bcachefs: add no_invalid_checks flag

Setting this flag on a filesystem results in validity checks being
skipped when writing bkeys. This flag will be used by tooling that
deliberately injects corruption into a filesystem in order to exercise
fsck. It shouldn't be set outside of testing/debugging code.

Signed-off-by: Thomas Bertschinger <tahbertschinger@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bcachefs.h

@@ -637,7 +637,8 @@ struct bch_dev {
 	x(error)			\
 	x(topology_error)		\
 	x(errors_fixed)			\
-	x(errors_not_fixed)
+	x(errors_not_fixed)		\
+	x(no_invalid_checks)
 
 enum bch_fs_flags {
 #define x(n)		BCH_FS_##n,

fs/bcachefs/bkey_methods.c

@@ -126,6 +126,9 @@ int bch2_bkey_val_invalid(struct bch_fs *c, struct bkey_s_c k,
 			  enum bch_validate_flags flags,
 			  struct printbuf *err)
 {
+	if (test_bit(BCH_FS_no_invalid_checks, &c->flags))
+		return 0;
+
 	const struct bkey_ops *ops = bch2_bkey_type_ops(k.k->type);
 	int ret = 0;
 
@@ -162,6 +165,9 @@ int __bch2_bkey_invalid(struct bch_fs *c, struct bkey_s_c k,
 			enum bch_validate_flags flags,
 			struct printbuf *err)
 {
+	if (test_bit(BCH_FS_no_invalid_checks, &c->flags))
+		return 0;
+
 	int ret = 0;
 
 	bkey_fsck_err_on(k.k->u64s < BKEY_U64s, c, err,