Print this page
Optimize creation and removal of temporary "user holds" placed on
snapshots by a zfs send, by ensuring all the required holds and
releases are done in a single dsl_sync_task.
Creation now collates the required holds during a dry run and
then uses a single lzc_hold call via zfs_hold_apply instead of
processing each snapshot in turn.
Defered (on exit) cleanup by the kernel is also now done in
dsl_sync_task by reusing dsl_dataset_user_release.
On a test with 11 volumes in a tree each with 8 snapshots on a
single HDD zpool this reduces the time required to perform a full
send from 20 seconds to under 0.8 seconds.
For reference eliminating the hold entirely reduces this 0.15
seconds.
While I'm here:-
* Remove some unused structures
* Fix nvlist_t leak in zfs_release_one

Split Close
Expand all
Collapse all
          --- old/usr/src/uts/common/fs/zfs/sys/dsl_userhold.h
          +++ new/usr/src/uts/common/fs/zfs/sys/dsl_userhold.h
↓ open down ↓ 35 lines elided ↑ open up ↑
  36   36  #endif
  37   37  
  38   38  struct dsl_pool;
  39   39  struct dsl_dataset;
  40   40  struct dmu_tx;
  41   41  
  42   42  int dsl_dataset_user_hold(nvlist_t *holds, minor_t cleanup_minor,
  43   43      nvlist_t *errlist);
  44   44  int dsl_dataset_user_release(nvlist_t *holds, nvlist_t *errlist);
  45   45  int dsl_dataset_get_holds(const char *dsname, nvlist_t *nvl);
  46      -void dsl_dataset_user_release_tmp(struct dsl_pool *dp, uint64_t dsobj,
  47      -    const char *htag);
  48   46  int dsl_dataset_user_hold_check_one(struct dsl_dataset *ds, const char *htag,
  49   47      boolean_t temphold, struct dmu_tx *tx);
  50   48  void dsl_dataset_user_hold_sync_one(struct dsl_dataset *ds, const char *htag,
  51   49      minor_t minor, uint64_t now, struct dmu_tx *tx);
  52   50  
  53   51  #ifdef  __cplusplus
  54   52  }
  55   53  #endif
  56   54  
  57   55  #endif /* _SYS_DSL_USERHOLD_H */
    
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX