Re: [PATCH v2 0/5] fs, xfs: block map immutable files for dax, dma-to-storage, and swap

[Christoph Hellwig]

On Fri, Aug 11, 2017 at 08:57:18PM -0700, Andy Lutomirski wrote:
> One thing that makes me quite nervous about S_IOMAP_IMMUTABLE is the
> degree to which things go badly if one program relies on it while
> another program clears the flag: you risk corrupting unrelated
> filesystem metadata.  I think a userspace interface to pin the extent
> mapping of a file really wants a way to reliably keep it pinned (or to
> reliably zap the userspace application if it gets unpinned).

The nice thing is that no application can rely on it anyway..