[NFS-Ganesha-Devel] Re: Ganesha 2.5.4 - usage of device major, minor

From: Jeff Layton [mailto:jlayton@redhat.com] I'd suggest that the fundamental problem here is the use of device major/minor in filehandles. Device major+minor (at least on Linux and probably BSD too) is often not stable across reboots, when devices are added and removed. Getting ESTALEs because your server rebooted is pretty sucky. It is for good reason that we moved away from doing that in Linux' knfsd years ago. It does still use that in legacy cases, when there is no filesystem UUID available. Most installations these days use filesystem UUID-based filehandles, which are stable no matter what device they show up on.

I'd counsel against trying to track mounts and unmounts automagically too. I think you'll find it very difficult to do that in a way that isn't subject to races. -- Jeff On Thu, 2018-10-11 at 04:28 +0000, Sriram Patil wrote: > I have also encountered same issue where the underlying file system is unmounted but ganesha still holds it details and the device major, minor reuse later causes problems. > > I can try and look into this and figure out a way to refresh the file systems list for ganesha. But, another problem in this is if the file system was exported by ganesha, should the export also be removed or should we wait for an explicit RemoveExport. Any way, since the file system is unmounted, the clients will start getting ESTALEs and may be even worse errors.

> > Thanks, > Sriram > On Oct 10, 2018, 11:04 PM +0530, Frank Filz <ffilzlnx(a)mindspring.com&gt;, wrote: > > > - On the issue itself, I forgot to mention that we used SIGHUP to > > > reload. As you suggested, will work on a patch to cleanup device > > > major/minor to reuse if possible, although I understand delete is not completely supported via SIGHUP. > > > But I do see some action to remove even with SIGHUP. > > > > You have to use DBUS to unexport. I couldn’t come up with a way to do unexport with SIGHUP. Actually, I do have an idea, add a Unexport = true; option. If that's set and the export is present, unexport, otherwise ignore the export - then you can leave exports in your config but have them not be present.... > > > > If an export is removed with unexport, that should release it's filesystems, and then a filesystem re-scan has the potential of removing filesystems no longer present (but we have to be careful there, GPFS has some issues with filesystems going offline and then messing up exports). > > > > Frank > > > > > - On this list subscription - I did subscribe to the list as well as registered myself. > > > But I had trouble posting to the list, I had to login directly and > > > post. I also not received my own post yet, although I do and did get other posts. > > > > > > Regards. > > > Krishna Harathi > > > > > > > > > On 10/9/18, 4:19 PM, "Frank Filz" <ffilzlnx(a)mindspring.com&gt; wrote: > > > > > > Ganesha's management of filesystems is probably not ideal. We can > > > add new ones, but I don't think we implemented removing unused ones. > > > > > > I would suggest looking at the filesystem management code to see > > > if there's a good way to remove them. > > > > > > You would have to unmount the filesystem, trigger Ganesha to clean > > > up and remove the filesystem, and then mount the new filesystem. > > > > > > The filesystem enumeration showed multiple entries using the same > > > device major and minor (all really related to the same filesystem, > > > but something about the way Linux handles volumes and such) which > > > means Ganesha must pick a filesystem to use for a given device > > > major and minor. If the device major and minor is reused and > > > Ganesha hasn't cleaned out the old filesystem, it will detect the > > > duplicate and just re-use the original filesystem (which of course no longer is mounted...). > > > > > > Frank > > > > > > > -----Original Message----- > > > > From: krishna.harathi(a)storagecraft.com > > > > [mailto:krishna.harathi@storagecraft.com] > > > > Sent: Tuesday, October 9, 2018 3:30 PM > > > > To: devel(a)lists.nfs-ganesha.org > > > > Subject: [NFS-Ganesha-Devel] Ganesha 2.5.4 - usage of device > > > > major, minor > > > > > > > > We are using Ganesha 2.5.4 VFS FSAL with FUSE based filesystem. > > > > > > > > During our testing of deleting existing exports and creating new > > > > ones, found > > > that > > > > if a device major and minor is reused, clients get ESTALE for > > > > accessing a > > > newly > > > > created export (nfs2 below). > > > > This seems to cause the following log entry, and explains the > > > > ESTALE > > > response. > > > > 04/10/2018 T15:16:59.769027-0700 : nfs-ganesha-26627[sigmgr] > > > > 1595 :claim_posix_filesystems :FSAL :INFO :Root fs for export > > > > /exports/nfs1 is > > > > /exports/nfs2 > > > > > > > > We use our own Exportid and unique FSID configured for each > > > > export in the configuration file. > > > > > > > > I would like to know more about the intent and purpose of the > > > > usage of > > > device > > > > major and minor of an export in this context. > > > > Any help in fixing this reuse issue is also appreciated. > > > > > > > > Thanks. > > > > > > > > > > > > Regards. > > > > Krishna Harathi > > > > _______________________________________________ > > > > Devel mailing list -- devel(a)lists.nfs-ganesha.org To unsubscribe > > > > send an > > > email to > > > > devel-leave(a)lists.nfs-ganesha.org > > > > > > > > > > _______________________________________________ > > Devel mailing list -- devel(a)lists.nfs-ganesha.org To unsubscribe > > send an email to devel-leave(a)lists.nfs-ganesha.org > > _______________________________________________ > Devel mailing list -- devel(a)lists.nfs-ganesha.org To unsubscribe send > an email to devel-leave(a)lists.nfs-ganesha.org -- Jeff Layton <jlayton(a)redhat.com&gt; _______________________________________________ Devel mailing list -- devel(a)lists.nfs-ganesha.org To unsubscribe send an email to devel-leave(a)lists.nfs-ganesha.org