1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _BCACHEFS_BTREE_LOCKING_H 3 #define _BCACHEFS_BTREE_LOCKING_H 4 5 /* 6 * Only for internal btree use: 7 * 8 * The btree iterator tracks what locks it wants to take, and what locks it 9 * currently has - here we have wrappers for locking/unlocking btree nodes and 10 * updating the iterator state 11 */ 12 13 #include "btree_iter.h" 14 #include "six.h" 15 16 void bch2_btree_lock_init(struct btree_bkey_cached_common *, enum six_lock_init_flags); 17 18 #ifdef CONFIG_LOCKDEP 19 void bch2_assert_btree_nodes_not_locked(void); 20 #else 21 static inline void bch2_assert_btree_nodes_not_locked(void) {} 22 #endif 23 24 void bch2_trans_unlock_noassert(struct btree_trans *); 25 26 static inline bool is_btree_node(struct btree_path *path, unsigned l) 27 { 28 return l < BTREE_MAX_DEPTH && !IS_ERR_OR_NULL(path->l[l].b); 29 } 30 31 static inline struct btree_transaction_stats *btree_trans_stats(struct btree_trans *trans) 32 { 33 return trans->fn_idx < ARRAY_SIZE(trans->c->btree_transaction_stats) 34 ? &trans->c->btree_transaction_stats[trans->fn_idx] 35 : NULL; 36 } 37 38 /* matches six lock types */ 39 enum btree_node_locked_type { 40 BTREE_NODE_UNLOCKED = -1, 41 BTREE_NODE_READ_LOCKED = SIX_LOCK_read, 42 BTREE_NODE_INTENT_LOCKED = SIX_LOCK_intent, 43 BTREE_NODE_WRITE_LOCKED = SIX_LOCK_write, 44 }; 45 46 static inline int btree_node_locked_type(struct btree_path *path, 47 unsigned level) 48 { 49 return BTREE_NODE_UNLOCKED + ((path->nodes_locked >> (level << 1)) & 3); 50 } 51 52 static inline bool btree_node_write_locked(struct btree_path *path, unsigned l) 53 { 54 return btree_node_locked_type(path, l) == BTREE_NODE_WRITE_LOCKED; 55 } 56 57 static inline bool btree_node_intent_locked(struct btree_path *path, unsigned l) 58 { 59 return btree_node_locked_type(path, l) == BTREE_NODE_INTENT_LOCKED; 60 } 61 62 static inline bool btree_node_read_locked(struct btree_path *path, unsigned l) 63 { 64 return btree_node_locked_type(path, l) == BTREE_NODE_READ_LOCKED; 65 } 66 67 static inline bool btree_node_locked(struct btree_path *path, unsigned level) 68 { 69 return btree_node_locked_type(path, level) != BTREE_NODE_UNLOCKED; 70 } 71 72 static inline void mark_btree_node_locked_noreset(struct btree_path *path, 73 unsigned level, 74 enum btree_node_locked_type type) 75 { 76 /* relying on this to avoid a branch */ 77 BUILD_BUG_ON(SIX_LOCK_read != 0); 78 BUILD_BUG_ON(SIX_LOCK_intent != 1); 79 80 path->nodes_locked &= ~(3U << (level << 1)); 81 path->nodes_locked |= (type + 1) << (level << 1); 82 } 83 84 static inline void mark_btree_node_unlocked(struct btree_path *path, 85 unsigned level) 86 { 87 EBUG_ON(btree_node_write_locked(path, level)); 88 mark_btree_node_locked_noreset(path, level, BTREE_NODE_UNLOCKED); 89 } 90 91 static inline void mark_btree_node_locked(struct btree_trans *trans, 92 struct btree_path *path, 93 unsigned level, 94 enum btree_node_locked_type type) 95 { 96 mark_btree_node_locked_noreset(path, level, (enum btree_node_locked_type) type); 97 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS 98 path->l[level].lock_taken_time = local_clock(); 99 #endif 100 } 101 102 static inline enum six_lock_type __btree_lock_want(struct btree_path *path, int level) 103 { 104 return level < path->locks_want 105 ? SIX_LOCK_intent 106 : SIX_LOCK_read; 107 } 108 109 static inline