On Mon, Mar 01, 2010 at 10:20:02PM -0500, J. Bruce Fields wrote: > On Mon, Mar 01, 2010 at 10:13:06PM +0100, Iustin Pop wrote: > > On Mon, Mar 01, 2010 at 03:40:10PM -0500, J. Bruce Fields wrote: > > > On Sun, Feb 28, 2010 at 11:06:43AM +0100, Iustin Pop wrote: > > > > Since nfs-utils 1.2.1, there are some problems with crossmnt usage. See > > > > Debian bug http://bugs.debian.org/567546, but in short the problem seems > > > > to be that sub-mounts (/a/b) take the top-level mount (/a) options > > > > instead of their own, due to a bug in how mountd generates the crossmnt > > > > subexports. > > > > > > > > I checked that reverting the write_secinfo changes in commit > > > > bc0a6ab03089fc1ea4fea26ed9635c2cc918b01b fix the issue, but that might > > > > only be a side effect, not the actual cause. > > > > > > > > A short test: > > > > - have /a and /a/b exported, with different flags (e.g. ro on /a, rw on > > > > /a/b) > > > > - restart the mountd, clear exports, etc. > > > > - try a mount on the client of /a/b, it gets readonly > > > > - umount & remount, it's now r/w > > > > - however, clearing the kernel export table (exportfs -f), makes the > > > > next mount again get read-only > > > > > > > > Disabling crossmnt fixes the issue completely, so I would venture to > > > > guess that the subexports creation code has some issue, but I don't know > > > > enough of this to be able to debug it. > > > > > > Thanks for the report. What's the latest nfs-utils version you've > > > tested? > > > > 1.2.2 - which is broken, as is 1.2.1. 1.2.0 works, because of the above > > commit which, again, I presume un-hides the problem. > > > > Also there are reports of older versions being broken. > > > > > On a quick skim of the latest code I see one clear bug > > > (path[strlen(path)] will never be '/'!), but that should have caused > > > crossmnt to never get enforced at all rather than to override anything. > > > > > > Could you retest the latest from the upstream git, with this patch > > > applied, and see if the problem is still present? > > > > I've tested right now with > > git://git.linux-nfs.org/projects/steved/nfs-utils.git (I hope this is the right > > upstream repo) plus the patch - still happens, no change. > > > > One thing that is interesting is that only the first mount gets the > > wrong options, if the client unmounts and remounts (at this point the > > exports are in the kernel's cache) the options are right. As long as the > > kernel cache is populated, the options are right, if one clears the > > cache, the first mount will be wrong. Maybe this helps, I find it an > > interesting behaviour. > > > > > Then if it is I'll try to go reproduce it myself.... > > > > For reference, here is the exports file I use for tests: > > /srv/nfs client(sec=sys,ro,sync,fsid=0,subtree_check,crossmnt) > > /srv/nfs/homes client(sec=sys,rw,sync,subtree_check) > > > > And here is the fstab entry on the client: > > server:/srv/nfs/homes /home nfs noauto,hard,bg,sec=sys,proto=tcp 0 0 > > > > The rest of the tools on server and client are Debian's nfs-utils 1.2.1 > > (they have just a few, very trivial and unrelated, patches). The problem > > manifests (in my case) with both nfsv3/sec=sys and nfsv4/sec=krb*. > > The loop in utils/mountd/cache.c:cache_export_ent() looks extremely > suspicious: it seems to be populating the kernel's export cache with > parameters taken from the parent export. I can't see why that's > necessary at all--those exports can be looked up on demand later when > they're needed. Something as simple as the following might help? > (Totally untested!) Sorry for the delayed response. I can confirm this solves my test case. I get the right mount options in both the "mount directly the sub-directory" case, and in the "mount parent and access the sub-directory via the crossmnt feature" case. thanks! iustin -- 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
