massively truncated files with XFS with sudden power loss on 2.6.27 and 2.6.28

[Christoph Hellwig]

On Mon, Dec 29, 2008 at 01:09:18PM -0600, Russell Cattelan wrote:
> I would have to look for sure when Dave's rewrite of the inode cache/fs 
> sync code went in but
> it could be around the time of 2.6.27.

That's all in the 2.6.29 queue.

> The other thing that is odd is why files full of nulls still? xfs 
> changed its behavior to write out size changes
> at flush time and not before, previously size changes would be synced 
> out prior to the data being synced
> out, thus creating "null files" or rather a file with size but no extent 
> data.
> 
> The "null files" problem should be an "empty files" problem at worst 
> now, so it is really curious that you
> are seeing null files still.

One good way would be to mount the partition with -o sync.  That way
you get data integrity for all files at the epense of really sucky
performance..