On Tue, Feb 12, 2019 at 09:26:48PM +0530, Aneesh Kumar K.V wrote: > Vivek Goyal <vgoyal@xxxxxxxxxx> writes: > > > Hi, > > > > Here are RFC patches for virtio-fs. Looking for feedback on this approach. > > > > These patches should apply on top of 4.20-rc5. We have also put code for > > various components here. > > > > https://gitlab.com/virtio-fs > > > > Problem Description > > =================== > > We want to be able to take a directory tree on the host and share it with > > guest[s]. Our goal is to be able to do it in a fast, consistent and secure > > manner. Our primary use case is kata containers, but it should be usable in > > other scenarios as well. > > > > Containers may rely on local file system semantics for shared volumes, > > read-write mounts that multiple containers access simultaneously. File > > system changes must be visible to other containers with the same consistency > > expected of a local file system, including mmap MAP_SHARED. > > > > Existing Solutions > > ================== > > We looked at existing solutions and virtio-9p already provides basic shared > > file system functionality although does not offer local file system semantics, > > causing some workloads and test suites to fail. > > Can you elaborate on this? Is this with 9p2000.L ? We did quiet a lot of > work to make sure posix test suite pass on 9p file system. Also > was the mount option with cache=loose? Hi Aneesh, Yes this is with 9p2000.L and cache=loose. I used following mount option. mount -t 9p -o trans=virtio hostShared /mnt/virtio-9p/ -oversion=9p2000.L,posixacl,cache=loose We noticed primarily two issues. - Ran pjdfstests and a lot of them are failing. I think even kata container folks also experienced pjdfstests failures. I have never looked into details of why it is failing. - We thought mmap(MAP_SHARED) will not work with virtio-9p when two clients are running in two different VMs and mapped same file with MAP_SHARED. Having said that, biggest concern with virtio-9p seems to be performance. We are looking for ways to improve performance with virtio-fs. Hoping DAX can provide faster data access and fuse protocol itself seems to be faster (in primilinary testing results). Thanks Vivek
