Re: Non-blocking lock requests during the grace period

[Juan Gomez <juang@us.ibm.com>]

                                                                                                               
                                                                                                               
                                                                                                               


Trond,

I think this would fix it but the patch I have tested locally is a bit
different.

1).-Instead of

+wait_on_grace:
+                        if (!argp->block)
+                                    return -EAGAIN;

I have

+wait_on_grace:
+                        if ((proc == NLMPROC_LOCK) && !argp->block)
+                                    return -EAGAIN;

2.-I also have this part enclosed in the if(resp->status ==
NLM_LCK_DENIED_GRACE_PERIOD) as follows:

if(resp->status == NLM_LCK_DENIED_GRACE_PERIOD) {

      blah blah...

wait_on_grace:
                         if ((proc == NLMPROC_LOCK) && !argp->block)
                                     return -EAGAIN
} else {

      ....
}

This with the intention to be very specific as to when we want the return
-EAGAIN to be called.

Juan



|---------+---------------------------->
|         |           Trond Myklebust  |
|         |           <trond.myklebust@|
|         |           fys.uio.no>      |
|         |                            |
|         |           11/14/02 06:33 PM|
|         |                            |
|---------+---------------------------->
  >-------------------------------------------------------------------------------------------------------------------------|
  |                                                                                                                         |
  |       To:       Juan Gomez/Almaden/IBM@IBMUS                                                                            |
  |       cc:       nfs@lists.sourceforge.net, linux-kernel@vger.kernel.org                                                 |
  |       Subject:  Re: Non-blocking lock requests during the grace period                                                  |
  |                                                                                                                         |
  |                                                                                                                         |
  >-------------------------------------------------------------------------------------------------------------------------|



>>>>> " " == Juan Gomez <juang@us.ibm.com> writes:

     > I found out that the current Linux client of lockd blocks
     > non-blocking lock requests while the server is in the grace
     > period.  I think this is incorrect behavior and I am wondering
     > if the will exists out there to correct this and return
     > "resource not available" to the process when a request is for a
     > *non-blocking* lock while the server is in the grace period.

Would the following fix it?

Cheers,
  Trond

--- linux-2.5.47/fs/lockd/clntproc.c.orig        2002-09-29
10:15:13.000000000 -0400
+++ linux-2.5.47/fs/lockd/clntproc.c             2002-11-14
21:32:26.000000000 -0500
@@ -256,10 +256,8 @@
                         msg.rpc_cred = NULL;

             do {
-                        if (host->h_reclaiming && !argp->reclaim) {
-
interruptible_sleep_on(&host->h_gracewait);
-                                    continue;
-                        }
+                        if (host->h_reclaiming && !argp->reclaim)
+                                    goto wait_on_grace;

                         /* If we have no RPC client yet, create one. */
                         if ((clnt = nlm_bind_host(host)) == NULL)
@@ -296,6 +294,9 @@
                                     dprintk("lockd: server returns status
%d\n", resp->status);
                                     return 0;         /* Okay, call
complete */
                         }
+wait_on_grace:
+                        if (!argp->block)
+                                    return -EAGAIN;

                         /* Back off a little and try again */
                         interruptible_sleep_on_timeout(&host->h_gracewait,
15*HZ);