The following series of patches implement NFS client support for crossing server submounts (assuming that the server is exporting them using the 'nohide' option). We wish to ensure that inode numbers remain unique on either side of the mountpoint, so that programs like 'tar' and 'rsync' do not get confused when confronted with files that have the same inode number, but are actually on different filesystems on the server. This is achieved by having the client automatically create a submount that mirrors the one on the server. In order to avoid confusing users, we would like for this mountpoint to be transparent to 'umount': IOW: when the user mounts the filesystem '/foo', then an automatic submount by the NFS client for /foo/bar should not cause 'umount /foo' (particularly since the kernel cannot create entries for /foo/bar in /etc/mtab). To get around this we mark automatically created submounts using the new flag MNT_SHRINKABLE, and then allow the NFS client to attempt to unmount them whenever the user calls umount on the parent. Note: This code also serves as the base for NFSv4 'referral' support, in which one server may direct the client to a different server as it crosses into a filesystem that has been migrated. Cheers, Trond - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
