t/zbd: check device for unrestricted read support

ZBD unit tests in t/zbd/test-zbd-support currently assume that the
drive that is being tested supports unrestricted reads, i.e. reads
that (partially or entirely) occur above the write pointer. This is
always the case with ZBD core code because Linux kernel rejects zoned
devices with restricted reads. However, libzbc ioengine does support
such devices.

The restricted/unrestricted reads feature is controlled by URSWRZ
device bit ("Unrestricted Reads of Sequential Write Required Zones")
which, depending on the device design, can be hard-coded to be reported
as 1 or 0 or it can be made configurable via MODE SET or SET FEATURES
commands. The unit tests need to behave correctly with any URSWRZ bit
value reported by the device if libzbc ioengine is used for testing.

Test #4 in the test script currently expects the device to have
unrestricted SWR zone reads. This test is guaranteed to fail if
the script is run against a drive that reports URSWRZ=0 with libzbc
ioengine.

Check if the drive has unrestricted read support disabled and process
the outcome of test #4 accordingly.

Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Reviewed-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20240206105755.214891-5-dmitry.fomichev@wdc.com
Signed-off-by: Vincent Fu <vincent.fu@samsung.com>

2 files changed, 35 insertions, 2 deletions

diff --git a/t/zbd/functions b/t/zbd/functions
index 028df4040..7734371e5 100644
--- a/t/zbd/functions
+++ b/t/zbd/functions
@@ -290,6 +290,28 @@ min_seq_write_size() {
 	fi
 }
 
+urswrz() {
+    local dev=$1
+
+    if [ -n "${sg_inq}" ] && [ ! -n "${use_libzbc}" ]; then
+	if ! ${sg_inq} -e --page=0xB6 --len=10 --hex "$dev" \
+		 > /dev/null 2>&1; then
+	    # Couldn't get URSWRZ bit. Assume the reads are unrestricted
+	    # because this configuration is more common.
+	    echo 1
+	else
+	    ${sg_inq} -e --page=0xB6 --len=10 --hex "$dev" | tail -1 |
+		{
+		    read -r offset b0 b1 b2 b3 b4 trailer && \
+			echo $(( $b4 & 0x01 )) || echo 0
+		}
+	fi
+    else
+	${zbc_info} "$dev" |
+	    sed -n 's/^[[:blank:]].*Read commands are \(un\)restricted*/\1/p' | grep -q ^ && echo 1 || echo 0
+    fi
+}
+
 is_zbc() {
 	local dev=$1
 
diff --git a/t/zbd/test-zbd-support b/t/zbd/test-zbd-support
index 532860ebc..defb36527 100755
--- a/t/zbd/test-zbd-support
+++ b/t/zbd/test-zbd-support
@@ -412,8 +412,16 @@ test4() {
     opts+=("--size=$size" "--thread=1" "--read_beyond_wp=1")
     opts+=("$(ioengine "psync")" "--rw=read" "--direct=1" "--disable_lat=1")
     opts+=("--zonemode=zbd" "--zonesize=${zone_size}")
-    run_fio "${opts[@]}" >> "${logfile}.${test_number}" 2>&1 || return $?
-    check_read $size || return $?
+    run_fio "${opts[@]}" >> "${logfile}.${test_number}" 2>&1
+    fio_rc=$?
+    if [[ $unrestricted_reads != 0 ]]; then
+	if [[ $fio_rc != 0 ]]; then
+		return "$fio_rc"
+	fi
+	check_read $size || return $?
+    else
+        [ $fio_rc == 0 ] && return 1 || return 0
+    fi
 }
 
 # Sequential write to sequential zones.
@@ -1664,6 +1672,7 @@ if [[ -b "$realdev" ]]; then
 		first_sequential_zone_sector=${result[0]}
 		sectors_per_zone=${result[1]}
 		zone_size=$((sectors_per_zone * 512))
+		unrestricted_reads=$(urswrz "$dev")
 		if ! max_open_zones=$(max_open_zones "$dev"); then
 			echo "Failed to determine maximum number of open zones"
 			exit 1
@@ -1681,6 +1690,7 @@ if [[ -b "$realdev" ]]; then
 		sectors_per_zone=$((zone_size / 512))
 		max_open_zones=128
 		max_active_zones=0
+		unrestricted_reads=1
 		set_io_scheduler "$basename" none || exit $?
 		;;
 	esac
@@ -1712,6 +1722,7 @@ elif [[ -c "$realdev" ]]; then
 	first_sequential_zone_sector=${result[0]}
 	sectors_per_zone=${result[1]}
 	zone_size=$((sectors_per_zone * 512))
+	unrestricted_reads=$(urswrz "$dev")
 	if ! max_open_zones=$(max_open_zones "$dev"); then
 		echo "Failed to determine maximum number of open zones"
 		exit 1