Here is my curious scenario. 1. create a file on overlayfs. 2. delete a file on upper directory. 3. can see file contents using read sys call. (may file operations all success) 4. cannot remove, rename. it return -ESTALE error (may inode operations fail) I understand this scenario onto the code level. But I don't understand this situation itself. I found a overlay kernel docs and it comments Changes to underlying filesystems section ... Changes to the underlying filesystems while part of a mounted overlay filesystem are not allowed. If the underlying filesystem is changed, the behavior of the overlay is undefined, though it will not result in a crash or deadlock. .... So here is my question (may it is suggestion) 1. underlying file system change is not allowed, then how about implementing shadow upper directory from user? 2. if read, write system call is allowed, how about changing remove, rename(and more I does not percept) operation success? Best Regards.
