3484 enhance and document tail follow support
Reviewed by: Joshua M. Clulow <jmc@joyent.com>

*** 21,30 ****
--- 21,33 ----
  /*
   * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
+ /*
+  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
+  */
  
  /*
   * File Events Notification
   * ------------------------
   *
*** 1963,1973 ****
                  event  |= FILE_ACCESS;
          }
          if (op & FOP_ATTRIB_MASK) {
                  event  |= FILE_ATTRIB;
          }
! 
          if (event) {
                  port_fop_sendevent(vp,  event, NULL, NULL);
          }
  }
  
--- 1966,1978 ----
                  event  |= FILE_ACCESS;
          }
          if (op & FOP_ATTRIB_MASK) {
                  event  |= FILE_ATTRIB;
          }
!         if (op & FOP_TRUNC_MASK) {
!                 event  |= FILE_TRUNC;
!         }
          if (event) {
                  port_fop_sendevent(vp,  event, NULL, NULL);
          }
  }
  
*** 2145,2154 ****
--- 2150,2162 ----
          int             retval;
          vnode_t         *vp = (vnode_t *)vf->fa_fnode->fn_available;
          int             events = 0;
  
          retval = vnext_setattr(vf, vap, flags, cr, ct);
+         if (vap->va_mask & AT_SIZE) {
+                 events |= FOP_FILE_TRUNC;
+         }
          if (vap->va_mask & (AT_SIZE|AT_MTIME)) {
                  events |= FOP_FILE_SETATTR_MTIME;
          }
          if (vap->va_mask & AT_ATIME) {
                  events |= FOP_FILE_SETATTR_ATIME;
*** 2320,2331 ****
                  break;
          case    VE_RMDIR:
                          port_fop_sendevent(vp, FILE_DELETE, dvp, name);
                  break;
          case    VE_CREATE:
!                         port_fop_sendevent(vp, FILE_MODIFIED|FILE_ATTRIB,
!                             NULL, NULL);
                  break;
          case    VE_LINK:
                          port_fop_sendevent(vp, FILE_ATTRIB, NULL, NULL);
                  break;
  
--- 2328,2339 ----
                  break;
          case    VE_RMDIR:
                          port_fop_sendevent(vp, FILE_DELETE, dvp, name);
                  break;
          case    VE_CREATE:
!                         port_fop_sendevent(vp,
!                             FILE_MODIFIED|FILE_ATTRIB|FILE_TRUNC, NULL, NULL);
                  break;
          case    VE_LINK:
                          port_fop_sendevent(vp, FILE_ATTRIB, NULL, NULL);
                  break;