Commit 8b9775912c added support for an NFSv4 mounted
root file system, but only if the NFSv4 configuration
used id numbers in the strings.
This patch adds support for the case where the NFSv4
configuration uses name<-->id mappings via nfsuserd(8)
by priming the mapping cache with just enough entries
so that it works until the nfsuserd(8) is running.
They are listed in nfs_prime_userd[] in
sys/fs/nfs/nfs_commonsubs.c.
The entries in nfs_prime_userd[] are also wired into
the kernel's cache for name<-->id mappings when nfsuserd(8)
starts up. This is necessary, since an upcall to the
nfsuserd(8) daemon for a mapping when looking up the
path to the passwd/group database files (/etc) will
hang the system, due to a vnode lock being held on
the entry in the path which blocks nfsuserd(8) from
accessing files.
To enable this case, the following must be put in the
NFS root file system's /boot/loader.conf:
boot.nfsroot.options="nfsv4"
boot.nfsroot.user_domain="<user.domain>"
where <user.domain> must be the same as nfsuserd
uses (usually set via the -domain flag).
If boot.nfsroot.user_domain does not exist or is
the empty string, ids is strings is configured.
MFC after: 1 week
Requested by: Dan Shelton <dan.f.shelton@gmail.com>
Fixes: 8b9775912c ("nfs_diskless: Add support for an NFSv4 root fs")
Rick Macklem
53b4ae3bf0