Plans for BTRFS in Fedora

Peter Jones pjones at redhat.com
Wed Feb 23 18:41:14 UTC 2011


On 02/23/2011 12:50 PM, Lars Seipel wrote:
> On Wednesday 23 February 2011 15:07:55 Peter Jones wrote:
> 
>> 1) can btrfs do encrypted volumes?
> 
> Not yet.  Although this was a planned feature at some point, according to
> Josef, nobody has done it yet.
> 
> If you want to stack it on top of dm-crypt there are caveats as well.

Right, which is what we'd wind up doing in the encrypted case.

>> From btrfs-wiki:
>> btrfs volumes on top of dm-crypt block devices (and possibly LVM) require
>> write-caching to be turned off on the underlying HDD. Failing to do so, in
>> the event of a power failure, may result in corruption not yet handled by
>> btrfs code. (2.6.33)
> 
> Is this still prevailing as of 2.6.38?

So, don't hold me to this, but it looks as if the normal lvm behaviour was
fixed at least as of d87f4c14f2 .  That being said, dm-crypt still just throws
REQ_FLUSH away instead of figuring out the block remaps involved and issuing
the right bios. Of course, this is a problem with dm-crypt and _any_ filesystem.

-- 
        Peter

RFC 882 put the dots in .com.

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