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 E321CC43603 for ; Fri, 20 Dec 2019 11:25:22 +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 AE61E2465E for ; Fri, 20 Dec 2019 11:25:22 +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="K+yAYa4t" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE61E2465E 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]:53400 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iiGPJ-0006lF-N6 for qemu-devel@archiver.kernel.org; Fri, 20 Dec 2019 06:25:21 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:46042) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iiGOB-00064i-Fc for qemu-devel@nongnu.org; Fri, 20 Dec 2019 06:24:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iiGO8-0005iB-Oe for qemu-devel@nongnu.org; Fri, 20 Dec 2019 06:24:09 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:60702) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iiGO8-0005bv-4n for qemu-devel@nongnu.org; Fri, 20 Dec 2019 06:24:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576841047; 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; bh=Kn6hOzgwUAX76JObcNAb9wWKeZNmZjG5/1ELqPvf4TU=; b=K+yAYa4tdC8++4+o+rCOtbDeQy4vW0LyfhnAvvK9i2GWT7qcYROEv3l4Q9Z35IIrDon3/F FXOISxllYpBqyiFkpsEQg7iHexRcyQwK8I+ibnrclY4Ay+BWzy5koWhx8Lo8T8YY3Hi76k f8fP+ynuTTrT6KswS7qSZMufU8Y06Hg= 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-1-LXyhQzNyMouqmTma62Ct2g-1; Fri, 20 Dec 2019 06:24:05 -0500 X-MC-Unique: LXyhQzNyMouqmTma62Ct2g-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8C86818552A0; Fri, 20 Dec 2019 11:24:04 +0000 (UTC) Received: from dhcp-200-226.str.redhat.com (dhcp-200-226.str.redhat.com [10.33.200.226]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A453526FB3; Fri, 20 Dec 2019 11:24:03 +0000 (UTC) Date: Fri, 20 Dec 2019 12:24:02 +0100 From: Kevin Wolf To: Max Reitz Subject: Re: [PATCH 02/18] fuse: Allow exporting BDSs via FUSE Message-ID: <20191220112402.GE4019@dhcp-200-226.str.redhat.com> References: <20191219143818.1646168-1-mreitz@redhat.com> <20191219143818.1646168-3-mreitz@redhat.com> <20191220102656.GD4019@dhcp-200-226.str.redhat.com> <1812e968-1197-523e-7039-caf29e3bbc4b@redhat.com> MIME-Version: 1.0 In-Reply-To: <1812e968-1197-523e-7039-caf29e3bbc4b@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="PmA2V3Z32TCmWXqI" Content-Disposition: inline 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: qemu-devel@nongnu.org, qemu-block@nongnu.org, armbru@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --PmA2V3Z32TCmWXqI Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Am 20.12.2019 um 11:48 hat Max Reitz geschrieben: > On 20.12.19 11:26, Kevin Wolf wrote: > > Am 19.12.2019 um 15:38 hat Max Reitz geschrieben: > >> fuse-export-add allows mounting block graph nodes via FUSE on some > >> existing regular file. That file should then appears like a raw disk > >> image, and accesses to it result in accesses to the exported BDS. > >> > >> Right now, we only set up the mount point and tear all mount points do= wn > >> in bdrv_close_all(). We do not implement any access functions, so > >> accessing the mount point only results in errors. This will be > >> addressed by a followup patch. > >> > >> The set of exported nodes is kept in a hash table so we can later add = a > >> fuse-export-remove that allows unmounting. > >> > >> Signed-off-by: Max Reitz > >=20 > >> diff --git a/qapi/block.json b/qapi/block.json > >> index 145c268bb6..03f8d1b537 100644 > >> --- a/qapi/block.json > >> +++ b/qapi/block.json > >> @@ -317,6 +317,29 @@ > >> ## > >> { 'command': 'nbd-server-stop' } > >> =20 > >> +## > >> +# @fuse-export-add: > >> +# > >> +# Exports a block graph node on some (file) mountpoint as a raw image= . > >> +# > >> +# @node-name: Node to be exported > >> +# > >> +# @mountpoint: Path on which to export the block