From: Chris Mason <chris.mason@ORACLE.COM>
To: Piavlo <piavka@cs.bgu.ac.il>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: error during umuont after set-default with 2.6.34-rc2
Date: Tue, 23 Mar 2010 11:10:56 -0400 [thread overview]
Message-ID: <20100323151056.GB30249@think> (raw)
In-Reply-To: <4BA7D24E.3040600@cs.bgu.ac.il>
On Mon, Mar 22, 2010 at 10:25:50PM +0200, Piavlo wrote:
> 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
Sorry old default = top level subvolume. It doesn't store the last
default when you run set-default.
> ?
>
> > 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?
Yes, its a magic number.
> > 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.
We could change the mount -o subvol option to parse the parameter and do
different things if it finds a number, but I think less magic in the
code is better. So I added a new mount -o subvolid option instead, and
mount -o subvol works inside the subvolid.
-chris
prev parent reply other threads:[~2010-03-23 15:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-21 20:45 error during umuont after set-default with 2.6.34-rc2 Alexander Piavlo
2010-03-21 20:58 ` Piavlo
2010-03-22 13:38 ` Chris Mason
2010-03-22 20:25 ` Piavlo
2010-03-23 15:10 ` Chris Mason [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20100323151056.GB30249@think \
--to=chris.mason@oracle.com \
--cc=linux-btrfs@vger.kernel.org \
--cc=piavka@cs.bgu.ac.il \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.