bcachefs: Kill gc_init_recurse()

This unifies the online and offline btree gc passes; we're not yet
running it online.

We now iterate over one level of the btree at a time - the same as
check_extents_to_backpointers(); this ordering preserves order of keys
regardless of btree splits and merges, which will be important when we
re-enable online gc.

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

1 files changed, 9 insertions, 21 deletions

diff --git a/fs/bcachefs/btree_gc.h b/fs/bcachefs/btree_gc.h
index 15315aab93bd..1b6489d8e0f4 100644
--- a/fs/bcachefs/btree_gc.h
+++ b/fs/bcachefs/btree_gc.h
@@ -34,16 +34,16 @@ static inline struct gc_pos gc_phase(enum gc_phase phase)
 {
 	return (struct gc_pos) {
 		.phase	= phase,
-		.pos	= POS_MIN,
 		.level	= 0,
+		.pos	= POS_MIN,
 	};
 }
 
 static inline int gc_pos_cmp(struct gc_pos l, struct gc_pos r)
 {
-	return  cmp_int(l.phase, r.phase) ?:
-		bpos_cmp(l.pos, r.pos) ?:
-		cmp_int(l.level, r.level);
+	return   cmp_int(l.phase, r.phase) ?:
+		-cmp_int(l.level, r.level) ?:
+		 bpos_cmp(l.pos, r.pos);
 }
 
 static inline enum gc_phase btree_id_to_gc_phase(enum btree_id id)
@@ -57,13 +57,13 @@ static inline enum gc_phase btree_id_to_gc_phase(enum btree_id id)
 	}
 }
 
-static inline struct gc_pos gc_pos_btree(enum btree_id id,
-					 struct bpos pos, unsigned level)
+static inline struct gc_pos gc_pos_btree(enum btree_id btree, unsigned level,
+					 struct bpos pos)
 {
 	return (struct gc_pos) {
-		.phase	= btree_id_to_gc_phase(id),
-		.pos	= pos,
+		.phase	= btree_id_to_gc_phase(btree),
 		.level	= level,
+		.pos	= pos,
 	};
 }
 
@@ -73,19 +73,7 @@ static inline struct gc_pos gc_pos_btree(enum btree_id id,
  */
 static inline struct gc_pos gc_pos_btree_node(struct btree *b)
 {
-	return gc_pos_btree(b->c.btree_id, b->key.k.p, b->c.level);
-}
-
-/*
- * GC position of the pointer to a btree root: we don't use
- * gc_pos_pointer_to_btree_node() here to avoid a potential race with
- * btree_split() increasing the tree depth - the new root will have level > the
- * old root and thus have a greater gc position than the old root, but that
- * would be incorrect since once gc has marked the root it's not coming back.
- */
-static inline struct gc_pos gc_pos_btree_root(enum btree_id id)
-{
-	return gc_pos_btree(id, SPOS_MAX, BTREE_MAX_DEPTH);
+	return gc_pos_btree(b->c.btree_id, b->c.level, b->key.k.p);
 }
 
 static inline bool gc_visited(struct bch_fs *c, struct gc_pos pos)