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 is_btree_node(struct btree_path * path,unsigned l)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 btree_trans_stats(struct btree_trans * trans)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 btree_node_locked_type(struct btree_path * path,unsigned level)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 btree_node_write_locked(struct btree_path * path,unsigned l)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 btree_node_intent_locked(struct btree_path * path,unsigned l)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 btree_node_read_locked(struct btree_path * path,unsigned l)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 btree_node_locked(struct btree_path * path,unsigned level)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 mark_btree_node_locked_noreset(struct btree_path * path,unsigned level,enum btree_node_locked_type type)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 mark_btree_node_unlocked(struct btree_path * path,unsigned level)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 mark_btree_node_locked(struct btree_trans * trans,struct btree_path * path,unsigned level,enum btree_node_locked_type type)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 __btree_lock_want(struct btree_path * path,int level)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 btree_lock_want(struct btree_path * path,int level)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 btree_trans_lock_hold_time_update(struct btree_trans * trans,struct btree_path * path,unsigned level)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 btree_node_unlock(struct btree_trans * trans,struct btree_path * path,unsigned level)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 btree_path_lowest_level_locked(struct btree_path * path)142 static inline int btree_path_lowest_level_locked(struct btree_path *path) 143 { 144 return __ffs(path->nodes_locked) >> 1; 145 } 146 btree_path_highest_level_locked(struct btree_path * path)147 static inline int btree_path_highest_level_locked(struct btree_path *path) 148 { 149 return __fls(path->nodes_locked) >> 1; 150 } 151 __bch2_btree_path_unlock(struct btree_trans * trans,struct btree_path * path)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 bch2_btree_node_unlock_write_inlined(struct btree_trans * trans,struct btree_path * path,struct btree * b)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 trans_set_locked(struct btree_trans * trans)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 trans_set_unlocked(struct btree_trans * trans)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 __btree_node_lock_nopath(struct btree_trans * trans,struct btree_bkey_cached_common * b,enum six_lock_type type,bool lock_may_not_fail,unsigned long ip)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 trans->lock_may_not_fail = lock_may_not_fail; 222 trans->lock_must_abort = false; 223 trans->locking = b; 224 225 int ret = six_lock_ip_waiter(&b->lock, type, &trans->locking_wait, 226 bch2_six_check_for_deadlock, trans, ip); 227 WRITE_ONCE(trans->locking, NULL); 228 WRITE_ONCE(trans->locking_wait.start_time, 0); 229 230 if (!ret) 231 trace_btree_path_lock(trans, _THIS_IP_, b); 232 return ret; 233 } 234 235 static inline int __must_check btree_node_lock_nopath(struct btree_trans * trans,struct btree_bkey_cached_common * b,enum six_lock_type type,unsigned long ip)236 btree_node_lock_nopath(struct btree_trans *trans, 237 struct btree_bkey_cached_common *b, 238 enum six_lock_type type, 239 unsigned long ip) 240 { 241 return __btree_node_lock_nopath(trans, b, type, false, ip); 242 } 243 btree_node_lock_nopath_nofail(struct btree_trans * trans,struct btree_bkey_cached_common * b,enum six_lock_type type)244 static inline void btree_node_lock_nopath_nofail(struct btree_trans *trans, 245 struct btree_bkey_cached_common *b, 246 enum six_lock_type type) 247 { 248 int ret = __btree_node_lock_nopath(trans, b, type, true, _THIS_IP_); 249 250 BUG_ON(ret); 251 } 252 253 /* 254 * Lock a btree node if we already have it locked on one of our linked 255 * iterators: 256 */ btree_node_lock_increment(struct btree_trans * trans,struct btree_bkey_cached_common * b,unsigned level,enum btree_node_locked_type want)257 static inline bool btree_node_lock_increment(struct btree_trans *trans, 258 struct btree_bkey_cached_common *b, 259 unsigned level, 260 enum btree_node_locked_type want) 261 { 262 struct btree_path *path; 263 unsigned i; 264 265 trans_for_each_path(trans, path, i) 266 if (&path->l[level].b->c == b && 267 btree_node_locked_type(path, level) >= want) { 268 six_lock_increment(&b->lock, (enum six_lock_type) want); 269 return true; 270 } 271 272 return false; 273 } 274 btree_node_lock(struct btree_trans * trans,struct btree_path * path,struct btree_bkey_cached_common * b,unsigned level,enum six_lock_type type,unsigned long ip)275 static inline int btree_node_lock(struct btree_trans *trans, 276 struct btree_path *path, 277 struct btree_bkey_cached_common *b, 278 unsigned level, 279 enum six_lock_type type, 280 unsigned long ip) 281 { 282 int ret = 0; 283 284 EBUG_ON(level >= BTREE_MAX_DEPTH); 285 bch2_trans_verify_not_unlocked(trans); 286 287 if (likely(six_trylock_type(&b->lock, type)) || 288 btree_node_lock_increment(trans, b, level, (enum btree_node_locked_type) type) || 289 !(ret = btree_node_lock_nopath(trans, b, type, btree_path_ip_allocated(path)))) { 290 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS 291 path->l[b->level].lock_taken_time = local_clock(); 292 #endif 293 } 294 295 return ret; 296 } 297 298 int __bch2_btree_node_lock_write(struct btree_trans *, struct btree_path *, 299 struct btree_bkey_cached_common *b, bool); 300 __btree_node_lock_write(struct btree_trans * trans,struct btree_path * path,struct btree_bkey_cached_common * b,bool lock_may_not_fail)301 static inline int __btree_node_lock_write(struct btree_trans *trans, 302 struct btree_path *path, 303 struct btree_bkey_cached_common *b, 304 bool lock_may_not_fail) 305 { 306 EBUG_ON(&path->l[b->level].b->c != b); 307 EBUG_ON(path->l[b->level].lock_seq != six_lock_seq(&b->lock)); 308 EBUG_ON(!btree_node_intent_locked(path, b->level)); 309 310 /* 311 * six locks are unfair, and read locks block while a thread wants a 312 * write lock: thus, we need to tell the cycle detector we have a write 313 * lock _before_ taking the lock: 314 */ 315 mark_btree_node_locked_noreset(path, b->level, BTREE_NODE_WRITE_LOCKED); 316 317 return likely(six_trylock_write(&b->lock)) 318 ? 0 319 : __bch2_btree_node_lock_write(trans, path, b, lock_may_not_fail); 320 } 321 322 static inline int __must_check bch2_btree_node_lock_write(struct btree_trans * trans,struct btree_path * path,struct btree_bkey_cached_common * b)323 bch2_btree_node_lock_write(struct btree_trans *trans, 324 struct btree_path *path, 325 struct btree_bkey_cached_common *b) 326 { 327 return __btree_node_lock_write(trans, path, b, false); 328 } 329 330 void bch2_btree_node_lock_write_nofail(struct btree_trans *, 331 struct btree_path *, 332 struct btree_bkey_cached_common *); 333 334 /* relock: */ 335 336 bool bch2_btree_path_relock_norestart(struct btree_trans *, struct btree_path *); 337 int __bch2_btree_path_relock(struct btree_trans *, 338 struct btree_path *, unsigned long); 339 bch2_btree_path_relock(struct btree_trans * trans,struct btree_path * path,unsigned long trace_ip)340 static inline int bch2_btree_path_relock(struct btree_trans *trans, 341 struct btree_path *path, unsigned long trace_ip) 342 { 343 return btree_node_locked(path, path->level) 344 ? 