From mboxrd@z Thu Jan 1 00:00:00 1970 From: Piavlo Subject: Re: error during umuont after set-default with 2.6.34-rc2 Date: Mon, 22 Mar 2010 22:25:50 +0200 Message-ID: <4BA7D24E.3040600@cs.bgu.ac.il> References: <201003212045.o2LKjBgg002162@indigo.cs.bgu.ac.il> <20100322133858.GB32521@think> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 To: Chris Mason , linux-btrfs@vger.kernel.org Return-path: In-Reply-To: <20100322133858.GB32521@think> List-ID: On 03/22/2010 03:38 PM, Chris Mason wrote: > On Sun, Mar 21, 2010 at 10:45:11PM +0200, Alexander Piavlo wrote: > >> Hi, >> trying the new btrfs tool and set-default with 2.6.34-rc2 i hit the the >> following problem: >> >> mkfs.btrfs -d single /dev/sys/btrfs >> mount -t btrfs /dev/sys/btrfs /btrfs >> btrfs subvolume create /btrfs/newroot >> mkdir /btrfs/newroot/.btrfs >> btrfs subvolume set-default 256 /btrfs >> umount /btrfs >> mount -t btrfs /dev/sys/btrfs /btrfs >> >> up till now everything works ok >> >> A question How do i access or mount the original root of btrfs? Which >> tree id does it have? >> It would be great if "btrfs subvolume list ..." would also list the >> original root. >> >> I guessed I need to use 0, so i tried: >> mount -t btrfs -o subvol=0 /dev/sys/btrfs /btrfs/.btrfs >> and: >> mount -t btrfs -o subvol=. /dev/sys/btrfs /btrfs/.btrfs >> but in both cases it mounted the newroot subvolume with id 256 under >> /btrfs/.btrfs >> >> So I tried setting the original root back with: >> btrfs subvolume set-default 0 /btrfs >> > Looks like set-default needs to understand 0 means use the old default, > old default = previous default or old default = top level subvolume ? > I'll add this in. > > btrfs subvolume set-default 5 /btrfs > > Why 5? is this the tree id of the root subvolume = top level path? > or mount -o subvolid=0 /dev/xxx /mnt > or mount -o subvolid=5 /dev/xxx /mnt > Did not know about the subvolid option, I though one can pass treeid to subvol option. Thanks > -chris >