Re: "Invalid argument" when mounting a btrfs raid1 filesystem

[Karel Zak <kzak@redhat.com>]

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.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com