nvme/050: add support for NVMe multipath devices

Add two helper functions to tests/nvme/rc:
- _nvme_dev_support_native_multipath(): Check if the test device is an
  NVMe native multipath device by examining the sysfs device path.
- _nvme_get_pci_from_dev_sysfs(): Get the PCI address for an NVMe
  device, handling multipath devices by reading from the multipath
  subdirectory.

Update nvme/050 to handle multipath devices correctly. When testing
I/O timeout on a multipath device, fio will not encounter I/O errors
because the multipath layer provides failover to alternate paths.
Adjust the test pass/fail logic accordingly:
- For multipath devices: pass if no I/O error (expected behavior)
- For non-multipath devices: pass if I/O error occurs (original behavior)

Signed-off-by: Yi Zhang <[email protected]>

Author: yizhanglinux

tests/nvme/050

@@ -20,13 +20,11 @@ requires() {
 }
 
 test_device() {
-	local nvme_ns
-	local pdev
-	local i
+	local nvme_ns pdev io_error i
 
 	echo "Running ${TEST_NAME}"
 
-	pdev=$(_get_pci_dev_from_blkdev)
+	pdev=$(_nvme_get_pci_from_dev_sysfs)
 	nvme_ns="$(basename "${TEST_DEV}")"
 	echo 1 > /sys/block/"${nvme_ns}"/io-timeout-fail
 
@@ -40,10 +38,19 @@ test_device() {
 	    --name=reads --direct=1 --filename="${TEST_DEV}" --group_reporting \
 	    --time_based --runtime=1m >& "$FULL"
 
-	if grep -q "Input/output error" "$FULL"; then
-		echo "Test complete"
+	io_error=false
+	grep -q "Input/output error" "$FULL" && io_error=true
+
+	# The timeout failure injection causes an I/O to fail immediately. For
+	# a single-path device, the failed I/O is propagated up the stack and
+	# eventually reported to user space as an error. For multipath devices,
+	# the block layer evaluates whether the I/O is eligible for retry via
+	# failover to an alternate path. Because the I/O fails before the
+	# per-I/O timeout expires, it remains eligible for retry.
+	if _nvme_dev_support_native_multipath; then
+		$io_error && echo "Test failed" || echo "Test complete"
 	else
-		echo "Test failed"
+		$io_error && echo "Test complete" || echo "Test failed"
 	fi
 
 	# Remove and rescan the NVME device to ensure that it has come back

tests/nvme/rc

@@ -87,6 +87,23 @@ _require_test_dev_is_not_nvme_multipath() {
 	return 0
 }
 
+_nvme_dev_support_native_multipath() {
+	if [[ "$(readlink -f "$TEST_DEV_SYSFS/device")" =~ /nvme-subsystem/ ]]; then
+		return 0
+	fi
+	return 1
+}
+
+_nvme_get_pci_from_dev_sysfs() {
+	if _nvme_dev_support_native_multipath; then
+		readlink --canonicalize "$TEST_DEV_SYSFS"/multipath/nvme*c*n*/device | \
+			grep -Eo '[0-9a-f]{4,5}:[0-9a-f]{2}:[0-9a-f]{2}\.[0-9a-f]' | \
+			tail -1
+	else
+		_get_pci_dev_from_blkdev
+	fi
+}
+
 _require_test_dev_support_sed() {
 	if ! nvme sed discover "$TEST_DEV" &> /dev/null; then
 		SKIP_REASONS+=("$TEST_DEV doesn't support SED operations")