>>> On 2/14/2014 at 01:10 AM, Jeff Layton <jlayton@xxxxxxxxx> wrote: > On Thu, 13 Feb 2014 18:29:45 +0100 > Gionatan Danti <g.danti@xxxxxxxxxx> wrote: > >> On 02/13/2014 12:37 PM, Jeff Layton wrote: >> > >> > Using cache=none sort of defeats the purpose. After all Gionatan said >> > that he was doing this specifically to use fscache, and that won't work >> > with cache=none. >> > >> >> Surely my idea was to use FSCACHE to speed up remote access. Without it, >> the entire discussion is pointless... >> >> > But, lets leave that aside for a moment and consider whether this could >> > work at all. Assume we have samba set up re-share a cifs mount: >> > >> > Client sends an open to samba and requests an oplock. Samba then opens >> > a file on the cifs mount, and does not request an oplock (because of >> > cache=none). We then attempt to set a lease, which will fail because we >> > don't have an oplock. Now you're no better off (and probably worse off) >> > since you have zero caching going on and are having to bounce each >> > request through an extra hop. >> > >> > So, suppose you disable "kernel oplocks" in samba in order to get samba >> > to hand out L2 oplocks in this situation. Another client then comes >> > along on the main (primary) server and changes a file. Samba is then >> > not aware of that change and hilarity (aka data corruption) ensues. >> > >> >> Are you of the same advice for low-frequency file changes (eg: office >> files)? >> >> What about using NFS to export the Fileserver directory, mount it (via >> mount.nfs) on the remote Linux box and then sharing via Samba? It is a >> horrible frankenstein? >> > > You'll have similar problems with NFS. > > You can't acquire leases on NFS either, so with kernel oplocks enabled > on samba you won't ever get oplocks on there. If you turn them off (so > that oplocks are tracked internally) you won't be aware of changes that > occur outside of samba. > >> > I just don't see how re-sharing a cifs mount is a good idea, unless you >> > are absolutely certain that the data you're resharing won't ever >> > change. If that's the case, then you're almost certainly better off >> > keeping a local copy on the samba server and sharing that out. >> > >> >> After many tests, I tend to agree. Using a Fedora 20 test machine with >> fscache+cachefilesd as the remote Linux box, I had one kernel panic and >> multiple failed file copies (with Windows complaing about a "bad >> signature"). >> >> I also found this: https://bugzilla.redhat.com/show_bug.cgi?id=646224 >> Maybe the CIFS FSCACHE is not really production-grade on latest distros >> also? >> > > I don't recall whether Suresh ever fixed those bugs. cifs+fsc is If you are referring to this oops http://thread.gmane.org/gmane.linux.file-systems.cachefs.general/2961 it was fixed by the below commit commit c902ce1bfb40d8b049bd2319b388b4b68b04bc27 Author: David Howells <dhowells@xxxxxxxxxx> Date: Thu Jul 7 12:19:48 2011 +0100 FS-Cache: Add a helper to bulk uncache pages on an inode I remember verifying it by running fsstress for many hours then. I'm not sure what other bugs you are referring to. > certainly not widely used, and it wouldn't surprise me if it were still > horribly buggy. Just curious, why would you say so? - Suresh Jayaraman -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
