From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30491C432C0 for ; Fri, 29 Nov 2019 13:37:25 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EB1F0216F4 for ; Fri, 29 Nov 2019 13:37:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="C14GKXf2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EB1F0216F4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59164 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iagSa-0001x6-6f for qemu-devel@archiver.kernel.org; Fri, 29 Nov 2019 08:37:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:50064) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iafjg-0004xI-Io for qemu-devel@nongnu.org; Fri, 29 Nov 2019 07:51:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iafjc-0003wZ-Gj for qemu-devel@nongnu.org; Fri, 29 Nov 2019 07:50:57 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:60611 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iafjc-0003ot-9b for qemu-devel@nongnu.org; Fri, 29 Nov 2019 07:50:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575031852; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=/IFWWqj4kplAK4sgvX+mIAWGZFIYWRKKOK5g1eAW+D4=; b=C14GKXf26qz+C53DCdkVxT8UoG4lb9+AiJMqIt9jo2iw+Zkkb9sD2FM1ryo7SRi7PLbv5L Zzvqq5pAbBGjyUJ8jhcwlRdCs45tqMNcW0esJp0EtCpVxQEtHeGwZhV/3zE7b9l/ABP2Lb EvO8VCl6+WYYYTw4GN3jsapJG3u9CvU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-43-0u3oJvOSM967UFfb0FKtdg-1; Fri, 29 Nov 2019 07:50:49 -0500 X-MC-Unique: 0u3oJvOSM967UFfb0FKtdg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EE80780183C; Fri, 29 Nov 2019 12:50:47 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-206-40.brq.redhat.com [10.40.206.40]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6F6A010013A7; Fri, 29 Nov 2019 12:50:46 +0000 (UTC) Subject: Re: [PATCH for-5.0 v2 10/23] quorum: Implement .bdrv_recurse_can_replace() To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" References: <20191111160216.197086-1-mreitz@redhat.com> <20191111160216.197086-11-mreitz@redhat.com> From: Max Reitz Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: <3e99345a-9ded-8801-0697-bd399d8cdfa8@redhat.com> Date: Fri, 29 Nov 2019 13:50:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="JvE7Sm4NgrpILjDg0e8UCXKxCfgBSOMZ6" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Alberto Garcia , "qemu-devel@nongnu.org" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --JvE7Sm4NgrpILjDg0e8UCXKxCfgBSOMZ6 Content-Type: multipart/mixed; boundary="PnaTogfwbsLqssF4vgZRgKQmo5zh5qJr7" --PnaTogfwbsLqssF4vgZRgKQmo5zh5qJr7 Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 29.11.19 11:18, Vladimir Sementsov-Ogievskiy wrote: > 11.11.2019 19:02, Max Reitz wrote: >> Signed-off-by: Max Reitz >> --- >> block/quorum.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 62 insertions(+) >> >> diff --git a/block/quorum.c b/block/quorum.c >> index 3a824e77e3..8ee03e9baf 100644 >> --- a/block/quorum.c >> +++ b/block/quorum.c >> @@ -825,6 +825,67 @@ static bool quorum_recurse_is_first_non_filter(Bloc= kDriverState *bs, >> return false; >> } >> =20 >> +static bool quorum_recurse_can_replace(BlockDriverState *bs, >> + BlockDriverState *to_replace) >> +{ >> + BDRVQuorumState *s =3D bs->opaque; >> + int i; >> + >> + for (i =3D 0; i < s->num_children; i++) { >> + /* >> + * We have no idea whether our children show the same data as >> + * this node (@bs). It is actually highly likely that >> + * @to_replace does not, because replacing a broken child is >> + * one of the main use cases here. >> + * >> + * We do know that the new BDS will match @bs, so replacing >> + * any of our children by it will be safe. It cannot change >> + * the data this quorum node presents to its parents. >> + * >> + * However, replacing @to_replace by @bs in any of our >> + * children's chains may change visible data somewhere in >> + * there. We therefore cannot recurse down those chains with >> + * bdrv_recurse_can_replace(). >> + * (More formally, bdrv_recurse_can_replace() requires that >> + * @to_replace will be replaced by something matching the @bs >> + * passed to it. We cannot guarantee that.) >> + * >> + * Thus, we can only check whether any of our immediate >> + * children matches @to_replace. >> + * >> + * (In the future, we might add a function to recurse down a >> + * chain that checks that nothing there cares about a change >> + * in data from the respective child in question. For >> + * example, most filters do not care when their child's data >> + * suddenly changes, as long as their parents do not care.) >> + */ >> + if (s->children[i].child->bs =3D=3D to_replace) { >> + Error *local_err =3D NULL; >=20 > bdrv_child_refresh_perms returns int, so I suggest instead: Good to know. :-) > bool ok; >=20 >> + >> + /* >> + * We now have to ensure that there is no other parent >> + * that cares about replacing this child by a node with >> + * potentially different data. >> + */ >> + s->children[i].to_be_replaced =3D true; >> + bdrv_child_refresh_perms(bs, s->children[i].child, &local_e= rr); >=20 > ok =3D !bdrv_child_refresh_perms(bs, s->children[i].child, NULL); >=20 >> + >> + /* Revert permissions */ >> + s->children[i].to_be_replaced =3D false; >> + bdrv_child_refresh_perms(bs, s->children[i].child, &error_a= bort); >=20 > return ok; >=20 > Or similar with // int ret; // ret =3D // return !ret; // Sounds good. Max --PnaTogfwbsLqssF4vgZRgKQmo5zh5qJr7-- --JvE7Sm4NgrpILjDg0e8UCXKxCfgBSOMZ6 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl3hFCQACgkQ9AfbAGHV z0AaeQgAtg7qZr5+8+IVMow9DUFAisdJq3G2NmOjUI+jFsswhtlxiEEKYm7+YVGO EP2ErofQJQnFyfjyGlATbCsTTPD3rcI2l5yVkehSTNgYhK4V1iRN8hbbxH+YmHzS OitNr0plYCdvYwVc0H5ZKG2fHuodaCu8Cp6vSab+QGs+rQfSYagNF3ScY1TOud69 Cbds82+uiwmme3nFLL1T7kaA9a0l+N2aPw4guKBEF+ZnHKT3kBRnJqAvndSmhdP7 2vQe+ozLYP/3FL8JYw9ZRrj3v59HtQLGrLI/JApJnjp+eljOCeFxdM3enu6V5Qtd eSlxuen1cbeiKwic1dXYyodmc2r/JA== =d2QR -----END PGP SIGNATURE----- --JvE7Sm4NgrpILjDg0e8UCXKxCfgBSOMZ6--