On Wed, Feb 6, 2019 at 3:06 PM Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > > This is a joint topic proposal with Vivek Goyal. > > Discuss remaining issues related to exporting a filesystem from host to > guest (see virtio-fs prototype posting[1] for more background): > > * How to provide strong coherency guarantees? > > - Fsnotify synchronous post op notification > - Extend lease (delegation) API to userspace There are some commonalities here with userspace networking file servers. I am interested in samba in particular and things that we can do to improve Linux interfaces for samba. SMB3 directory leases for example. Thanks, Amir. > - Multi-component path revalidation > > * Issues related to c/m/atime handling: > > - Clock synchronization between host and guest (not an fs issue, but fs > has to deal with lack of it) > > - Could we have O_NOCMTIME open flag? > > * Shared access to file data: > > - Use DAX in guest to access host page cache (mmap/munmap sections of > file in guest address space; happens dynamically on a need basis); is > this design reasonable? > > - Avoids memory copies and cache duplication, but host page table setup > may have high cost. Can that be improved? (E.g. fault-ahead) > > - Too many VMA’s on host per qemu instance? > > * File locking: > > - Host API for POSIX lock sharing? > > * Ideas for the future: > > - Buffering directory operations (e.g. "tar xfz ..." with as few > synchronous ops as possible) > > [1] https://lore.kernel.org/lkml/20181210171318.16998-1-vgoyal@xxxxxxxxxx/
