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Wed, 29 Apr 2020 09:31:57 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-113-19.ams2.redhat.com [10.36.113.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 156F25D9C9; Wed, 29 Apr 2020 09:31:50 +0000 (UTC) Subject: Re: [Virtio-fs] [PATCH] virtiofsd: Show submounts To: Miklos Szeredi References: <20200424133516.73077-1-mreitz@redhat.com> <20200427175902.GM2923@work-vm> <20200428145143.GB107541@stefanha-x1.localdomain> <20200428191523.GU2794@work-vm> <0da9422f-6399-6ef0-1042-4b2b90d49ed8@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: Date: Wed, 29 Apr 2020 11:31:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="EwsuK18nZn2W7T7QSjzF9UHriesKfQycx" Received-SPF: pass client-ip=205.139.110.61; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/29 00:53:13 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.61 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: virtio-fs-list , "Dr. David Alan Gilbert" , Stefan Hajnoczi , 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) --EwsuK18nZn2W7T7QSjzF9UHriesKfQycx Content-Type: multipart/mixed; boundary="WDB7GMBz84t3sPeKFMKQSSDlFSWqHgEWq" --WDB7GMBz84t3sPeKFMKQSSDlFSWqHgEWq Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 29.04.20 10:52, Miklos Szeredi wrote: > On Wed, Apr 29, 2020 at 10:31 AM Max Reitz wrote: >> >> On 28.04.20 21:15, Dr. David Alan Gilbert wrote: >=20 >>> So are you saying we need a: >>> if (mount(NULL, "/", NULL, MS_REC | MS_SHARED, NULL) < 0) { >>> >>> and can this go straight after (1) ? >> >> Isn=E2=80=99t MS_SHARED and MS_SLAVE mutually exclusive, that is, both a= re just >> different propagation types? So shouldn=E2=80=99t putting this after (1= ) be >> effectively the same as replacing (1)? >=20 > No, think of it more like a set of groups (mounts in a group have the > same "shared:$ID" tag in /proc/self/mountinfo) and these groups being > arranged into a tree, where child groups get propagation from the > parent group (mounts have a "master:$PARENT_ID" tag), but not the > other way round. >=20 > So if a mount is part of a shared group and this group is also the > child of another shared group, then it will have both a "shared:$ID" > and a "master:$PARENT_ID" tag in /proc/self/mountinfo. Ah, OK. Thanks a lot for the explanation! > For the gory details see Documentation/filesystems/sharedsubtree.txt Not sure whether I want to *cough* O:) Max --WDB7GMBz84t3sPeKFMKQSSDlFSWqHgEWq-- --EwsuK18nZn2W7T7QSjzF9UHriesKfQycx Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl6pSYUACgkQ9AfbAGHV z0BcVAf/Zq6s9xku0URumDj4hVZWaSNCyJaeFYkIsG3rnD1YJgm865JXXNKGVeED tk4ls7lGyIF12/cisyRUm5EYNv9gIjk7sFrW6PJzh7I5OaLrQoE8OcG/Px0Bcg6B TGuEEXVj3BJiDY0Pc9l4ljeI/HGG/PxftRMRosHzvV2TWwh/M1p487NMYyWMsW61 P+h4E19uXJjLLsVdrqYpN6fvOuvsRgwGY/n39dRNKqeMsDdTNDse9v1AcYHWaI34 XPYrD4M/7Rxh9IUMcZe/bpkAgQQ4cojKvegtCf7f2xI8nn+9UgqFZlRM76RW3QcI AaTEUahZHB72K3GhOaQgN2ZrP6hCvA== =i23r -----END PGP SIGNATURE----- --EwsuK18nZn2W7T7QSjzF9UHriesKfQycx--