[pnfs] CVS: nfsv4

[Marc Eshel]

"Iyer, Rahul" <Rahul.Iyer at netapp.com> wrote on 08/01/2006 01:26:12 PM:

> Using the rpc_clnt struct gets the a reference to the counter, but the
> rpc shutdown code forcefully causes the task to exit with -EIO.
> Unfortunately, having a referennce does not help.

What happens to sync rpc and other layout that are cached in the case of 
rpc shutdown?

> 
> Incidentally, returning of delegations is also done in a similar fashion
> (async call followed by a wait for its completion)
> Regards
> Rahul
> 
> 
> -----Original Message-----
> From: William A.(Andy) Adamson [mailto:andros at citi.umich.edu] 
> Sent: Tuesday, August 01, 2006 12:55 PM
> To: Iyer, Rahul
> Cc: Marc Eshel; Rahul Iyer (NetApp); pnfs at linux-nfs.org;
> andros at citi.umich.edu
> Subject: Re: [pnfs] CVS: nfsv4 
> 
> > Hi,
> > I mean the inode freeing routines, not the free_layout () call. Here's
> 
> > the problem...
> > The xdr encode routine takes the inode as part of the arguments. It 
> > uses this to get the file handle for the PUTFH in the compound 
> > containing the LAYOUTRETURN. I agree, we could get the file handle 
> > earlier and then pass this down instead of the inode.
> > 
> > But the other problem is that we need the rpc_clnt struct too. This is
> 
> > also present in the inode. We could extract this also, but we wind up 
> > in a race with umount. During umount, the rpc_shutdown_clients kills 
> > all outstanding rpc_clnt structs.
> > 
> > So, here's my plan. I plan to make ir sort of async, but not exactly. 
> > I will issue the rpc asynchronously, but wait for it to complete. 
> > While this is not truly asynchronous, it avoids the races we have. It 
> > however, is slightly better than synchronous because the user can now 
> > interrupt it.
> 
> can't you hold a reference to the structures that you need while the
> async rpc is in flight?
> 
> -->Andy
> 
> > Thanks
> > Regards
> > Rahul
> > 
> > 
> > -----Original Message-----
> > From: Marc Eshel [mailto:eshel at almaden.ibm.com]
> > Sent: Tuesday, August 01, 2006 9:20 AM
> > To: Iyer, Rahul
> > Cc: Rahul Iyer (NetApp); pnfs at linux-nfs.org
> > Subject: RE: [pnfs] CVS: nfsv4
> > 
> > What exactly is the problem? Can't you remove the pointer 
> > current_layout from the inode (set it to NULL) and than you can either
> 
> > free it even before the async call or if you need it for some reason 
> > free it in rpc_call_done ?
> > I think that this call should be async.
> > Marc.
> > 
> > pnfs-bounces at linux-nfs.org wrote on 07/31/2006 10:29:22 PM:
> > 
> > > PFA the patch for the following commit. 
> > > Regards
> > > Rahul
> > > 
> > > 
> > > -----Original Message-----
> > > From: Rahul Iyer (NetApp) [mailto:iyer at citi.umich.edu]
> > > Sent: Monday, July 31, 2006 10:28 PM
> > > To: pnfs at linux-nfs.org
> > > Subject: [pnfs] CVS: nfsv4
> > > 
> > > CVSROOT:   /cvs
> > > Module name:   nfsv4
> > > Changes by:   iyer at citi.   2006/08/01 01:28:20
> > > 
> > > Modified files:
> > >    cvs/pnfs/fs/nfs: nfs4proc.c
> > > 
> > > Log message:
> > > Making LAYOUTRETURN synchronous. Having LAYOUTRETURN be asynchronous
> 
> > > causes race condition between LAYOUTRETURN and the inode freeing 
> > > routines.
> > > 
> > > _______________________________________________
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> > > pNFS at linux-nfs.org
> > > http://linux-nfs.org/cgi-bin/mailman/listinfo/pnfs
> > > [attachment "diff" deleted by Marc Eshel/Almaden/IBM] 
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