enum btree_node_locked_type 110 btree_lock_want(struct btree_path *path, int level) 111 { 112 if (level < path->level) 113 return BTREE_NODE_UNLOCKED; 114 if (level < path->locks_want) 115 return BTREE_NODE_INTENT_LOCKED; 116 if (level == path->level) 117 return BTREE_NODE_READ_LOCKED; 118 return BTREE_NODE_UNLOCKED; 119 } 120 121 static void btree_trans_lock_hold_time_update(struct btree_trans *trans, 122 struct btree_path *path, unsigned level) 123 { 124 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS 125 struct btree_transaction_stats *s = btree_trans_stats(trans); 126 127 if (s) 128 __bch2_time_stats_update(&s->lock_hold_times, 129 path->l[level].lock_taken_time, 130 local_clock()); 131 #endif 132 } 133 134 /* unlock: */ 135 136 static inline void btree_node_unlock(struct btree_trans *trans, 137 struct btree_path *path, unsigned level) 138 { 139 int lock_type = btree_node_locked_type(path, level); 140 141 EBUG_ON(level >= BTREE_MAX_DEPTH); 142 143 if (lock_type != BTREE_NODE_UNLOCKED) { 144 six_unlock_type(&path->l[level].b->c.lock, lock_type); 145 btree_trans_lock_hold_time_update(trans, path, level); 146 } 147 mark_btree_node_unlocked(path, level); 148 } 149 150 static inline int btree_path_lowest_level_locked(struct btree_path *path) 151 { 152 return __ffs(path->nodes_locked) >> 1; 153 } 154 155 static inline int btree_path_highest_level_locked(struct btree_path *path) 156 { 157 return __fls(path->nodes_locked) >> 1; 158 } 159 160 static inline void __bch2_btree_path_unlock(struct btree_trans *trans, 161 struct btree_path *path) 162 { 163 btree_path_set_dirty(path, BTREE_ITER_NEED_RELOCK); 164 165 while (path->nodes_locked) 166 btree_node_unlock(trans, path, btree_path_lowest_level_locked(path)); 167 } 168 169 /* 170 * Updates the saved lock sequence number, so that bch2_btree_node_relock() will 171 * succeed: 172 */ 173 static inline void 174 bch2_btree_node_unlock_write_inlined(struct btree_trans *trans, struct btree_path *path, 175 struct btree *b) 176 { 177 struct btree_path *linked; 178 179 EBUG_ON(path->l[b->c.level].b != b); 180 EBUG_ON(path->l[b->c.level].lock_seq != six_lock_seq(&b->c.lock)); 181 EBUG_ON(btree_node_locked_type(path, b->c.level) != SIX_LOCK_write); 182 183 mark_btree_node_locked_noreset(path, b->c.level, BTREE_NODE_INTENT_LOCKED); 184 185 trans_for_each_path_with_node(trans, b, linked) 186 linked->l[b->c.level].lock_seq++; 187 188 six_unlock_write(&b->c.lock); 189 } 190 191 void bch2_btree_node_unlock_write(struct btree_trans *, 192 struct btree_path *, struct btree *); 193 194 int bch2_six_check_for_deadlock(struct six_lock *lock, void *p); 195 196 /* lock: */ 197 198 static inline int __btree_node_lock_nopath(struct btree_trans *trans, 199 struct btree_bkey_cached_common *b, 200 enum six_lock_type type, 201 bool lock_may_not_fail, 202 unsigned long ip) 203 { 204 int ret; 205 206 trans->lock_may_not_fail = lock_may_not_fail; 207 trans->lock_must_abort = false; 208 trans->locking = b; 209 210 ret = six_lock_ip_waiter(&b->lock, type, &trans->locking_wait, 211 bch2_six_check_for_deadlock, trans, ip); 212 WRITE_ONCE(trans->locking, NULL); 213 WRITE_ONCE(trans->locking_wait.start_time, 0); 214 return ret; 215 } 216 217 static inline int __must_check 218 btree_node_lock_nopath(struct btree_trans *trans, 219 struct btree_bkey_cached_common *b, 220 enum six_lock_type type, 221 