bcachefs: New on disk format to fix reflink_p pointers

We had a bug where reflink_p pointers weren't being initialized to 0,
and when we started using the second word, things broke badly.

This patch revs the on disk format version and adds cleanup code to zero
out the second word of reflink_p pointers before we start using it.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

1 files changed, 67 insertions, 1 deletions

diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index a36bc840a62c..b43c31b95dff 100644
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -2154,6 +2154,71 @@ static int check_nlinks(struct bch_fs *c)
 	return ret;
 }
 
+static int fix_reflink_p_key(struct btree_trans *trans, struct btree_iter *iter)
+{
+	struct bkey_s_c k;
+	struct bkey_s_c_reflink_p p;
+	struct bkey_i_reflink_p *u;
+	int ret;
+
+	k = bch2_btree_iter_peek(iter);
+	if (!k.k)
+		return 0;
+
+	ret = bkey_err(k);
+	if (ret)
+		return ret;
+
+	if (k.k->type != KEY_TYPE_reflink_p)
+		return 0;
+
+	p = bkey_s_c_to_reflink_p(k);
+
+	if (!p.v->v2)
+		return 0;
+
+	u = bch2_trans_kmalloc(trans, sizeof(*u));
+	ret = PTR_ERR_OR_ZERO(u);
+	if (ret)
+		return ret;
+
+	bkey_reassemble(&u->k_i, k);
+	u->v.v2 = 0;
+
+	return bch2_trans_update(trans, iter, &u->k_i, 0);
+}
+
+static int fix_reflink_p(struct bch_fs *c)
+{
+	struct btree_trans trans;
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	int ret;
+
+	if (c->sb.version >= bcachefs_metadata_version_reflink_p_fix)
+		return 0;
+
+	bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
+
+	for_each_btree_key(&trans, iter, BTREE_ID_extents, POS_MIN,
+			   BTREE_ITER_INTENT|
+			   BTREE_ITER_PREFETCH|
+			   BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
+		if (k.k->type == KEY_TYPE_reflink_p) {
+			ret = __bch2_trans_do(&trans, NULL, NULL,
+					      BTREE_INSERT_NOFAIL|
+					      BTREE_INSERT_LAZY_RW,
+					      fix_reflink_p_key(&trans, &iter));
+			if (ret)
+				break;
+		}
+	}
+	bch2_trans_iter_exit(&trans, &iter);
+
+	bch2_trans_exit(&trans);
+	return ret;
+}
+
 /*
  * Checks for inconsistencies that shouldn't happen, unless we have a bug.
  * Doesn't fix them yet, mainly because they haven't yet been observed:
@@ -2168,7 +2233,8 @@ int bch2_fsck_full(struct bch_fs *c)
 		check_xattrs(c) ?:
 		check_root(c) ?:
 		check_directory_structure(c) ?:
-		check_nlinks(c);
+		check_nlinks(c) ?:
+		fix_reflink_p(c);
 }
 
 int bch2_fsck_walk_inodes_only(struct bch_fs *c)