NFS - fix recent breakage to NFS error handling.

From c6d615d2b97fe305cbf123a8751ced859dca1d5e Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Wed, 16 Nov 2011 09:39:05 +1100
Subject: [PATCH] NFS - fix recent breakage to NFS error handling.

commit 02c24a82 made a small and
presumably unintended change to write error handling in NFS.

Previously an error from filemap_write_and_wait_range would only be of
interest if nfs_file_fsync did not return an error.  After this commit,
an error from filemap_write_and_wait_range would mean that (the rest of)
nfs_file_fsync would not even be called.

This means that:
 1/ you are more likely to see EIO than e.g. EDQUOT or ENOSPC.
 2/ NFS_CONTEXT_ERROR_WRITE remains set for longer so more writes are
    synchronous.

This patch restores previous behaviour.

Cc: stable@kernel.org
Cc: Josef Bacik <josef@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>