XXXX give me a better summary

*** 18,27 ****
--- 18,28 ----
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 1987, 2010, Oracle and/or its affiliates. All rights reserved.
+  * Copyright 2015, OmniTI Computer Consulting, Inc. All rights reserved.
   */
  
  /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  /*        All Rights Reserved   */
  
*** 132,142 ****
   * swap device. Flags are one of:
   *      SA_NOT  Must have a slot from a physical swap device other than the
   *              the one containing input (*vpp, *offp).
   * Less slots than requested may be returned. *lenp allocated slots are
   * returned starting at *offp on *vpp.
!  * Returns 1 for a successful allocation, 0 for couldn't allocate any slots.
   */
  int
  swap_phys_alloc(
          struct vnode **vpp,
          u_offset_t *offp,
--- 133,144 ----
   * swap device. Flags are one of:
   *      SA_NOT  Must have a slot from a physical swap device other than the
   *              the one containing input (*vpp, *offp).
   * Less slots than requested may be returned. *lenp allocated slots are
   * returned starting at *offp on *vpp.
!  * Returns 1 for a successful allocation, 0 for couldn't allocate any slots,
!  * and -1 when there are no swap devices on this system.
   */
  int
  swap_phys_alloc(
          struct vnode **vpp,
          u_offset_t *offp,
*** 146,155 ****
--- 148,162 ----
          struct swapinfo *sip;
          offset_t soff, noff;
          size_t len;
  
          mutex_enter(&swapinfo_lock);
+         if (swapinfo == NULL) {
+                 /* NO SWAP DEVICES on this system currently. */
+                 mutex_exit(&swapinfo_lock);
+                 return (-1);
+         }
          sip = silast;
  
          /* Find a desirable physical device and allocate from it. */
          do {
                  if (sip == NULL)
*** 1656,1665 ****
--- 1663,1673 ----
   * backed as [*offp, *offp + *lenp) and the physical offsets used to
   * back them from *pvpp in the range [*pstartp, *pstartp + *lenp).
   * Returns      0 for success
   *              SE_NOANON -- no anon slot for requested paged
   *              SE_NOSWAP -- no physical swap space available
+  *              SE_NODEV -- no swap devices on this system
   */
  int
  swap_newphysname(
          struct vnode *vp,
          u_offset_t offset,
*** 1678,1688 ****
  
          ASSERT(*offp <= offset && offset < *offp + *lenp);
  
          /* Get new physical swap slots. */
          plen = *lenp;
!         if (!swap_phys_alloc(&pvp, &pstart, &plen, 0)) {
                  /*
                   * No swap available so return error unless requested
                   * offset is already backed in which case return that.
                   */
                  ahm = AH_MUTEX(vp, offset);
--- 1686,1697 ----
  
          ASSERT(*offp <= offset && offset < *offp + *lenp);
  
          /* Get new physical swap slots. */
          plen = *lenp;
!         error = swap_phys_alloc(&pvp, &pstart, &plen, 0);
!         if (error != 1) {
                  /*
                   * No swap available so return error unless requested
                   * offset is already backed in which case return that.
                   */
                  ahm = AH_MUTEX(vp, offset);
*** 1690,1700 ****
                  if ((ap = swap_anon(vp, offset)) == NULL) {
                          error = SE_NOANON;
                          mutex_exit(ahm);
                          return (error);
                  }
!                 error = (ap->an_pvp ? 0 : SE_NOSWAP);
                  *offp = offset;
                  *lenp = PAGESIZE;
                  *pvpp = ap->an_pvp;
                  *poffp = ap->an_poff;
                  mutex_exit(ahm);
--- 1699,1709 ----
                  if ((ap = swap_anon(vp, offset)) == NULL) {
                          error = SE_NOANON;
                          mutex_exit(ahm);
                          return (error);
                  }
!                 error = (ap->an_pvp ? 0 : (error == 0) ? SE_NOSWAP : SE_NODEV);
                  *offp = offset;
                  *lenp = PAGESIZE;
                  *pvpp = ap->an_pvp;
                  *poffp = ap->an_poff;
                  mutex_exit(ahm);