On Sun, Jan 13, 2019 at 12:25 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote: > Did you give any consideration to the locking order of copy up > from write fault context? > > I suppose you are aware of this hence the proposal of pre_mmap op: > https://marc.info/?l=linux-fsdevel&m=152760695502640&w=2 Apparently ->fault() is allowed to release mmap_sem and return VM_FAULT_RETRY, which is perfect for doing the copy up. > Do we gain anything (simplicity? relaxed locking order) if we always > copy up metadata on open O_RDWR and only delay data copy up > until first write/page fault? Yeah, maybe doing that as a start makes sense. Thanks, Miklos
