optimize locking a wee bit by holding it for critical parts only

diff --git a/sys/nfs/nfs_node.c b/sys/nfs/nfs_node.c
index b3c234a..0a63a74 100644 (file)
--- a/sys/nfs/nfs_node.c
+++ b/sys/nfs/nfs_node.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: nfs_node.c,v 1.59 2014/12/16 18:30:04 tedu Exp $      */
+/*     $OpenBSD: nfs_node.c,v 1.60 2014/12/23 04:48:47 tedu Exp $      */
 /*     $NetBSD: nfs_node.c,v 1.16 1996/02/18 11:53:42 fvdl Exp $       */
 
 /*
@@ -118,23 +118,27 @@ loop:
         */
        rw_exit_write(&nfs_hashlock);
        error = getnewvnode(VT_NFS, mnt, &nfs_vops, &nvp);
-       /* note that we don't have this vnode set up completely yet */
-       rw_enter_write(&nfs_hashlock);
        if (error) {
                *npp = NULL;
-               rw_exit_write(&nfs_hashlock);
                return (error);
        }
+       /* grab one of these too while we're outside the lock */
+       np2 = pool_get(&nfs_node_pool, PR_WAITOK | PR_ZERO);
+
+       /* note that we don't have this vnode set up completely yet */
+       rw_enter_write(&nfs_hashlock);
        nvp->v_flag |= VLARVAL;
        np = RB_FIND(nfs_nodetree, &nmp->nm_ntree, &find);
+       /* lost race. undo and repeat */
        if (np != NULL) {
+               pool_put(&nfs_node_pool, np2);
                vgone(nvp);
                rw_exit_write(&nfs_hashlock);
                goto loop;
        }
 
        vp = nvp;
-       np = pool_get(&nfs_node_pool, PR_WAITOK | PR_ZERO);
+       np = np2;
        vp->v_data = np;
        /* we now have an nfsnode on this vnode */
        vp->v_flag &= ~VLARVAL;