Re: [NFS] [Linux-cluster] [RFC] NLM lock failover admin interface

[Wendy Cheng <wcheng redhat com>]

J. Bruce Fields wrote:

> On Mon, Jun 12, 2006 at 01:25:43AM -0400, Wendy Cheng wrote:
>  
>
> > 2. Adding a new flag into "exportfs" command, say "h", such that
> >
> >   "exportfs -uh *:/export_path"
> >
> > would un-export the entry and drop the NLM locks associated with the
> > entry.
> >    
>
> What does the kernel interface end up looking like in that case?
>
>  
Happy to see this new exportfs command gets positive response - it was 
our original pick too.

Uploaded is part of a draft version of 2.4 base kernel patch - we're 
cleaning up 2.6 patches at this moment. It basically adds a new export 
flag (NFSEXP_FOLOCK - note that ex_flags is an int but is currently only 
defined up to 16 bits) so nfs-util and kernel can communicate.

The nice thing about this approach is the recovery part - the take-over 
server can use the counter part command to export and set grace period 
for one particular interface within the same system call.

-- Wendy

--- linux-2.4.21-43.EL/fs/nfsd/export.c	2006-05-14 17:16:21.000000000 -0400
+++ linux/fs/nfsd/export.c	2006-05-29 02:13:29.000000000 -0400
@@ -388,6 +388,10 @@ exp_unexport(struct nfsctl_export *nxp)
 			exp_do_unexport(exp);
 			err = 0;
 		}
+		if (nxp->ex_flags & NFSEXP_FOLOCK) {
+			dprintk("exp_unexport: nfsd_lockd_unexport called\n");
+			nfsd_lockd_unexport(clp);
+		}
 	}
 
 	exp_unlock();
--- linux-2.4.21-43.EL/include/linux/nfsd/export.h	2006-05-14 17:23:57.000000000 -0400
+++ linux/include/linux/nfsd/export.h	2006-05-29 02:12:07.000000000 -0400
@@ -42,7 +42,7 @@
 #define NFSEXP_FSID			0x2000
 #define NFSEXP_NOACL			0x8000	/* turn off acl support */
 #define NFSEXP_ALLFLAGS		0xFFFF
-
+#define NFSEXP_FOLOCK			0x00010000	/* NLM lock failover */
 
 #ifdef __KERNEL__