On Sat, Jun 18, 2011 at 09:27:30AM -0400, Steve Dickson wrote: > Hey Bruce, > > On 06/14/2011 10:58 AM, J. Bruce Fields wrote: > > We've long had a bug with crossmnt handling which could cause a parent's > > export options to override those of a child in some cases. > > > > While I was there, I also did some cleanup, mainly of nfsd_fh(). It was > > long and complicated, now it's short and complicated. We could probably > > simplify the logic with a little more work. > > > > --b. > Which bug are you referring to? Suppose /etc/exports contains: /foo *(rw,crossmnt) /foo/bar *(ro) The "crossmnt" tells us to export all filesystems under /foo recursively with the same options as /foo is exported with. So there's a conflict: should /foo/bar be exported ro, or rw? The logical thing to do is to make the "ro" on the explicit export of /foo/bar override the inherited "rw" from /foo, and in practice that's what people have obviously expected in every case I've seen. But we don't do that. Actually, it's worse than that: the /foo export wins in the nfsd_fh upcall, and the /foo/bar export wins in the nfsd_export upcall. So you can get inconsistent results depending on which order things happen in. So the first patch fixes nfsd_fh to behave like nfsd_export does, and prefer /foo/bar. This was most commonly a problem with people doing fsid=0 exports, so it's less of a problem now that we have the v4root stuff, but definitely it still needs fixing. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
