* Max Reitz ([email protected]) wrote: > Hi, > > This RFC consists of two patch series, one for virtiofsd (i.e., to be > applied to the qemu repo), and one for Linux. > > The problem it wants to solve is that virtiofsd just passes through the > stat.st_ino value from the host to the guest, without taking stat.st_dev > into account. Therefore, it is generally impossible to uniquely > identify nodes in the guest by their st_dev/st_ino combinations. > > One way to fix this would be to derive some algorithm to derive a unique > st_ino value from the st_dev/st_ino combination on the host, but this is > not always possible. > > So what this series does it basically passing through st_dev alongside > st_ino: We can let the guest create auto-mounted submounts for every > host mount point, so that they get their own dedicated st_dev. This is > similar to what NFS does with the crossmnt option.
Nice; this should probably get cc'd to fuse-devel and/or put as a pull into their github to see what they have to say. Dave > Announcing submounts to the guest (the FUSE client) is done by the FUSE > server (virtiofsd) of setting st_rdev to a non-zero value (e.g. st_dev) > for every mount point. > > In this version here, duplicate mounts on the host (same st_dev) will > not necessarily have the same st_dev in the guest. That would be more > complicated to implement, and there is probably no real need to. > > Furthermore, note that virtiofsd identifies files based on > st_dev/st_ino, so if you do have duplicate mounts on the guest, it is > very much possible that you will run into problems when trying to pass > them through to the guest (because virtiofsd may treat them as one and > the same tree). > > -- > 2.26.2 > > _______________________________________________ > Virtio-fs mailing list > [email protected] > https://www.redhat.com/mailman/listinfo/virtio-fs -- Dr. David Alan Gilbert / [email protected] / Manchester, UK _______________________________________________ Virtio-fs mailing list [email protected] https://www.redhat.com/mailman/listinfo/virtio-fs
