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 __bch2_time_stats_update(&btree_trans_stats(trans)->lock_hold_times, 126 path->l[level].lock_taken_time, 127 local_clock()); 128 #endif 129 } 130 131 /* unlock: */ 132 133 static inline void btree_node_unlock(struct btree_trans *trans, 134 struct btree_path *path, unsigned level) 135 { 136 int lock_type = btree_node_locked_type(path, level); 137 138 EBUG_ON(level >= BTREE_MAX_DEPTH); 139 140 if (lock_type != BTREE_NODE_UNLOCKED) { 141 six_unlock_type(&path->l[level].b->c.lock, lock_type); 142 btree_trans_lock_hold_time_update(trans, path, level); 143 } 144 mark_btree_node_unlocked(path, level); 145 } 146 147 static inline int btree_path_lowest_level_locked(struct btree_path *path) 148 { 149 return __ffs(path->nodes_locked) >> 1; 150 } 151 152 static inline int btree_path_highest_level_locked(struct btree_path *path) 153 { 154 return __fls(path->nodes_locked) >> 1; 155 } 156 157 static inline void __bch2_btree_path_unlock(struct btree_trans *trans, 158 struct btree_path *path) 159 { 160 btree_path_set_dirty(path, BTREE_ITER_NEED_RELOCK); 161 162 while (path->nodes_locked) 163 btree_node_unlock(trans, path, btree_path_lowest_level_locked(path)); 164 } 165 166 /* 167 * Updates the saved lock sequence number, so that bch2_btree_node_relock() will 168 * succeed: 169 */ 170 static inline void 171 bch2_btree_node_unlock_write_inlined(struct btree_trans *trans, struct btree_path *path, 172 struct btree *b) 173 { 174 struct btree_path *linked; 175 unsigned i; 176 177 EBUG_ON(path->l[b->c.level].b != b); 178 EBUG_ON(path->l[b->c.level].lock_seq != six_lock_seq(&b->c.lock)); 179 EBUG_ON(btree_node_locked_type(path, b->c.level) != SIX_LOCK_write); 180 181 mark_btree_node_locked_noreset(path, b->c.level, BTREE_NODE_INTENT_LOCKED); 182 183 trans_for_each_path_with_node(trans, b, linked, i) 184 linked->l[b->c.level].lock_seq++; 185 186 six_unlock_write(&b->c.lock); 187 } 188 189 void bch2_btree_node_unlock_write(struct btree_trans *, 190 struct btree_path *, struct btree *); 191 192 int bch2_six_check_for_deadlock(struct six_lock *lock, void *p); 193 194 /* lock: */ 195 196 static inline int __btree_node_lock_nopath(struct btree_trans *trans, 197 struct btree_bkey_cached_common *b, 198 enum six_lock_type type, 199 bool lock_may_not_fail, 200 unsigned long ip) 201 { 202 int ret; 203 204 trans->lock_may_not_fail = lock_may_not_fail; 205 trans->lock_must_abort = false; 206 trans->locking = b; 207 208 ret = six_lock_ip_waiter(&b->lock, type, &trans->locking_wait, 209 bch2_six_check_for_deadlock, trans, ip); 210 WRITE_ONCE(trans->locking, NULL); 211 WRITE_ONCE(trans->locking_wait.start_time, 0); 212 return ret; 213 } 214 215 static inline int __must_check 216 btree_node_lock_nopath(struct btree_trans *trans, 217 struct btree_bkey_cached_common *b, 218 enum six_lock_type type, 219 unsigned long ip) 220 { 221 return __btree_node_lock_nopath(trans, b, type, false, ip); 222 } 223 224 static inline void btree_node_lock_nopath_nofail(struct btree_trans *trans, 225 struct btree_bkey_cached_common *b, 226 enum six_lock_type type) 227 { 228 int ret = __btree_node_lock_nopath(trans, b, type, true, _THIS_IP_); 229 230 BUG_ON(ret); 231 } 232 233 /* 234 * Lock a btree node if we already have it locked on one of our linked 235 * iterators: 236 */ 237 static inline bool btree_node_lock_increment(struct btree_trans *trans, 238 struct btree_bkey_cached_common *b, 239 unsigned level, 240 enum btree_node_locked_type want) 241 { 242 struct btree_path *path; 243 unsigned i; 244 245 trans_for_each_path(trans, path, i) 246 if (&path->l[level].b->c == b && 247 btree_node_locked_type(path, level) >= want) { 248 six_lock_increment(&b->lock, (enum six_lock_type) want); 249 return true; 250 } 251 252 return false; 253 } 254 255 static inline int btree_node_lock(struct btree_trans *trans, 256 struct btree_path *path, 257 struct btree_bkey_cached_common *b, 258 unsigned level, 259 enum six_lock_type type, 260 unsigned long ip) 261 { 262 int ret = 0; 263 264 EBUG_ON(level >= BTREE_MAX_DEPTH); 265 266 if (likely(six_trylock_type(&b->lock, type)) || 267 btree_node_lock_increment(trans, b, level, (enum btree_node_locked_type) type) || 268 !(ret = btree_node_lock_nopath(trans, b, type, btree_path_ip_allocated(path)))) { 269 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS 270 path->l[b->level].lock_taken_time = local_clock(); 271 #endif 272 } 273 274 return ret; 275 } 276 277 int __bch2_btree_node_lock_write(struct btree_trans *, struct btree_path *, 278 struct btree_bkey_cached_common *b, bool); 279 280 static inline int __btree_node_lock_write(struct btree_trans *trans, 281 struct btree_path *path, 282 struct btree_bkey_cached_common *b, 283 bool lock_may_not_fail) 284 { 285 EBUG_ON(&path->l[b->level].b->c != b); 286 EBUG_ON(path->l[b->level].lock_seq != six_lock_seq(&b->lock)); 287 EBUG_ON(!btree_node_intent_locked(path, b->level)); 288 289 /* 290 * six locks are unfair, and read locks block while a thread wants a 291 * write lock: thus, we need to tell the cycle detector we have a write 292 * lock _before_ taking the lock: 293 */ 294 mark_btree_node_locked_noreset(path, b->level, BTREE_NODE_WRITE_LOCKED); 295 296 return likely(six_trylock_write(&b->lock)) 297 ? 