3752 want more verifiable dbuf user eviction
Submitted by:   Justin Gibbs <justing@spectralogic.com>
Submitted by:   Will Andrews <willa@spectralogic.com>

*** 43,52 ****
--- 43,55 ----
  
  struct dsl_dataset;
  struct dsl_dir;
  struct dsl_pool;
  
+ #define DS_HAS_PHYS(ds) \
+         ((ds)->ds_dbuf != NULL && (ds)->ds_dbuf->db_data != NULL)
+ 
  #define DS_FLAG_INCONSISTENT    (1ULL<<0)
  #define DS_IS_INCONSISTENT(ds)  \
          ((ds)->ds_phys->ds_flags & DS_FLAG_INCONSISTENT)
  /*
   * Note: nopromote can not yet be set, but we want support for it in this
*** 109,123 ****
          uint64_t ds_props_obj;          /* DMU_OT_DSL_PROPS for snaps */
          uint64_t ds_userrefs_obj;       /* DMU_OT_USERREFS */
          uint64_t ds_pad[5]; /* pad out to 320 bytes for good measure */
  } dsl_dataset_phys_t;
  
  typedef struct dsl_dataset {
          /* Immutable: */
          struct dsl_dir *ds_dir;
!         dsl_dataset_phys_t *ds_phys;
!         dmu_buf_t *ds_dbuf;
          uint64_t ds_object;
          uint64_t ds_fsid_guid;
  
          /* only used in syncing context, only valid for non-snapshots: */
          struct dsl_dataset *ds_prev;
--- 112,135 ----
          uint64_t ds_props_obj;          /* DMU_OT_DSL_PROPS for snaps */
          uint64_t ds_userrefs_obj;       /* DMU_OT_USERREFS */
          uint64_t ds_pad[5]; /* pad out to 320 bytes for good measure */
  } dsl_dataset_phys_t;
  
+ typedef struct dsl_dataset_dbuf {
+         uint8_t dsdb_pad[offsetof(dmu_buf_t, db_data)];
+         dsl_dataset_phys_t *dsdb_data;
+ } dsl_dataset_dbuf_t;
+ 
  typedef struct dsl_dataset {
+         dmu_buf_user_t db_evict;
+ 
          /* Immutable: */
          struct dsl_dir *ds_dir;
!         union {
!                 dmu_buf_t *ds_dmu_db;
!                 dsl_dataset_dbuf_t *ds_db;
!         } ds_db_u;
          uint64_t ds_object;
          uint64_t ds_fsid_guid;
  
          /* only used in syncing context, only valid for non-snapshots: */
          struct dsl_dataset *ds_prev;
*** 161,170 ****
--- 173,195 ----
  
          /* Protected by ds_lock; keep at end of struct for better locality */
          char ds_snapname[MAXNAMELEN];
  } dsl_dataset_t;
  
+ /* See sys/dmu.h:dmu_buf_user_t for why we have these. */
+ #define ds_dbuf ds_db_u.ds_dmu_db
+ #define ds_phys ds_db_u.ds_db->dsdb_data
+ 
+ struct dsl_ds_destroyarg {
+         dsl_dataset_t *ds;              /* ds to destroy */
+         dsl_dataset_t *rm_origin;       /* also remove our origin? */
+         boolean_t is_origin_rm;         /* set if removing origin snap */
+         boolean_t defer;                /* destroy -d requested? */
+         boolean_t releasing;            /* destroying due to release? */
+         boolean_t need_prep;            /* do we need to retry due to EBUSY? */
+ };
+ 
  /*
   * The max length of a temporary tag prefix is the number of hex digits
   * required to express UINT64_MAX plus one for the hyphen.
   */
  #define MAX_TAG_PREFIX_LEN      17