Problem writing to ovl with CIFS as lower dir

Hello,

[I'm not subscribed to the list please CC me when replying]

I'm testing overlayfs on 3.12 (own-made port) and on 4.4 (to confirm behavior) and what I observe is that when I try to write to a file in the merge directory e.g:

echo "test" > merged/test-file1

I get -EINVAL on 3.12 and -ENXIO on 4.4. However, when I try to touch a file in the merged directory I have no issues. This happens only when the lower mount is either CIFS/NFS. When it's another ext4 directory I have no problems whatsoever. Is this behavior expected, I'm willing to assume I've screwed up the 3.12 port but given that I see this on 4.4 (no custom modifications) I'm beginning to think this is innate into the the design?

Regards,
Nikolay

Ummm... I wouldn't've thought that CIFS was allowed as the lower dir since it supports case-independent filenames.

David

Well, since the ovl_is_allowed_fs_type was removed I guess there is no limitation as to what networked fs you could mount. But in any case, that's why I also tested with NFS and also got the same result.