reassign 634658 udev
thanks

Hi!

On BTRFS kernel mailing Karel Zak suggest to use udev rules in order to 
call btrfs device scan for multi volume BTRFS configurations. Calvin hinted 
at some udev rules that Dracut ships.

Please consider adding udev rules to support RAID / multi volume 
configurations of BTRFS for booting.

Note: This may still need a change in initramfs, as they command needs to 
be available at that time. Nonetheless I am reassigning to udev for now to 
bring this issue to the attention of the Debian udev package developers. 
Please feel free to reassign, when you think this should be fixed in btrfs-
tools or somewhere else nonetheless. Maybe it also needs to be cloned if 
changes in more than one package are required.


PS: The following two bug reports seem to be related, so mine is likely a 
duplicate of them - not merging yet, feel free to do so if you agree:

btrfs-tools: add initramfs boot and hook scripts
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=559710

please provide non-initramfs-tools integration
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=585568

Thanks,
Martin


----------  Weitergeleitete Nachricht  ----------

Subject: Re: "Invalid argument" when mounting a btrfs raid1 filesystem
Date: Montag, 26. März 2012
From: Calvin Walton <calvin.wal...@kepstin.ca>
To: Karel Zak <k...@redhat.com>

On Mon, 2012-03-26 at 10:51 +0200, Karel Zak wrote:
> On Sat, Mar 24, 2012 at 06:21:05PM +0000, Hugo Mills wrote:
> >    As Sadner says, you have to run "btrfs dev scan" before you try to
> > mount the FS. If you have root on btrfs, this will have to go in an
> > initrd; otherwise, it can go in your initscripts anywhere before the
> > non-root filesystem mounts.
> > 
> >    Basically, the kernel needs to know which devices hold which btrfs
> > filesystems (organised by UUID) before it tries to mount them. So,
> > there's an ioctl that is used for sending that data to the kernel, and
> > a userspace tool (btrfs dev scan) that enumerates all of the block
> > devices it can see, looks for a btrfs superblock on them, and tells
> > the kernel.
> 
>  Please, move all this logic to udev rules where we already scans all
>  devices. It's really bad to scan all device more than once. We spent
>  years to fix this problem for LVM, I don't think that btrfs has to
>  repeat the same mistakes.

Oh, this is already possible to do with udev rules, quite easily. In
fact, dracut ships with the appropriate udev rules, which it uses to
initialize btrfs filesystems in the initramfs:

http://git.kernel.org/?p=boot/dracut/dracut.git;a=blob;f=modules.d/90btrfs/80-
btrfs.rules;hb=HEAD

which would be suitable with minor modifications for use in a system
udev installation as well.

-- 
Calvin Walton <calvin.wal...@kepstin.ca>

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-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7



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