bcachefs: trans_for_each_path() no longer uses path->idx

path->idx is now a code smell: we should be using path_idx_t, since it's
stable across btree path reallocation.

This is also a bit faster, using the same loop counter vs. fetching
path->idx from each path we iterate over.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -241,8 +241,9 @@ static void bch2_btree_path_verify(struct btree_trans *trans,
 void bch2_trans_verify_paths(struct btree_trans *trans)
 {
 	struct btree_path *path;
+	unsigned iter;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, iter)
 		bch2_btree_path_verify(trans, path);
 }
 
@@ -962,7 +963,8 @@ static int bch2_btree_path_traverse_all(struct btree_trans *trans)
 	struct bch_fs *c = trans->c;
 	struct btree_path *path;
 	unsigned long trace_ip = _RET_IP_;
-	int i, ret = 0;
+	unsigned i;
+	int ret = 0;
 
 	if (trans->in_traverse_all)
 		return -BCH_ERR_transaction_restart_in_traverse_all;
@@ -972,7 +974,7 @@ static int bch2_btree_path_traverse_all(struct btree_trans *trans)
 	trans->restarted = 0;
 	trans->last_restarted_ip = 0;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		path->should_be_locked = false;
 
 	btree_trans_sort_paths(trans);
@@ -2530,9 +2532,9 @@ static void btree_trans_verify_sorted_refs(struct btree_trans *trans)
 
 	BUG_ON(trans->nr_sorted != bitmap_weight(trans->paths_allocated, BTREE_ITER_MAX) - 1);
 
-	trans_for_each_path(trans, path) {
+	trans_for_each_path(trans, path, i) {
 		BUG_ON(path->sorted_idx >= trans->nr_sorted);
-		BUG_ON(trans->sorted[path->sorted_idx] != path->idx);
+		BUG_ON(trans->sorted[path->sorted_idx] != i);
 	}
 
 	for (i = 0; i < trans->nr_sorted; i++) {
@@ -2774,8 +2776,9 @@ void bch2_trans_srcu_unlock(struct btree_trans *trans)
 	if (trans->srcu_held) {
 		struct bch_fs *c = trans->c;
 		struct btree_path *path;
+		unsigned i;
 
-		trans_for_each_path(trans, path)
+		trans_for_each_path(trans, path, i)
 			if (path->cached && !btree_node_locked(path, 0))
 				path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_srcu_reset);
 
@@ -2807,6 +2810,7 @@ static void bch2_trans_srcu_lock(struct btree_trans *trans)
 u32 bch2_trans_begin(struct btree_trans *trans)
 {
 	struct btree_path *path;
+	unsigned i;
 	u64 now;
 
 	bch2_trans_reset_updates(trans);
@@ -2815,7 +2819,7 @@ u32 bch2_trans_begin(struct btree_trans *trans)
 	trans->mem_top			= 0;
 	trans->journal_entries		= NULL;
 
-	trans_for_each_path(trans, path) {
+	trans_for_each_path(trans, path, i) {
 		path->should_be_locked = false;
 
 		/*
@@ -2832,7 +2836,7 @@ u32 bch2_trans_begin(struct btree_trans *trans)
 		 * iterators if we do that
 		 */
 		if (!path->ref && !path->preserve)
-			__bch2_path_free(trans, path->idx);
+			__bch2_path_free(trans, i);
 		else
 			path->preserve = false;
 	}
@@ -2972,14 +2976,15 @@ static void check_btree_paths_leaked(struct btree_trans *trans)
 #ifdef CONFIG_BCACHEFS_DEBUG
 	struct bch_fs *c = trans->c;
 	struct btree_path *path;
+	unsigned i;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		if (path->ref)
 			goto leaked;
 	return;
 leaked:
 	bch_err(c, "btree paths leaked from %s!", trans->fn);
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		if (path->ref)
 			printk(KERN_ERR "  btree %s %pS\n",
 			       bch2_btree_id_str(path->btree_id),

fs/bcachefs/btree_iter.h

@@ -63,22 +63,6 @@ static inline void btree_trans_sort_paths(struct btree_trans *trans)
 	__bch2_btree_trans_sort_paths(trans);
 }
 
