5045 use atomic_{inc,dec}_* instead of atomic_add_*

*** 850,860 ****
           * hang the snapshot on.
           */
          nmnp = mntgetnode(vp);
  
          *vpp = MTOV(nmnp);
!         atomic_add_32(&MTOD(nmnp)->mnt_nopen, 1);
          VN_RELE(vp);
          return (0);
  }
  
  /* ARGSUSED */
--- 850,860 ----
           * hang the snapshot on.
           */
          nmnp = mntgetnode(vp);
  
          *vpp = MTOV(nmnp);
!         atomic_inc_32(&MTOD(nmnp)->mnt_nopen);
          VN_RELE(vp);
          return (0);
  }
  
  /* ARGSUSED */
*** 873,883 ****
          if (vp->v_count == 1) {
                  rw_enter(&mnp->mnt_contents, RW_WRITER);
                  mntfs_freesnap(mnp, &mnp->mnt_read);
                  mntfs_freesnap(mnp, &mnp->mnt_ioctl);
                  rw_exit(&mnp->mnt_contents);
!                 atomic_add_32(&MTOD(mnp)->mnt_nopen, -1);
          }
          return (0);
  }
  
  /* ARGSUSED */
--- 873,883 ----
          if (vp->v_count == 1) {
                  rw_enter(&mnp->mnt_contents, RW_WRITER);
                  mntfs_freesnap(mnp, &mnp->mnt_read);
                  mntfs_freesnap(mnp, &mnp->mnt_ioctl);
                  rw_exit(&mnp->mnt_contents);
!                 atomic_dec_32(&MTOD(mnp)->mnt_nopen);
          }
          return (0);
  }
  
  /* ARGSUSED */