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 void bch2_trans_unlock_noassert(struct btree_trans *); 19 20 static inline bool is_btree_node(struct btree_path *path, unsigned l) 21 { 22 return l < BTREE_MAX_DEPTH && !IS_ERR_OR_NULL(path->l[l].b); 23 } 24 25 static inline struct btree_transaction_stats *btree_trans_stats(struct btree_trans *trans) 26 { 27 return trans->fn_idx < ARRAY_SIZE(trans->c->btree_transaction_stats) 28 ? &trans->c->btree_transaction_stats[trans->fn_idx] 29 : NULL; 30 } 31 32 /* matches six lock types */ 33 enum btree_node_locked_type { 34 BTREE_NODE_UNLOCKED = -1, 35 BTREE_NODE_READ_LOCKED = SIX_LOCK_read, 36 BTREE_NODE_INTENT_LOCKED = SIX_LOCK_intent, 37 BTREE_NODE_WRITE_LOCKED = SIX_LOCK_write, 38 }; 39 40 static inline int btree_node_locked_type(struct btree_path *path, 41 unsigned level) 42 { 43 return BTREE_NODE_UNLOCKED + ((path->nodes_locked >> (level << 1)) & 3); 44 } 45 46 static inline bool btree_node_write_locked(struct btree_path *path, unsigned l) 47 { 48 return btree_node_locked_type(path, l) == BTREE_NODE_WRITE_LOCKED; 49 } 50 51 static inline bool btree_node_intent_locked(struct btree_path *path, unsigned l) 52 { 53 return btree_node_locked_type(path, l) == BTREE_NODE_INTENT_LOCKED; 54 } 55 56 static inline bool btree_node_read_locked(struct btree_path *path, unsigned l) 57 { 58 return btree_node_locked_type(path, l) == BTREE_NODE_READ_LOCKED; 59 } 60 61 static inline bool btree_node_locked(struct btree_path *path, unsigned level) 62 { 63 return btree_node_locked_type(path, level) != BTREE_NODE_UNLOCKED; 64 } 65 66 static inline void mark_btree_node_locked_noreset(struct btree_path *path, 67 unsigned level, 68 enum btree_node_locked_type type) 69 { 70 /* relying on this to avoid a branch */ 71 BUILD_BUG_ON(SIX_LOCK_read != 0); 72 BUILD_BUG_ON(SIX_LOCK_intent != 1); 73 74 path->nodes_locked &= ~(3U << (level << 1)); 75 path->nodes_locked |= (type + 1) << (level << 1); 76 } 77 78 static inline void mark_btree_node_unlocked(struct btree_path *path, 79 unsigned level) 80 { 81 EBUG_ON(btree_node_write_locked(path, level)); 82 mark_btree_node_locked_noreset(path, level, BTREE_NODE_UNLOCKED); 83 } 84 85 static inline void mark_btree_node_locked(struct btree_trans *trans, 86 struct btree_path *path, 87 unsigned level, 88 enum btree_node_locked_type type) 89 { 90 mark_btree_node_locked_noreset(path, level, (enum btree_node_locked_type) type); 91 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS 92 path->l[level].lock_taken_time = local_clock(); 93 #endif 94 } 95 96 static inline enum six_lock_type __btree_lock_want(struct btree_path *path, int level) 97 { 98 return level < path->locks_want 99 ? SIX_LOCK_intent 100 : SIX_LOCK_read; 101 } 102 103 static inline enum btree_node_locked_type 104 btree_lock_want(struct btree_path *path, int level) 105 { 106 if (level < path->level) 107 return BTREE_NODE_UNLOCKED; 108 if (level < path->locks_want) 109 return BTREE_NODE_INTENT_LOCKED; 110 if (level == path->level) 111 return BTREE_NODE_READ_LOCKED; 112 return BTREE_NODE_UNLOCKED; 113 } 114 115 static void btree_trans_lock_hold_time_update(struct btree_trans *trans, 116 struct btree_path *path, unsigned level) 117 { 118 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS 119 __bch2_time_stats_update(&btree_trans_stats(trans)->lock_hold_times, 120 