Hello,
I noticed overlayfs will possibly do fadvise operation on upper or lower
files.
So I'm little curious when doing fadvise with flag 'POSIX_FADV_DONTNEED'
to evict page cache on lower file which is shared with other overlayfs
instances,
isn't there any unexpected side effect?
I have not done very detail test for exact result for it but when
I run vmtouch(to evict page cache) and append write(to copy-up) in
different instances,
sometimes, copy-up seems failed with EIO.
If above is correct, I would like to propose to do fadvise only for
upper layer.
What do you think for this?
Thanks,
Chengguang
