Hi *,
we recently have switched to using CephFS (with Luminous 12.2.1). On
one node, we're kernel-mounting the CephFS (kernel 4.4.75, openSUSE
version) and export it via kernel nfsd. As we're transitioning right
now, a number of machines still auto-mount users home directories from
that nfsd.
A strange error that was not present when using the same nfsd
exporting local-disk-based file systems, has recently surfaced. The
problem is most visible to the user when doing a ssh-keygen operation
to remove old keys from their "known_hosts", but it seems likely that
this error will occur in other constellations, too.
The error report from "ssh_keygen" is:
--- cut here ---
user@host:~> ssh-keygen -R somehost -f /home/user/.ssh/known_hosts
# Host somehost found: line 232
link /home/user/.ssh/known_hosts to /home/user/.ssh/known_hosts.old:
Not a directory
user@host:~>
--- cut here ---
This error persists... until the user lists the contents of the
directory containing the "known_hosts" file (~/.ssh). Once that is
done (i.e. "ls -l ~/.ssh"), ssh_keygen works as expected.
We've strace'd ssh_keygen and see the following steps (and more, of course):
- the original known_hosts file is opened successfully
- a temp file is created in .ssh (successfully)
- a previous backup copy (known_hosts.old) is unlink()ed (not
successful, since not present)
- a link() from known_hosts to known_hosts.old is tried - ENOTDIR
--- cut here ---
[...]
unlink("/home/user/.ssh/known_hosts.old") = -1 ENOENT (No such file or
directory)
link("/home/user/.ssh/known_hosts", "/home/user/.ssh/known_hosts.old")
= -1 ENOTDIR (Not a directory)
--- cut here ---
Once the directory was listed, the link() call works nicely:
--- cut here ---
unlink("/home/user/.ssh/known_hosts.old") = -1 ENOENT (No such file or
directory)
link("/home/user/.ssh/known_hosts", "/home/user/.ssh/known_hosts.old") = 0
rename("/home/user/.ssh/known_hosts.5trpXBpIgB",
"/home/user/.ssh/known_hosts") = 0
--- cut here ---
When link() returns an error, the rename is not called, leaving the
user with ("try" times) temporary files in .ssh - they never got
renamed.
This does sound like a bug to me, has anybody else stumbled across
similar symptoms as well?
Regards,
Jens
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