Linux vfs.file.* functions do not seem to work on smbshares

[ulistaerk]

With the old zabbix agent from debian lenny everything worked fine. But since upgrading to squeeze the following problem occurs:

# ls -al /mnt/pdf-signer/.mountpoint
-rwxrwxrwx 1 root root 0 Jan 26 19:26 /mnt/pdf-signer/.mountpoint
# zabbix_agent -c /etc/zabbix/zabbix_agentd.conf -t "vfs.file.exists[/mnt/pdf-signer/.mountpoint]"
vfs.file.exists[/mnt/pdf-signer/.mountpoint]  [u|0]

Permissions are correct I checked this first. It works on local files on the root file system, but all files mounted via cifs (rw,file_mode=0777,dir_mode=0777) can not be monitored although Zabbix can "see" the item according to strace because the agent acts different on os level if the file does exist and behaves the same (see fstat64 call) for a working local file:

# strace -s 1000 zabbix_agent -c /etc/zabbix/zabbix_agentd.conf -t "vfs.file.exists[/mnt/pdf-signer/.mountpoint]"
stat64("/mnt/pdf-signer/.mountpoint", 0xbfdc9d4c) = -1 ENOENT (No such file or directory)
write(1, "vfs.file.exists[/mnt/pdf-signer/.mountpoint]  [u|0]\n", 52) = 52

# touch "/mnt/pdf-signer/.mountpoint"

# strace -s 1000 zabbix_agent -c /etc/zabbix/zabbix_agentd.conf -t "vfs.file.exists[/mnt/pdf-signer/.mountpoint]"
stat64("/mnt/pdf-signer/.mountpoint", {st_mode=S_IFREG|0777, st_size=0, ...}) = 0
fstat64(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(136, 0), ...}) = 0
write(1, "vfs.file.exists[/mnt/pdf-signer/.mountpoint]  [u|0]\n", 52) = 52

# strace -s 1000 zabbix_agent -c /etc/zabbix/zabbix_agentd.conf -t "vfs.file.exists[/root/.mountpoint]"
stat64("/root/.mountpoint", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
fstat64(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(136, 0), ...}) = 0
write(1, "vfs.file.exists[/root/.mountpoint]            [u|1]\n", 52) = 52

The Debian Squeeze Version is:

# zabbix_agent -V
Zabbix Agent v1.8.2 (revision 11211) (29 March 2010)
Compilation time:  Jan 15 2011 14:43:19

Anybody an idea how to fix this?