t/zbd: skip tests that need too many sequential zones

Test cases #3, #4, #28, #29 and #48 require rather large numbers of
sequential zones to run properly and they fail if the test target
device has not enough of such zones in its zone configuration.

Check how many sequential zones are present on the test device and
skip any test cases for which this number is not enough.

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

t/zbd/test-zbd-support

@@ -226,6 +226,17 @@ require_regular_block_dev() {
 	return 0
 }
 
+require_seq_zones() {
+	local req_seq_zones=${1}
+	local seq_bytes=$((disk_size - first_sequential_zone_sector * 512))
+
+	if ((req_seq_zones > seq_bytes / zone_size)); then
+		SKIP_REASON="$dev does not have $req_seq_zones sequential zones"
+		return 1
+	fi
+	return 0
+}
+
 # Check whether buffered writes are refused.
 test1() {
     run_fio --name=job1 --filename="$dev" --rw=write --direct=0 --bs=4K	\
@@ -265,6 +276,7 @@ test2() {
 test3() {
     local off opts=() rc
 
+    require_seq_zones 129 || return $SKIP_TESTCASE
     off=$((first_sequential_zone_sector * 512 + 128 * zone_size))
     size=$((zone_size))
     [ -n "$is_zbd" ] && reset_zone "$dev" $((off / 512))
@@ -282,6 +294,7 @@ test3() {
 test4() {
     local off opts=()
 
+    require_seq_zones 130 || return $SKIP_TESTCASE
     off=$((first_sequential_zone_sector * 512 + 129 * zone_size))
     size=$((zone_size))
     [ -n "$is_zbd" ] && reset_zone "$dev" $((off / 512))
@@ -631,6 +644,7 @@ test27() {
 test28() {
     local i jobs=16 off opts
 
+    require_seq_zones 65 || return $SKIP_TESTCASE
     off=$((first_sequential_zone_sector * 512 + 64 * zone_size))
     [ -n "$is_zbd" ] && reset_zone "$dev" $((off / 512))
     prep_write
@@ -655,6 +669,7 @@ test28() {
 test29() {
     local i jobs=16 off opts=()
 
+    require_seq_zones 80 || return $SKIP_TESTCASE
     off=$((first_sequential_zone_sector * 512 + 64 * zone_size))
     size=$((16*zone_size))
     prep_write
@@ -931,6 +946,7 @@ test48() {
     local i jobs=16 off opts=()
 
     require_zbd || return $SKIP_TESTCASE
+    require_seq_zones 80 || return $SKIP_TESTCASE
 
     off=$((first_sequential_zone_sector * 512 + 64 * zone_size))
     size=$((16*zone_size))