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 u8 bch2_btree_key_recalc_oldest_gen(struct bch_fs *, struct bkey_s_c);
14 int bch2_btree_mark_key_initial(struct bch_fs *, enum bkey_type,
16 void bch2_mark_dev_superblock(struct bch_fs *, struct bch_dev *, unsigned);
19 * For concurrent mark and sweep (with other index updates), we define a total
20 * ordering of _all_ references GC walks:
22 * Note that some references will have the same GC position as others - e.g.
23 * everything within the same btree node; in those cases we're relying on
24 * whatever locking exists for where those references live, i.e. the write lock
27 * That locking is also required to ensure GC doesn't pass the updater in
28 * between the updater adding/removing the reference and updating the GC marks;
29 * without that, we would at best double count sometimes.
31 * That part is important - whenever calling bch2_mark_pointers(), a lock _must_
32 * be held that prevents GC from passing the position the updater is at.
34 * (What about the start of gc, when we're clearing all the marks? GC clears the
35 * mark with the gc pos seqlock held, and bch_mark_bucket checks against the gc
36 * position inside its cmpxchg loop, so crap magically works).
39 /* Position of (the start of) a gc phase: */
40 static inline struct gc_pos gc_phase(enum gc_phase phase)
42 return (struct gc_pos) {
49 #define GC_POS_MIN gc_phase(0)
51 static inline int gc_pos_cmp(struct gc_pos l, struct gc_pos r)
53 if (l.phase != r.phase)
54 return l.phase < r.phase ? -1 : 1;
55 if (bkey_cmp(l.pos, r.pos))
56 return bkey_cmp(l.pos, r.pos);
57 if (l.level != r.level)
58 return l.level < r.level ? -1 : 1;
63 * GC position of the pointers within a btree node: note, _not_ for &b->key
64 * itself, that lives in the parent node:
66 static inline struct gc_pos gc_pos_btree_node(struct btree *b)
68 return (struct gc_pos) {
76 * GC position of the pointer to a btree root: we don't use
77 * gc_pos_pointer_to_btree_node() here to avoid a potential race with
78 * btree_split() increasing the tree depth - the new root will have level > the
79 * old root and thus have a greater gc position than the old root, but that
80 * would be incorrect since once gc has marked the root it's not coming back.
82 static inline struct gc_pos gc_pos_btree_root(enum btree_id id)
84 return (struct gc_pos) {
91 static inline struct gc_pos gc_pos_alloc(struct bch_fs *c, struct open_bucket *ob)
93 return (struct gc_pos) {
94 .phase = GC_PHASE_ALLOC,
95 .pos = POS(ob ? ob - c->open_buckets : 0, 0),
99 static inline bool gc_will_visit(struct bch_fs *c, struct gc_pos pos)
105 seq = read_seqcount_begin(&c->gc_pos_lock);
106 ret = gc_pos_cmp(c->gc_pos, pos) < 0;
107 } while (read_seqcount_retry(&c->gc_pos_lock, seq));
112 #endif /* _BCACHEFS_BTREE_GC_H */