Recent Linux kernels (4.0.2+, LTS 3.14.41+), pushed to the [core] repository in the past couple of weeks, were affected by a bug that can cause data corruption on file systems mounted with the `discard` option and residing on software RAID 0 arrays.
The issue has been addressed in the `linux 4.0.4-2` and `linux-lts 3.14.43-2` updates. Due to the nature of the bug, however, it is likely that data corruption has already occurred on systems running the aforementioned kernels. It is strongly advised to verify the integrity of affected file systems using `fsck` and/or restore their data from known good backups.
For further information please read the [LKML post] by Holger Kiehl, the [related article] on Phoronix, as well as the [proposed fix] that was backported to the Arch kernels.
: http://www.phoronix.com/scan.php?page=news_item&px=Linux-4-EXT4-RAID- Issue-Found
: http://git.neil.brown.name/?p=md.git;a=commitdiff;h=a81157768a00e8cf8a7b 43b5ea5cac931262374f