Introduce dedupused/dedupsaved pool properties

Currently there is only a dedup ratio reported via pool properties.
If dedup is enabled only for some datasets, it is impossible to say
how much space the ratio actually covers.  Fix this by introducing
dedupused/dedupsaved pool properties, similar to earlier added
block cloning ones.  Combined with work to expose allocation classes
stats, it should give user-space enough visibility to correlate
`zpool list` and `zfs list` space numbers.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Ryan Moeller <ryan.moeller@klarasystems.com>
Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
Closes openzfs#18245

Author: amotin

include/sys/ddt.h

@@ -396,6 +396,8 @@ extern void ddt_get_dedup_histogram(spa_t *spa, ddt_histogram_t *ddh);
 extern void ddt_get_dedup_stats(spa_t *spa, ddt_stat_t *dds_total);
 
 extern uint64_t ddt_get_dedup_dspace(spa_t *spa);
+extern uint64_t ddt_get_dedup_used(spa_t *spa);
+extern uint64_t ddt_get_dedup_saved(spa_t *spa);
 extern uint64_t ddt_get_pool_dedup_ratio(spa_t *spa);
 extern int ddt_get_pool_dedup_cached(spa_t *spa, uint64_t *psize);
 

include/sys/fs/zfs.h

@@ -272,6 +272,8 @@ typedef enum {
 	ZPOOL_PROP_DEDUP_TABLE_QUOTA,
 	ZPOOL_PROP_DEDUPCACHED,
 	ZPOOL_PROP_LAST_SCRUBBED_TXG,
+	ZPOOL_PROP_DEDUPUSED,
+	ZPOOL_PROP_DEDUPSAVED,
 	ZPOOL_NUM_PROPS
 } zpool_prop_t;
 

lib/libzfs/libzfs.abi

@@ -3199,7 +3199,9 @@
       <enumerator name='ZPOOL_PROP_DEDUP_TABLE_QUOTA' value='37'/>
       <enumerator name='ZPOOL_PROP_DEDUPCACHED' value='38'/>
       <enumerator name='ZPOOL_PROP_LAST_SCRUBBED_TXG' value='39'/>
-      <enumerator name='ZPOOL_NUM_PROPS' value='40'/>
+      <enumerator name='ZPOOL_PROP_DEDUPUSED' value='40'/>
+      <enumerator name='ZPOOL_PROP_DEDUPSAVED' value='41'/>
+      <enumerator name='ZPOOL_NUM_PROPS' value='42'/>
     </enum-decl>
     <typedef-decl name='zpool_prop_t' type-id='af1ba157' id='5d0c23fb'/>
     <typedef-decl name='regoff_t' type-id='95e97e5e' id='54a2a2a8'/>

lib/libzfs/libzfs_pool.c

@@ -380,6 +380,8 @@ zpool_get_prop(zpool_handle_t *zhp, zpool_prop_t prop, char *buf,
 		case ZPOOL_PROP_BCLONESAVED:
 		case ZPOOL_PROP_BCLONEUSED:
 		case ZPOOL_PROP_DEDUP_TABLE_SIZE:
+		case ZPOOL_PROP_DEDUPUSED:
+		case ZPOOL_PROP_DEDUPSAVED:
 		case ZPOOL_PROP_DEDUPCACHED:
 			if (literal)
 				(void) snprintf(buf, len, "%llu",

man/man7/zpoolprops.7

@@ -80,6 +80,21 @@ See
 .Xr zpool-prefetch 8 .
 .It Sy dedup_table_size
 Total on-disk size of the deduplication table.
+.It Sy dedupratio
+The ratio of the total amount of storage that would be required to store all
+the deduplicated blocks without deduplication to the actual storage used.
+The
+.Sy dedupratio
+property is calculated as:
+.Pp
+.Sy ( ( dedupsaved + dedupused ) * 100 ) / dedupused
+.It Sy dedupsaved
+The amount of additional storage that would be required if deduplication
+was not used.
+This represents the space saved by deduplication.
+.It Sy dedupused
+The amount of storage used by deduplicated blocks.
+This is the actual physical space occupied on disk after deduplication.
 .It Sy expandsize
 Amount of uninitialized space within the pool or device that can be used to
 increase the total capacity of the pool.

