Created attachment 1013565 [details]
Network traces with EOF

Description of problem:
NFS client mounted using flex-files layout reads past EOF (forever) if both conditions are true:

* open O_DIRECT
* block size >= 512k

Version-Release number of selected component (if applicable):
* Client fedora rawhide 4.0.0-0.rc5.git4.1.fc23.x86_64
* Primary Data MDS b630 3.11.9-integration-630-90182a7f

How reproducible:
Every time

Steps to Reproduce:
> mount pd-mds:/share1 /mnt/test
> perl -e 'print "x" x 1048576' > /mnt/test/jean-test
> dd bs=512k of=/dev/null if=/mnt/test/jean-test iflag=direct

Actual results:
The client keeps "reading" forever or until the target fills up.
Note that the client is writing the last chunk it read continuously to the output file, even though it gets 0 bytes on subsequent reads.

Expected results:
The client stops reading upon reaching EOF

Additional info:
* I see partial reads being reported, but adding iflag=fullblock doesn't change the behavior (but removes the warning)
* Mount options
> pd-mds:/share1 on /mnt/test type nfs4 (rw,relatime,vers=4.1,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=X.X.X.X,local_lock=none,addr=Y.Y.Y.Y)
* Network traces attached