NFSD: Refactor nfsd_dispatch() error paths

nfsd_dispatch() is a hot path. Ensure the compiler takes the
processing of rare error cases out of line.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index aa51683..e793344 100644 (file)
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -1021,29 +1021,24 @@ int nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
        dprintk("nfsd_dispatch: vers %d proc %d\n",
                                rqstp->rq_vers, rqstp->rq_proc);
 
-       if (nfs_request_too_big(rqstp, proc)) {
-               dprintk("nfsd: NFSv%d argument too large\n", rqstp->rq_vers);
-               *statp = rpc_garbage_args;
-               return 1;
-       }
+       if (nfs_request_too_big(rqstp, proc))
+               goto out_too_large;
+
        /*
         * Give the xdr decoder a chance to change this if it wants
         * (necessary in the NFSv4.0 compound case)
         */
        rqstp->rq_cachetype = proc->pc_cachetype;
-       if (!proc->pc_decode(rqstp, argv->iov_base)) {
-               dprintk("nfsd: failed to decode arguments!\n");
-               *statp = rpc_garbage_args;
-               return 1;
-       }
+       if (!proc->pc_decode(rqstp, argv->iov_base))
+               goto out_decode_err;
 
        switch (nfsd_cache_lookup(rqstp)) {
        case RC_DOIT:
                break;
        case RC_REPLY:
-               return 1;
+               goto out_cached_reply;
        case RC_DROPIT:
-               return 0;
+               goto out_dropit;
        }
 
        /*
@@ -1055,11 +1050,8 @@ int nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
 
        nfserr = proc->pc_func(rqstp);
        nfserr = map_new_errors(rqstp->rq_vers, nfserr);
-       if (nfserr == nfserr_dropit || test_bit(RQ_DROPME, &rqstp->rq_flags)) {
-               dprintk("nfsd: Dropping request; may be revisited later\n");
-               nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
-               return 0;
-       }
+       if (nfserr == nfserr_dropit || test_bit(RQ_DROPME, &rqstp->rq_flags))
+               goto out_update_drop;
 
        if (rqstp->rq_proc != 0)
                *nfserrp++ = nfserr;
@@ -1067,16 +1059,34 @@ int nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
        /*
         * For NFSv2, additional info is never returned in case of an error.
         */
-       if (!(nfserr && rqstp->rq_vers == 2)) {
-               if (!proc->pc_encode(rqstp, nfserrp)) {
-                       dprintk("nfsd: failed to encode result!\n");
-                       nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
-                       *statp = rpc_system_err;
-                       return 1;
-               }
-       }
+       if (!(nfserr && rqstp->rq_vers == 2))
+               if (!proc->pc_encode(rqstp, nfserrp))
+                       goto out_encode_err;
 
        nfsd_cache_update(rqstp, rqstp->rq_cachetype, statp + 1);
+out_cached_reply:
+       return 1;
+
+out_too_large:
+       dprintk("nfsd: NFSv%d argument too large\n", rqstp->rq_vers);
+       *statp = rpc_garbage_args;
+       return 1;
+
+out_decode_err:
+       dprintk("nfsd: failed to decode arguments!\n");
+       *statp = rpc_garbage_args;
+       return 1;
+
+out_update_drop:
+       dprintk("nfsd: Dropping request; may be revisited later\n");
+       nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
+out_dropit:
+       return 0;
+
+out_encode_err:
+       dprintk("nfsd: failed to encode result!\n");
+       nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
+       *statp = rpc_system_err;
        return 1;
 }