X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libbcachefs%2Fbtree_locking.h;h=a49f1dd1d223613c5f9c59b28a6a53f1410a5143;hb=8d8a9f3e9bdd1d84fbbe0531e81977cc9044654a;hp=9bbed99eb6acbcd5fdf2ee827c158c6b150e912d;hpb=cef2f30ae2a25df41704b9b06fc13882d737cc27;p=bcachefs-tools-debian

diff --git a/libbcachefs/btree_locking.h b/libbcachefs/btree_locking.h
index 9bbed99..a49f1dd 100644
--- a/libbcachefs/btree_locking.h
+++ b/libbcachefs/btree_locking.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _BCACHEFS_BTREE_LOCKING_H
 #define _BCACHEFS_BTREE_LOCKING_H
 
@@ -10,207 +11,423 @@
  */
 
 #include "btree_iter.h"
-#include "btree_io.h"
 #include "six.h"
 
+void bch2_btree_lock_init(struct btree_bkey_cached_common *, enum six_lock_init_flags);
+
+#ifdef CONFIG_LOCKDEP
+void bch2_assert_btree_nodes_not_locked(void);
+#else
+static inline void bch2_assert_btree_nodes_not_locked(void) {}
+#endif
+
+void bch2_trans_unlock_noassert(struct btree_trans *);
+
+static inline bool is_btree_node(struct btree_path *path, unsigned l)
+{
+	return l < BTREE_MAX_DEPTH && !IS_ERR_OR_NULL(path->l[l].b);
+}
+
+static inline struct btree_transaction_stats *btree_trans_stats(struct btree_trans *trans)
+{
+	return trans->fn_idx < ARRAY_SIZE(trans->c->btree_transaction_stats)
+		? &trans->c->btree_transaction_stats[trans->fn_idx]
+		: NULL;
+}
+
 /* matches six lock types */
 enum btree_node_locked_type {
 	BTREE_NODE_UNLOCKED		= -1,
 	BTREE_NODE_READ_LOCKED		= SIX_LOCK_read,
 	BTREE_NODE_INTENT_LOCKED	= SIX_LOCK_intent,
+	BTREE_NODE_WRITE_LOCKED		= SIX_LOCK_write,
 };
 
-static inline int btree_node_locked_type(struct btree_iter *iter,
+static inline int btree_node_locked_type(struct btree_path *path,
 					 unsigned level)
 {
-	/*
-	 * We're relying on the fact that if nodes_intent_locked is set
-	 * nodes_locked must be set as well, so that we can compute without
-	 * branches:
-	 */
-	return BTREE_NODE_UNLOCKED +
-		((iter->nodes_locked >> level) & 1) +
-		((iter->nodes_intent_locked >> level) & 1);
+	return BTREE_NODE_UNLOCKED + ((path->nodes_locked >> (level << 1)) & 3);
 }
 
-static inline bool btree_node_intent_locked(struct btree_iter *iter,
-					    unsigned level)
+static inline bool btree_node_write_locked(struct btree_path *path, unsigned l)
 {
-	return btree_node_locked_type(iter, level) == BTREE_NODE_INTENT_LOCKED;
+	return btree_node_locked_type(path, l) == BTREE_NODE_WRITE_LOCKED;
 }
 
-static inline bool btree_node_read_locked(struct btree_iter *iter,
-					  unsigned level)
+static inline bool btree_node_intent_locked(struct btree_path *path, unsigned l)
 {
-	return btree_node_locked_type(iter, level) == BTREE_NODE_READ_LOCKED;
+	return btree_node_locked_type(path, l) == BTREE_NODE_INTENT_LOCKED;
 }
 
-static inline bool btree_node_locked(struct btree_iter *iter, unsigned level)
+static inline bool btree_node_read_locked(struct btree_path *path, unsigned l)
 {
-	return iter->nodes_locked & (1 << level);
+	return btree_node_locked_type(path, l) == BTREE_NODE_READ_LOCKED;
 }
 
-static inline void mark_btree_node_unlocked(struct btree_iter *iter,
-					    unsigned level)
+static inline bool btree_node_locked(struct btree_path *path, unsigned level)
 {
-	iter->nodes_locked &= ~(1 << level);
-	iter->nodes_intent_locked &= ~(1 << level);
+	return btree_node_locked_type(path, level) != BTREE_NODE_UNLOCKED;
 }
 
