free_inc lists, |
| 322 | * possibly issue discards to them, then we add the bucket to |
| 323 | * the free list: |
| 324 | */ |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 325 | while (!fifo_empty(&ca->free_inc)) { |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 326 | long bucket; |
| 327 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 328 | fifo_pop(&ca->free_inc, bucket); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 329 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 330 | if (ca->discard) { |
Kent Overstreet | 49b1212 | 2013-07-24 17:16:09 -0700 | [diff] [blame] | 331 | mutex_unlock(&ca->set->bucket_lock); |
| 332 | blkdev_issue_discard(ca->bdev, |
| 333 | bucket_to_sector(ca->set, bucket), |
| 334 | ca->sb.block_size, GFP_KERNEL, 0); |
| 335 | mutex_lock(&ca->set->bucket_lock); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 336 | } |
Kent Overstreet | 49b1212 | 2013-07-24 17:16:09 -0700 | [diff] [blame] | 337 | |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 338 | allocator_wait(ca, bch_allocator_push(ca, bucket)); |
Kent Overstreet | 0a63b66 | 2014-03-17 17:15:53 -0700 | [diff] [blame] | 339 | wake_up(&ca->set->btree_cache_wait); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 340 | wake_up(&ca->set->bucket_wait); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 341 | } |
| 342 | |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 343 | /* |
| 344 | * We've run out of free buckets, we need to find some buckets |
| 345 | * we can invalidate. First, invalidate them in memory and add |
| 346 | * them to the free_inc list: |
| 347 | */ |
| 348 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 349 | retry_invalidate: |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 350 | allocator_wait(ca, ca->set->gc_mark_valid && |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 351 | !ca->invalidate_needs_gc); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 352 | invalidate_buckets(ca); |
| 353 | |
Kent Overstreet | 86b26b8 | 2013-04-30 19:14:40 -0700 | [diff] [blame] | 354 | /* |
| 355 | * Now, we write their new gens to disk so we can start writing |
| 356 | * new stuff to them: |
| 357 | */ |
| 358 | allocator_wait(ca, !atomic_read(&ca->set->prio_blocked)); |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 359 | if (CACHE_SYNC(&ca->set->sb)) { |
| 360 | /* |
| 361 | * This could deadlock if an allocation with a btree |
| 362 | * node locked ever blocked - having the btree node |
| 363 | * locked would block garbage collection, but here we're |
| 364 | * waiting on garbage collection before we invalidate |
| 365 | * and free anything. |
| 366 | * |
| 367 | * But this should be safe since the btree code always |
| 368 | * uses btree_check_reserve() before allocating now, and |
| 369 | * if it fails it blocks without btree nodes locked. |
| 370 | */ |
| 371 | if (!fifo_full(&ca->free_inc)) |
| 372 | goto retry_invalidate; |
| 373 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 374 | bch_prio_write(ca); |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 375 | } |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 376 | } |
| 377 | } |
| 378 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 379 | /* Allocation */ |
| 380 | |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 381 | long bch_bucket_alloc(struct cache *ca, unsigned reserve, bool wait) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 382 | { |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 383 | DEFINE_WAIT(w); |
| 384 | struct bucket *b; |
| 385 | long r; |
| 386 | |
| 387 | /* fastpath */ |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 388 | if (fifo_pop(&ca->free[RESERVE_NONE], r) || |
| 389 | fifo_pop(&ca->free[reserve], r)) |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 390 | goto out; |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 391 | |
Kent Overstreet | 7159b1a | 2014-02-12 18:43:32 -0800 | [diff] [blame] | 392 | if (!wait) { |
| 393 | trace_bcache_alloc_fail(ca, reserve); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 394 | return -1; |
Kent Overstreet | 7159b1a | 2014-02-12 18:43:32 -0800 | [diff] [blame] | 395 | } |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 396 | |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 397 | do { |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 398 | prepare_to_wait(&ca->set->bucket_wait, &w, |
