Hi, I was recently experimenting with NFS re-exporting using the new patch set that is in the Linux 5.11 kernel (https://patchwork.kernel.org/project/linux-nfs/list/?series=393561). After applying these patches, I consistently faced an error when trying to perform a previously working NFS re-export: "exportfs: /files does not support NFS export". I (with help from some other interested parties) began troubleshooting and after stepping through each patch individually we identified that the error only occurred when the following patch was applied: https://patchwork.kernel.org/project/linux-nfs/patch/20201130220319.501064-3-trond.myklebust@xxxxxxxxxxxxxxx/. This patch prevents re-exporting if subtree checking is enabled on the originating NFS server. The strange thing was that no_subtree_check export option was already set on the export from the originating NFS Filer, but the error message persisted. After lots of troubleshooting, eventually we tried updating NFS Utils from 1.3.4 to 2.5.2 and we were able to successfully perform re-export. It appears that the old version of the nfs-utils package was the cause of the issue. I appreciate that 1.3.4 is a very old version of nfs-utils, but it is the default version that ships with Ubuntu and Debian and the error message does not immediately point to the outdated version being the cause of the problem. I was wondering if it was possible to detail the requirement for a more recent version of nfs-utils in the NFS Re-exporting section of the Wiki (http://wiki.linux-nfs.org/wiki/index.php/NFS_re-export) to help others who may encounter this problem in the future? Kind Regards Benjamin Maynard