0 298 : __bch2_btree_node_lock_write(trans, path, b, lock_may_not_fail); 299 } 300 301 static inline int __must_check 302 bch2_btree_node_lock_write(struct btree_trans *trans, 303 struct btree_path *path, 304 struct btree_bkey_cached_common *b) 305 { 306 return __btree_node_lock_write(trans, path, b, false); 307 } 308 309 void bch2_btree_node_lock_write_nofail(struct btree_trans *, 310 struct btree_path *, 311 struct btree_bkey_cached_common *); 312 313 /* relock: */ 314 315 bool bch2_btree_path_relock_norestart(struct btree_trans *, 316 struct btree_path *, unsigned long); 317 int __bch2_btree_path_relock(struct btree_trans *, 318 struct btree_path *, unsigned long); 319 320 static inline int bch2_btree_path_relock(struct btree_trans *trans, 321 struct btree_path *path, unsigned long trace_ip) 322 { 323 return btree_node_locked(path, path->level) 324 ? 0 325 : __bch2_btree_path_relock(trans, path, trace_ip); 326 } 327 328 bool __bch2_btree_node_relock(struct btree_trans *, struct btree_path *, unsigned, bool trace); 329 330 static inline bool bch2_btree_node_relock(struct btree_trans *trans, 331 struct btree_path *path, unsigned level) 332 { 333 EBUG_ON(btree_node_locked(path, level) && 334 !btree_node_write_locked(path, level) && 335 btree_node_locked_type(path, level) != __btree_lock_want(path, level)); 336 337 return likely(btree_node_locked(path, level)) || 338 (!IS_ERR_OR_NULL(path->l[level].b) && 339 __bch2_btree_node_relock(trans, path, level, true)); 340 } 341 342 static inline bool bch2_btree_node_relock_notrace(struct btree_trans *trans, 343 struct btree_path *path, unsigned level) 344 { 345 EBUG_ON(btree_node_locked(path, level) && 346 !btree_node_write_locked(path, level) && 347 btree_node_locked_type(path, level) != __btree_lock_want(path, level)); 348 349 return likely(btree_node_locked(path, level)) || 350 (!IS_ERR_OR_NULL(path->l[level].b) && 351 __bch2_btree_node_relock(trans, path, level, false)); 352 } 353 354 /* upgrade */ 355 356 357 struct get_locks_fail { 358 unsigned l; 359 struct btree *b; 360 }; 361 362 bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *, 363 struct btree_path *, unsigned, 364 struct get_locks_fail *); 365 366 bool __bch2_btree_path_upgrade(struct btree_trans *, 367 struct btree_path *, unsigned, 368 struct get_locks_fail *); 369 370 static inline int bch2_btree_path_upgrade(struct btree_trans *trans, 371 struct btree_path *path, 372 unsigned new_locks_want) 373 { 374 struct get_locks_fail f; 375 unsigned old_locks_want = path->locks_want; 376 377 new_locks_want = min(new_locks_want, BTREE_MAX_DEPTH); 378 379 if (path->locks_want < new_locks_want 380 ? __bch2_btree_path_upgrade(trans, path, new_locks_want, &f) 381 : path->uptodate == BTREE_ITER_UPTODATE) 382 return 0; 383 384 trace_and_count(trans->c, trans_restart_upgrade, trans, _THIS_IP_, path, 385 old_locks_want, new_locks_want, &f); 386 return btree_trans_restart(trans, BCH_ERR_transaction_restart_upgrade); 387 } 388 389 /* misc: */ 390 391 static inline void btree_path_set_should_be_locked(struct btree_path *path) 392 { 393 EBUG_ON(!btree_node_locked(path, path->level)); 394 EBUG_ON(path->uptodate); 395 396 path->should_be_locked = true; 397 } 398 399 static inline void __btree_path_set_level_up(struct btree_trans *trans, 400 struct btree_path *path, 401 unsigned l) 402 { 403 btree_node_unlock(trans, path, l); 404 path->l[l].b = ERR_PTR(-BCH_ERR_no_btree_node_up); 405 } 406 407 static inline void btree_path_set_level_up(struct btree_trans *trans, 408 struct btree_path *path) 409 { 410 __btree_path_set_level_up(trans, path, path->level++); 411 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE); 412 } 413 414 /* debug */ 415 416 struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *, 417 struct btree_path *, 418 struct btree_bkey_cached_common *b, 419 unsigned); 420 421 int bch2_check_for_deadlock(struct btree_trans *, struct printbuf *); 422 423 #ifdef CONFIG_BCACHEFS_DEBUG 424 void bch2_btree_path_verify_locks(struct btree_path *); 425 void bch2_trans_verify_locks(struct btree_trans *); 426 #else 427 static inline void bch2_btree_path_verify_locks(struct btree_path *path) {} 428 static inline void bch2_trans_verify_locks(struct btree_trans *trans) {} 429 #endif 430 431 #endif /* _BCACHEFS_BTREE_LOCKING_H */ 432