| 399 | TASK_UNINTERRUPTIBLE); |
| 400 | |
| 401 | mutex_unlock(&ca->set->bucket_lock); |
| 402 | schedule(); |
| 403 | mutex_lock(&ca->set->bucket_lock); |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 404 | } while (!fifo_pop(&ca->free[RESERVE_NONE], r) && |
| 405 | !fifo_pop(&ca->free[reserve], r)); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 406 | |
| 407 | finish_wait(&ca->set->bucket_wait, &w); |
| 408 | out: |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 409 | wake_up_process(ca->alloc_thread); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 410 | |
Kent Overstreet | 7159b1a | 2014-02-12 18:43:32 -0800 | [diff] [blame] | 411 | trace_bcache_alloc(ca, reserve); |
| 412 | |
Kent Overstreet | 280481d | 2013-10-24 16:36:03 -0700 | [diff] [blame] | 413 | if (expensive_debug_checks(ca->set)) { |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 414 | size_t iter; |
| 415 | long i; |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 416 | unsigned j; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 417 | |
| 418 | for (iter = 0; iter < prio_buckets(ca) * 2; iter++) |
| 419 | BUG_ON(ca->prio_buckets[iter] == (uint64_t) r); |
| 420 | |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 421 | for (j = 0; j < RESERVE_NR; j++) |
| 422 | fifo_for_each(i, &ca->free[j], iter) |
| 423 | BUG_ON(i == r); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 424 | fifo_for_each(i, &ca->free_inc, iter) |
| 425 | BUG_ON(i == r); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 426 | } |
Kent Overstreet | 280481d | 2013-10-24 16:36:03 -0700 | [diff] [blame] | 427 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 428 | b = ca->buckets + r; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 429 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 430 | BUG_ON(atomic_read(&b->pin) != 1); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 431 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 432 | SET_GC_SECTORS_USED(b, ca->sb.bucket_size); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 433 | |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 434 | if (reserve <= RESERVE_PRIO) { |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 435 | SET_GC_MARK(b, GC_MARK_METADATA); |
Nicholas Swenson | 981aa8c | 2013-11-07 17:53:19 -0800 | [diff] [blame] | 436 | SET_GC_MOVE(b, 0); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 437 | b->prio = BTREE_PRIO; |
| 438 | } else { |
| 439 | SET_GC_MARK(b, GC_MARK_RECLAIMABLE); |
Nicholas Swenson | 981aa8c | 2013-11-07 17:53:19 -0800 | [diff] [blame] | 440 | SET_GC_MOVE(b, 0); |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 441 | b->prio = INITIAL_PRIO; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 442 | } |
| 443 | |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 444 | return r; |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 445 | } |
| 446 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 447 | void __bch_bucket_free(struct cache *ca, struct bucket *b) |
| 448 | { |
| 449 | SET_GC_MARK(b, 0); |
| 450 | SET_GC_SECTORS_USED(b, 0); |
| 451 | } |
| 452 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 453 | void bch_bucket_free(struct cache_set *c, struct bkey *k) |
| 454 | { |
| 455 | unsigned i; |
| 456 | |
Kent Overstreet | 2531d9ee | 2014-03-17 16:55:55 -0700 | [diff] [blame^] | 457 | for (i = 0; i < KEY_PTRS(k); i++) |
| 458 | __bch_bucket_free(PTR_CACHE(c, k, i), |
| 459 | PTR_BUCKET(c, k, i)); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 460 | } |
| 461 | |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 462 | int __bch_bucket_alloc_set(struct cache_set *c, unsigned reserve, |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 463 | struct bkey *k, int n, bool wait) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 464 | { |
| 465 | int i; |
| 466 | |
| 467 | lockdep_assert_held(&c->bucket_lock); |
| 468 | BUG_ON(!n || n > c->caches_loaded || n > 8); |
| 469 | |
| 470 | bkey_init(k); |
| 471 | |
| 472 | /* sort by free space/prio of oldest data in caches */ |
| 473 | |
| 474 | for (i = 0; i < n; i++) { |
| 475 | struct cache *ca = c->cache_by_alloc[i]; |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 476 | long b = bch_bucket_alloc(ca, reserve, wait); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 477 | |
