bcachefs: Check for writing btree_ptr_v2.sectors_written == 0

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/extents.c

@@ -201,6 +201,11 @@ int bch2_btree_ptr_v2_invalid(struct bch_fs *c, struct bkey_s_c k,
 			 c, err, btree_ptr_v2_min_key_bad,
 			 "min_key > key");
 
+	if (flags & BKEY_INVALID_WRITE)
+		bkey_fsck_err_on(!bp.v->sectors_written,
+				 c, err, btree_ptr_v2_written_0,
+				 "sectors_written == 0");
+
 	ret = bch2_bkey_ptrs_invalid(c, k, flags, err);
 fsck_err:
 	return ret;

fs/bcachefs/sb-errors_types.h

@@ -272,7 +272,8 @@
 	x(snapshot_node_missing,				264)	\
 	x(dup_backpointer_to_bad_csum_extent,			265)	\
 	x(btree_bitmap_not_marked,				266)	\
-	x(sb_clean_entry_overrun,				267)
+	x(sb_clean_entry_overrun,				267)	\
+	x(btree_ptr_v2_written_0,				268)
 
 enum bch_sb_error_id {
 #define x(t, n) BCH_FSCK_ERR_##t = n,