Release topology restrictions on special/dedup

Special vdevs were originally designed as a small blocks storage
for dRAID, for which role RAIDZ/dRAID topologies are not good.
But it is more often used as SSD storage for metadata and hot
data of HDD pools.  In these use cases narrow RAIDZ of SSDs might
be fine, so we should not introduce unnecessary restrictions,
and ZFS internally does not care.

Similar applies to dedup vdevs.  Original DDT used 4KB blocks,
for which anything but mirror was a terrible storage.  But new
FDT implementation uses 32KB blocks by default, which are much
less demanding even including compression, and which could be
increased even higher now, if needed.

Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.

Author: amotin

cmd/zpool/zpool_vdev.c

@@ -876,6 +876,18 @@ check_replication(nvlist_t *config, nvlist_t *newroot)
 				    (u_longlong_t)mirror->zprl_children);
 				ret = -1;
 			}
+		} else if (is_raidz_draid(current, new)) {
+			if (current->zprl_parity != new->zprl_parity) {
+				vdev_error(gettext(
+				    "mismatched replication level: pool and "
+				    "new vdev with different redundancy, %s "
+				    "and %s vdevs, %llu vs. %llu\n"),
+				    current->zprl_type,
+				    new->zprl_type,
+				    (u_longlong_t)current->zprl_parity,
+				    (u_longlong_t)new->zprl_parity);
+				ret = -1;
+			}
 		} else if (strcmp(current->zprl_type, new->zprl_type) != 0) {
 			vdev_error(gettext(
 			    "mismatched replication level: pool uses %s "
@@ -1581,13 +1593,12 @@ construct_spec(nvlist_t *props, int argc, char **argv)
 				is_dedup = is_spare = B_FALSE;
 			}
 
-			if (is_log || is_special || is_dedup) {
+			if (is_log) {
 				if (strcmp(type, VDEV_TYPE_MIRROR) != 0) {
 					(void) fprintf(stderr,
 					    gettext("invalid vdev "
-					    "specification: unsupported '%s' "
-					    "device: %s\n"), is_log ? "log" :
-					    "special", type);
+					    "specification: unsupported 'log' "
+					    "device: %s\n"), type);
 					goto spec_out;
 				}
 				nlogs++;

tests/zfs-tests/tests/functional/alloc_class/alloc_class_002_neg.ksh

@@ -41,9 +41,4 @@ log_mustnot zpool create $TESTPOOL $ZPOOL_DISKS special mirror \
 log_mustnot display_status $TESTPOOL
 log_mustnot zpool destroy -f $TESTPOOL
 
-log_mustnot zpool create $TESTPOOL raidz $ZPOOL_DISKS special raidz \
-    $CLASS_DISK0 $CLASS_DISK1 $CLASS_DISK2
-log_mustnot display_status $TESTPOOL
-log_mustnot zpool destroy -f $TESTPOOL
-
 log_pass $claim

tests/zfs-tests/tests/functional/alloc_class/alloc_class_003_pos.ksh

@@ -32,7 +32,7 @@ log_onexit cleanup
 
 log_must disk_setup
 
-for type in "" "mirror" "raidz"
+for type in "" "mirror" "raidz" "draid"
 do
 	log_must zpool create $TESTPOOL $type $ZPOOL_DISKS
 
@@ -47,6 +47,12 @@ do
 		    $CLASS_DISK0 $CLASS_DISK1
 		log_must zpool iostat -H $TESTPOOL $CLASS_DISK0
 		log_must zpool iostat -H $TESTPOOL $CLASS_DISK1
+	elif [ "$type" = "draid" ]; then
+		log_must zpool add $TESTPOOL special raidz \
+		    $CLASS_DISK0 $CLASS_DISK1 $CLASS_DISK2
+		log_must zpool iostat -H $TESTPOOL $CLASS_DISK0
+		log_must zpool iostat -H $TESTPOOL $CLASS_DISK1
+		log_must zpool iostat -H $TESTPOOL $CLASS_DISK2
 	else
 		log_must zpool add $TESTPOOL special $CLASS_DISK0
 		log_must zpool iostat -H $TESTPOOL $CLASS_DISK0

tests/zfs-tests/tests/functional/alloc_class/alloc_class_004_pos.ksh

@@ -37,14 +37,17 @@ typeset ac_value
 typeset stype=""
 typeset sdisks=""
 
-for type in "" "mirror" "raidz"
+for type in "" "mirror" "raidz" "draid"
 do
 	if [ "$type" = "mirror" ]; then
 		stype="mirror"
 		sdisks="${CLASS_DISK0} ${CLASS_DISK1} ${CLASS_DISK2}"
 	elif [ "$type" = "raidz" ]; then
 		stype="mirror"
 		sdisks="${CLASS_DISK0} ${CLASS_DISK1}"
+	elif [ "$type" = "draid" ]; then
+		stype="raidz"
+		sdisks="${CLASS_DISK0} ${CLASS_DISK1} ${CLASS_DISK2}"
 	else
 		stype=""
 		sdisks="${CLASS_DISK0}"

tests/zfs-tests/tests/functional/alloc_class/alloc_class_009_pos.ksh

@@ -36,7 +36,7 @@ typeset stype=""
 typeset sdisks=""
 typeset props=""
 
-for type in "" "mirror" "raidz"
+for type in "" "mirror" "raidz" "draid"
 do
 	if [ "$type" = "mirror" ]; then
 		stype="mirror"
@@ -45,6 +45,9 @@ do
 	elif [ "$type" = "raidz" ]; then
 		stype="mirror"
 		sdisks="${CLASS_DISK0} ${CLASS_DISK1}"
+	elif [ "$type" = "draid" ]; then
+		stype="raidz"
+		sdisks="${CLASS_DISK0} ${CLASS_DISK1} ${CLASS_DISK2}"
 	else
 		stype=""
 		sdisks="${CLASS_DISK0}"