Revert exi_zone to exi_zoneid, and install exi_ne backpointer

*** 471,489 ****
          struct exportinfo  *tree_exi;
          struct exp_visible *tree_vis;
  } treenode_t;
  
  /*
   * TREE_ROOT checks if the node corresponds to a filesystem root or
   * the zone's root directory.
   * TREE_EXPORTED checks if the node is explicitly shared
   */
  
  #define TREE_ROOT(t) \
          ((t)->tree_exi != NULL && \
          (((t)->tree_exi->exi_vp->v_flag & VROOT) || \
!         VN_CMP((t)->tree_exi->exi_zone->zone_rootvp, (t)->tree_exi->exi_vp)))
  
  #define TREE_EXPORTED(t) \
          ((t)->tree_exi && !PSEUDO((t)->tree_exi))
  
  #define EXPTABLESIZE   256
--- 471,495 ----
          struct exportinfo  *tree_exi;
          struct exp_visible *tree_vis;
  } treenode_t;
  
  /*
+  * Now that we have links to chase, we can get the zone rootvp just from
+  * an export.  No current-zone-context needed.
+  */
+ #define EXI_TO_ZONEROOTVP(exi) ((exi)->exi_ne->exi_root->exi_vp)
+ 
+ /*
   * TREE_ROOT checks if the node corresponds to a filesystem root or
   * the zone's root directory.
   * TREE_EXPORTED checks if the node is explicitly shared
   */
  
  #define TREE_ROOT(t) \
          ((t)->tree_exi != NULL && \
          (((t)->tree_exi->exi_vp->v_flag & VROOT) || \
!         VN_CMP(EXI_TO_ZONEROOTVP((t)->tree_exi), (t)->tree_exi->exi_vp)))
  
  #define TREE_EXPORTED(t) \
          ((t)->tree_exi && !PSEUDO((t)->tree_exi))
  
  #define EXPTABLESIZE   256
*** 521,530 ****
--- 527,537 ----
          struct treenode         *exi_tree;
          fhandle_t               exi_fh;
          krwlock_t               exi_cache_lock;
          kmutex_t                exi_lock;
          uint_t                  exi_count;
+         zoneid_t                exi_zoneid;
          vnode_t                 *exi_vp;
          vnode_t                 *exi_dvp;
          avl_tree_t              *exi_cache[AUTH_TABLESIZE];
          struct log_buffer       *exi_logbuffer;
          struct exp_visible      *exi_visible;
*** 532,561 ****
          unsigned                exi_volatile_dev:1;
          unsigned                exi_moved:1;
          int                     exi_id;
          avl_node_t              exi_id_link;
          /*
!          * Soft-reference/backpointer to the zone.  The ZSD callbacks we have
!          * invoke cleanup code that crosses into OTHER cleanup functions that
!          * may assume same-zone context and attempt to find their own ZSD,
!          * using "curzone" when in fact "curzone" is global when called from
!          * NFS's ZSD cleanup (see lm_unexport->nlm_unexport for an example).
!          *
!          * During ZSD shutdown or destroy callbacks, the zone structure
!          * does not have its mutex held, and it has just-enough references
!          * to not free from underneath us.  This field is not a proper
!          * referenced-held zone pointer, and only ZSD callbacks should use
!          * it.
           */
!         struct zone             *exi_zone;
  #ifdef VOLATILE_FH_TEST
          uint32_t                exi_volatile_id;
          struct ex_vol_rename    *exi_vol_rename;
          kmutex_t                exi_vol_rename_lock;
  #endif /* VOLATILE_FH_TEST -- keep last! */
  };
- #define exi_zoneid exi_zone->zone_id
  
  typedef struct exportinfo exportinfo_t;
  typedef struct exportdata exportdata_t;
  typedef struct secinfo secinfo_t;
  
--- 539,560 ----
          unsigned                exi_volatile_dev:1;
          unsigned                exi_moved:1;
          int                     exi_id;
          avl_node_t              exi_id_link;
          /*
!          * Soft-reference/backpointer to zone's nfs_export_t.
!          * This allows us access to the zone's rootvp (stored in
!          * exi_ne->exi_root->exi_vp) even if the current thread isn't in
!          * same-zone context.
           */
!         struct nfs_export       *exi_ne;
  #ifdef VOLATILE_FH_TEST
          uint32_t                exi_volatile_id;
          struct ex_vol_rename    *exi_vol_rename;
          kmutex_t                exi_vol_rename_lock;
  #endif /* VOLATILE_FH_TEST -- keep last! */
  };
  
  typedef struct exportinfo exportinfo_t;
  typedef struct exportdata exportdata_t;
  typedef struct secinfo secinfo_t;
  
*** 673,683 ****
           * must be held when searching or modifiying the exportinfo list.
           */
          krwlock_t exported_lock;
  
          /* "public" and default (root) location for public filehandle */
!         struct exportinfo *exi_public, *exi_root;
          /* For checking default public file handle */
          fid_t exi_rootfid;
          /* For comparing V2 filehandles */
          fhandle_t nullfh2;
  
--- 672,683 ----
           * must be held when searching or modifiying the exportinfo list.
           */
          krwlock_t exported_lock;
  
          /* "public" and default (root) location for public filehandle */
!         struct exportinfo *exi_public;
!         struct exportinfo *exi_root;
          /* For checking default public file handle */
          fid_t exi_rootfid;
          /* For comparing V2 filehandles */
          fhandle_t nullfh2;