[PATCH v2 6/6] nfsd: Reorder nfsd_cache_match to check more powerful discriminators first

[Trond Myklebust <trond.myklebust@primarydata.com>]

We would normally expect the xid and the checksum to be the best
discriminators. Check them before looking at the procedure number,
etc.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
 fs/nfsd/nfscache.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 74603654b7f9..122f69185ef5 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -338,20 +338,24 @@ nfsd_cache_csum(struct svc_rqst *rqstp)
 static bool
 nfsd_cache_match(struct svc_rqst *rqstp, __wsum csum, struct svc_cacherep *rp)
 {
-	/* Check RPC header info first */
-	if (rqstp->rq_xid != rp->c_xid || rqstp->rq_proc != rp->c_proc ||
-	    rqstp->rq_prot != rp->c_prot || rqstp->rq_vers != rp->c_vers ||
-	    rqstp->rq_arg.len != rp->c_len ||
-	    !rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) ||
-	    rpc_get_port(svc_addr(rqstp)) != rpc_get_port((struct sockaddr *)&rp->c_addr))
+	/* Check RPC XID first */
+	if (rqstp->rq_xid != rp->c_xid)
 		return false;
-
 	/* compare checksum of NFS data */
 	if (csum != rp->c_csum) {
 		++payload_misses;
 		return false;
 	}
 
+	/* Other discriminators */
+	if (rqstp->rq_proc != rp->c_proc ||
+	    rqstp->rq_prot != rp->c_prot ||
+	    rqstp->rq_vers != rp->c_vers ||
+	    rqstp->rq_arg.len != rp->c_len ||
+	    !rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) ||
+	    rpc_get_port(svc_addr(rqstp)) != rpc_get_port((struct sockaddr *)&rp->c_addr))
+		return false;
+
 	return true;
 }
 
-- 
1.9.3