path: root/fs/bcachefs/btree_update.c

// SPDX-License-Identifier: GPL-2.0

#include "bcachefs.h"
#include "btree_update.h"
#include "btree_iter.h"
#include "btree_journal_iter.h"
#include "btree_locking.h"
#include "buckets.h"
#include "debug.h"
#include "errcode.h"
#include "error.h"
#include "extents.h"
#include "keylist.h"
#include "snapshot.h"
#include "trace.h"

static inline int btree_insert_entry_cmp(const struct btree_insert_entry *l,
					 const struct btree_insert_entry *r)
{
	return   cmp_int(l->sort_order,	r->sort_order) ?:
		 cmp_int(l->cached,	r->cached) ?:
		 -cmp_int(l->level,	r->level) ?:
		 bpos_cmp(l->k->k.p,	r->k->k.p);
}

static int __must_check
bch2_trans_update_by_path(struct btree_trans *, btree_path_idx_t,
			  struct bkey_i *, enum btree_iter_update_trigger_flags,
			  unsigned long ip);

static noinline int extent_front_merge(struct btree_trans *trans,
				       struct btree_iter *iter,
				       struct bkey_s_c k,
				       struct bkey_i **insert,
				       enum btree_iter_update_trigger_flags flags)
{
	struct bch_fs *c = trans->c;
	struct bkey_i *update;
	int ret;

	if (unlikely(trans->journal_replay_not_finished))
		return 0;

	update = bch2_bkey_make_mut_noupdate(trans, k);
	ret = PTR_ERR_OR_ZERO(update);
	if (ret)
		return ret;

	if (!bch2_bkey_merge(c, bkey_i_to_s(update), bkey_i_to_s_c(*insert)))
		return 0;

	ret =   bch2_key_has_snapshot_overwrites(trans, iter->btree_id, k.k->p) ?:
		bch2_key_has_snapshot_overwrites(trans, iter->btree_id, (*insert)->k.p);
	if (ret < 0)
		return ret;
	if (ret)
		return 0;

	ret = bch2_btree_delete_at(trans, iter, flags);
	if (ret)
		return ret;

	*insert = update;
	return 0;
}

static noinline int extent_back_merge(struct btree_trans *trans,
				      struct btree_iter *iter,
				      struct bkey_i *insert,
				      struct bkey_s_c k)
{
	struct bch_fs *c = trans->c;
	int ret;

	if (unlikely(trans->journal_replay_not_finished))
		return 0;

	ret =   bch2_key_has_snapshot_overwrites(trans, iter->btree_id, insert->k.p) ?:
		bch2_key_has_snapshot_overwrites(trans, iter->btree_id, k.k->p);
	if (ret < 0)
		return ret;
	if (ret)
		return 0;

	bch2_bkey_merge(c, bkey_i_to_s(insert), k);
	return 0;
}

/*
 * When deleting, check if we need to emit a whiteout (because we're overwriting
 * something in an ancestor snapshot)
 */
static int need_whiteout_for_snapshot(struct btree_trans *trans,
				      enum btree_id btree_id, struct bpos pos)
{
	struct btree_iter iter;
	struct bkey_s_c k;
	u32 snapshot = pos.snapshot;
	int ret;

	if (!bch2_snapshot_parent(trans->c, pos.snapshot))
		return 0;

	pos.snapshot++;

	for_each_btree_key_norestart(trans, iter, btree_id, pos,
			   BTREE_ITER_all_snapshots|
			   BTREE_ITER_nopreserve, k, ret) {
		if (!bkey_eq(k.k->p, pos))
			break;

		if (bch2_snapshot_is_ancestor(trans->c, snapshot,
					      k.k->p.snapshot)) {
			ret = !bkey_whiteout(k.k);
			break;
		}
	}
	bch2_trans_iter_exit(trans, &iter);

	return ret;
}

int __bch2_insert_snapshot_whiteouts(struct btree_trans *trans,
				   enum btree_id id,
				   struct bpos old_pos,
				   struct bpos new_pos)
{
	struct bch_fs *c = trans->c;
	struct btree_iter old_iter, new_iter = {};
	struct bkey_s_c old_k, new_k;
	snapshot_id_list s;
	struct bkey_i *update;
	int ret = 0;

	if (!bch2_snapshot_has_children(c, old_pos.snapshot))
		return 0;

	darray_init(&s);

	bch2_trans_iter_init(trans, &old_iter, id, old_pos,
			     BTREE_ITER_not_extents|
			     BTREE_ITER_all_snapshots);
	while ((old_k = bch2_btree_iter_prev(trans, &old_iter)).k &&
	       !(ret = bkey_err(old_k)) &&
	       bkey_eq(old_pos, old_k.k->p)) {
		struct bpos whiteout_pos =
			SPOS(new_pos.inode, new_pos.offset, old_k.k->p.snapshot);

		if (!bch2_snapshot_is_ancestor(c, old_k.k->p.snapshot, old_pos.snapshot) ||
		    snapshot_list_has_ancestor(c, &s, old_k.k->p.snapshot))
			continue;

		new_k = bch2_bkey_get_iter(trans, &new_iter, id, whiteout_pos,
					   BTREE_ITER_not_extents|
					   BTREE_ITER_intent);
		ret = bkey_err(new_k);
		if (ret)
			break;

		if (new_k.k->type == KEY_TYPE_deleted) {
			update = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
			ret = PTR_ERR_OR_ZERO(update);
			if (ret)
				break;

			bkey_init(&update->k);
			update->k.p		= whiteout_pos;
			update->k.type		= KEY_TYPE_whiteout;

			ret = bch2_trans_update(trans, &new_iter, update,
						BTREE_UPDATE_internal_snapshot_node);
		}
		bch2_trans_iter_exit(trans, &new_iter);

		ret = snapshot_list_add(c, &s, old_k.k->p.snapshot);
		if (ret)
			break;
	}
	bch2_trans_iter_exit(trans, &new_iter);
	bch2_trans_iter_exit(trans, &old_iter);
	darray_exit(&s);

	return ret;
}

int bch2_trans_update_extent_overwrite(struct