unsigned long ip) 222 { 223 return __btree_node_lock_nopath(trans, b, type, false, ip); 224 } 225 226 static inline void btree_node_lock_nopath_nofail(struct btree_trans *trans, 227 struct btree_bkey_cached_common *b, 228 enum six_lock_type type) 229 { 230 int ret = __btree_node_lock_nopath(trans, b, type, true, _THIS_IP_); 231 232 BUG_ON(ret); 233 } 234 235 /* 236 * Lock a btree node if we already have it locked on one of our linked 237 * iterators: 238 */ 239 static inline bool btree_node_lock_increment(struct btree_trans *trans, 240 struct btree_bkey_cached_common *b, 241 unsigned level, 242 enum btree_node_locked_type want) 243 { 244 struct btree_path *path; 245 246 trans_for_each_path(trans, path) 247 if (&path->l[level].b->c == b && 248 btree_node_locked_type(path, level) >= want) { 249 six_lock_increment(&b->lock, (enum six_lock_type) want); 250 return true; 251 } 252 253 return false; 254 } 255 256 static inline int btree_node_lock(struct btree_trans *trans, 257 struct btree_path *path, 258 struct btree_bkey_cached_common *b, 259 unsigned level, 260 enum six_lock_type type, 261 unsigned long ip) 262 { 263 int ret = 0; 264 265 EBUG_ON(level >= BTREE_MAX_DEPTH); 266 EBUG_ON(!(trans->paths_allocated & (1ULL << path->idx))); 267 268 if (likely(six_trylock_type(&b->lock, type)) || 269 btree_node_lock_increment(trans, b, level, (enum btree_node_locked_type) type) || 270 !(ret = btree_node_lock_nopath(trans, b, type, btree_path_ip_allocated(path)))) { 271 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS 272 path->l[b->level].lock_taken_time = local_clock(); 273 #endif 274 } 275 276 return ret; 277 } 278 279 int __bch2_btree_node_lock_write(struct btree_trans *, struct btree_path *, 280 struct btree_bkey_cached_common *b, bool); 281 282 static inline int __btree_node_lock_write(struct btree_trans *trans, 283 struct btree_path *path, 284 struct btree_bkey_cached_common *b, 285 bool lock_may_not_fail) 286 { 287 EBUG_ON(&path->l[b->level].b->c != b); 288 EBUG_ON(path->l[b->level].lock_seq != six_lock_seq(&b->lock)); 289 EBUG_ON(!btree_node_intent_locked(path, b->level)); 290 291 /* 292 * six locks are unfair, and read locks block while a thread wants a 293 * write lock: thus, we need to tell the cycle detector we have a write 294 * lock _before_ taking the lock: 295 */ 296 mark_btree_node_locked_noreset(path, b->level, BTREE_NODE_WRITE_LOCKED); 297 298 return likely(six_trylock_write(&b->lock)) 299 ? 0 300 : __bch2_btree_node_lock_write(trans, path, b, lock_may_not_fail); 301 } 302 303 static inline int __must_check 304 bch2_btree_node_lock_write(struct btree_trans *trans, 305 struct btree_path *path, 306 struct btree_bkey_cached_common *b) 307 { 308 return __btree_node_lock_write(trans, path, b, false); 309 } 310 311 void bch2_btree_node_lock_write_nofail(struct btree_trans *, 312 struct btree_path *, 313 struct btree_bkey_cached_common *); 314 315 /* relock: */ 316 317 bool bch2_btree_path_relock_norestart(struct btree_trans *, 318 struct btree_path *, unsigned long); 319 int __bch2_btree_path_relock(struct btree_trans *, 320 struct btree_path *, unsigned long); 321 322 static inline int bch2_btree_path_relock(struct btree_trans *trans, 323 struct btree_path *path, unsigned long trace_ip) 324 { 325 return btree_node_locked(path, path->level) 326 ? 