bcachefs: Avoid spurious transaction restarts

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -160,7 +160,7 @@ static bool bch2_btree_node_upgrade(struct btree_iter *iter, unsigned level)
 }
 
 static inline bool btree_iter_get_locks(struct btree_iter *iter,
-					bool upgrade)
+					bool upgrade, bool trace)
 {
 	unsigned l = iter->level;
 	int fail_idx = -1;
@@ -172,16 +172,10 @@ static inline bool btree_iter_get_locks(struct btree_iter *iter,
 		if (!(upgrade
 		      ? bch2_btree_node_upgrade(iter, l)
 		      : bch2_btree_node_relock(iter, l))) {
-			if (upgrade)
-				trace_node_upgrade_fail(l, iter->l[l].lock_seq,
-						is_btree_node(iter, l)
-						? 0
-						: (unsigned long) iter->l[l].b,
-						is_btree_node(iter, l)
-						? iter->l[l].b->c.lock.state.seq
-						: 0);
-			else
-				trace_node_relock_fail(l, iter->l[l].lock_seq,
+			if (trace)
+				(upgrade
+				 ? trace_node_upgrade_fail
+				 : trace_node_relock_fail)(l, iter->l[l].lock_seq,
 						is_btree_node(iter, l)
 						? 0
 						: (unsigned long) iter->l[l].b,
@@ -251,7 +245,7 @@ bool __bch2_btree_node_lock(struct btree *b, struct bpos pos,
 				linked->locks_want = max_t(unsigned,
 						linked->locks_want,
 						__fls(linked->nodes_locked) + 1);
-				btree_iter_get_locks(linked, true);
+				btree_iter_get_locks(linked, true, false);
 			}
 			ret = false;
 		}
@@ -268,7 +262,7 @@ bool __bch2_btree_node_lock(struct btree *b, struct bpos pos,
 					max(level + 1, max_t(unsigned,
 					    linked->locks_want,
 					    iter->locks_want));
-				btree_iter_get_locks(linked, true);
+				btree_iter_get_locks(linked, true, false);
 			}
 			ret = false;
 		}
@@ -312,10 +306,10 @@ void bch2_btree_trans_verify_locks(struct btree_trans *trans)
 #endif
 
 __flatten
-static bool bch2_btree_iter_relock(struct btree_iter *iter)
+static bool bch2_btree_iter_relock(struct btree_iter *iter, bool trace)
 {
 	return iter->uptodate >= BTREE_ITER_NEED_RELOCK
-		? btree_iter_get_locks(iter, false)
+		? btree_iter_get_locks(iter, false, trace)
 		: true;
 }
 
@@ -328,7 +322,7 @@ bool __bch2_btree_iter_upgrade(struct btree_iter *iter,
 
 	iter->locks_want = new_locks_want;
 
-	if (btree_iter_get_locks(iter, true))
+	if (btree_iter_get_locks(iter, true, true))
 		return true;
 
 	/*
@@ -341,7 +335,7 @@ bool __bch2_btree_iter_upgrade(struct btree_iter *iter,
 		    linked->btree_id == iter->btree_id &&
 		    linked->locks_want < new_locks_want) {
 			linked->locks_want = new_locks_want;
-			btree_iter_get_locks(linked, true);
+			btree_iter_get_locks(linked, true, false);
 		}
 
 	return false;
@@ -416,7 +410,8 @@ bool bch2_trans_relock(struct btree_trans *trans)
 	bool ret = true;
 
 	trans_for_each_iter(trans, iter)
-		ret &= bch2_btree_iter_relock(iter);
+		if (iter->uptodate == BTREE_ITER_NEED_RELOCK)
+			ret &= bch2_btree_iter_relock(iter, true);
 
 	return ret;
 }
@@ -1061,7 +1056,7 @@ int __must_check __bch2_btree_iter_traverse(struct btree_iter *iter)
 	if (unlikely(iter->level >= BTREE_MAX_DEPTH))
 		return 0;
 
-	if (bch2_btree_iter_relock(iter))
+	if (bch2_btree_iter_relock(iter, false))
 		return 0;
 
 	/*
@@ -1672,11 +1667,13 @@ int bch2_trans_iter_free_on_commit(struct btree_trans *trans,
 	return ret;
 }
 
-static int btree_trans_realloc_iters(struct btree_trans *trans,
-				     unsigned new_size)
+int bch2_trans_realloc_iters(struct btree_trans *trans,
+				    unsigned new_size)
 {
 	void *new_iters, *new_updates;
 
+	new_size = roundup_pow_of_two(new_size);
+
 	BUG_ON(new_size > BTREE_ITER_MAX);
 
 	if (new_size <= trans->size)
@@ -1727,7 +1724,7 @@ static int btree_trans_realloc_iters(struct btree_trans *trans,
 
 void bch2_trans_preload_iters(struct btree_trans *trans)
 {
-	btree_trans_realloc_iters(trans, BTREE_ITER_MAX);
+	bch2_trans_realloc_iters(trans, BTREE_ITER_MAX);
 }
 
 static int btree_trans_iter_alloc(struct btree_trans *trans)
@@ -1738,7 +1735,7 @@ static int btree_trans_iter_alloc(struct btree_trans *trans)
 		goto got_slot;
 
 	if (trans->nr_iters == trans->size) {
-		int ret = btree_trans_realloc_iters(trans, trans->size * 2);
+		int ret = bch2_trans_realloc_iters(trans, trans->size * 2);
 		if (ret)
 			return ret;
 	}

fs/bcachefs/btree_iter.h

@@ -258,7 +258,9 @@ static inline int bkey_err(struct bkey_s_c k)
 
 /* new multiple iterator interface: */
 
+int bch2_trans_realloc_iters(struct btree_trans *, unsigned);
 void bch2_trans_preload_iters(struct btree_trans *);
+
 int bch2_trans_iter_put(struct btree_trans *, struct btree_iter *);
 int bch2_trans_iter_free(struct btree_trans *, struct btree_iter *);
 int bch2_trans_iter_free_on_commit(struct btree_trans *, struct btree_iter *);

fs/bcachefs/fs.c

@@ -415,6 +415,7 @@ __bch2_create(struct mnt_idmap *idmap,
 		mutex_lock(&dir->ei_update_lock);
 
 	bch2_trans_init(&trans, c);
+	bch2_trans_realloc_iters(&trans, 8);
 retry:
 	bch2_trans_begin(&trans);