[plug] NFS mount problem

[Mike Holland]

After upgrading my server from redHat 6.0 to 6.2, it refuses to allow
remote mounting of the root directory. Only the root export seems to be
affected.

/etc/exports:
/usr    (ro)
/       (ro)

"showmount -e" gives:
Export list for salween.golden.wattle.id.au:
/          (everyone)
/usr       (everyone)

The server log has:
Jul 14 16:53:31 salween mountd[835]: authenticated mount request from 
donau:992 for / (/)
Jul 14 16:53:31 salween mountd[835]: getfh failed: Operation not permitted

Its a nearly useless error message, so I run a trace on the mount demon to
find where it actually fails. Its a nfsservctl() call, just after writing
to /var/lib/nfs/xtab . This file has no man page.
  The 1st arg. to nfsservctl() is 0x7, which is undocumented in the man
pages. Now I'm starting to get bothered.
 Before I look further, does anyone recognise this problem? Suggestions
please? I can see what I'm doing thats unusual. Is this a mountd bug?


"strace" log of mountd system calls, before failure, follows:

rt_sigaction(SIGPIPE, {SIG_DFL}, NULL, 8) = 0
stat("/", {st_mode=S_IFDIR|0755, st_size=1024, ...}) = 0
nfsservctl(0x1, 0xbfffd01c, 0)          = 0
stat("/", {st_mode=S_IFDIR|0755, st_size=1024, ...}) = 0
nfsservctl(0x3, 0xbfffd01c, 0)          = -1 EINVAL (Invalid argument)
open("/var/lib/nfs/xtab", O_RDWR)       = 8
rt_sigaction(SIGALRM, {0x804df50, [], 0x4000000}, {SIG_DFL}, 8) = 0
alarm(10)                               = 0
fcntl(8, F_SETLKW, {type=F_WRLCK, whence=SEEK_SET, start=0, len=0}) = 0
alarm(0)                                = 10
rt_sigaction(SIGALRM, {SIG_DFL}, NULL, 8) = 0
open("/var/lib/nfs/xtab", O_WRONLY|O_APPEND|O_CREAT, 0666) = 9
fstat(9, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0
x40015000
fstat(9, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
_llseek(9, 0, [0], SEEK_SET)            = 0
write(9, "/\tdonau(ro,async,wdelay,hide,sec"..., 116) = 116
close(9)                                = 0
munmap(0x40015000, 4096)                = 0
close(8)                                = 0
nfsservctl(0x7, 0xbfffdcb0, 0x80546a0)  = -1 EPERM (Operation not
permitted)


-- 
Mike Holland  <mike at golden.wattle.id.au>
                          --==--