If the filesystem allows you to interrupt a non-idempotent operation
part way through, then the filesystem is doing something very wrong.
The observed behaviour is that multiple 32K writes are outstanding
(in different nfsd threads) when a signal is delivered to each nfsd.
OCFS2 appears to be serialising these writes.
One of the writes completes returning a length that is less than 32K.
This length is returned to the client. A quick look at the client
code suggests that it complains with a printk, and tries to write the
remainder, which seems correct.
The other writes all complete with ERESTARTSYS. Presumably they
haven't started at all. If they had, you might expect a partial
return from them too.
So far, what OCFS2 is doing seems credible and doesn't leave us in an
awkward position with respect to incomplete idempotent operations.
I cannot be certain, but I'm willing to believe that OCFS2 only
returns ERESTARTSYS when the operation hasn't been performed at all
(or has been wound-back to the starting condition).
I agree that NFS3ERR_JUKEBOX is more appropriate than no reply, but I
don't think there is any reason to suspect that will not be
sufficient.
Thanks,
NeilBrown
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