Commit 1c31b83a authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: bch2_snapshot_is_ancestor() now safe to call in early recovery 



this fixes an assertion pop in
  bch2_check_snapshot_trees() ->
  check_snapshot_tree() ->
  bch2_snapshot_tree_master_subvol() ->
  bch2_snapshot_is_ancestor()

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 1ba6f48f

fs/bcachefs/snapshot.c

+18 −14
Original line number Diff line number Diff line
@@ -91,18 +91,20 @@ static int bch2_snapshot_tree_create(struct btree_trans *trans, 


/* Snapshot nodes: */



static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor)

static bool __bch2_snapshot_is_ancestor_early(struct snapshot_table *t, u32 id, u32 ancestor)

{

	struct snapshot_table *t;



	rcu_read_lock();

	t = rcu_dereference(c->snapshots);



	while (id && id < ancestor)

		id = __snapshot_t(t, id)->parent;

	return id == ancestor;

}



static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor)

{

	rcu_read_lock();

	bool ret = __bch2_snapshot_is_ancestor_early(rcu_dereference(c->snapshots), id, ancestor);

	rcu_read_unlock();



	return id == ancestor;

	return ret;

}



static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor)
@@ -120,13 +122,15 @@ static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ances 


bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)

{

	struct snapshot_table *t;

	bool ret;



	EBUG_ON(c->recovery_pass_done <= BCH_RECOVERY_PASS_check_snapshots);



	rcu_read_lock();

	t = rcu_dereference(c->snapshots);

	struct snapshot_table *t = rcu_dereference(c->snapshots);



	if (unlikely(c->recovery_pass_done <= BCH_RECOVERY_PASS_check_snapshots)) {

		ret = __bch2_snapshot_is_ancestor_early(t, id, ancestor);

		goto out;

	}



	while (id && id < ancestor - IS_ANCESTOR_BITMAP)

		id = get_ancestor_below(t, id, ancestor);
@@ -134,11 +138,11 @@ bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor) 
	if (id && id < ancestor) {

		ret = test_bit(ancestor - id - 1, __snapshot_t(t, id)->is_ancestor);



		EBUG_ON(ret != bch2_snapshot_is_ancestor_early(c, id, ancestor));

		EBUG_ON(ret != __bch2_snapshot_is_ancestor_early(t, id, ancestor));

	} else {

		ret = id == ancestor;

	}



out:

	rcu_read_unlock();



	return ret;
@@ -547,7 +551,7 @@ static int check_snapshot_tree(struct btree_trans *trans, 
			"snapshot tree points to missing subvolume:\n  %s",

			(printbuf_reset(&buf),

			 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||

	    fsck_err_on(!bch2_snapshot_is_ancestor_early(c,

	    fsck_err_on(!bch2_snapshot_is_ancestor(c,

						le32_to_cpu(subvol.snapshot),

						root_id),

			c, snapshot_tree_to_wrong_subvol,