On 05/17/2018 02:26 PM, Vivek Goyal wrote: > On Mon, Apr 16, 2018 at 09:35:25AM -0500, Goldwyn Rodrigues wrote: >> From: Fabian Vogt <fvogt@xxxxxxxx> >> >> xattrs are not guarantees to be compatible across different filesystems. >> Operations which lead to copying of files to the upper layer fail with an >> "Operation not supported" error from the filesystem if a xattr could not be >> written in the upper layer. We can safely ignore "system" xattrs. >> >> One easy to hit example is using NFS as a read-only lower layer and !NFS as >> upper layer to store changes. Files on NFS can have the "system.nfs4_acl" > > I don't know much about nfs4_acl. But name suggests that it stored ACLs > there. So if we ignore these over copy up, does that mean we are not > enforcing ACL policy over copy up. So say some user which was not able > to read a file when it was on lower, might be able to read it after > copy up? > > Or I have completely misunderstood it? > > As far as I know, all "system" attributes are filesystem specific (even if they are the same fstype) and cannot be comprehended by other filesystems. Hence, they can be ignored. Unfortunately, system.nfs4_acl is a part of protocol and is null most of the times. Here is an earlier discussion I found which did not conclude: https://www.spinics.net/lists/linux-nfs/msg61045.html -- Goldwyn -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
