dmu_tx kstat cleanup

A few counters in the dmu_tx kstats are obsolete or no longer
bumped properly.

- The sync task restructuring commit
  13fe019 removed the code
  that bumpted dmu_tx_quota. The counter is now bumped in two
  cases, instead of just the one case as before (after the result
  of dsl_dataset_check_quota call). The second case is where
  we check the requested reservation against the actual pool size,
  as this is an implicit quota of sorts.

- The write throttle restructuring commit
  e8b96c6 makes dmu_tx_how and
  dmu_tx_inflight obsolete, so they are removed.

Signed-off-by: Kohsuke Kawaguchi <[email protected]>
Signed-off-by: Ned Bass <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes openzfs#1914

include/sys/dmu_tx.h

@@ -130,10 +130,8 @@ typedef struct dmu_tx_stats {
 	kstat_named_t dmu_tx_error;
 	kstat_named_t dmu_tx_suspended;
 	kstat_named_t dmu_tx_group;
-	kstat_named_t dmu_tx_how;
 	kstat_named_t dmu_tx_memory_reserve;
 	kstat_named_t dmu_tx_memory_reclaim;
-	kstat_named_t dmu_tx_memory_inflight;
 	kstat_named_t dmu_tx_dirty_throttle;
 	kstat_named_t dmu_tx_dirty_delay;
 	kstat_named_t dmu_tx_dirty_over_max;

module/zfs/dmu_tx.c

@@ -48,10 +48,8 @@ dmu_tx_stats_t dmu_tx_stats = {
 	{ "dmu_tx_error",		KSTAT_DATA_UINT64 },
 	{ "dmu_tx_suspended",		KSTAT_DATA_UINT64 },
 	{ "dmu_tx_group",		KSTAT_DATA_UINT64 },
-	{ "dmu_tx_how",			KSTAT_DATA_UINT64 },
 	{ "dmu_tx_memory_reserve",	KSTAT_DATA_UINT64 },
 	{ "dmu_tx_memory_reclaim",	KSTAT_DATA_UINT64 },
-	{ "dmu_tx_memory_inflight",	KSTAT_DATA_UINT64 },
 	{ "dmu_tx_dirty_throttle",	KSTAT_DATA_UINT64 },
 	{ "dmu_tx_dirty_delay",		KSTAT_DATA_UINT64 },
 	{ "dmu_tx_dirty_over_max",	KSTAT_DATA_UINT64 },

module/zfs/dsl_dir.c

@@ -635,6 +635,7 @@ dsl_dir_tempreserve_impl(dsl_dir_t *dd, uint64_t asize, boolean_t netfree,
 		    asize, est_inflight, &used_on_disk, &ref_rsrv);
 		if (error) {
 			mutex_exit(&dd->dd_lock);
+			DMU_TX_STAT_BUMP(dmu_tx_quota);
 			return (error);
 		}
 	}
@@ -683,6 +684,7 @@ dsl_dir_tempreserve_impl(dsl_dir_t *dd, uint64_t asize, boolean_t netfree,
 		    used_on_disk>>10, est_inflight>>10,
 		    quota>>10, asize>>10, retval);
 		mutex_exit(&dd->dd_lock);
+		DMU_TX_STAT_BUMP(dmu_tx_quota);
 		return (SET_ERROR(retval));
 	}