-static inline void mark_btree_node_locked(struct btree_iter *iter,
-					  unsigned level,
-					  enum six_lock_type type)
+static inline void mark_btree_node_locked_noreset(struct btree_path *path,
+						  unsigned level,
+						  enum btree_node_locked_type type)
 {
 	/* relying on this to avoid a branch */
 	BUILD_BUG_ON(SIX_LOCK_read   != 0);
 	BUILD_BUG_ON(SIX_LOCK_intent != 1);
 
-	iter->nodes_locked |= 1 << level;
-	iter->nodes_intent_locked |= type << level;
+	path->nodes_locked &= ~(3U << (level << 1));
+	path->nodes_locked |= (type + 1) << (level << 1);
 }
 
-static inline void mark_btree_node_intent_locked(struct btree_iter *iter,
-						 unsigned level)
+static inline void mark_btree_node_unlocked(struct btree_path *path,
+					    unsigned level)
 {
-	mark_btree_node_locked(iter, level, SIX_LOCK_intent);
+	EBUG_ON(btree_node_write_locked(path, level));
+	mark_btree_node_locked_noreset(path, level, BTREE_NODE_UNLOCKED);
 }
 
-static inline enum six_lock_type __btree_lock_want(struct btree_iter *iter, int level)
+static inline void mark_btree_node_locked(struct btree_trans *trans,
+					  struct btree_path *path,
+					  unsigned level,
+					  enum btree_node_locked_type type)
 {
-	return level < iter->locks_want
+	mark_btree_node_locked_noreset(path, level, (enum btree_node_locked_type) type);
+#ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
+	path->l[level].lock_taken_time = local_clock();
+#endif
+}
+
+static inline enum six_lock_type __btree_lock_want(struct btree_path *path, int level)
+{
+	return level < path->locks_want
 		? SIX_LOCK_intent
 		: SIX_LOCK_read;
 }
 
 static inline enum btree_node_locked_type
-btree_lock_want(struct btree_iter *iter, int level)
+btree_lock_want(struct btree_path *path, int level)
 {
-	if (level < iter->level)
+	if (level < path->level)
 		return BTREE_NODE_UNLOCKED;
-	if (level < iter->locks_want)
+	if (level < path->locks_want)
 		return BTREE_NODE_INTENT_LOCKED;
-	if (level == iter->level)
+	if (level == path->level)
 		return BTREE_NODE_READ_LOCKED;
 	return BTREE_NODE_UNLOCKED;
 }
 
-static inline void btree_node_unlock(struct btree_iter *iter, unsigned level)
+static void btree_trans_lock_hold_time_update(struct btree_trans *trans,
+					      struct btree_path *path, unsigned level)
+{
+#ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
+	struct btree_transaction_stats *s = btree_trans_stats(trans);
+
+	if (s)
+		__bch2_time_stats_update(&s->lock_hold_times,
+					 path->l[level].lock_taken_time,
+					 local_clock());
+#endif
+}
+
+/* unlock: */
+
+static inline void btree_node_unlock(struct btree_trans *trans,
+				     struct btree_path *path, unsigned level)
 {
-	int lock_type = btree_node_locked_type(iter, level);
+	int lock_type = btree_node_locked_type(path, level);
 
 	EBUG_ON(level >= BTREE_MAX_DEPTH);
 
-	if (lock_type != BTREE_NODE_UNLOCKED)
-		six_unlock_type(&iter->l[level].b->lock, lock_type);
-	mark_btree_node_unlocked(iter, level);
+	if (lock_type != BTREE_NODE_UNLOCKED) {
+		six_unlock_type(&path->l[level].b->c.lock, lock_type);
+		btree_trans_lock_hold_time_update(trans, path, level);
+	}
+	mark_btree_node_unlocked(path, level);
 }
 
-static inline void __bch2_btree_iter_unlock(struct btree_iter *iter)
+static inline int btree_path_lowest_level_locked(struct btree_path *path)
 {
-	btree_iter_set_dirty(iter, BTREE_ITER_NEED_RELOCK);
+	return __ffs(path->nodes_locked) >> 1;
+}
 