path->l[level].lock_taken_time, 121 local_clock()); 122 #endif 123 } 124 125 /* unlock: */ 126 127 static inline void btree_node_unlock(struct btree_trans *trans, 128 struct btree_path *path, unsigned level) 129 { 130 int lock_type = btree_node_locked_type(path, level); 131 132 EBUG_ON(level >= BTREE_MAX_DEPTH); 133 EBUG_ON(lock_type == BTREE_NODE_WRITE_LOCKED); 134 135 if (lock_type != BTREE_NODE_UNLOCKED) { 136 six_unlock_type(&path->l[level].b->c.lock, lock_type); 137 btree_trans_lock_hold_time_update(trans, path, level); 138 } 139 mark_btree_node_unlocked(path, level); 140 } 141 142 static inline int btree_path_lowest_level_locked(struct btree_path *path) 143 { 144 return __ffs(path->nodes_locked) >> 1; 145 } 146 147 static inline int btree_path_highest_level_locked(struct btree_path *path) 148 { 149 return __fls(path->nodes_locked) >> 1; 150 } 151 152 static inline void __bch2_btree_path_unlock(struct btree_trans *trans, 153 struct btree_path *path) 154 { 155 btree_path_set_dirty(path, BTREE_ITER_NEED_RELOCK); 156 157 while (path->nodes_locked) 158 btree_node_unlock(trans, path, btree_path_lowest_level_locked(path)); 159 } 160 161 /* 162 * Updates the saved lock sequence number, so that bch2_btree_node_relock() will 163 * succeed: 164 */ 165 static inline void 166 bch2_btree_node_unlock_write_inlined(struct btree_trans *trans, struct btree_path *path, 167 struct btree *b) 168 { 169 struct btree_path *linked; 170 unsigned i; 171 172 EBUG_ON(path->l[b->c.level].b != b); 173 EBUG_ON(path->l[b->c.level].lock_seq != six_lock_seq(&b->c.lock)); 174 EBUG_ON(btree_node_locked_type(path, b->c.level) != SIX_LOCK_write); 175 176 mark_btree_node_locked_noreset(path, b->c.level, BTREE_NODE_INTENT_LOCKED); 177 178 trans_for_each_path_with_node(trans, b, linked, i) 179 linked->l[b->c.level].lock_seq++; 180 181 six_unlock_write(&b->c.lock); 182 } 183 184 void bch2_btree_node_unlock_write(struct btree_trans *, 185 struct btree_path *, struct btree *); 186 187 int bch2_six_check_for_deadlock(struct six_lock *lock, void *p); 188 189 /* lock: */ 190 191 static inline void trans_set_locked(struct btree_trans *trans) 192 { 193 if (!trans->locked) { 194 lock_acquire_exclusive(&trans->dep_map, 0, 0, NULL, _THIS_IP_); 195 trans->locked = true; 196 trans->last_unlock_ip = 0; 197 198 trans->pf_memalloc_nofs = (current->flags & PF_MEMALLOC_NOFS) != 0; 199 current->flags |= PF_MEMALLOC_NOFS; 200 } 201 } 202 203 static inline void trans_set_unlocked(struct btree_trans *trans) 204 { 205 if (trans->locked) { 206 lock_release(&trans->dep_map, _THIS_IP_); 207 trans->locked = false; 208 trans->last_unlock_ip = _RET_IP_; 209 210 if (!trans->pf_memalloc_nofs) 211 current->flags &= ~PF_MEMALLOC_NOFS; 212 } 213 } 214 215 static inline int __btree_node_lock_nopath(struct btree_trans *trans, 216 struct btree_bkey_cached_common *b, 217 enum six_lock_type type, 218 bool lock_may_not_fail, 219 unsigned long ip) 220 { 221 int ret; 222 223 trans->lock_may_not_fail = lock_may_not_fail; 224 trans->lock_must_abort = false; 225 trans->locking = b; 226 227 ret = six_lock_ip_waiter(&b->lock, type, &trans->locking_wait, 228 bch2_six_check_for_deadlock, trans, ip); 229 WRITE_ONCE(trans->locking, NULL); 230 WRITE_ONCE(trans->locking_wait.start_time, 0); 231 return ret; 232 } 233 234 static inline int __must_check 235 btree_node_lock_nopath(struct