From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailgw-02.dd24.net ([193.46.215.43]:37231 "EHLO mailgw-02.dd24.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751982AbbLLCdD (ORCPT ); Fri, 11 Dec 2015 21:33:03 -0500 Message-ID: <1449887577.31388.91.camel@scientia.net> Subject: Re: subvols and parents - how? From: Christoph Anton Mitterer To: Duncan <1i5t5.duncan@cox.net>, linux-btrfs@vger.kernel.org Date: Sat, 12 Dec 2015 03:32:57 +0100 In-Reply-To: References: <1448340960.14125.51.camel@scientia.net> <1448400350.21291.88.camel@scientia.net> <1449635882.20578.2.camel@scientia.net> Content-Type: multipart/signed; micalg="sha-512"; protocol="application/x-pkcs7-signature"; boundary="=-W4jBmCnCLHSIEdkKyNrc" Mime-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org List-ID: --=-W4jBmCnCLHSIEdkKyNrc Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2015-12-09 at 11:26 +0000, Duncan wrote: > > Hmm good point... I think it would be great if you could add that > > scenario somewhere to the documentation. :-) > FWIW, I (personally, not sure if that "you" was singular or plural) > am=20 > much more comfortable on the lists than on wikis, which I tend to > treat=20 > much as I did printed encyclopedias back in the day -- as great=20 > references, but read-only from my perspective. Well you (since it was your idea and I'd consider you "senior" enough to do it, at least more senior than myself ;) )... or any developer of course ;) I did that now, or better said I largely rewrote: https://btrfs.wiki.kernel.org/index.php/SysadminGuide#Subvolumes which I think should rather be its own wiki article. One of the devs/experts... please double check it and pick/drop what you like/dislike. Especially notice that I've changed what was in the wiki, namely subvolid=3D0 would mount the toplevel subovl,... I changed that to 5. Also I assumed the manpage would be correct and subvol=3D is always relative to the top level subvol, thus subvol=3D/ should mount that. What's still missing now, IMHO, is: - the snapshots subchapter itself is not complete (especially ro vs. rw snapshots)... and implications like not mounting snapshots noatime, and write amplification effects - a guide when one should make subvole (e.g. keeping things on the root fs together, unless it's separate like /var/www is usually, but /var/lib typically "corresponds" to a state of /etc and /usr. - what I've asked in another mail,.. about subvols and mountopts. That rework also contains your security idea... shamelessly not quoting you there O:-) Well, I hope me editing such central part of the wiki wasn't to bold,... but if it was, then I guess Chris Mason placing me on the pillory would be nearly as big of an honour as being insulted by Linus ;-) > While the appropriate place would be on the wiki, where there's a > page=20 > for that (here, the request is likely to be lost to history, while on > the=20 > wiki it's in a nice list that both devs and other requesters can look > at,=20 > a year, five years, a decade... into the future), in this case... I think I'm simply going to add it there, in another bold step... O:-) > There's already a framework for it and a limited implementation, tho > only=20 > a small subset of possible options are yet available.=C2=A0=C2=A0The UI > exposure is=20 > as btrfs property (see the btrfs-property manpage), with the > properties,=20 > in general, implemented as extented attributes. Mhh,... I've only recently learned about that properties... well if that's technically possible to cleanly solve it with XATTRS... fine for me. 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