0 327 : __bch2_btree_path_relock(trans, path, trace_ip); 328 } 329 330 bool __bch2_btree_node_relock(struct btree_trans *, struct btree_path *, unsigned, bool trace); 331 332 static inline bool bch2_btree_node_relock(struct btree_trans *trans, 333 struct btree_path *path, unsigned level) 334 { 335 EBUG_ON(btree_node_locked(path, level) && 336 !btree_node_write_locked(path, level) && 337 btree_node_locked_type(path, level) != __btree_lock_want(path, level)); 338 339 return likely(btree_node_locked(path, level)) || 340 (!IS_ERR_OR_NULL(path->l[level].b) && 341 __bch2_btree_node_relock(trans, path, level, true)); 342 } 343 344 static inline bool bch2_btree_node_relock_notrace(struct btree_trans *trans, 345 struct btree_path *path, unsigned level) 346 { 347 EBUG_ON(btree_node_locked(path, level) && 348 !btree_node_write_locked(path, level) && 349 btree_node_locked_type(path, level) != __btree_lock_want(path, level)); 350 351 return likely(btree_node_locked(path, level)) || 352 (!IS_ERR_OR_NULL(path->l[level].b) && 353 __bch2_btree_node_relock(trans, path, level, false)); 354 } 355 356 /* upgrade */ 357 358 359 struct get_locks_fail { 360 unsigned l; 361 struct btree *b; 362 }; 363 364 bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *, 365 struct btree_path *, unsigned, 366 struct get_locks_fail *); 367 368 bool __bch2_btree_path_upgrade(struct btree_trans *, 369 struct btree_path *, unsigned, 370 struct get_locks_fail *); 371 372 static inline int bch2_btree_path_upgrade(struct btree_trans *trans, 373 struct btree_path *path, 374 unsigned new_locks_want) 375 { 376 struct get_locks_fail f; 377 unsigned old_locks_want = path->locks_want; 378 379 new_locks_want = min(new_locks_want, BTREE_MAX_DEPTH); 380 381 if (path->locks_want < new_locks_want 382 ? __bch2_btree_path_upgrade(trans, path, new_locks_want, &f) 383 : path->uptodate == BTREE_ITER_UPTODATE) 384 return 0; 385 386 trace_and_count(trans->c, trans_restart_upgrade, trans, _THIS_IP_, path, 387 old_locks_want, new_locks_want, &f); 388 return btree_trans_restart(trans, BCH_ERR_transaction_restart_upgrade); 389 } 390 391 /* misc: */ 392 393 static inline void btree_path_set_should_be_locked(struct btree_path *path) 394 { 395 EBUG_ON(!btree_node_locked(path, path->level)); 396 EBUG_ON(path->uptodate); 397 398 path->should_be_locked = true; 399 } 400 401 static inline void __btree_path_set_level_up(struct btree_trans *trans, 402 struct btree_path *path, 403 unsigned l) 404 { 405 btree_node_unlock(trans, path, l); 406 path->l[l].b = ERR_PTR(-BCH_ERR_no_btree_node_up); 407 } 408 409 static inline void btree_path_set_level_up(struct btree_trans *trans, 410 struct btree_path *path) 411 { 412 __btree_path_set_level_up(trans, path, path->level++); 413 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE); 414 } 415 416 /* debug */ 417 418 struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *, 419 struct btree_path *, 420 struct btree_bkey_cached_common *b, 421 unsigned); 422 423 int bch2_check_for_deadlock(struct btree_trans *, struct printbuf *); 424 425 #ifdef CONFIG_BCACHEFS_DEBUG 426 void bch2_btree_path_verify_locks(struct btree_path *); 427 void bch2_trans_verify_locks(struct btree_trans *); 428 #else 429 static inline void bch2_btree_path_verify_locks(struct btree_path *path) {} 430 static inline void bch2_trans_verify_locks(struct btree_trans *trans) {} 431 #endif 432 433 #endif /* _BCACHEFS_BTREE_LOCKING_H */ 434