> > On Fri, Apr 1, 2016 at 11:48 AM, Benjamin Coddington > > <bcodding@xxxxxxxxxx> wrote: > > > On Fri, 1 Apr 2016, Trond Myklebust wrote: > > > > > >> On Fri, Apr 1, 2016 at 11:34 AM, Benjamin Coddington > > >> <bcodding@xxxxxxxxxx> wrote: > > >> > The client sends IO only under the open stateid when using OFD > > >> > (and flock) locking instead of the appropriate lock stateid > > >> > because the nfs_lock_context only tracks POSIX lockowners, which > > >> > is the reference to the process' file table. > > >> > > > >> > This is a problem for two reasons. The first is that rfc7530, > > >> > section-9.1.4.5 states that IO sent by an entity corresponding to > > >> > the lock-owner which holds a byte-range lock should be sent under > > >> > the lock stateid for that lock. Otherwise, a server enforcing > > >> > mandatory byte-range locking might reject that operation. > > >> > Secondly, not tracking OFD lock owners means that accounting for > > >> > IO sent under those owners is broken. That creates a problem for > > >> > some work to guarantee an unlock will be sent after operations > scheduled under a lock complete. > > >> > > >> OK. Can we just kill this in the bud? No support for OFD locks in NFS: > > >> this is nuts.... > > > > > > Will you explain why it is nuts? That would be helpful for me. > > > > The point of the OFD crap was that they should work exactly like POSIX > > locks except for the unlock-on-close, the latter being managed by the > > VFS layer. If we have to make loads of changes to NFS in order to > > change the tracking of lock owners, then the design itself is broken, > > and needs to be fixed. > > > No, there were other reasons for them as well. > > For instance, traditional POSIX locks are useless for serializing betwee > threads within the same process because the lock owner is always the same > regardless of which thread you're using. With OFD locks, this is possible if > each thread has its own file description. Which is a feature humongously useful for Ganesha... Not that Ganesha will ever use OFD locks over NFS... I have used OFD locks over NFS to make sure that Ganesha handles one open-owner to many lock-owners correctly. Of course it may be a real question if anyone other than Ganesha (and maybe Samba) will ever use OFD locks since they aren't a POSIX standard... Frank --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus -- 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
