[PATCH] nfsd: check error status from nfsd_sync_dir

Change nfsd_sync_dir to return an error if ->sync fails, and pass that error
up through the stack.  This involves a number of rearrangements of error
paths, and care to distinguish between Linux -errno numbers and NFSERR
numbers.

In the 'create' routines, we continue with the 'setattr' even if a previous
sync_dir failed.

This patch is quite different from Takashi's in a few ways, but there is still
a strong lineage.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>