From owner-freebsd-fs@freebsd.org Fri Nov 22 14:16:16 2019 Return-Path: Delivered-To: freebsd-fs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id EE8CB1B93FB for ; Fri, 22 Nov 2019 14:16:16 +0000 (UTC) (envelope-from jbe-mlist@magnetkern.de) Received: from sapphire.magnetkern.de (sapphire.magnetkern.de [185.228.139.199]) by mx1.freebsd.org (Postfix) with ESMTP id 47KJPq5R1fz3LDb for ; Fri, 22 Nov 2019 14:16:14 +0000 (UTC) (envelope-from jbe-mlist@magnetkern.de) Received: from titanium (p57A35420.dip0.t-ipconnect.de [87.163.84.32]) by sapphire.magnetkern.de (Postfix) with ESMTPSA id CA81B20045; Fri, 22 Nov 2019 14:16:02 +0000 (UTC) Date: Fri, 22 Nov 2019 15:16:02 +0100 From: Jan Behrens To: Borja Marcos Cc: Martin Simmons , freebsd-fs@freebsd.org Subject: Re: ZFS snapdir readability (Crosspost) OT: mount -t zfs for snapshots Message-Id: <20191122151602.c84f717ca3d1a9bb6a66aab8@magnetkern.de> In-Reply-To: References: <20191107004635.c6d2e7d464d3d556a0d87465@magnetkern.de> <9B22AD46-BE87-4305-9638-74D23AD4C8CA@sarenet.es> <261FE331-EC5C-48C8-9249-9BCBF887CE38@sarenet.es> <913f7040-6e38-452d-6187-e17fae63b652@sentex.net> <20191120144041.7f916360dc0c69bf509c9bd1@magnetkern.de> <20191120163437.691abd369ab9c0a6d7d45ff2@magnetkern.de> <20191120175803.03401c3316fe756cc46f79f1@magnetkern.de> <3C5DC6DD-C44B-41EE-B7AB-6D8F94E43174@sarenet.es> <201911211259.xALCxShX008743@higson.cam.lispworks.com> <462E2C53-2490-4B8C-BB54-BCE8B75BAEB0@sarenet.es> <201911211630.xALGUT5Z010705@higson.cam.lispworks.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; amd64-portbld-freebsd12.0) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 47KJPq5R1fz3LDb X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of jbe-mlist@magnetkern.de designates 185.228.139.199 as permitted sender) smtp.mailfrom=jbe-mlist@magnetkern.de X-Spamd-Result: default: False [-1.44 / 15.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_PBL(0.00)[32.84.163.87.khpj7ygk5idzvmvt5x4ziurxhy.zen.dq.spamhaus.net : 127.0.0.10]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; R_SPF_ALLOW(-0.20)[+mx]; MV_CASE(0.50)[]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[magnetkern.de]; NEURAL_HAM_LONG(-0.91)[-0.912,0]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; NEURAL_HAM_MEDIUM(-0.97)[-0.973,0]; IP_SCORE(0.15)[ipnet: 185.228.136.0/22(1.39), asn: 197540(-0.63), country: DE(-0.01)]; RCVD_NO_TLS_LAST(0.10)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:197540, ipnet:185.228.136.0/22, country:DE]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 22 Nov 2019 14:16:17 -0000 On Fri, 22 Nov 2019 09:09:52 +0100 Borja Marcos wrote: > > On 21 Nov 2019, at 17:30, Martin Simmons wrote: > > > >> I’ve never seen that and, indeed, on FreeBSD 12.1 it’s not possible. Or I am terribly > >> sloppy today! > >> > >> Did I miss anything? Is it a new ZFS on Linux feature? > >> > >> root@micro1:~ # mount -t zfs -o ro pool/dataset@snapshot /mnt > >> mount: unpul/wwwnfsen@antesinst: Device busy > >> root@micro1:~ # > > > > It looks like unpul/wwwnfsen@antesinst is already mounted -- probably in .zfs :-) > > (This is a bit of off-topic now, the behavior of mount -t zfs) > > Yep, it’s only uglier! > > Whenever you access any of the directories below .zfs/snapshot the snapshot > is automagically mounted. It’s also sort of invisible except when you run “mount -v”. In that > case those snapshot mounts are visible. You can also unmount them. I also just confirmed that once I manually mount a snapshot, I can't access it through .zfs/snapshot anymore. Of course, this is doesn't help with solving the original problem because in order to prohibit snapshot access for non-privileged users, it would require all snapshots to be mounted atomically at the same time the associated filesystem is mounted. > [...] > > Borja. Regards, Jan