| 478 | if (b == -1) |
| 479 | goto err; |
| 480 | |
| 481 | k->ptr[i] = PTR(ca->buckets[b].gen, |
| 482 | bucket_to_sector(c, b), |
| 483 | ca->sb.nr_this_dev); |
| 484 | |
| 485 | SET_KEY_PTRS(k, i + 1); |
| 486 | } |
| 487 | |
| 488 | return 0; |
| 489 | err: |
| 490 | bch_bucket_free(c, k); |
Kent Overstreet | 3a3b6a4 | 2013-07-24 16:46:42 -0700 | [diff] [blame] | 491 | bkey_put(c, k); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 492 | return -1; |
| 493 | } |
| 494 | |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 495 | int bch_bucket_alloc_set(struct cache_set *c, unsigned reserve, |
Kent Overstreet | 35fcd84 | 2013-07-24 17:29:09 -0700 | [diff] [blame] | 496 | struct bkey *k, int n, bool wait) |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 497 | { |
| 498 | int ret; |
| 499 | mutex_lock(&c->bucket_lock); |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 500 | ret = __bch_bucket_alloc_set(c, reserve, k, n, wait); |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 501 | mutex_unlock(&c->bucket_lock); |
| 502 | return ret; |
| 503 | } |
| 504 | |
Kent Overstreet | 2599b53 | 2013-07-24 18:11:11 -0700 | [diff] [blame] | 505 | /* Sector allocator */ |
| 506 | |
| 507 | struct open_bucket { |
| 508 | struct list_head list; |
| 509 | unsigned last_write_point; |
| 510 | unsigned sectors_free; |
| 511 | BKEY_PADDED(key); |
| 512 | }; |
| 513 | |
| 514 | /* |
| 515 | * We keep multiple buckets open for writes, and try to segregate different |
| 516 | * write streams for better cache utilization: first we look for a bucket where |
| 517 | * the last write to it was sequential with the current write, and failing that |
| 518 | * we look for a bucket that was last used by the same task. |
| 519 | * |
| 520 | * The ideas is if you've got multiple tasks pulling data into the cache at the |
| 521 | * same time, you'll get better cache utilization if you try to segregate their |
| 522 | * data and preserve locality. |
| 523 | * |
| 524 | * For example, say you've starting Firefox at the same time you're copying a |
| 525 | * bunch of files. Firefox will likely end up being fairly hot and stay in the |
| 526 | * cache awhile, but the data you copied might not be; if you wrote all that |
| 527 | * data to the same buckets it'd get invalidated at the same time. |
| 528 | * |
| 529 | * Both of those tasks will be doing fairly random IO so we can't rely on |
| 530 | * detecting sequential IO to segregate their data, but going off of the task |
| 531 | * should be a sane heuristic. |
| 532 | */ |
| 533 | static struct open_bucket *pick_data_bucket(struct cache_set *c, |
| 534 | const struct bkey *search, |
| 535 | unsigned write_point, |
| 536 | struct bkey *alloc) |
| 537 | { |
| 538 | struct open_bucket *ret, *ret_task = NULL; |
| 539 | |
| 540 | list_for_each_entry_reverse(ret, &c->data_buckets, list) |
| 541 | if (!bkey_cmp(&ret->key, search)) |
| 542 | goto found; |
| 543 | else if (ret->last_write_point == write_point) |
| 544 | ret_task = ret; |
| 545 | |
| 546 | ret = ret_task ?: list_first_entry(&c->data_buckets, |
| 547 | struct open_bucket, list); |
| 548 | found: |
| 549 | if (!ret->sectors_free && KEY_PTRS(alloc)) { |
| 550 | ret->sectors_free = c->sb.bucket_size; |
| 551 | bkey_copy(&ret->key, alloc); |
| 552 | bkey_init(alloc); |
| 553 | } |
| 554 | |
| 555 | if (!ret->sectors_free) |
| 556 | ret = NULL; |
| 557 | |
| 558 | return ret; |
| 559 | } |
| 560 | |
| 561 | /* |
| 562 | * Allocates some space in the cache to write to, and k to point to the newly |
| 563 | * allocated space, and updates KEY_SIZE(k) and KEY_OFFSET(k) (to point to the |
| 564 | * end of the newly allocated space). |
| 565 | * |
| 566 | * May allocate fewer sectors than @sectors, KEY_SIZE(k) indicates how many |
| 567 | * sectors were actually allocated. |
| 568 | * |
| 569 | * If s->writeback is true, will not fail. |
| 570 | */ |
| 571 | bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, unsigned sectors, |
| 572 | unsigned write_point, unsigned write_prio, bool wait) |
| 573 | { |
| 574 | struct open_bucket *b; |
| 575 | BKEY_PADDED(key) alloc; |
| 576 | unsigned i; |
| 577 | |
| 578 | /* |
| 579 | * We might have to allocate a new bucket, which we can't do with a |
| 580 | * spinlock held. So if we have to allocate, we drop the lock, allocate |