btree_trans *trans, 236 struct btree_bkey_cached_common *b, 237 enum six_lock_type type, 238 unsigned long ip) 239 { 240 return __btree_node_lock_nopath(trans, b, type, false, ip); 241 } 242 243 static inline void btree_node_lock_nopath_nofail(struct btree_trans *trans, 244 struct btree_bkey_cached_common *b, 245 enum six_lock_type type) 246 { 247 int ret = __btree_node_lock_nopath(trans, b, type, true, _THIS_IP_); 248 249 BUG_ON(ret); 250 } 251 252 /* 253 * Lock a btree node if we already have it locked on one of our linked 254 * iterators: 255 */ 256 static inline bool btree_node_lock_increment(struct btree_trans *trans, 257 struct btree_bkey_cached_common *b, 258 unsigned level, 259 enum btree_node_locked_type want) 260 { 261 struct btree_path *path; 262 unsigned i; 263 264 trans_for_each_path(trans, path, i) 265 if (&path->l[level].b->c == b && 266 btree_node_locked_type(path, level) >= want) { 267 six_lock_increment(&b->lock, (enum six_lock_type) want); 268 return true; 269 } 270 271 return false; 272 } 273 274 static inline int btree_node_lock(struct btree_trans *trans, 275 struct btree_path *path, 276 struct btree_bkey_cached_common *b, 277 unsigned level, 278 enum six_lock_type type, 279 unsigned long ip) 280 { 281 int ret = 0; 282 283 EBUG_ON(level >= BTREE_MAX_DEPTH); 284 285 if (likely(six_trylock_type(&b->lock, type)) || 286 btree_node_lock_increment(trans, b, level, (enum btree_node_locked_type) type) || 287 !(ret = btree_node_lock_nopath(trans, b, type, btree_path_ip_allocated(path)))) { 288 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS 289 path->l[b->level].lock_taken_time = local_clock(); 290 #endif 291 } 292 293 return ret; 294 } 295 296 int __bch2_btree_node_lock_write(struct btree_trans *, struct btree_path *, 297 struct btree_bkey_cached_common *b, bool); 298 299 static inline int __btree_node_lock_write(struct btree_trans *trans, 300 struct btree_path *path, 301 struct btree_bkey_cached_common *b, 302 bool lock_may_not_fail) 303 { 304 EBUG_ON(&path->l[b->level].b->c != b); 305 EBUG_ON(path->l[b->level].lock_seq != six_lock_seq(&b->lock)); 306 EBUG_ON(!btree_node_intent_locked(path, b->level)); 307 308 /* 309 * six locks are unfair, and read locks block while a thread wants a 310 * write lock: thus, we need to tell the cycle detector we have a write 311 * lock _before_ taking the lock: 312 */ 313 mark_btree_node_locked_noreset(path, b->level, BTREE_NODE_WRITE_LOCKED); 314 315 return likely(six_trylock_write(&b->lock)) 316 ? 0 317 : __bch2_btree_node_lock_write(trans, path, b, lock_may_not_fail); 318 } 319 320 static inline int __must_check 321 bch2_btree_node_lock_write(struct btree_trans *trans, 322 struct btree_path *path, 323 struct btree_bkey_cached_common *b) 324 { 325 return __btree_node_lock_write(trans, path, b, false); 326 } 327 328 void bch2_btree_node_lock_write_nofail(struct btree_trans *, 329 struct btree_path *, 330 struct btree_bkey_cached_common *); 331 332 /* relock: */ 333 334 bool bch2_btree_path_relock_norestart(struct btree_trans *, struct btree_path *); 335 int __bch2_btree_path_relock(struct btree_trans *, 336 struct btree_path *, unsigned long); 337 338 static inline int bch2_btree_path_relock(struct btree_trans *trans, 339 struct btree_path *path, unsigned long trace_ip) 340 { 341 return btree_node_locked(path, path->level) 342 ? 