-	while (iter->nodes_locked)
-		btree_node_unlock(iter, __ffs(iter->nodes_locked));
+static inline int btree_path_highest_level_locked(struct btree_path *path)
+{
+	return __fls(path->nodes_locked) >> 1;
 }
 
-static inline enum bch_time_stats lock_to_time_stat(enum six_lock_type type)
+static inline void __bch2_btree_path_unlock(struct btree_trans *trans,
+					    struct btree_path *path)
 {
-	switch (type) {
-	case SIX_LOCK_read:
-		return BCH_TIME_btree_lock_contended_read;
-	case SIX_LOCK_intent:
-		return BCH_TIME_btree_lock_contended_intent;
-	case SIX_LOCK_write:
-		return BCH_TIME_btree_lock_contended_write;
-	default:
-		BUG();
-	}
+	btree_path_set_dirty(path, BTREE_ITER_NEED_RELOCK);
+
+	while (path->nodes_locked)
+		btree_node_unlock(trans, path, btree_path_lowest_level_locked(path));
 }
 
 /*
- * wrapper around six locks that just traces lock contended time
+ * Updates the saved lock sequence number, so that bch2_btree_node_relock() will
+ * succeed:
  */
-static inline void __btree_node_lock_type(struct bch_fs *c, struct btree *b,
-					  enum six_lock_type type)
+static inline void
+bch2_btree_node_unlock_write_inlined(struct btree_trans *trans, struct btree_path *path,
+				     struct btree *b)
+{
+	struct btree_path *linked;
+
+	EBUG_ON(path->l[b->c.level].b != b);
+	EBUG_ON(path->l[b->c.level].lock_seq != six_lock_seq(&b->c.lock));
+	EBUG_ON(btree_node_locked_type(path, b->c.level) != SIX_LOCK_write);
+
+	mark_btree_node_locked_noreset(path, b->c.level, BTREE_NODE_INTENT_LOCKED);
+
+	trans_for_each_path_with_node(trans, b, linked)
+		linked->l[b->c.level].lock_seq++;
+
+	six_unlock_write(&b->c.lock);
+}
+
+void bch2_btree_node_unlock_write(struct btree_trans *,
+			struct btree_path *, struct btree *);
+
+int bch2_six_check_for_deadlock(struct six_lock *lock, void *p);
+
+/* lock: */
+
+static inline int __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)
 {
-	u64 start_time = local_clock();
+	int ret;
+
+	trans->lock_may_not_fail = lock_may_not_fail;
+	trans->lock_must_abort	= false;
+	trans->locking		= b;
 
-	six_lock_type(&b->lock, type);
-	bch2_time_stats_update(&c->times[lock_to_time_stat(type)], start_time);
+	ret = six_lock_ip_waiter(&b->lock, type, &trans->locking_wait,
+				 bch2_six_check_for_deadlock, trans, ip);
+	WRITE_ONCE(trans->locking, NULL);
+	WRITE_ONCE(trans->locking_wait.start_time, 0);
+	return ret;
 }
 
-static inline void btree_node_lock_type(struct bch_fs *c, struct btree *b,
-					enum six_lock_type type)
+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)
 {
-	if (!six_trylock_type(&b->lock, type))
-		__btree_node_lock_type(c, b, type);
+	return __btree_node_lock_nopath(trans, b, type, false, ip);
+}
+
+static inline void btree_node_lock_nopath_nofail(struct btree_trans *trans,
+					 struct btree_bkey_cached_common *b,
+					 enum six_lock_type type)
+{
+	int ret = __btree_node_lock_nopath(trans, b, type, true, _THIS_IP_);
+
+	BUG_ON(ret);
 }
 
 /*
  * Lock a btree node if we already have it locked on one of our linked
  * iterators:
  */
-static inline bool btree_node_lock_increment(struct btree_iter *iter,
-					     struct btree *b, unsigned level,
+static inline bool btree_node_lock_increment(struct btree_trans *trans,
+					     struct btree_bkey_cached_common *b,
+					     unsigned level,
 					     enum btree_node_locked_type want)
 {
-	struct btree_iter *linked;
+	struct btree_path *path;
 
