1 #ifndef _BCACHEFS_BTREE_GC_H
2 #define _BCACHEFS_BTREE_GC_H
4 #include "btree_types.h"
8 void bch2_coalesce(struct bch_fs *);
9 void bch2_gc(struct bch_fs *);
10 void bch2_gc_thread_stop(struct bch_fs *);
11 int bch2_gc_thread_start(struct bch_fs *);
12 int bch2_initial_gc(struct bch_fs *, struct list_head *);
13 void bch2_mark_dev_superblock(struct bch_fs *, struct bch_dev *, unsigned);
16 * For concurrent mark and sweep (with other index updates), we define a total
17 * ordering of _all_ references GC walks:
19 * Note that some references will have the same GC position as others - e.g.
20 * everything within the same btree node; in those cases we're relying on
21 * whatever locking exists for where those references live, i.e. the write lock
24 * That locking is also required to ensure GC doesn't pass the updater in
25 * between the updater adding/removing the reference and updating the GC marks;
26 * without that, we would at best double count sometimes.
28 * That part is important - whenever calling bch2_mark_pointers(), a lock _must_
29 * be held that prevents GC from passing the position the updater is at.
31 * (What about the start of gc, when we're clearing all the marks? GC clears the
32 * mark with the gc pos seqlock held, and bch_mark_bucket checks against the gc
33 * position inside its cmpxchg loop, so crap magically works).
36 /* Position of (the start of) a gc phase: */
37 static inline struct gc_pos gc_phase(enum gc_phase phase)
39 return (struct gc_pos) {
46 static inline int gc_pos_cmp(struct gc_pos l, struct gc_pos r)
48 if (l.phase != r.phase)
49 return l.phase < r.phase ? -1 : 1;
50 if (bkey_cmp(l.pos, r.pos))
51 return bkey_cmp(l.pos, r.pos);
52 if (l.level != r.level)
53 return l.level < r.level ? -1 : 1;
57 static inline struct gc_pos gc_pos_btree(enum btree_id id,
58 struct bpos pos, unsigned level)
60 return (struct gc_pos) {
61 .phase = GC_PHASE_BTREE_EXTENTS + id,
68 * GC position of the pointers within a btree node: note, _not_ for &b->key
69 * itself, that lives in the parent node:
71 static inline struct gc_pos gc_pos_btree_node(struct btree *b)
73 return gc_pos_btree(b->btree_id, b->key.k.p, b->level);
77 * GC position of the pointer to a btree root: we don't use
78 * gc_pos_pointer_to_btree_node() here to avoid a potential race with
79 * btree_split() increasing the tree depth - the new root will have level > the
80 * old root and thus have a greater gc position than the old root, but that
81 * would be incorrect since once gc has marked the root it's not coming back.
83 static inline struct gc_pos gc_pos_btree_root(enum btree_id id)
85 return gc_pos_btree(id, POS_MAX, BTREE_MAX_DEPTH);
88 static inline struct gc_pos gc_pos_alloc(struct bch_fs *c, struct open_bucket *ob)
90 return (struct gc_pos) {
91 .phase = GC_PHASE_ALLOC,
92 .pos = POS(ob ? ob - c->open_buckets : 0, 0),
96 static inline bool gc_will_visit(struct bch_fs *c, struct gc_pos pos)
102 seq = read_seqcount_begin(&c->gc_pos_lock);
103 ret = gc_pos_cmp(c->gc_pos, pos) < 0;
104 } while (read_seqcount_retry(&c->gc_pos_lock, seq));
109 #endif /* _BCACHEFS_BTREE_GC_H */