odd phantom directory

[jb]

Brian Gold <bgold <at> simons-rock.edu> writes:

> 
> Hi all,
> 
> I ran into a rather odd issue this morning with my FreeBSD 9.0-Release
> system running ZFS v28. This system serves as an RSYNC host which all of our
> other systems back up to each night. Last night, I started getting the
> following error:
> 
> file has vanished: "/backup/ldap1/etc/pki"
> 
> Now, usually when I get a file has vanished error during an RSYNC run, it
> indicates that the source file/directory on the system that is sending the
> rsync backup has been deleted or moved before rsync got a chance to actually
> send it. That doesn't appear to be the case here. "/backup/ldap1/etc/pki" is
> the destination directory on my Freebsd/ZFS server. I take a look in
> "/backup/ldap1/etc" on my Freebsd server and the "pki" subdirectory is no
> longer listed.
> 
> Ok, so I run "mkdir /backup/ldap1/etc/pki" and get the following error:
> "mkdir: /backup/ldap1/etc/pki: File exists". Odd
> 
> Just to double check, I run "ls -la /backup/ldap1/etc/pki" and get the
> following: "ls: /backup/ldap1/etc/pki: No such file or directory"
> ...

There have been cases like that reported in the past.

One was dated 2006:
http://lists.freebsd.org/pipermail/freebsd-bugs/2006-April/018069.html
I assume the backup host was on UFS.
This comment seems to be interesting:
"Such behavior usually caused by lost vnode reference and/or bugs in the 
 vnode traversal code. ..."

Next dated 2011:
http://freebsd.1045724.n5.nabble.com/carsten-c-otto-de-ftpsync-freebsd-ftp-ftp-1013-rsync-ERROR-on-2011-03-04-09-23-00-td4073512.html
I assume the backup host was on UFS2.
There was a fix commited:
"...John Baldwin commited very promising MFC yesterday, see
http://svn.freebsd.org/changeset/base/219744 ."

Next dated 2011:
http://lists.freebsd.org/pipermail/freebsd-current/2011-October/027902.html
The backup host was on ZFS.

Yours is similar to the last one.

Perhaps looking for the solution to this problem should start at top VFS
layer ?
The description in /usr/src/sys/sys/vnode.h is a good reference.

I would suggest you file a PR# to get VFS and fs devs have a look at it.
jb