-	for_each_linked_btree_iter(iter, linked)
-		if (linked->l[level].b == b &&
-		    btree_node_locked_type(linked, level) >= want) {
-			six_lock_increment(&b->lock, want);
+	trans_for_each_path(trans, path)
+		if (&path->l[level].b->c == b &&
+		    btree_node_locked_type(path, level) >= want) {
+			six_lock_increment(&b->lock, (enum six_lock_type) want);
 			return true;
 		}
 
 	return false;
 }
 
-bool __bch2_btree_node_lock(struct btree *, struct bpos, unsigned,
-			    struct btree_iter *, enum six_lock_type, bool);
-
-static inline bool btree_node_lock(struct btree *b, struct bpos pos,
-				   unsigned level,
-				   struct btree_iter *iter,
-				   enum six_lock_type type,
-				   bool may_drop_locks)
+static inline int 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)
 {
+	int ret = 0;
+
 	EBUG_ON(level >= BTREE_MAX_DEPTH);
+	EBUG_ON(!test_bit(path->idx, trans->paths_allocated));
+
+	if (likely(six_trylock_type(&b->lock, type)) ||
+	    btree_node_lock_increment(trans, b, level, (enum btree_node_locked_type) type) ||
+	    !(ret = btree_node_lock_nopath(trans, b, type, btree_path_ip_allocated(path)))) {
+#ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
+		path->l[b->level].lock_taken_time = local_clock();
+#endif
+	}
 
-	return likely(six_trylock_type(&b->lock, type)) ||
-		btree_node_lock_increment(iter, b, level, type) ||
-		__bch2_btree_node_lock(b, pos, level, iter,
-				       type, may_drop_locks);
+	return ret;
 }
 
-bool __bch2_btree_node_relock(struct btree_iter *, unsigned);
+int __bch2_btree_node_lock_write(struct btree_trans *, struct btree_path *,
+				 struct btree_bkey_cached_common *b, bool);
 
-static inline bool bch2_btree_node_relock(struct btree_iter *iter,
-					  unsigned level)
+static inline int __btree_node_lock_write(struct btree_trans *trans,
+					  struct btree_path *path,
+					  struct btree_bkey_cached_common *b,
+					  bool lock_may_not_fail)
 {
-	EBUG_ON(btree_node_locked(iter, level) &&
-		btree_node_locked_type(iter, level) !=
-		__btree_lock_want(iter, level));
+	EBUG_ON(&path->l[b->level].b->c != b);
+	EBUG_ON(path->l[b->level].lock_seq != six_lock_seq(&b->lock));
+	EBUG_ON(!btree_node_intent_locked(path, b->level));
+
+	/*
+	 * six locks are unfair, and read locks block while a thread wants a
+	 * write lock: thus, we need to tell the cycle detector we have a write
+	 * lock _before_ taking the lock:
+	 */
+	mark_btree_node_locked_noreset(path, b->level, BTREE_NODE_WRITE_LOCKED);
+
+	return likely(six_trylock_write(&b->lock))
+		? 0
+		: __bch2_btree_node_lock_write(trans, path, b, lock_may_not_fail);
+}
+
+static inline int __must_check
+bch2_btree_node_lock_write(struct btree_trans *trans,
+			   struct btree_path *path,
+			   struct btree_bkey_cached_common *b)
+{
+	return __btree_node_lock_write(trans, path, b, false);
+}
+
+void bch2_btree_node_lock_write_nofail(struct btree_trans *,
+				       struct btree_path *,
+				       struct btree_bkey_cached_common *);
 
-	return likely(btree_node_locked(iter, level)) ||
-		__bch2_btree_node_relock(iter, level);
+/* relock: */
+
+bool bch2_btree_path_relock_norestart(struct btree_trans *,
+				      struct btree_path *, unsigned long);
+int __bch2_btree_path_relock(struct btree_trans *,
+			     struct btree_path *, unsigned long);
+
+static inline int bch2_btree_path_relock(struct btree_trans *trans,
+				struct btree_path *path, unsigned long trace_ip)
+{
+	return btree_node_locked(path, path->level)
+		? 0
+		: __bch2_btree_path_relock(trans, path, trace_ip);
 }
 
-bool bch2_btree_iter_relock(struct btree_iter *);
+bool __bch2_btree_node_relock(struct btree_trans *, struct btree_path *, unsigned, bool trace);
 
