bcachefs: Check for bad key version number

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

fs/bcachefs/btree_gc.c

@@ -126,7 +126,11 @@ static int bch2_gc_mark_key(struct bch_fs *c, struct bkey_s_c k,
 		BUG_ON(journal_seq_verify(c) &&
 		       k.k->version.lo > journal_cur_seq(&c->journal));
 
-		if (k.k->version.lo > atomic64_read(&c->key_version))
+		/* XXX change to fsck check */
+		if (fsck_err_on(k.k->version.lo > atomic64_read(&c->key_version), c,
+				"key version number higher than recorded: %llu > %llu",
+				k.k->version.lo,
+				atomic64_read(&c->key_version)))
 			atomic64_set(&c->key_version, k.k->version.lo);
 
 		if (test_bit(BCH_FS_REBUILD_REPLICAS, &c->flags) ||

fs/bcachefs/io.c

@@ -943,7 +943,7 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp,
 
 		if (bch2_csum_type_is_encryption(op->csum_type)) {
 			if (bversion_zero(version)) {
-				version.lo = atomic64_inc_return(&c->key_version) + 1;
+				version.lo = atomic64_inc_return(&c->key_version);
 			} else {
 				crc.nonce = op->nonce;
 				op->nonce += src_len >> 9;