-static inline struct btree_path *
-__trans_next_path(struct btree_trans *trans, unsigned idx)
-{
-	idx = find_next_bit(trans->paths_allocated, BTREE_ITER_MAX, idx);
-	if (idx == BTREE_ITER_MAX)
-		return NULL;
-	EBUG_ON(idx > BTREE_ITER_MAX);
-	EBUG_ON(trans->paths[idx].idx != idx);
-	return &trans->paths[idx];
-}
-
-#define trans_for_each_path(_trans, _path)				\
-	for (_path = __trans_next_path((_trans), 1);			\
-	     (_path);							\
-	     _path = __trans_next_path((_trans), (_path)->idx + 1))
-
 static inline struct btree_path *
 __trans_next_path_safe(struct btree_trans *trans, unsigned *idx)
 {
@@ -102,6 +86,19 @@ __trans_next_path_safe(struct btree_trans *trans, unsigned *idx)
 #define trans_for_each_path_safe(_trans, _path, _idx)			\
 	trans_for_each_path_safe_from(_trans, _path, _idx, 1)
 
+static inline struct btree_path *
+__trans_next_path(struct btree_trans *trans, unsigned *idx)
+{
+	struct btree_path *path = __trans_next_path_safe(trans, idx);
+	EBUG_ON(path && path->idx != *idx);
+	return path;
+}
+
+#define trans_for_each_path(_trans, _path, _iter)			\
+	for (_iter = 1;							\
+	     (_path = __trans_next_path((_trans), &_iter));		\
+	     _iter++)
+
 static inline struct btree_path *next_btree_path(struct btree_trans *trans, struct btree_path *path)
 {
 	unsigned idx = path ? path->sorted_idx + 1 : 0;
@@ -156,10 +153,11 @@ static inline struct btree_path *
 __trans_next_path_with_node(struct btree_trans *trans, struct btree *b,
 			    unsigned idx)
 {
-	struct btree_path *path = __trans_next_path(trans, idx);
+	struct btree_path *path = __trans_next_path(trans, &idx);
 
-	while (path && !__path_has_node(path, b))
-		path = __trans_next_path(trans, path->idx + 1);
+	while ((path = __trans_next_path(trans, &idx)) &&
+		!__path_has_node(path, b))
+	       idx++;
 
 	return path;
 }

fs/bcachefs/btree_key_cache.c

@@ -690,8 +690,9 @@ static int btree_key_cache_flush_pos(struct btree_trans *trans,
 		}
 	} else {
 		struct btree_path *path2;
+		unsigned i;
 evict:
-		trans_for_each_path(trans, path2)
+		trans_for_each_path(trans, path2, i)
 			if (path2 != path)
 				__bch2_btree_path_unlock(trans, path2);
 

fs/bcachefs/btree_locking.c

@@ -32,13 +32,14 @@ struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *trans,
 {
 	struct btree_path *path;
 	struct six_lock_count ret;
+	unsigned i;
 
 	memset(&ret, 0, sizeof(ret));
 
 	if (IS_ERR_OR_NULL(b))
 		return ret;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		if (path != skip && &path->l[level].b->c == b) {
 			int t = btree_node_locked_type(path, level);
 
@@ -417,7 +418,7 @@ void bch2_btree_node_lock_write_nofail(struct btree_trans *trans,
 				       struct btree_bkey_cached_common *b)
 {
 	struct btree_path *linked;
-	unsigned i;
+	unsigned i, iter;
 	int ret;
 
 	/*
@@ -431,7 +432,7 @@ void bch2_btree_node_lock_write_nofail(struct btree_trans *trans,
 	 * already taken are no longer needed:
 	 */
 
-	trans_for_each_path(trans, linked) {
+	trans_for_each_path(trans, linked, iter) {
 		if (!linked->nodes_locked)
 			continue;
 
@@ -643,8 +644,6 @@ bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 			       unsigned new_locks_want,
 			       struct get_locks_fail *f)
 {
-	struct btree_path *linked;
-
 	if (bch2_btree_path_upgrade_noupgrade_sibs(trans, path, new_locks_want, f))
 		return true;
 
@@ -667,8 +666,11 @@ bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 	 * before interior nodes - now that's handled by
 	 * bch2_btree_path_traverse_all().
 	 */
-	if (!path->cached && !trans->in_traverse_all)
-		trans_for_each_path(trans, linked)
+	if (!path->cached && !trans->in_traverse_all) {
+		struct btree_path *linked;
+		unsigned i;
+
+		trans_for_each_path(trans, linked, i)
 			if (linked != path &&
 			    linked->cached == path->cached &&
 			    linked->btree_id == path->btree_id &&
@@ -676,6 +678,7 @@ bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 				linked->locks_want = new_locks_want;
 				btree_path_get_locks(trans, linked, true, NULL);
 			}
+	}
 
