1 files changed, 87 insertions, 0 deletions
diff --git a/fs/bcachefs/btree_gc.h b/fs/bcachefs/btree_gc.h
new file mode 100644
index 000000000000..8a47e8bd0791
--- /dev/null
+++ b/fs/bcachefs/btree_gc.h
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHEFS_BTREE_GC_H
+#define _BCACHEFS_BTREE_GC_H
+
+#include "bkey.h"
+#include "btree_gc_types.h"
+#include "btree_types.h"
+
+int bch2_check_topology(struct bch_fs *);
+int bch2_check_allocations(struct bch_fs *);
+
+/*
+ * For concurrent mark and sweep (with other index updates), we define a total
+ * ordering of _all_ references GC walks:
+ *
+ * Note that some references will have the same GC position as others - e.g.
+ * everything within the same btree node; in those cases we're relying on
+ * whatever locking exists for where those references live, i.e. the write lock
+ * on a btree node.
+ *
+ * That locking is also required to ensure GC doesn't pass the updater in
+ * between the updater adding/removing the reference and updating the GC marks;
+ * without that, we would at best double count sometimes.
+ *
+ * That part is important - whenever calling bch2_mark_pointers(), a lock _must_
+ * be held that prevents GC from passing the position the updater is at.
+ *
+ * (What about the start of gc, when we're clearing all the marks? GC clears the
+ * mark with the gc pos seqlock held, and bch_mark_bucket checks against the gc
+ * position inside its cmpxchg loop, so crap magically works).
+ */
+
+/* Position of (the start of) a gc phase: */
+static inline struct gc_pos gc_phase(enum gc_phase phase)
+{
+	return (struct gc_pos) { .phase	= phase, };
+}
+
+static inline struct gc_pos gc_pos_btree(enum btree_id btree, unsigned level,
+					 struct bpos pos)
+{
+	return (struct gc_pos) {
+		.phase	= GC_PHASE_btree,
+		.btree	= btree,
+		.level	= level,
+		.pos	= pos,
+	};
+}
+
+static inline int gc_btree_order(enum btree_id btree)
+{
+	if (btree == BTREE_ID_alloc)
+		return -2;
+	if (btree == BTREE_ID_stripes)
+		return -1;
+	return btree;
+}
+
+static inline int gc_pos_cmp(struct gc_pos l, struct gc_pos r)
+{
+	return  cmp_int(l.phase, r.phase) ?:
+		cmp_int(gc_btree_order(l.btree),
+			gc_btree_order(r.btree)) ?:
+		cmp_int(l.level, r.level) ?:
+		bpos_cmp(l.pos, r.pos);
+}
+
+static inline bool gc_visited(struct bch_fs *c, struct gc_pos pos)
+{
+	unsigned seq;
+	bool ret;
+
+	do {
+		seq = read_seqcount_begin(&c->gc_pos_lock);
+		ret = gc_pos_cmp(pos, c->gc_pos) <= 0;
+	} while (read_seqcount_retry(&c->gc_pos_lock, seq));
+
+	return ret;
+}
+
+void bch2_gc_pos_to_text(struct printbuf *, struct gc_pos *);
+
+int bch2_gc_gens(struct bch_fs *);
+void bch2_gc_gens_async(struct bch_fs *);
+void bch2_fs_gc_init(struct bch_fs *);
+
+#endif /* _BCACHEFS_BTREE_GC_H */