From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hugo Mills Subject: Re: A =?utf-8?Q?Plumber=E2=80=99?= =?utf-8?Q?s?= Wish List for Linux Date: Fri, 7 Oct 2011 16:21:37 +0100 Message-ID: <20111007152137.GE28351@carfax.org.uk> References: <1317943022.1095.25.camel@mop> <20111007111231.6e11d18e@lxorguk.ukuu.org.uk> <20111007113820.3b8424a8@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="UnaWdueM1EBWVRzC" Cc: Alan Cox , linux-kernel@vger.kernel.org, lennart@poettering.net, harald@redhat.com, david@fubar.dk, greg@kroah.com, Chris Mason , Btrfs mailing list To: Kay Sievers Return-path: In-Reply-To: List-ID: --UnaWdueM1EBWVRzC Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Oct 07, 2011 at 02:46:23PM +0200, Kay Sievers wrote: > On Fri, Oct 7, 2011 at 12:38, Alan Cox wrote: > > On Fri, 7 Oct 2011 12:28:46 +0200 Kay Sievers wrote: > > > >> What do you mean would be ugly? > > > > I have an ext4fs. It supports every possible file name allowed by POSIX > > and SuS. What name are you going to use for your 'hidden directory' that > > won't clash with a real file ? > > Ah, no. The label on FAT (similar on NTFS) are 'magic entries' in the > root dir list, not a real file in the root dir. > > We need kernel support for changing a mounted fs, because, unlike > ext4, the blocks containing the strings are inside the fs, which the > kernel might change any time. It's worth noting that there are similar issues with btrfs around changing label. A common API for it would make sense. The only btrfs patches I've seen to change label after mkfs-time work either as: * unmounted only, single underlying device only, pure userspace implementation * mounted only, multiple underlying devices, kernel support needed The kernel-side patches never got integrated, so we're still unable to change the label on the majority of btrfs filesystems. Changing the UUID for the filesystem is even harder, as I think it's written to every metadata block. I'm not sure we can do that sanely on a mounted filesystem. Hugo (just a spear-carrier from the btrfs chorus). -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Anyone using a computer to generate random numbers is, of --- course, in a state of sin. --UnaWdueM1EBWVRzC Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iD8DBQFOjxkBIKyzvlFcI40RAgIDAJ4vnYgjZebmA0wpEQzy1qi44MwNZQCghJ5b 41HHyafRYZchbGY+XaFpOjc= =0xMq -----END PGP SIGNATURE----- --UnaWdueM1EBWVRzC--