8115 parallel zfs mount

*** 21,31 ****
  
  /*
   * Copyright (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright 2016 Joyent, Inc.
   * Copyright 2016 Toomas Soome <tsoome@me.com>
!  * Copyright (c) 2016 by Delphix. All rights reserved.
   * Copyright 2016 Nexenta Systems, Inc.
   * Copyright 2017 RackTop Systems.
   */
  
  /*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
--- 21,31 ----
  
  /*
   * Copyright (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright 2016 Joyent, Inc.
   * Copyright 2016 Toomas Soome <tsoome@me.com>
!  * Copyright (c) 2016, 2017 by Delphix. All rights reserved.
   * Copyright 2016 Nexenta Systems, Inc.
   * Copyright 2017 RackTop Systems.
   */
  
  /*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
*** 1289,1299 ****
                   * Do a lookupname prior to taking the
                   * writelock. Mark this as completed if
                   * successful for later cleanup and addition to
                   * the mount in progress table.
                   */
!                 if ((uap->flags & MS_GLOBAL) == 0 &&
                      lookupname(uap->spec, fromspace,
                      FOLLOW, NULL, &bvp) == 0) {
                          addmip = 1;
                  }
  
--- 1289,1300 ----
                   * Do a lookupname prior to taking the
                   * writelock. Mark this as completed if
                   * successful for later cleanup and addition to
                   * the mount in progress table.
                   */
!                 if ((vswp->vsw_flag & VSW_MOUNTDEV) &&
!                     (uap->flags & MS_GLOBAL) == 0 &&
                      lookupname(uap->spec, fromspace,
                      FOLLOW, NULL, &bvp) == 0) {
                          addmip = 1;
                  }
  
*** 1505,1515 ****
           * on a spliced, non-global fs. If so, we don't want to do it again
           * since we cannot do a lookupname after taking the
           * wlock above. This case is for a non-spliced, non-global filesystem.
           */
          if (!addmip) {
!                 if ((uap->flags & MS_GLOBAL) == 0 &&
                      lookupname(uap->spec, fromspace, FOLLOW, NULL, &bvp) == 0) {
                          addmip = 1;
                  }
          }
  
--- 1506,1517 ----
           * on a spliced, non-global fs. If so, we don't want to do it again
           * since we cannot do a lookupname after taking the
           * wlock above. This case is for a non-spliced, non-global filesystem.
           */
          if (!addmip) {
!                 if ((vswp->vsw_flag & VSW_MOUNTDEV) &&
!                     (uap->flags & MS_GLOBAL) == 0 &&
                      lookupname(uap->spec, fromspace, FOLLOW, NULL, &bvp) == 0) {
                          addmip = 1;
                  }
          }