| 581 | * and then retry. KEY_PTRS() indicates whether alloc points to |
| 582 | * allocated bucket(s). |
| 583 | */ |
| 584 | |
| 585 | bkey_init(&alloc.key); |
| 586 | spin_lock(&c->data_bucket_lock); |
| 587 | |
| 588 | while (!(b = pick_data_bucket(c, k, write_point, &alloc.key))) { |
| 589 | unsigned watermark = write_prio |
Kent Overstreet | 7836541 | 2013-12-17 01:29:34 -0800 | [diff] [blame] | 590 | ? RESERVE_MOVINGGC |
| 591 | : RESERVE_NONE; |
Kent Overstreet | 2599b53 | 2013-07-24 18:11:11 -0700 | [diff] [blame] | 592 | |
| 593 | spin_unlock(&c->data_bucket_lock); |
| 594 | |
| 595 | if (bch_bucket_alloc_set(c, watermark, &alloc.key, 1, wait)) |
| 596 | return false; |
| 597 | |
| 598 | spin_lock(&c->data_bucket_lock); |
| 599 | } |
| 600 | |
| 601 | /* |
| 602 | * If we had to allocate, we might race and not need to allocate the |
| 603 | * second time we call find_data_bucket(). If we allocated a bucket but |
| 604 | * didn't use it, drop the refcount bch_bucket_alloc_set() took: |
| 605 | */ |
| 606 | if (KEY_PTRS(&alloc.key)) |
Kent Overstreet | 3a3b6a4 | 2013-07-24 16:46:42 -0700 | [diff] [blame] | 607 | bkey_put(c, &alloc.key); |
Kent Overstreet | 2599b53 | 2013-07-24 18:11:11 -0700 | [diff] [blame] | 608 | |
| 609 | for (i = 0; i < KEY_PTRS(&b->key); i++) |
| 610 | EBUG_ON(ptr_stale(c, &b->key, i)); |
| 611 | |
| 612 | /* Set up the pointer to the space we're allocating: */ |
| 613 | |
| 614 | for (i = 0; i < KEY_PTRS(&b->key); i++) |
| 615 | k->ptr[i] = b->key.ptr[i]; |
| 616 | |
| 617 | sectors = min(sectors, b->sectors_free); |
| 618 | |
| 619 | SET_KEY_OFFSET(k, KEY_OFFSET(k) + sectors); |
| 620 | SET_KEY_SIZE(k, sectors); |
| 621 | SET_KEY_PTRS(k, KEY_PTRS(&b->key)); |
| 622 | |
| 623 | /* |
| 624 | * Move b to the end of the lru, and keep track of what this bucket was |
| 625 | * last used for: |
| 626 | */ |
| 627 | list_move_tail(&b->list, &c->data_buckets); |
| 628 | bkey_copy_key(&b->key, k); |
| 629 | b->last_write_point = write_point; |
| 630 | |
| 631 | b->sectors_free -= sectors; |
| 632 | |
| 633 | for (i = 0; i < KEY_PTRS(&b->key); i++) { |
| 634 | SET_PTR_OFFSET(&b->key, i, PTR_OFFSET(&b->key, i) + sectors); |
| 635 | |
| 636 | atomic_long_add(sectors, |
| 637 | &PTR_CACHE(c, &b->key, i)->sectors_written); |
| 638 | } |
| 639 | |
| 640 | if (b->sectors_free < c->sb.block_size) |
| 641 | b->sectors_free = 0; |
| 642 | |
| 643 | /* |
| 644 | * k takes refcounts on the buckets it points to until it's inserted |
| 645 | * into the btree, but if we're done with this bucket we just transfer |
| 646 | * get_data_bucket()'s refcount. |
| 647 | */ |
| 648 | if (b->sectors_free) |
| 649 | for (i = 0; i < KEY_PTRS(&b->key); i++) |
| 650 | atomic_inc(&PTR_BUCKET(c, &b->key, i)->pin); |
| 651 | |
| 652 | spin_unlock(&c->data_bucket_lock); |
| 653 | return true; |
| 654 | } |
| 655 | |
Kent Overstreet | cafe563 | 2013-03-23 16:11:31 -0700 | [diff] [blame] | 656 | /* Init */ |
| 657 | |
Kent Overstreet | 2599b53 | 2013-07-24 18:11:11 -0700 | [diff] [blame] | 658 | void bch_open_buckets_free(struct cache_set *c) |
| 659 | { |
| 660 | struct open_bucket *b; |
| 661 | |
| 662 | while (!list_empty(&c->data_buckets)) { |
| 663 | b = list_first_entry(&c->data_buckets, |
| 664 | struct open_bucket, list); |
| 665 | list_del(&b->list); |
| 666 | kfree(b); |
| 667 | } |
| 668 | } |
| 669 | |
| 670 | int bch_open_buckets_alloc(struct cache_set *c) |
| 671 | { |
| 672 | int i; |
| 673 | |
| 674 | spin_lock_init(&c->data_bucket_lock); |
| 675 | |
| 676 | for (i = 0; i < 6; i++) { |
| 677 | struct open_bucket *b = kzalloc(sizeof(*b), GFP_KERNEL); |
| 678 | if (!b) |
| 679 | return -ENOMEM; |
| 680 | |
| 681 | list_add(&b->list, &c->data_buckets); |
| 682 | } |
| 683 | |
| 684 | return 0; |
| 685 | } |
| 686 | |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 687 | int bch_cache_allocator_start(struct cache *ca) |
| 688 | { |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 689 | struct task_struct *k = kthread_run(bch_allocator_thread, |
| 690 | ca, "bcache_allocator"); |
| 691 | if (IS_ERR(k)) |
| 692 | return PTR_ERR(k); |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 693 | |
Kent Overstreet | 79826c3 | 2013-07-10 18:31:58 -0700 | [diff] [blame] | 694 | ca->alloc_thread = k; |
Kent Overstreet | 119ba0f | 2013-04-24 19:01:12 -0700 | [diff] [blame] | 695 | return 0; |
| 696 | } |