module/zcommon/zpool_prop.c

@@ -117,6 +117,12 @@ zpool_prop_init(void)
 	zprop_register_number(ZPOOL_PROP_DEDUPRATIO, "dedupratio", 0,
 	    PROP_READONLY, ZFS_TYPE_POOL, "<1.00x or higher if deduped>",
 	    "DEDUP", B_FALSE, sfeatures);
+	zprop_register_number(ZPOOL_PROP_DEDUPUSED, "dedupused", 0,
+	    PROP_READONLY, ZFS_TYPE_POOL, "<size>",
+	    "DEDUP_USED", B_FALSE, sfeatures);
+	zprop_register_number(ZPOOL_PROP_DEDUPSAVED, "dedupsaved", 0,
+	    PROP_READONLY, ZFS_TYPE_POOL, "<size>",
+	    "DEDUP_SAVED", B_FALSE, sfeatures);
 	zprop_register_number(ZPOOL_PROP_BCLONEUSED, "bcloneused", 0,
 	    PROP_READONLY, ZFS_TYPE_POOL, "<size>",
 	    "BCLONE_USED", B_FALSE, sfeatures);

module/zfs/ddt_stats.c

@@ -297,6 +297,21 @@ ddt_get_dedup_dspace(spa_t *spa)
 	return (spa->spa_dedup_dspace);
 }
 
+uint64_t
+ddt_get_dedup_used(spa_t *spa)
+{
+	ddt_stat_t dds_total = { 0 };
+
+	ddt_get_dedup_stats(spa, &dds_total);
+	return (dds_total.dds_dsize);
+}
+
+uint64_t
+ddt_get_dedup_saved(spa_t *spa)
+{
+	return (ddt_get_dedup_dspace(spa));
+}
+
 uint64_t
 ddt_get_pool_dedup_ratio(spa_t *spa)
 {

module/zfs/spa.c

@@ -483,6 +483,10 @@ spa_prop_get_config(spa_t *spa, nvlist_t *nv)
 
 		spa_prop_add_list(nv, ZPOOL_PROP_DEDUPRATIO, NULL,
 		    ddt_get_pool_dedup_ratio(spa), src);
+		spa_prop_add_list(nv, ZPOOL_PROP_DEDUPUSED, NULL,
+		    ddt_get_dedup_used(spa), src);
+		spa_prop_add_list(nv, ZPOOL_PROP_DEDUPSAVED, NULL,
+		    ddt_get_dedup_saved(spa), src);
 		spa_prop_add_list(nv, ZPOOL_PROP_BCLONEUSED, NULL,
 		    brt_get_used(spa), src);
 		spa_prop_add_list(nv, ZPOOL_PROP_BCLONESAVED, NULL,

tests/zfs-tests/tests/functional/cli_root/zpool_get/zpool_get.cfg

@@ -65,6 +65,8 @@ typeset -a properties=(
     "bclonesaved"
     "bcloneratio"
     "last_scrubbed_txg"
+    "dedupused"
+    "dedupsaved"
     "feature@async_destroy"
     "feature@empty_bpobj"
     "feature@lz4_compress"

tests/zfs-tests/tests/functional/cli_root/zpool_get/zpool_get_parsable.cfg

@@ -30,5 +30,5 @@
 #
 
 # Set the expected properties of zpool
-typeset -a properties=("allocated" "capacity" "expandsize" "free" "freeing"
-    "leaked" "size")
+typeset -a properties=("allocated" "bcloneused" "bclonesaved" "capacity"
+    "dedupused" "dedupsaved" "expandsize" "free" "freeing" "leaked" "size")