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We have foreground btree node merging now, and any future btree node merging improvements are going to be based off of that code. Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
115 lines
3.3 KiB
C
115 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _BCACHEFS_BTREE_GC_H
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#define _BCACHEFS_BTREE_GC_H
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#include "btree_types.h"
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int bch2_gc(struct bch_fs *, bool, bool);
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int bch2_gc_gens(struct bch_fs *);
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void bch2_gc_thread_stop(struct bch_fs *);
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int bch2_gc_thread_start(struct bch_fs *);
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void bch2_mark_dev_superblock(struct bch_fs *, struct bch_dev *, unsigned);
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/*
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* For concurrent mark and sweep (with other index updates), we define a total
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* ordering of _all_ references GC walks:
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*
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* Note that some references will have the same GC position as others - e.g.
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* everything within the same btree node; in those cases we're relying on
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* whatever locking exists for where those references live, i.e. the write lock
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* on a btree node.
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*
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* That locking is also required to ensure GC doesn't pass the updater in
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* between the updater adding/removing the reference and updating the GC marks;
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* without that, we would at best double count sometimes.
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*
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* That part is important - whenever calling bch2_mark_pointers(), a lock _must_
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* be held that prevents GC from passing the position the updater is at.
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*
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* (What about the start of gc, when we're clearing all the marks? GC clears the
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* mark with the gc pos seqlock held, and bch_mark_bucket checks against the gc
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* position inside its cmpxchg loop, so crap magically works).
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*/
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/* Position of (the start of) a gc phase: */
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static inline struct gc_pos gc_phase(enum gc_phase phase)
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{
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return (struct gc_pos) {
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.phase = phase,
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.pos = POS_MIN,
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.level = 0,
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};
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}
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static inline int gc_pos_cmp(struct gc_pos l, struct gc_pos r)
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{
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return cmp_int(l.phase, r.phase) ?:
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bpos_cmp(l.pos, r.pos) ?:
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cmp_int(l.level, r.level);
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}
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static inline enum gc_phase btree_id_to_gc_phase(enum btree_id id)
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{
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switch (id) {
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#define x(name, v) case BTREE_ID_##name: return GC_PHASE_BTREE_##name;
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BCH_BTREE_IDS()
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#undef x
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default:
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BUG();
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}
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}
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static inline struct gc_pos gc_pos_btree(enum btree_id id,
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struct bpos pos, unsigned level)
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{
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return (struct gc_pos) {
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.phase = btree_id_to_gc_phase(id),
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.pos = pos,
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.level = level,
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};
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}
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/*
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* GC position of the pointers within a btree node: note, _not_ for &b->key
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* itself, that lives in the parent node:
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*/
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static inline struct gc_pos gc_pos_btree_node(struct btree *b)
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{
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return gc_pos_btree(b->c.btree_id, b->key.k.p, b->c.level);
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}
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/*
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* GC position of the pointer to a btree root: we don't use
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* gc_pos_pointer_to_btree_node() here to avoid a potential race with
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* btree_split() increasing the tree depth - the new root will have level > the
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* old root and thus have a greater gc position than the old root, but that
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* would be incorrect since once gc has marked the root it's not coming back.
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*/
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static inline struct gc_pos gc_pos_btree_root(enum btree_id id)
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{
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return gc_pos_btree(id, POS_MAX, BTREE_MAX_DEPTH);
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}
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static inline struct gc_pos gc_pos_alloc(struct bch_fs *c, struct open_bucket *ob)
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{
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return (struct gc_pos) {
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.phase = GC_PHASE_ALLOC,
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.pos = POS(ob ? ob - c->open_buckets : 0, 0),
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};
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}
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static inline bool gc_visited(struct bch_fs *c, struct gc_pos pos)
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{
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unsigned seq;
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bool ret;
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do {
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seq = read_seqcount_begin(&c->gc_pos_lock);
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ret = gc_pos_cmp(pos, c->gc_pos) <= 0;
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} while (read_seqcount_retry(&c->gc_pos_lock, seq));
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return ret;
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}
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#endif /* _BCACHEFS_BTREE_GC_H */
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