Re: [PATCH v2 19/19] sunrpc: Disable splice for krb5i

Christoph Hellwig
2017-06-18T07:34:38Z

On Sat, Jun 17, 2017 at 01:23:24PM -0400, Chuck Lever wrote:
>
> > On Jun 17, 2017, at 11:07 AM, Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> wrote:
> >
> > On Fri, Jun 16, 2017 at 11:22:54AM -0400, Chuck Lever wrote:
> >> Running a multi-threaded 8KB fio test (70/30 mix), three or four out
> >> of twelve of the jobs fail when using krb5i. The failure is an EIO
> >> on a read.
> >
> > Just curious: what is the backing fs that you tested with? I'd be
> > curious if you see this on XFS for example.
>
> I was able to reproduce this with a tmpfs share and
> with an XFS share on NVMe LUNs.

Interesting. XFS actually locks out all writes while doing a buffered
read, so we end up with two different read instance for the hash vs
the data, which does indeed sound dangerous.