Steps to reproduce:

1. Log into a monitored Linux host via SSH
2. Create a nested filesystem mount, e.g. /data/nested_mount 
3. Make the top directory of the mount not browsable by Zabbix agent user (chown root:root /data && chmod o= /data)
4. Run "zabbix_agent2 -t vfs.fs.get | grep -c  nested_mount"

Result:
"vfs.fs.get" key value does not list the /data/nested_mount partition because Zabbix agent is running as non-privileged user "zabbix" who cannot run the "stat" syscall for it.

Expected:
Please state this behavior clearly in the documentation of the "vfs.fs.get" agent key and Discovery of mounted filesystems article .

As far as I can tell there is no indication whatsoever when Zabbix agent fails to include some partitions in the "vfs.fs.get" output, which makes this a hidden time bomb for system administrators.

To makes things worse, the official Zabbix Linux template relies on "vfs.fs.get" specifically for filesystem discovery, not "vfs.fs.discovery" - the latter not being affected by lack of permissions.

Thank you.