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 9 int bch2_check_topology(struct bch_fs *); 10 int 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: */ 34 static inline struct gc_pos gc_phase(enum gc_phase phase) 35 { 36 return (struct gc_pos) { .phase = phase, }; 37 } 38 39 static 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 */ 54 static 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 59 static inline int gc_btree_order(enum btree_id btree) 60 { 61 if (btree == BTREE_ID_stripes) 62 return -1; 63 return btree; 64 } 65 66 static 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 75 static 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 88 int bch2_gc_gens(struct bch_fs *); 89 void bch2_gc_gens_async(struct bch_fs *); 90 void bch2_fs_gc_init(struct bch_fs *); 91 92 #endif /* _BCACHEFS_BTREE_GC_H */ 93