If mknod() returns ENOSYS, it most probably means quota is not supported
here, so return the appropriate error.
This is a conservative* fix to regression in vfs graph driver introduced
by commit 7a1618ced359a3ac92 ("add quota support to VFS graphdriver").
On some filesystems, vfs fails to init with the following error:
> Error starting daemon: error initializing graphdriver: Failed to mknod
> /go/src/github.com/docker/docker/bundles/test-integration/d6bcf6de610e9/root/vfs/backingFsBlockDev:
> function not implemented
Reported-by: Brian Goff <cpuguy83@gmail.com>
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
(cherry picked from commit 2dd39b7841bdb9968884bbedc5db97ff77d4fe3e)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
092e59ef76