An entire extent could be lost(or zeroed?) which means serious corruption to your file(s) at time of writing if the cards fall in the right order. I see no ind

An entire extent could be lost(or zeroed?) which means serious corruption to your file(s) at time of writing if the cards fall in the right order. I see no indication that this is a 4.0-specific issue. This code has existed for a long time. They fixed it in "stable kernels 4.0.3 as well as much older stable kernels." edit: major corruption is possible, not just slight, because an extent can be 128Mib on a 4K block size filesystem.