4045 zfs write throttle & i/o scheduler performance work
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>

*** 21,31 ****
  /*
   * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  /*
!  * Copyright (c) 2012 by Delphix. All rights reserved.
   */
  
  #ifndef _SYS_DMU_TX_H
  #define _SYS_DMU_TX_H
  
--- 21,31 ----
  /*
   * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  /*
!  * Copyright (c) 2013 by Delphix. All rights reserved.
   */
  
  #ifndef _SYS_DMU_TX_H
  #define _SYS_DMU_TX_H
  
*** 58,69 ****
          uint64_t tx_lastsnap_txg;
          uint64_t tx_lasttried_txg;
          txg_handle_t tx_txgh;
          void *tx_tempreserve_cookie;
          struct dmu_tx_hold *tx_needassign_txh;
!         list_t tx_callbacks; /* list of dmu_tx_callback_t on this dmu_tx */
!         uint8_t tx_anyobj;
          int tx_err;
  #ifdef ZFS_DEBUG
          uint64_t tx_space_towrite;
          uint64_t tx_space_tofree;
          uint64_t tx_space_tooverwrite;
--- 58,83 ----
          uint64_t tx_lastsnap_txg;
          uint64_t tx_lasttried_txg;
          txg_handle_t tx_txgh;
          void *tx_tempreserve_cookie;
          struct dmu_tx_hold *tx_needassign_txh;
! 
!         /* list of dmu_tx_callback_t on this dmu_tx */
!         list_t tx_callbacks;
! 
!         /* placeholder for syncing context, doesn't need specific holds */
!         boolean_t tx_anyobj;
! 
!         /* has this transaction already been delayed? */
!         boolean_t tx_waited;
! 
!         /* time this transaction was created */
!         hrtime_t tx_start;
! 
!         /* need to wait for sufficient dirty space */
!         boolean_t tx_wait_dirty;
! 
          int tx_err;
  #ifdef ZFS_DEBUG
          uint64_t tx_space_towrite;
          uint64_t tx_space_tofree;
          uint64_t tx_space_tooverwrite;