When the NFSv4.1 pNFS client gets an error for a DS I/O operation using a
Flexible File layout, it returns the layout with an error.
This patch changes the code slightly, so that it returns the layout for all
errors except EACCES and lets the MDS decide what to do based on the error.
It also makes a couple of changes to nfscl_layoutrecall() to ensure that
the first layoutreturn(s) will have the error in the reply.
Plus, the patch adds a wakeup() so that the "nfscl" thread won't wait 1sec
before doing the LayoutReturn.
Tested against the pNFS service.
This patch should not affect non-pNFS use of the client.
The unused "dsp" argument will be used by a future patch that disables the
connection to the DS when possible.
MFC after: 2 weeks
bc671da98b