On Fri, 15 Nov 2013 16:56:51 +0000 "Myklebust, Trond" <Trond.Myklebust@xxxxxxxxxx> wrote: > On Thu, 2013-11-14 at 07:25 -0500, Jeff Layton wrote: > > rpc.gssd will naturally hold open any pipe named */clnt*/gssd that shows > > up under rpc_pipefs. That behavior gives us a reliable mechanism to tell > > whether it's actually running or not. > > > > Create a new toplevel "gssd" directory in rpc_pipefs when it's mounted. > > Under that directory create another directory called "clntXX", and then > > within that a pipe called "gssd". > > > > We'll never send an upcall along that pipe, and any downcall written to > > it will just return -EINVAL. > > > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > > Hi Jeff, > > Don't you need something in rpc_kill_sb() in order to remove the pipe > and the clntXX directory? > > Also please see rpc_mkdir_populate() and rpc_mkdir_depopulate() for how > you can simplify the creation/destruction of the clntXX+clntXX/gssd. > > Cheers > Trond The concerned me too when I was working on this patch, but I don't think that's the case. Note that rpc_kill_sb() doesn't call rpc_depopulate() or anything for the top level directories in files[] either, which puzzled me until I dove in to figure out why... Basically what happens is that we take a dentry reference to those when they are instantiated and that keeps them pinned in memory. The last thing that rpc_kill_sb() does is call kill_litter_super(), which calls d_gencode() to put a reference on any dentry reachable from s->root. After that, it calls generic_shutdown_super() which then calls shrink_dcache_for_umount() to go through and purge all of the dentries that are now at 0. At that point you should see "Dentry ... still in use" messages if any still have a non-zero refcount. I've tested mounting and unmounting rpc_pipefs with this set and I've never seen those warnings pop. So, I don't think we need to do any cleanup of them, but I will admit that none of this is particularly obvious. ;) -- Jeff Layton <jlayton@xxxxxxxxxx> -- 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
