linux/fs/bcachefs/btree_gc.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHEFS_BTREE_GC_H
#define _BCACHEFS_BTREE_GC_H

#include "bkey.h"
#include "btree_gc_types.h"
#include "btree_types.h"

int bch2_check_topology(struct bch_fs *);
int bch2_check_allocations(struct bch_fs *);

/*
 * For concurrent mark and sweep (with other index updates), we define a total
 * ordering of _all_ references GC walks:
 *
 * Note that some references will have the same GC position as others - e.g.
 * everything within the same btree node; in those cases we're relying on
 * whatever locking exists for where those references live, i.e. the write lock
 * on a btree node.
 *
 * That locking is also required to ensure GC doesn't pass the updater in
 * between the updater adding/removing the reference and updating the GC marks;
 * without that, we would at best double count sometimes.
 *
 * That part is important - whenever calling bch2_mark_pointers(), a lock _must_
 * be held that prevents GC from passing the position the updater is at.
 *
 * (What about the start of gc, when we're clearing all the marks? GC clears the
 * mark with the gc pos seqlock held, and bch_mark_bucket checks against the gc
 * position inside its cmpxchg loop, so crap magically works).
 */

/* Position of (the start of) a gc phase: */
static inline struct gc_pos gc_phase(enum gc_phase phase)
{ … }

static inline struct gc_pos gc_pos_btree(enum btree_id btree, unsigned level,
					 struct bpos pos)
{ … }

static inline int gc_btree_order(enum btree_id btree)
{ … }

static inline int gc_pos_cmp(struct gc_pos l, struct gc_pos r)
{ … }

static inline bool gc_visited(struct bch_fs *c, struct gc_pos pos)
{ … }

void bch2_gc_pos_to_text(struct printbuf *, struct gc_pos *);

int bch2_gc_gens(struct bch_fs *);
void bch2_gc_gens_async(struct bch_fs *);
void bch2_fs_gc_init(struct bch_fs *);

#endif /* _BCACHEFS_BTREE_GC_H */