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>

*** 18,28 ****
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 2012 by Delphix. All rights reserved.
   * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
   */
  
  #ifndef _SYS_DBUF_H
  #define _SYS_DBUF_H
--- 18,28 ----
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 2013 by Delphix. All rights reserved.
   * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
   */
  
  #ifndef _SYS_DBUF_H
  #define _SYS_DBUF_H
*** 110,119 ****
--- 110,122 ----
          struct dbuf_dirty_record *dr_next;
  
          /* pointer to parent dirty record */
          struct dbuf_dirty_record *dr_parent;
  
+         /* How much space was changed to dsl_pool_dirty_space() for this? */
+         unsigned int dr_accounted;
+ 
          union dirty_types {
                  struct dirty_indirect {
  
                          /* protect access to list */
                          kmutex_t dr_mtx;
*** 252,262 ****
  dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
      void *tag);
  int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid, int create,
      void *tag, dmu_buf_impl_t **dbp);
  
! void dbuf_prefetch(struct dnode *dn, uint64_t blkid);
  
  void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
  uint64_t dbuf_refcount(dmu_buf_impl_t *db);
  
  void dbuf_rele(dmu_buf_impl_t *db, void *tag);
--- 255,265 ----
  dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
      void *tag);
  int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid, int create,
      void *tag, dmu_buf_impl_t **dbp);
  
! void dbuf_prefetch(struct dnode *dn, uint64_t blkid, zio_priority_t prio);
  
  void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
  uint64_t dbuf_refcount(dmu_buf_impl_t *db);
  
  void dbuf_rele(dmu_buf_impl_t *db, void *tag);