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[85.1.249.31]) by mx.google.com with ESMTPSA id bn13sm50379683eeb.11.2013.10.27.17.44.27 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 27 Oct 2013 17:44:27 -0700 (PDT) Message-ID: <526DB36A.7090201@gmail.com> Date: Mon, 28 Oct 2013 01:44:26 +0100 From: =?UTF-8?B?VmxhZGltaXIgJ8+GLWNvZGVyL3BoY29kZXInIFNlcmJpbmVua28=?= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131005 Icedove/17.0.9 MIME-Version: 1.0 To: The development of GNU GRUB Subject: Re: booting btrfs References: <0C284942-C2D0-4520-93B1-3982E6AA38DF@colorremedies.com> <525AF8CD.7050100@gmail.com> <525B2D55.8060502@gmail.com> <339EF7EB-F50A-47F6-99BA-F46ABFECCF74@colorremedies.com> <20131014092807.6917958c@opensuse.site> <3D77CF50-285F-42C2-9325-47AC5ACF5FDC@colorremedies.com> <525C4615.5080803@gmail.com> <4B3D9706-740B-49A2-8314-FF3893071A12@colorremedies.com> <20131016065045.51027e72@opensuse.site> In-Reply-To: X-Enigmail-Version: 1.5.1 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="----enig2DCVMPBRNOIAUEVLEIMFI" X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2a00:1450:4013:c01::22c Cc: Chris Murphy X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Oct 2013 00:44:41 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2DCVMPBRNOIAUEVLEIMFI Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 16.10.2013 05:37, Chris Murphy wrote: >=20 > On Oct 15, 2013, at 8:50 PM, Andrey Borzenkov wro= te: >=20 >> =D0=92 Mon, 14 Oct 2013 14:20:14 -0600 >> Chris Murphy =D0=BF=D0=B8=D1=88=D0=B5=D1=82:= >> >>> >>>> Is there a way to detect that mountinfo gives garbage and somehow ge= t >>>> where the real root points? >>> >>> I don't know. I've asked on linux-btrfs@. Instead of rebooting, I mer= ely tried mounting without options after changing the default subvolume t= o a nested subvolume (one attempt subvolume in a subvolume, another a sub= volume in a directory): in both cases /proc/self/mountinfo reports / as t= he root, not the full path or ID of the subvolume actually mounted. >>> >>> Somehow it seems like the mountinfo root field should return a block = device and full path to the mounted subvolume or its ID. Currently it see= ms like a problem. >>> >> >> To quote one of btrfs developer (I had unrelated discussion on openSUS= E >> list): >> >> --><-- >> This is a known problem, on my todo list, with a few non-working >> solutions. >> >> If you mount via subvol=3D/subvol then /proc/self/mountinfo will show >> 'subvol' as the mounted subvolume (4th column) >> >> 4 19 0:17 /subvol /mnt/ rw,relatime - btrfs /dev/sda15 rw,space_cache >> >> but if the subvolume is set-default and then implicitly mounted, >> mountinfo will not show that (that's the bug). >=20 > If mounted with subvolid=3D the same thing happens. Mountinfo doesn't s= how the subvolume name, it's just /. It's also a problem understanding fr= om mountinfo all of the devices that make up a btrfs volume. This can be = learned from btrfsprogs. >> --><-- >> >> That said, information can be obtained also using different means >> (btrfs utility or directly btrfs IOCTL). The question is to which >> extent we want to depend on existence of btrfsprogs. >=20 > Yeah at the moment if I use subvolid=3D to mount, I then have no idea h= ow to find out what subvolume is mounted. As far as I know btrfsprogs doe= sn't a way to determine what subvols are mounted. It must be inferred (by= mountpoint or by contents of the mountpoint). >=20 > Anyway, as for support for subvolid in GRUB, I still think it would be = nice as it's shorter than full paths. But this is not an enhancement hill= I'm willing to die on by any means. >=20 I changed in trunk to make / refer to real root and modified grub-mkrelpath to follow the same convention, even if disk is mounted with subvolid. ------enig2DCVMPBRNOIAUEVLEIMFI Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) Comment: Using GnuPG with Icedove - http://www.enigmail.net/ iF4EAREKAAYFAlJts2oACgkQNak7dOguQgkcZgD8D0U2q0S8P5yQbGBFK6JvwbkB JxlS55dBodbfPHnO87MA/2qnpTL+2/WBBtpxGkjsflRybElIB3qlHRHgPHSu5G3w =iYfg -----END PGP SIGNATURE----- ------enig2DCVMPBRNOIAUEVLEIMFI--