[PATCH] NFSD: nfsd4_open Avoid race with grace period expiration

[Boaz Harrosh <bharrosh@panasas.com>]

locks_in_grace() was called twice one for the "yes" case second
for the "no" case. If the status changes between these two calls
the Server would do the wrong thing. Sample it only once.

Also Add a DMESG print in the case of a bad (old) client that does
*not* send a RECLAIM_COMPLETE before doing new opens. The admin might
want to know it has an unsupported client at hand. Because in this
case with our server the client will get stuck in an endless loop.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
---
 fs/nfsd/nfs4proc.c |   23 ++++++++++++++++-------
 1 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index a68384f..efc6369 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -301,8 +301,12 @@ nfsd4_open(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	 */
 	if (nfsd4_has_session(cstate) &&
 	    !cstate->session->se_client->cl_firststate &&
-	    open->op_claim_type != NFS4_OPEN_CLAIM_PREVIOUS)
+	    open->op_claim_type != NFS4_OPEN_CLAIM_PREVIOUS) {
+		printk(KERN_INFO
+			"NFSD: nfsd4_open: Broken client, "
+			"open sent before RECLAIM_COMPLETE done\n");
 		return nfserr_grace;
+	}
 
 	if (nfsd4_has_session(cstate))
 		copy_clientid(&open->op_clientid, cstate->session);
@@ -333,12 +337,17 @@ nfsd4_open(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 
 	/* Openowner is now set, so sequence id will get bumped.  Now we need
 	 * these checks before we do any creates: */
-	status = nfserr_grace;
-	if (locks_in_grace() && open->op_claim_type != NFS4_OPEN_CLAIM_PREVIOUS)
-		goto out;
-	status = nfserr_no_grace;
-	if (!locks_in_grace() && open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS)
-		goto out;
+	if (locks_in_grace()) {
+		if (open->op_claim_type != NFS4_OPEN_CLAIM_PREVIOUS) {
+			status = nfserr_grace;
+			goto out;
+		}
+	} else {
+		if (open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS) {
+			status = nfserr_no_grace;
+			goto out;
+		}
+	}
 
 	switch (open->op_claim_type) {
 		case NFS4_OPEN_CLAIM_DELEGATE_CUR:
-- 
1.7.6