Workaround for race condition at boot

Workaround for race condition at boot

[Mark Rada]

Hi,

In my time playing around with btrfs I have had difficulty in mounting =
and btrfs partitions that use multiple devices. I'm aware that there is=
 a note about a gotcha on the wiki, but I'm not trying to mount the btr=
fs partition as the root.

However, I have noticed that if I force a btrfs filesystem scan before =
trying to mount, then everything will work.

I originally created a bug report on the Gentoo Bugzilla:
http://bugs.gentoo.org/show_bug.cgi?id=3D309219


Thanks,

=97
Mark Rada
marada@uwaterloo.ca

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Re: Workaround for race condition at boot

[Chris Mason]

On Mon, Mar 29, 2010 at 10:40:12PM -0400, Mark Rada wrote:
> Hi,
> 
> In my time playing around with btrfs I have had difficulty in mounting and btrfs partitions that use multiple devices. I'm aware that there is a note about a gotcha on the wiki, but I'm not trying to mount the btrfs partition as the root.
> 
> However, I have noticed that if I force a btrfs filesystem scan before trying to mount, then everything will work.
> 
> I originally created a bug report on the Gentoo Bugzilla:
> http://bugs.gentoo.org/show_bug.cgi?id=309219
> 

This isn't a race condition, it is built into the filesystem.  Later
versions of btrfs progs will pull the details right out of udev instead
of needing btrfsctl -a, but today the btrfsctl -a is the only way.

This is similar to what needs to happen on lvm, its just that the
initramfs tools already understand lvm ;)

-chris

Re: Workaround for race condition at boot

[Mark Rada]

Ah, ok, thank you for explaining.

Sent from my iPhone

On 2010-03-30, at 9:08, Chris Mason <chris.mason@oracle.com> wrote:

> On Mon, Mar 29, 2010 at 10:40:12PM -0400, Mark Rada wrote:
>> Hi,
>>
>> In my time playing around with btrfs I have had difficulty in  
>> mounting and btrfs partitions that use multiple devices. I'm aware  
>> that there is a note about a gotcha on the wiki, but I'm not trying  
>> to mount the btrfs partition as the root.
>>
>> However, I have noticed that if I force a btrfs filesystem scan  
>> before trying to mount, then everything will work.
>>
>> I originally created a bug report on the Gentoo Bugzilla:
>> http://bugs.gentoo.org/show_bug.cgi?id=309219
>>
>
> This isn't a race condition, it is built into the filesystem.  Later
> versions of btrfs progs will pull the details right out of udev  
> instead
> of needing btrfsctl -a, but today the btrfsctl -a is the only way.
>
> This is similar to what needs to happen on lvm, its just that the
> initramfs tools already understand lvm ;)
>
> -chris