Arch Linux

Description: Currently there is a bug with 'btrfs balance' and preallocated files (the journal comes to mind here). It can cause faulty checksums and in some cases data corruption. A patch has been around for some time, but somehow was forgotten to be included in 3.12. It is currently in a btrfs pull request by Chris Mason that was posted today (2013-11-21), so it should be included in the mainline tree very soon. At that point it will be able to be backported to the stable kernels, but as 3.12.1 has just been released, I know that will be at least a week away.

Other distributions that I have checked are all shipping their kernels with this patch included. I have tested it on both Linus' git tree as well as the Arch kernels, and it works just fine. I don't know if it would be better to put this patch in right away or wait for it to be included, as that point *should* be close. But I have watched as this patch has been forgotten and overlooked, and nothing has come of it for a few weeks now. So although I am very hopeful that it will be included soon, so far it has looked that way several times.

Here is the email with in which the patch was first posted (called btrfs-relocate-csums-properly-with-prealloc-extents):
http://www.spinics.net/lists/linux-btrfs/msg27836.html


Additional info:
* linux 3.12*


Steps to reproduce:
On a btrfs filesystem, do a balance and watch as your journal files are reported as corrupt. Hopefully it won't actually corrupt them, but it might.