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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _BCACHEFS_BTREE_GC_H
3#define _BCACHEFS_BTREE_GC_H
4
5#include "bkey.h"
6#include "btree_gc_types.h"
7#include "btree_types.h"
8
9int bch2_check_topology(struct bch_fs *);
10int bch2_check_allocations(struct bch_fs *);
11
12/*
13 * For concurrent mark and sweep (with other index updates), we define a total
14 * ordering of _all_ references GC walks:
15 *
16 * Note that some references will have the same GC position as others - e.g.
17 * everything within the same btree node; in those cases we're relying on
18 * whatever locking exists for where those references live, i.e. the write lock
19 * on a btree node.
20 *
21 * That locking is also required to ensure GC doesn't pass the updater in
22 * between the updater adding/removing the reference and updating the GC marks;
23 * without that, we would at best double count sometimes.
24 *
25 * That part is important - whenever calling bch2_mark_pointers(), a lock _must_
26 * be held that prevents GC from passing the position the updater is at.
27 *
28 * (What about the start of gc, when we're clearing all the marks? GC clears the
29 * mark with the gc pos seqlock held, and bch_mark_bucket checks against the gc
30 * position inside its cmpxchg loop, so crap magically works).
31 */
32
33/* Position of (the start of) a gc phase: */
34static inline struct gc_pos gc_phase(enum gc_phase phase)
35{
36 return (struct gc_pos) { .phase = phase, };
37}
38
39static inline struct gc_pos gc_pos_btree(enum btree_id btree, unsigned level,
40 struct bpos pos)
41{
42 return (struct gc_pos) {
43 .phase = GC_PHASE_btree,
44 .btree = btree,
45 .level = level,
46 .pos = pos,
47 };
48}
49
50/*
51 * GC position of the pointers within a btree node: note, _not_ for &b->key
52 * itself, that lives in the parent node:
53 */
54static inline struct gc_pos gc_pos_btree_node(struct btree *b)
55{
56 return gc_pos_btree(b->c.btree_id, b->c.level, b->key.k.p);
57}
58
59static inline int gc_btree_order(enum btree_id btree)
60{
61 if (btree == BTREE_ID_stripes)
62 return -1;
63 return btree;
64}
65
66static inline int gc_pos_cmp(struct gc_pos l, struct gc_pos r)
67{
68 return cmp_int(l.phase, r.phase) ?:
69 cmp_int(gc_btree_order(l.btree),
70 gc_btree_order(r.btree)) ?:
71 -cmp_int(l.level, r.level) ?:
72 bpos_cmp(l.pos, r.pos);
73}
74
75static inline bool gc_visited(struct bch_fs *c, struct gc_pos pos)
76{
77 unsigned seq;
78 bool ret;
79
80 do {
81 seq = read_seqcount_begin(&c->gc_pos_lock);
82 ret = gc_pos_cmp(pos, c->gc_pos) <= 0;
83 } while (read_seqcount_retry(&c->gc_pos_lock, seq));
84
85 return ret;
86}
87
88int bch2_gc_gens(struct bch_fs *);
89void bch2_gc_gens_async(struct bch_fs *);
90void bch2_fs_gc_init(struct bch_fs *);
91
92#endif /* _BCACHEFS_BTREE_GC_H */