 	return false;
 }
@@ -716,22 +719,24 @@ void __bch2_btree_path_downgrade(struct btree_trans *trans,
 void bch2_trans_downgrade(struct btree_trans *trans)
 {
 	struct btree_path *path;
+	unsigned i;
 
 	if (trans->restarted)
 		return;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		bch2_btree_path_downgrade(trans, path);
 }
 
 int bch2_trans_relock(struct btree_trans *trans)
 {
 	struct btree_path *path;
+	unsigned i;
 
 	if (unlikely(trans->restarted))
 		return -((int) trans->restarted);
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		if (path->should_be_locked &&
 		    !bch2_btree_path_relock_norestart(trans, path, _RET_IP_)) {
 			trace_and_count(trans->c, trans_restart_relock, trans, _RET_IP_, path);
@@ -743,11 +748,12 @@ int bch2_trans_relock(struct btree_trans *trans)
 int bch2_trans_relock_notrace(struct btree_trans *trans)
 {
 	struct btree_path *path;
+	unsigned i;
 
 	if (unlikely(trans->restarted))
 		return -((int) trans->restarted);
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		if (path->should_be_locked &&
 		    !bch2_btree_path_relock_norestart(trans, path, _RET_IP_)) {
 			return btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
@@ -758,16 +764,18 @@ int bch2_trans_relock_notrace(struct btree_trans *trans)
 void bch2_trans_unlock_noassert(struct btree_trans *trans)
 {
 	struct btree_path *path;
+	unsigned i;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		__bch2_btree_path_unlock(trans, path);
 }
 
 void bch2_trans_unlock(struct btree_trans *trans)
 {
 	struct btree_path *path;
+	unsigned i;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		__bch2_btree_path_unlock(trans, path);
 }
 
@@ -780,8 +788,9 @@ void bch2_trans_unlock_long(struct btree_trans *trans)
 bool bch2_trans_locked(struct btree_trans *trans)
 {
 	struct btree_path *path;
+	unsigned i;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		if (path->nodes_locked)
 			return true;
 	return false;
@@ -827,8 +836,9 @@ void bch2_btree_path_verify_locks(struct btree_path *path)
 void bch2_trans_verify_locks(struct btree_trans *trans)
 {
 	struct btree_path *path;
+	unsigned i;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		bch2_btree_path_verify_locks(path);
 }
 

fs/bcachefs/btree_locking.h

@@ -242,8 +242,9 @@ static inline bool btree_node_lock_increment(struct btree_trans *trans,
 					     enum btree_node_locked_type want)
 {
 	struct btree_path *path;
+	unsigned i;
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		if (&path->l[level].b->c == b &&
 		    btree_node_locked_type(path, level) >= want) {
 			six_lock_increment(&b->lock, (enum six_lock_type) want);

fs/bcachefs/btree_update_interior.c

@@ -190,7 +190,7 @@ static void bch2_btree_node_free_inmem(struct btree_trans *trans,
 				       struct btree *b)
 {
 	struct bch_fs *c = trans->c;
-	unsigned level = b->c.level;
+	unsigned i, level = b->c.level;
 
 	bch2_btree_node_lock_write_nofail(trans, path, &b->c);
 	bch2_btree_node_hash_remove(&c->btree_cache, b);
@@ -198,7 +198,7 @@ static void bch2_btree_node_free_inmem(struct btree_trans *trans,
 	six_unlock_write(&b->c.lock);
 	mark_btree_node_locked_noreset(path, level, BTREE_NODE_INTENT_LOCKED);
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		if (path->l[level].b == b) {
 			btree_node_unlock(trans, path, level);
 			path->l[level].b = ERR_PTR(-BCH_ERR_no_btree_node_init);
@@ -212,7 +212,7 @@ static void bch2_btree_node_free_never_used(struct btree_update *as,
 	struct bch_fs *c = as->c;
 	struct prealloc_nodes *p = &as->prealloc_nodes[b->c.lock.readers != NULL];
 	struct btree_path *path;
-	unsigned level = b->c.level;
+	unsigned i, level = b->c.level;
 
 	BUG_ON(!list_empty(&b->write_blocked));
 	BUG_ON(b->will_make_reachable != (1UL|(unsigned long) as));
@@ -235,7 +235,7 @@ static void bch2_btree_node_free_never_used(struct btree_update *as,
 
 	six_unlock_intent(&b->c.lock);
 
-	trans_for_each_path(trans, path)
+	trans_for_each_path(trans, path, i)
 		if (path->l[level].b == b) {
 			btree_node_unlock(trans, path, level);
 			path->l[level].b = ERR_PTR(-BCH_ERR_no_btree_node_init);