Bug 1753865

Description of problem:
As rhel7 Bug 1563319 says, the NFS client should be able to automatically load module "blocklayoutdriver".
But seems there is always a blkmapd warning after starting nfs-blkmap.service:
"""
blkmapd[43744]: open pipe file /var/lib/nfs/rpc_pipefs/nfs/blocklayout failed: No such file or directory
"""

However, it doesn't affect the following function.

I'm not sure whether this is a real bug. But in the future may receive some complain as more customers using this scenario.


Version-Release number of selected component (if applicable):
nfs-utils-1.3.0-0.65.el7

How reproducible:
always

Steps to Reproduce:
1. modprobe -r blocklayoutdriver
2. systemctl restart nfs-blkmap.service
3. systemctl status nfs-blkmap.service

Actual results:
[05:51:28 root@ ~~]# lsmod | grep blocklayoutdriver
[05:51:28 root@ ~~]# service nfs-blkmap restart
Redirecting to /bin/systemctl restart nfs-blkmap.service
[05:51:28 root@ ~~]# service nfs-blkmap status
Redirecting to /bin/systemctl status nfs-blkmap.service
* nfs-blkmap.service - pNFS block layout mapping daemon
   Loaded: loaded (/usr/lib/systemd/system/nfs-blkmap.service; disabled; vendor preset: disabled)
   Active: active (running) since Mon 2019-09-16 05:51:28 IDT; 43ms ago
  Process: 12014 ExecStart=/usr/sbin/blkmapd $BLKMAPDARGS (code=exited, status=0/SUCCESS)
 Main PID: 12015 (blkmapd)
   CGroup: /system.slice/nfs-blkmap.service
           `-12015 /usr/sbin/blkmapd

Sep 16 05:51:28 kvm-01-guest05.rhts.eng.tlv.redhat.com systemd[1]: Starting pNFS block layout mapping daemon...
Sep 16 05:51:28 kvm-01-guest05.rhts.eng.tlv.redhat.com blkmapd[12015]: open pipe file /var/lib/nfs/rpc_pipefs/nfs/blocklayout failed: No such file or directory                 <<<<<<<<<<<<<<<<<<
Sep 16 05:51:28 kvm-01-guest05.rhts.eng.tlv.redhat.com systemd[1]: Started pNFS block layout mapping daemon.

Expected results:
No warning

Additional info:
RHEL8 also has this problem.