device via FUSE. > >> +# This must point to an existing regular file. > >> +# > >> +# @writable: Whether clients should be able to write to the block > >> +# device via the FUSE export. (default: false) > >> +# > >> +# Since: 5.0 > >> +## > >> +{ 'command': 'fuse-export-add', > >> + 'data': { > >> + 'node-name': 'str', > >> + 'mountpoint': 'str', > >> + '*writable': 'bool' > >> + }, > >> + 'if': 'defined(CONFIG_FUSE)' } > >=20 > > Can this use a BlockExport union from the start like I'm introducing in > > the storage daemon series, together with a generic block-export-add? >=20 > Hm, you mean still adding a FuseExport structure that would be part of > BlockExport and then dropping fuse-export-add in favor of a > block-export-add that we want anyway? Yes. > > It also looks like node-name and writable should be part of the common > > base of BlockExport. >=20 > node-name definitely, I=E2=80=99m not so sure about writable. Or, to be = more > precise, I think that if we want writable to be in the base, we also > want growable to be there: Both are primarily options for the > BlockBackend that the exports use. >=20 > But both of course also need to be supported by the export > implementation. nbd can make its BB growable all it wants, but that > doesn=E2=80=99t make it work. Right. Pragmatically, I think exports are very like to support writable, but probably rather unlikely to support growable. So I do think there would be a point for making writable part of the common base, but not growable. > So if we kept writable and growable in the common base, then the schema > would give no information about what exports actually support them. >=20 > On one hand, I don=E2=80=99t know whether it=E2=80=99s important to have = this > information in a static form, or whether it=E2=80=99s sufficient to learn= at > runtime. >=20 > On the other, I don=E2=80=99t know whether it=E2=80=99s important to have= those fields > in the base or not. Would it make a difference on the wire? Not for the command itself, so I think we're free to change it later. It might make a difference for introspection, though, not sure. Markus? Having it in the base might allow us to remove some duplication in the code. Probably not much, though, so not too important. > > Unfortunately this would mean that I can't use the > > same BlockExportNbd for the existing nbd-server-add command any more. I > > guess I could somehow get a shared base type for both, though. >=20 > Hm. This sounds like you want to make it your problem. Can I take that > to mean that you want to implement block-export-add and I can wait with > v2 until that=E2=80=99s done? :-) The NBD integration, yes. I already added the BlockExport type to my patches, too, but I expect you would beat me to it. I'm not currently planning to write a block-export-add because it doesn't add anything new for the storage daemon, so FuseExport and the command this is your part. The type currently only exists for --export. Kevin --PmA2V3Z32TCmWXqI Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIcBAEBAgAGBQJd/K9SAAoJEH8JsnLIjy/WfTYP/1pvBX2oQbNzz/pZ8lfudm8G BDO6C4gXf4j5QPH/JHpgsTuUeUfmcC3RF9N8mj38AJhEDggydh3r9yHt8FrSU99A PwyEXHZwbqsuCnH8Ck2AVs71/97siqRaZBWRj2BFlWb7xU4LAC08ZLOpjD6oij5Q wm5z9JbeCSzi6IfPn3fVmI2GzFS2Ma34y+yP7ymDSmo+KFxVAoA9Pf9grEU030Cb Ek4xtFiXHxqI9V8OvNUvhCiLTZyqGNWsJK34aAS44S3iQCKqHSPFlrYkTto5TSVb xQEkaZNpqjR4znY/ejovDL3JPNVSMR8xgl+D5su26DveJlD25izipV2IvajxPXTI YQMD+HYPzrPo45/BLDP0TAUdVog+6rvCLYpKiFKbhfFxnMtvHn+IcuOOgT35nG6c TO2gB0qp3K4EqiFbPjaD6oOiuTUZS5OjA/m7fQ146GtqyxpUtg1EfUWLRxzZRd81 bpVCExFMq7feMQOvYaFjudcnWYJKpACQMrIS1lGDIchH6hO21eGC0Kh9MCS6BtyC YWlcJeIftNOu40Ikgnv3FuGarzu62+hbWfvi1Ej/ZnUBeKBrav1Jp4C7z1MBaY7P JUztPqDisdA4Hi20MPWkoY93drSSw80fHa8ugb6UErikiOK1TXkxE1STkVYP8J7X vnz2yHx7iTLn1M/vQnrf =A8Ij -----END PGP SIGNATURE----- --PmA2V3Z32TCmWXqI--