Commit c986dd7e authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Improve check_snapshot_exists() 



Check if we have snapshot_trees or subvolumes that refer to the snapshot
node being reconstructed, and use them.

With this, the kill_btree_root test that blows away the snapshots btree
now passes, and we're able to successfully reconstruct.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 9183c2b1

fs/bcachefs/snapshot.c

+30 −2
Original line number Diff line number Diff line
@@ -905,12 +905,30 @@ static int check_snapshot_exists(struct btree_trans *trans, u32 id) 
	if (bch2_snapshot_equiv(c, id))

		return 0;



	/* 0 is an invalid tree ID */

	/* Do we need to reconstruct the snapshot_tree entry as well? */

	struct btree_iter iter;

	struct bkey_s_c k;

	int ret = 0;

	u32 tree_id = 0;

	int ret = bch2_snapshot_tree_create(trans, id, 0, &tree_id);



	for_each_btree_key_norestart(trans, iter, BTREE_ID_snapshot_trees, POS_MIN,

				     0, k, ret) {

		if (le32_to_cpu(bkey_s_c_to_snapshot_tree(k).v->root_snapshot) == id) {

			tree_id = k.k->p.offset;

			break;

		}

	}

	bch2_trans_iter_exit(trans, &iter);



	if (ret)

		return ret;



	if (!tree_id) {

		ret = bch2_snapshot_tree_create(trans, id, 0, &tree_id);

		if (ret)

			return ret;

	}



	struct bkey_i_snapshot *snapshot = bch2_trans_kmalloc(trans, sizeof(*snapshot));

	ret = PTR_ERR_OR_ZERO(snapshot);

	if (ret)
@@ -921,6 +939,16 @@ static int check_snapshot_exists(struct btree_trans *trans, u32 id) 
	snapshot->v.tree	= cpu_to_le32(tree_id);

	snapshot->v.btime.lo	= cpu_to_le64(bch2_current_time(c));



	for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN,

				     0, k, ret) {

		if (le32_to_cpu(bkey_s_c_to_subvolume(k).v->snapshot) == id) {

			snapshot->v.subvol = cpu_to_le32(k.k->p.offset);

			SET_BCH_SNAPSHOT_SUBVOL(&snapshot->v, true);

			break;

		}

	}

	bch2_trans_iter_exit(trans, &iter);



	return  bch2_btree_insert_trans(trans, BTREE_ID_snapshots, &snapshot->k_i, 0) ?:

		bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,

				   bkey_s_c_null, bkey_i_to_s(&snapshot->k_i), 0) ?: