bcachefs: Kill trans->flags

Recursive transaction commits are occasionally necessary - in
particular, for the upcoming btree write buffer's flush path.

This avoids bugs due to trans->flags being accidentally mutated
mid-commit, which can cause c->writes refcount leaks.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_key_cache.c

@@ -769,6 +769,7 @@ int bch2_btree_key_cache_flush(struct btree_trans *trans,
 }
 
 bool bch2_btree_insert_key_cached(struct btree_trans *trans,
+				  unsigned flags,
 				  struct btree_path *path,
 				  struct bkey_i *insert)
 {
@@ -778,7 +779,7 @@ bool bch2_btree_insert_key_cached(struct btree_trans *trans,
 
 	BUG_ON(insert->u64s > ck->u64s);
 
-	if (likely(!(trans->flags & BTREE_INSERT_JOURNAL_REPLAY))) {
+	if (likely(!(flags & BTREE_INSERT_JOURNAL_REPLAY))) {
 		int difference;
 
 		BUG_ON(jset_u64s(insert->u64s) > trans->journal_preres.u64s);

fs/bcachefs/btree_key_cache.h

@@ -29,7 +29,7 @@ bch2_btree_key_cache_find(struct bch_fs *, enum btree_id, struct bpos);
 int bch2_btree_path_traverse_cached(struct btree_trans *, struct btree_path *,
 				    unsigned);
 
-bool bch2_btree_insert_key_cached(struct btree_trans *,
+bool bch2_btree_insert_key_cached(struct btree_trans *, unsigned,
 			struct btree_path *, struct bkey_i *);
 int bch2_btree_key_cache_flush(struct btree_trans *,
 			       enum btree_id, struct bpos);

fs/bcachefs/btree_types.h

@@ -458,7 +458,6 @@ struct btree_trans {
 	struct journal_preres	journal_preres;
 	u64			*journal_seq;
 	struct disk_reservation *disk_res;
-	unsigned		flags;
 	unsigned		journal_u64s;
 	unsigned		journal_preres_u64s;
 	struct replicas_delta_list *fs_usage_deltas;

fs/bcachefs/btree_update.h

@@ -80,7 +80,7 @@ int __must_check bch2_trans_update(struct btree_trans *, struct btree_iter *,
 
 void bch2_trans_commit_hook(struct btree_trans *,
 			    struct btree_trans_commit_hook *);
-int __bch2_trans_commit(struct btree_trans *);
+int __bch2_trans_commit(struct btree_trans *, unsigned);
 
 int bch2_trans_log_msg(struct btree_trans *, const char *, ...);
 int bch2_fs_log_msg(struct bch_fs *, const char *, ...);
@@ -101,9 +101,8 @@ static inline int bch2_trans_commit(struct btree_trans *trans,
 {
 	trans->disk_res		= disk_res;
 	trans->journal_seq	= journal_seq;
-	trans->flags		= flags;
 
-	return __bch2_trans_commit(trans);
+	return __bch2_trans_commit(trans, flags);
 }
 
 #define commit_do(_trans, _disk_res, _journal_seq, _flags, _do)	\