我的 MontaVista 2.6.37 Linux 编译了 NFS 模块。我按顺序启动它们：
rpcbind
rpc.nfsd 4
rpc.mountd
rpc.statd
默认配置文件和 etab 为：
/mnt/sda1 192.168.50.0/24(rw,sync,wdelay,hide,nocrossmnt,secure,no_root_squash,no_all_squash,no_subtree_check,secure_locks,acl,fsid=1,anonuid=65534,anongid=65534)
作为客户端，我的 FC32 一切正常：
[root@leonp mnt]# mount -v 192.168.1.1:/mnt/sda1/ srv
mount.nfs: timeout set for Mon Aug 3 16:04:08 2020
mount.nfs: trying text-based options 'vers=4.2,addr=192.168.1.1,clientaddr=192.168.1.57'
mount.nfs: mount(2): Protocol not supported
mount.nfs: trying text-based options 'vers=4,minorversion=1,addr=192.168.1.1,clientaddr=192.168.1.57'
mount.nfs: mount(2): Protocol not supported
mount.nfs: trying text-based options 'vers=4,addr=192.168.1.1,clientaddr=192.168.1.57'
mount.nfs: mount(2): Protocol not supported
mount.nfs: trying text-based options 'addr=192.168.1.1'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 192.168.1.1 prog 100003 vers 3 prot TCP port 2049
mount.nfs: prog 100005, trying vers=3, prot=17
mount.nfs: trying 192.168.1.1 prog 100005 vers 3 prot UDP port 39445
[root@leonp mnt]#
当我尝试连接仅支持 NFSv2 的客户端时，问题就出现了。因此，要从 PC 进行测试：
[root@leonp mnt]# mount -vvv -o vers=2 192.168.1.1:/mnt/sda1/ srv
mount.nfs: timeout set for Mon Aug 3 13:50:14 2020
mount.nfs: trying text-based options 'vers=2,addr=192.168.1.1'
mount.nfs: prog 100003, trying vers=2, prot=6
mount.nfs: trying 192.168.1.1 prog 100003 vers 2 prot TCP port 2049
mount.nfs: prog 100005, trying vers=1, prot=17
mount.nfs: trying 192.168.1.1 prog 100005 vers 1 prot UDP port 36357
mount.nfs: mount(2): Protocol not supported
mount.nfs: Protocol not supported
为什么这个？我检查了：
[root@leonp mnt]# rpcinfo 192.168.1.1
program version netid address service owner
100000 4 tcp 0.0.0.0.0.111 portmapper superuser
100000 3 tcp 0.0.0.0.0.111 portmapper superuser
100000 2 tcp 0.0.0.0.0.111 portmapper superuser
100000 4 udp 0.0.0.0.0.111 portmapper superuser
100000 3 udp 0.0.0.0.0.111 portmapper superuser
100000 2 udp 0.0.0.0.0.111 portmapper superuser
100000 4 local /var/run/rpcbind.sock portmapper superuser
100000 3 local /var/run/rpcbind.sock portmapper superuser
100003 2 tcp 0.0.0.0.8.1 nfs unknown
100003 3 tcp 0.0.0.0.8.1 nfs unknown
100003 2 udp 0.0.0.0.8.1 nfs unknown
100003 3 udp 0.0.0.0.8.1 nfs unknown
100021 1 udp 0.0.0.0.148.56 nlockmgr unknown
100021 3 udp 0.0.0.0.148.56 nlockmgr unknown
100021 4 udp 0.0.0.0.148.56 nlockmgr unknown
100021 1 tcp 0.0.0.0.228.206 nlockmgr unknown
100021 3 tcp 0.0.0.0.228.206 nlockmgr unknown
100021 4 tcp 0.0.0.0.228.206 nlockmgr unknown
100005 1 udp 0.0.0.0.142.5 mountd superuser
100005 1 tcp 0.0.0.0.130.95 mountd superuser
100005 2 udp 0.0.0.0.218.108 mountd superuser
100005 2 tcp 0.0.0.0.174.251 mountd superuser
100005 3 udp 0.0.0.0.154.21 mountd superuser
100005 3 tcp 0.0.0.0.132.150 mountd superuser
唯一不支持 v2 的是 nlockmgr - 它会成为挂载拒绝的原因吗？为了测试这一点，我尝试从运行中删除 nlockmgr - 没有成功。我试图通过注释掉 100021 在 /etc/rpc 中阻止它 - 没有成功。
更新：
#rcp.nfsd -d
rpc.nfsd: Checking netconfig for visible protocols.
rpc.nfsd: Enabling inet udp.
rpc.nfsd: Enabling inet tcp.
rpc.nfsd: knfsd is currently down
rpc.nfsd: Writing version string to kernel: +4.1 +2 +3 +4
#cat /proc/fs/nfsd/versions
+2 +3
============
任何帮助将不胜感激。
答案1
您需要调整 NFS 内核服务器以提供版本 2（正如您所注意到的，默认情况下它不再包含该版本）。在服务器上运行此命令将允许您测试建议的修复是否有效
rpc.nfsd 0 && sleep 1 # Stop all previous threads
rpc.nfsd --nfs-version 2,3 8 # Restart 8 threads with versions 2 and 3
如果有效，您需要将其永久化。在我的 Debian（“buster”）系统上，似乎仍然涉及编辑/etc/default/nfs-kernel-server.在您的系统上，它可能会有所不同。
原始代码
# Number of servers to start up
RPCNFSDCOUNT=32
修改后的代码
# Options and number of servers to start up
RPCNFSDCOUNT='--nfs-version 2,3 8'