0 345 : __bch2_btree_path_relock(trans, path, trace_ip); 346 } 347 348 bool __bch2_btree_node_relock(struct btree_trans *, struct btree_path *, unsigned, bool trace); 349 bch2_btree_node_relock(struct btree_trans * trans,struct btree_path * path,unsigned level)350 static inline bool bch2_btree_node_relock(struct btree_trans *trans, 351 struct btree_path *path, unsigned level) 352 { 353 EBUG_ON(btree_node_locked(path, level) && 354 !btree_node_write_locked(path, level) && 355 btree_node_locked_type(path, level) != __btree_lock_want(path, level)); 356 357 return likely(btree_node_locked(path, level)) || 358 (!IS_ERR_OR_NULL(path->l[level].b) && 359 __bch2_btree_node_relock(trans, path, level, true)); 360 } 361 bch2_btree_node_relock_notrace(struct btree_trans * trans,struct btree_path * path,unsigned level)362 static inline bool bch2_btree_node_relock_notrace(struct btree_trans *trans, 363 struct btree_path *path, unsigned level) 364 { 365 EBUG_ON(btree_node_locked(path, level) && 366 !btree_node_write_locked(path, level) && 367 btree_node_locked_type(path, level) != __btree_lock_want(path, level)); 368 369 return likely(btree_node_locked(path, level)) || 370 (!IS_ERR_OR_NULL(path->l[level].b) && 371 __bch2_btree_node_relock(trans, path, level, false)); 372 } 373 374 /* upgrade */ 375 376 bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *, 377 struct btree_path *, unsigned, 378 struct get_locks_fail *); 379 380 bool __bch2_btree_path_upgrade(struct btree_trans *, 381 struct btree_path *, unsigned, 382 struct get_locks_fail *); 383 bch2_btree_path_upgrade(struct btree_trans * trans,struct btree_path * path,unsigned new_locks_want)384 static inline int bch2_btree_path_upgrade(struct btree_trans *trans, 385 struct btree_path *path, 386 unsigned new_locks_want) 387 { 388 struct get_locks_fail f = {}; 389 unsigned old_locks_want = path->locks_want; 390 391 new_locks_want = min(new_locks_want, BTREE_MAX_DEPTH); 392 393 if (path->locks_want < new_locks_want 394 ? __bch2_btree_path_upgrade(trans, path, new_locks_want, &f) 395 : path->nodes_locked) 396 return 0; 397 398 trace_and_count(trans->c, trans_restart_upgrade, trans, _THIS_IP_, path, 399 old_locks_want, new_locks_want, &f); 400 return btree_trans_restart(trans, BCH_ERR_transaction_restart_upgrade); 401 } 402 403 /* misc: */ 404 btree_path_set_should_be_locked(struct btree_trans * trans,struct btree_path * path)405 static inline void btree_path_set_should_be_locked(struct btree_trans *trans, struct btree_path *path) 406 { 407 EBUG_ON(!btree_node_locked(path, path->level)); 408 EBUG_ON(path->uptodate); 409 410 path->should_be_locked = true; 411 trace_btree_path_should_be_locked(trans, path); 412 } 413 __btree_path_set_level_up(struct btree_trans * trans,struct btree_path * path,unsigned l)414 static inline void __btree_path_set_level_up(struct btree_trans *trans, 415 struct btree_path *path, 416 unsigned l) 417 { 418 btree_node_unlock(trans, path, l); 419 path->l[l].b = ERR_PTR(-BCH_ERR_no_btree_node_up); 420 } 421 btree_path_set_level_up(struct btree_trans * trans,struct btree_path * path)422 static inline void btree_path_set_level_up(struct btree_trans *trans, 423 struct btree_path *path) 424 { 425 __btree_path_set_level_up(trans, path, path->level++); 426 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE); 427 } 428 429 /* debug */ 430 431 struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *, 432 struct btree_path *, 433 struct btree_bkey_cached_common *b, 434 unsigned); 435 436 int bch2_check_for_deadlock(struct btree_trans *, struct printbuf *); 437 438 #ifdef CONFIG_BCACHEFS_DEBUG 439 void bch2_btree_path_verify_locks(struct btree_path *); 440 void bch2_trans_verify_locks(struct btree_trans *); 441 #else bch2_btree_path_verify_locks(struct btree_path * path)442 static inline void bch2_btree_path_verify_locks(struct btree_path *path) {} bch2_trans_verify_locks(struct btree_trans * trans)443 static inline void bch2_trans_verify_locks(struct btree_trans *trans) {} 444 #endif 445 446 #endif /* _BCACHEFS_BTREE_LOCKING_H */ 447