0 343 : __bch2_btree_path_relock(trans, path, trace_ip); 344 } 345 346 bool __bch2_btree_node_relock(struct btree_trans *, struct btree_path *, unsigned, bool trace); 347 348 static inline bool bch2_btree_node_relock(struct btree_trans *trans, 349 struct btree_path *path, unsigned level) 350 { 351 EBUG_ON(btree_node_locked(path, level) && 352 !btree_node_write_locked(path, level) && 353 btree_node_locked_type(path, level) != __btree_lock_want(path, level)); 354 355 return likely(btree_node_locked(path, level)) || 356 (!IS_ERR_OR_NULL(path->l[level].b) && 357 __bch2_btree_node_relock(trans, path, level, true)); 358 } 359 360 static inline bool bch2_btree_node_relock_notrace(struct btree_trans *trans, 361 struct btree_path *path, unsigned level) 362 { 363 EBUG_ON(btree_node_locked(path, level) && 364 !btree_node_write_locked(path, level) && 365 btree_node_locked_type(path, level) != __btree_lock_want(path, level)); 366 367 return likely(btree_node_locked(path, level)) || 368 (!IS_ERR_OR_NULL(path->l[level].b) && 369 __bch2_btree_node_relock(trans, path, level, false)); 370 } 371 372 /* upgrade */ 373 374 bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *, 375 struct btree_path *, unsigned, 376 struct get_locks_fail *); 377 378 bool __bch2_btree_path_upgrade(struct btree_trans *, 379 struct btree_path *, unsigned, 380 struct get_locks_fail *); 381 382 static inline int bch2_btree_path_upgrade(struct btree_trans *trans, 383 struct btree_path *path, 384 unsigned new_locks_want) 385 { 386 struct get_locks_fail f = {}; 387 unsigned old_locks_want = path->locks_want; 388 389 new_locks_want = min(new_locks_want, BTREE_MAX_DEPTH); 390 391 if (path->locks_want < new_locks_want 392 ? __bch2_btree_path_upgrade(trans, path, new_locks_want, &f) 393 : path->nodes_locked) 394 return 0; 395 396 trace_and_count(trans->c, trans_restart_upgrade, trans, _THIS_IP_, path, 397 old_locks_want, new_locks_want, &f); 398 return btree_trans_restart(trans, BCH_ERR_transaction_restart_upgrade); 399 } 400 401 /* misc: */ 402 403 static inline void btree_path_set_should_be_locked(struct btree_path *path) 404 { 405 EBUG_ON(!btree_node_locked(path, path->level)); 406 EBUG_ON(path->uptodate); 407 408 path->should_be_locked = true; 409 } 410 411 static inline void __btree_path_set_level_up(struct btree_trans *trans, 412 struct btree_path *path, 413 unsigned l) 414 { 415 btree_node_unlock(trans, path, l); 416 path->l[l].b = ERR_PTR(-BCH_ERR_no_btree_node_up); 417 } 418 419 static inline void btree_path_set_level_up(struct btree_trans *trans, 420 struct btree_path *path) 421 { 422 __btree_path_set_level_up(trans, path, path->level++); 423 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE); 424 } 425 426 /* debug */ 427 428 struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *, 429 struct btree_path *, 430 struct btree_bkey_cached_common *b, 431 unsigned); 432 433 int bch2_check_for_deadlock(struct btree_trans *, struct printbuf *); 434 435 #ifdef CONFIG_BCACHEFS_DEBUG 436 void bch2_btree_path_verify_locks(struct btree_path *); 437 void bch2_trans_verify_locks(struct btree_trans *); 438 #else 439 static inline void bch2_btree_path_verify_locks(struct btree_path *path) {} 440 static inline void bch2_trans_verify_locks(struct btree_trans *trans) {} 441 #endif 442 443 #endif /* _BCACHEFS_BTREE_LOCKING_H */ 444