[dm-devel] Proposal for annotating _unstable_ pages

[Kent Overstreet]

On Fri, May 22, 2015 at 11:17:59AM -0700, Darrick J. Wong wrote:
> Back when I was writing the stable pages patches, I observed that some of the
> filesystems didn't hold the pages containing their own metadata stable during
> writeback on a stable-writes device.  The journalling filesystems were fine
> because they had various means to take care of that.
> 
> ISTR ext2 and vfat were the biggest culprits, but both maintainers rejected
> the patches to fix that behavior.  This might no longer be the case; those
> patches were so long ago I can't find them in Google.

Not at all surprised. Yeah, this would solve that problem - we just annotate
those bios so we don't bounce them until we hit a point where we need to.