Created attachment 11751 [details]
Logfile

I setup a NFS4 / SMB fileserver:
uname –a: Debian 3.16.7-ckt20-1+deb8u1 (2015-12-14) x86_64 GNU/Linux 
nmbd –version: Version 4.1.17-Debian
Filesystem: ext4

nfsv4 /etc/exports
/export/fs-test    (anonuid=1100,ro,async,no_wdelay,no_root_squash,insecure_locks)

/etc/fstab
proc                    /proc   proc    nodev,noexec,nosuid     0       0
/data/fs-test   /export/fs-test bind    bind    0

smb.conf
[fs-ro]
	directory mode = 775
	force directory mode = 775
	locking = no
	create mode = 775
	writeable = yes
	path = /data/fs-ro
	force create mode = 775
	comment = fs-ro comment
	wide links = no
	hide dot files = no
	oplocks = no

[fs-test]
	path = /data/fs-test
	copy = fs-ro 


When the nfs share is accessed, the kernel creates locks:
lslocks
…
nfsd              660 LEASE    0B READ  0     0   0 /export/fs-test
nfsd              660 LEASE    0B READ  0     0   0 /export/fs-test
...

When files are written to the SMB share fs-test, the Windows 7 Client reports an error.
Samba log (Debuglevel=10) reports
[2015/12/30 10:41:52.350764, 10, pid=5402, effective(1001, 100), real(1001, 0)] ../source3/smbd/open.c:4094(create_file_unixpath)
  create_file_unixpath: NT_STATUS_NETWORK_BUSY

The problem does not occur
- when lslocks does not show read locks
- NFSV3 is used