Moving a file from the container to a shared file succeeds, but shows error messages such as:
mv: preserving times for '...': Operation not permitted
mv: preserving permissions for '...': Operation not permitted

joelhockey@penguin:~$ touch a.txt
joelhockey@penguin:~$ ls -al a.txt
-rw-r--r-- 1 joelhockey joelhockey 0 Dec  6 16:44 a.txt
joelhockey@penguin:~$ mv a.txt /mnt/chromeos/MyFiles/Downloads/downloads-shared-prefs/
mv: preserving permissions for ‘/mnt/chromeos/MyFiles/Downloads/downloads-shared-prefs/a.txt’: Operation not permitted
joelhockey@penguin:~$ ls -l /mnt/chromeos/MyFiles/Downloads/downloads-shared-prefs/a.txt 
-rw------- 1 joelhockey joelhockey 0 Dec  6 16:44 /mnt/chromeos/MyFiles/Downloads/downloads-shared-prefs/a.txt


strace shows call:
fchmod(4, 0100644)                      = -1 EPERM (Operation not permitted)

I understand this is expected behavior since p9 server does not allow setattr/chmod:
https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/vm_tools/p9/src/server.rs#637

Should we return success from this case even if we don't change any attrs to avoid confusing error messages?