Problem booting instances from images larger than 20GB with NFS backend.

Issue

When boot an instance from image where image is larger than 20GB the instance boot fails with:

2463:2016-12-07 12:51:55.682 28644 ERROR nova.compute.manager [instance: bfc6b84f-ba07-4dbb-963d-ec6243c91043] InvalidDiskInfo: Disk info file is invalid: qemu-img failed to execute on /var/lib/nova/instances/_base/8a3fc144ac7fe323269310f45a2df09c221a669b.part : Unexpected error while running command.
2464:2016-12-07 12:51:55.682 28644 ERROR nova.compute.manager [instance: bfc6b84f-ba07-4dbb-963d-ec6243c91043] Command: /usr/bin/python2 -m oslo_concurrency.prlimit --as=1073741824 --cpu=2 -- env LC_ALL=C LANG=C qemu-img info /var/lib/nova/instances/_base/8a3fc144ac7fe323269310f45a2df09c221a669b.part
2465:2016-12-07 12:51:55.682 28644 ERROR nova.compute.manager [instance: bfc6b84f-ba07-4dbb-963d-ec6243c91043] Exit code: -9
2466:2016-12-07 12:51:55.682 28644 ERROR nova.compute.manager [instance: bfc6b84f-ba07-4dbb-963d-ec6243c91043] Stdout: u''
2467:2016-12-07 12:51:55.682 28644 ERROR nova.compute.manager [instance: bfc6b84f-ba07-4dbb-963d-ec6243c91043] Stderr: u''
2468:2016-12-07 12:51:55.682 28644 ERROR nova.compute.manager [instance: bfc6b84f-ba07-4dbb-963d-ec6243c91043] 
2474:2016-12-07 12:51:56.005 28644 ERROR nova.compute.manager [req-77fdc7e1-ee3a-4d4f-9e18-b5ffc0432570 7e96b4757412457a8d2e30118109bfe0 425cbc5131c94e0a98893150bcc44fde - - -] [instance: bfc6b84f-ba07-4dbb-963d-ec6243c91043] Build of instance bfc6b84f-ba07-4dbb-963d-ec6243c91043 aborted: Disk info file is invalid: qemu-img failed to execute on /var/lib/nova/instances/_base/8a3fc144ac7fe323269310f45a2df09c221a669b.part : Unexpected error while running command.