From owner-freebsd-fs@freebsd.org Thu Nov 21 15:01:43 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 751421C1B32 for ; Thu, 21 Nov 2019 15:01:43 +0000 (UTC) (envelope-from borjam@sarenet.es) Received: from cu1176c.smtpx.saremail.com (cu1176c.smtpx.saremail.com [195.16.148.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 47JjSk3Qlxz4Wc3 for ; Thu, 21 Nov 2019 15:01:42 +0000 (UTC) (envelope-from borjam@sarenet.es) Received: from [172.16.8.16] (unknown [192.148.167.11]) by proxypop02.sare.net (Postfix) with ESMTPA id 17D459DC7A3; Thu, 21 Nov 2019 16:01:39 +0100 (CET) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) Subject: Re: ZFS snapdir readability (Crosspost) From: Borja Marcos In-Reply-To: <51805C8F-75D6-4DA1-A28E-68DAFC8A0276@sarenet.es> Date: Thu, 21 Nov 2019 16:01:38 +0100 Cc: Eric Borisch , freebsd-fs Content-Transfer-Encoding: quoted-printable Message-Id: 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> <51805C8F-75D6-4DA1-A28E-68DAFC8A0276@sarenet.es> To: Borja Marcos X-Mailer: Apple Mail (2.3445.104.11) X-Rspamd-Queue-Id: 47JjSk3Qlxz4Wc3 X-Spamd-Bar: ----- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=pass (policy=none) header.from=sarenet.es; spf=pass (mx1.freebsd.org: domain of borjam@sarenet.es designates 195.16.148.151 as permitted sender) smtp.mailfrom=borjam@sarenet.es X-Spamd-Result: default: False [-5.30 / 15.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; R_SPF_ALLOW(-0.20)[+ip4:195.16.148.0/24]; MV_CASE(0.50)[]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_LAST(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; DMARC_POLICY_ALLOW(-0.50)[sarenet.es,none]; RCVD_IN_DNSWL_NONE(0.00)[151.148.16.195.list.dnswl.org : 127.0.10.0]; IP_SCORE(-3.00)[ip: (-8.38), ipnet: 195.16.128.0/19(-3.85), asn: 3262(-2.83), country: ES(0.04)]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:3262, ipnet:195.16.128.0/19, country:ES]; FREEMAIL_CC(0.00)[gmail.com]; 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: Thu, 21 Nov 2019 15:01:43 -0000 > On 21 Nov 2019, at 15:57, Borja Marcos wrote: >=20 > ZFS originally didn=E2=80=99t offer any mechanism to mount snapshots = explicitly. Except by cloning.=20 Hmm. Looking at = https://github.com/zfsonfreebsd/ZoF/blob/projects/zfsbsd/cmd/mount_zfs/mou= nt_zfs.c snippet 1 =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94 /* try to open the dataset to access the mount point */ if ((zhp =3D zfs_open(g_zfs, dataset, ZFS_TYPE_FILESYSTEM | ZFS_TYPE_SNAPSHOT)) =3D=3D NULL) { (void) fprintf(stderr, gettext("filesystem '%s' cannot = be " "mounted, unable to open the dataset\n"), dataset); libzfs_fini(g_zfs); return (MOUNT_USAGE); } =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94 snippet 2 =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94 /* treat all snapshots as legacy mount points */ if (zfs_get_type(zhp) =3D=3D ZFS_TYPE_SNAPSHOT) (void) strlcpy(prop, ZFS_MOUNTPOINT_LEGACY, = ZFS_MAXPROPLEN); else (void) zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, prop, sizeof (prop), NULL, NULL, 0, B_FALSE); =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94 Does this really make sense? Workaround (setting its mountpoint as = legacy) in order to break=20 previous behavior? I don=E2=80=99t see the problem in cloning snapshots = in order to mount them. But this looks like something that can bite back in the future! Borja.