bcachefs: New locking functions

In the future, with the new deadlock cycle detector, we won't be using
bare six_lock_* anymore: lock wait entries will all be embedded in
btree_trans, and we will need a btree_trans context whenever locking a
btree node.

This patch plumbs a btree_trans to the few places that need it, and adds
two new locking functions
 - btree_node_lock_nopath, which may fail returning a transaction
   restart, and
 - btree_node_lock_nopath_nofail, to be used in places where we know we
   cannot deadlock (i.e. because we're holding no other locks).

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/fs/bcachefs/btree_locking.h b/fs/bcachefs/btree_locking.h
index ab3161c1b1f4..32c28c1341e9 100644
--- a/fs/bcachefs/btree_locking.h
+++ b/fs/bcachefs/btree_locking.h
@@ -185,6 +185,24 @@ void bch2_btree_node_unlock_write(struct btree_trans *,
 
 /* lock: */
 
+static inline int __must_check
+btree_node_lock_nopath(struct btree_trans *trans,
+		       struct btree_bkey_cached_common *b,
+		       enum six_lock_type type)
+{
+	six_lock_type(&b->lock, type, NULL, NULL);
+	return 0;
+}
+
+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);
+
+	BUG_ON(ret);
+}
+
 static inline int btree_node_lock_type(struct btree_trans *trans,
 				       struct btree_path *path,
 				       struct btree_bkey_cached_common *b,