NFS: Create a common read and write data struct

At this point, the only difference between nfs_read_data and
nfs_write_data is the write verifier.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --cc fs/nfs/blocklayout/blocklayout.c
Simple merge

diff --cc fs/nfs/internal.h
Simple merge

diff --cc fs/nfs/nfs3proc.c
Simple merge

diff --cc fs/nfs/nfs4_fs.h
Simple merge

diff --cc fs/nfs/nfs4filelayout.c
Simple merge

diff --cc fs/nfs/nfs4proc.c
Simple merge

diff --cc fs/nfs/nfs4trace.h
Simple merge

diff --cc fs/nfs/objlayout/objio_osd.c
Simple merge

diff --cc fs/nfs/objlayout/objlayout.c
Simple merge

diff --cc fs/nfs/objlayout/objlayout.h
Simple merge

diff --cc fs/nfs/pnfs.c
Simple merge

diff --cc fs/nfs/pnfs.h
Simple merge

diff --cc fs/nfs/proc.c
Simple merge

diff --cc fs/nfs/read.c
Simple merge

diff --cc fs/nfs/write.c
Simple merge

diff --cc include/linux/nfs_fs.h
Simple merge

diff --cc include/linux/nfs_xdr.h
Simple merge