NFS服务意外断开，导致挂载的客户端“df -Th”命令无法使用，及挂载目录无法“cd”“ls”
检查
[root@test ~]# strace df -h execve("/usr/bin/df", ["df", "-h"], 0x7ffd59cf01e8 /* 22 vars */) = 0 brk(NULL) = 0x23d4000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f635d450000 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory) open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=33888, ...}) = 0 mmap(NULL, 33888, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f635d447000 close(3) = 0 open("/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3 read(3, "177ELF2113 3 > 1 `&2 "..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=2156240, ...}) = 0 mmap(NULL, 3985920, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f635ce62000 mprotect(0x7f635d025000, 2097152, PROT_NONE) = 0 mmap(0x7f635d225000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c3000) = 0x7f635d225000 mmap(0x7f635d22b000, 16896, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f635d22b000 close(3) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f635d446000 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f635d444000 arch_prctl(ARCH_SET_FS, 0x7f635d444740) = 0 mprotect(0x7f635d225000, 16384, PROT_READ) = 0 mprotect(0x617000, 4096, PROT_READ) = 0 mprotect(0x7f635d451000, 4096, PROT_READ) = 0 munmap(0x7f635d447000, 33888) = 0 brk(NULL) = 0x23d4000 brk(0x23f5000) = 0x23f5000 brk(NULL) = 0x23f5000 open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=106172832, ...}) = 0 mmap(NULL, 106172832, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f6356920000 close(3) = 0 open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=2502, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f635d44f000 read(3, "# Locale name alias data base. #"..., 4096) = 2502 read(3, "", 4096) = 0 close(3) = 0 munmap(0x7f635d44f000, 4096) = 0 open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/proc/self/mountinfo", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f635d44f000 read(3, "18 40 0:18 / /sys rw,nosuid,node"..., 1024) = 1024 stat("/etc/sysconfig/64bit_strstr_via_64bit_strstr_sse2_unaligned", 0x7ffe3bf78430) = -1 ENOENT (No such file or directory) read(3, " efivarfs rw 29 25 0:25 / /sys/f"..., 1024) = 1024 read(3, ",noexec,relatime shared:19 - cgr"..., 1024) = 1024 read(3, "55,hard,proto=tcp,timeo=600,retr"..., 1024) = 319 read(3, "", 1024) = 0 lseek(3, 0, SEEK_CUR) = 3391 close(3) = 0 munmap(0x7f635d44f000, 4096) = 0 stat("/dev", {st_mode=S_IFDIR|0755, st_size=2960, ...}) = 0 stat("/sys/kernel/security", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/dev/shm", {st_mode=S_IFDIR|S_ISVTX|0777, st_size=40, ...}) = 0 stat("/run", {st_mode=S_IFDIR|0755, st_size=1060, ...}) = 0 stat("/sys/fs/cgroup", {st_mode=S_IFDIR|0755, st_size=340, ...}) = 0 stat("/sys/fs/cgroup/systemd", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/pstore", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/firmware/efi/efivars", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/blkio", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/net_cls,net_prio", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/devices", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/cpu,cpuacct", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/cpuset", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/freezer", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/memory", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/hugetlb", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/pids", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/fs/cgroup/perf_event", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/sys/kernel/config", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/", {st_mode=S_IFDIR|0555, st_size=284, ...}) = 0 stat("/dev/hugepages", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 stat("/boot/efi", {st_mode=S_IFDIR|0700, st_size=16384, ...}) = 0 stat("/data", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0 stat("/run/user/0", {st_mode=S_IFDIR|0700, st_size=40, ...}) = 0 stat("/data/share",
是由于/data/share导致的无法使用命令，/data/share为nfs挂载目录
解决思路：
1.强制取消客户端挂载
2.重启NFS服务，客户端和服务端都需要重启
3.重新挂载NFS
处理方法：
1.强制取消客户端挂载
cat /etc/mtab
umount -lf /mnt