-void bch2_btree_node_unlock_write(struct btree *, struct btree_iter *);
+static inline bool bch2_btree_node_relock(struct btree_trans *trans,
+					  struct btree_path *path, unsigned level)
+{
+	EBUG_ON(btree_node_locked(path, level) &&
+		!btree_node_write_locked(path, level) &&
+		btree_node_locked_type(path, level) != __btree_lock_want(path, level));
 
-void __bch2_btree_node_lock_write(struct btree *, struct btree_iter *);
+	return likely(btree_node_locked(path, level)) ||
+		(!IS_ERR_OR_NULL(path->l[level].b) &&
+		 __bch2_btree_node_relock(trans, path, level, true));
+}
 
-static inline void bch2_btree_node_lock_write(struct btree *b, struct btree_iter *iter)
+static inline bool bch2_btree_node_relock_notrace(struct btree_trans *trans,
+						  struct btree_path *path, unsigned level)
 {
-	EBUG_ON(iter->l[b->level].b != b);
-	EBUG_ON(iter->l[b->level].lock_seq != b->lock.state.seq);
+	EBUG_ON(btree_node_locked(path, level) &&
+		!btree_node_write_locked(path, level) &&
+		btree_node_locked_type(path, level) != __btree_lock_want(path, level));
 
-	if (!six_trylock_write(&b->lock))
-		__bch2_btree_node_lock_write(b, iter);
+	return likely(btree_node_locked(path, level)) ||
+		(!IS_ERR_OR_NULL(path->l[level].b) &&
+		 __bch2_btree_node_relock(trans, path, level, false));
 }
 
-#endif /* _BCACHEFS_BTREE_LOCKING_H */
+/* upgrade */
 
 
+struct get_locks_fail {
+	unsigned	l;
+	struct btree	*b;
+};
+
+bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *,
+			       struct btree_path *, unsigned,
+			       struct get_locks_fail *);
+
+bool __bch2_btree_path_upgrade(struct btree_trans *,
+			       struct btree_path *, unsigned,
+			       struct get_locks_fail *);
+
+static inline int bch2_btree_path_upgrade(struct btree_trans *trans,
+					  struct btree_path *path,
+					  unsigned new_locks_want)
+{
+	struct get_locks_fail f;
+	unsigned old_locks_want = path->locks_want;
+
+	new_locks_want = min(new_locks_want, BTREE_MAX_DEPTH);
+
+	if (path->locks_want < new_locks_want
+	    ? __bch2_btree_path_upgrade(trans, path, new_locks_want, &f)
+	    : path->uptodate == BTREE_ITER_UPTODATE)
+		return 0;
+
+	trace_and_count(trans->c, trans_restart_upgrade, trans, _THIS_IP_, path,
+			old_locks_want, new_locks_want, &f);
+	return btree_trans_restart(trans, BCH_ERR_transaction_restart_upgrade);
+}
+
+/* misc: */
+
+static inline void btree_path_set_should_be_locked(struct btree_path *path)
+{
+	EBUG_ON(!btree_node_locked(path, path->level));
+	EBUG_ON(path->uptodate);
+
+	path->should_be_locked = true;
+}
+
+static inline void __btree_path_set_level_up(struct btree_trans *trans,
+				      struct btree_path *path,
+				      unsigned l)
+{
+	btree_node_unlock(trans, path, l);
+	path->l[l].b = ERR_PTR(-BCH_ERR_no_btree_node_up);
+}
+
+static inline void btree_path_set_level_up(struct btree_trans *trans,
+				    struct btree_path *path)
+{
+	__btree_path_set_level_up(trans, path, path->level++);
+	btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
+}
+
+/* debug */
+
+struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *,
+				struct btree_path *,
+				struct btree_bkey_cached_common *b,
+				unsigned);
+
+int bch2_check_for_deadlock(struct btree_trans *, struct printbuf *);
+
+#ifdef CONFIG_BCACHEFS_DEBUG
+void bch2_btree_path_verify_locks(struct btree_path *);
+void bch2_trans_verify_locks(struct btree_trans *);
+#else
+static inline void bch2_btree_path_verify_locks(struct btree_path *path) {}
+static inline void bch2_trans_verify_locks(struct btree_trans *trans) {}
+#endif
+
+#endif /* _BCACHEFS_BTREE_LOCKING_H */