nfsclient: Fix problems with the NFS over RDMA glueHEADmain

There were a couple of problems detected w.r.t. the
"glue" for the nfsclrdma.ko module.
- When the NFS server has a small reply for a read,
  it can choose to not use the reduction chunk
  (separate memory area for the read data).  I did
  not realize this was the case.
- There was a bug in rpc_copy_uio_pages() function
  that caused intermittent crashes in memcpy().

This patch fixes the above cases.  It uses M_PROTO6
to mark that an RPC reply has used a reduction chunk,
so that read can handle it correctly.  Read also now
provides a reduction chunk for all read sizes, since
the worst case for the rest of the read RPC reply is
close to the 1024 byte limit.  (NFSv4 uses strings
instead of uid/gid in the attributes and these name
strings can be rather large.)

I wanted to get the "glue" into main so that others
could test the module more easily.  Avaliability of
the module will be announced on freebsd-current@ soon.

It should not affect non-RDMA operation.

I've specified a long MFC, since the module still
requires extensive testing and, hopefully, a review.

MFC after:	3 months
Fixes:	884ee8d6c9b4 ("nfscl: Add some glue for client side NFS over RDMA")

0 files changed, 0 insertions, 0 deletions