Implement 'podman run --blkio-weight-device'

`--blkio-weight-device` is not fully implemented and this causes an
unexpected panic when specified because an entry is put into an
uninitialized map at parsing.

This fix implements the `--blkio-weight-device` and adds a system test.
When creating a spec generator on a client, a major number and a minor
number of a device cannot be set. So, these numbers are inspected on a
server and set to a runtime spec.

Signed-off-by: Hironori Shiina <shiina.hironori@jp.fujitsu.com>

pkg/specgen/generate/oci.go

@@ -329,6 +329,14 @@ func SpecGenToOCI(ctx context.Context, s *specgen.SpecGenerator, rt *libpod.Runt
 		g.AddLinuxResourcesDevice(true, dev.Type, dev.Major, dev.Minor, dev.Access)
 	}
 
+	for k, v := range s.WeightDevice {
+		statT := unix.Stat_t{}
+		if err := unix.Stat(k, &statT); err != nil {
+			return nil, errors.Wrapf(err, "failed to inspect '%s' in --blkio-weight-device", k)
+		}
+		g.AddLinuxResourcesBlockIOWeightDevice((int64(unix.Major(uint64(statT.Rdev)))), (int64(unix.Minor(uint64(statT.Rdev)))), *v.Weight)
+	}
+
 	BlockAccessToKernelFilesystems(s.Privileged, s.PidNS.IsHost(), s.Mask, s.Unmask, &g)
 
 	g.ClearProcessEnv()

pkg/specgenutil/specgen.go

@@ -85,7 +85,7 @@ func getIOLimits(s *specgen.SpecGenerator, c *entities.ContainerCreateOptions) (
 	}
 
 	if len(c.BlkIOWeightDevice) > 0 {
-		if err := parseWeightDevices(s, c.BlkIOWeightDevice); err != nil {
+		if s.WeightDevice, err = parseWeightDevices(c.BlkIOWeightDevice); err != nil {
 			return nil, err
 		}
 		hasLimits = true
@@ -791,29 +791,30 @@ func makeHealthCheckFromCli(inCmd, interval string, retries uint, timeout, start
 	return &hc, nil
 }
 
-func parseWeightDevices(s *specgen.SpecGenerator, weightDevs []string) error {
+func parseWeightDevices(weightDevs []string) (map[string]specs.LinuxWeightDevice, error) {
+	wd := make(map[string]specs.LinuxWeightDevice)
 	for _, val := range weightDevs {
 		split := strings.SplitN(val, ":", 2)
 		if len(split) != 2 {
-			return fmt.Errorf("bad format: %s", val)
+			return nil, fmt.Errorf("bad format: %s", val)
 		}
 		if !strings.HasPrefix(split[0], "/dev/") {
-			return fmt.Errorf("bad format for device path: %s", val)
+			return nil, fmt.Errorf("bad format for device path: %s", val)
 		}
 		weight, err := strconv.ParseUint(split[1], 10, 0)
 		if err != nil {
-			return fmt.Errorf("invalid weight for device: %s", val)
+			return nil, fmt.Errorf("invalid weight for device: %s", val)
 		}
 		if weight > 0 && (weight < 10 || weight > 1000) {
-			return fmt.Errorf("invalid weight for device: %s", val)
+			return nil, fmt.Errorf("invalid weight for device: %s", val)
 		}
 		w := uint16(weight)
-		s.WeightDevice[split[0]] = specs.LinuxWeightDevice{
+		wd[split[0]] = specs.LinuxWeightDevice{
 			Weight:     &w,
 			LeafWeight: nil,
 		}
 	}
-	return nil
+	return wd, nil
 }
 
 func parseThrottleBPSDevices(bpsDevices []string) (map[string]specs.LinuxThrottleDevice, error) {

test/system/180-blkio.bats

@@ -0,0 +1,69 @@
+#!/usr/bin/env bats   -*- bats -*-
+#
+# podman blkio-related tests
+#
+
+load helpers
+
+function teardown() {
+    lofile=${PODMAN_TMPDIR}/disk.img
+    if [ -f ${lofile} ]; then
+        run_podman '?' rm -t 0 --all --force
+
+        while read path dev; do
+            if [[ "$path" == "$lofile" ]]; then
+                losetup -d $dev
+            fi
+        done < <(losetup -l --noheadings --output BACK-FILE,NAME)
+
+        rm ${lofile}
+    fi
+    basic_teardown
+}
+
+@test "podman run --blkio-weight-device" {
+
+    skip_if_rootless "cannot create devices in rootless mode"
+
+    # create loopback device
+    lofile=${PODMAN_TMPDIR}/disk.img
+    fallocate -l 1k  ${lofile}
+    losetup -f ${lofile}
+
+    run losetup -l --noheadings --output BACK-FILE,NAME,MAJ:MIN
+    is "$output" ".\+" "Empty output from losetup"
+
+    lodevice=$(awk "\$1 == \"$lofile\" { print \$2 }" <<<"$output")
+    lomajmin=$(awk "\$1 == \"$lofile\" { print \$3 }" <<<"$output")
+
+    is "$lodevice" ".\+" "Could not determine device for $lofile"
+    is "$lomajmin" ".\+" "Could not determine major/minor for $lofile"
+
+    # use bfq io scheduler
+    run grep -w bfq /sys/block/$(basename ${lodevice})/queue/scheduler
+    if [ $status -ne 0 ]; then
+        skip "BFQ scheduler is not supported on the system"
+    fi
+    echo bfq > /sys/block/$(basename ${lodevice})/queue/scheduler
+
+    # run podman
+    if is_cgroupsv2; then
+        if [ ! -f /sys/fs/cgroup/system.slice/io.bfq.weight ]; then
+            skip "Kernel does not support BFQ IO scheduler"
+        fi
+        run_podman run --device ${lodevice}:${lodevice} --blkio-weight-device ${lodevice}:123 --rm $IMAGE \
+            /bin/sh -c "cat /sys/fs/cgroup/\$(sed -e 's/0:://' < /proc/self/cgroup)/io.bfq.weight"
+        is "${lines[1]}" "${lomajmin}\s\+123"
+    else
+        if [ ! -f /sys/fs/cgroup/blkio/system.slice/blkio.bfq.weight_device ]; then
+            skip "Kernel does not support BFQ IO scheduler"
+        fi
+        if [ $(podman_runtime) = "crun" ]; then
+            # As of crun 1.2, crun doesn't support blkio.bfq.weight_device
+            skip "crun doesn't support blkio.bfq.weight_device"
+        fi
+        run_podman run --device ${lodevice}:${lodevice} --blkio-weight-device ${lodevice}:123 --rm $IMAGE \
+            /bin/sh -c "cat /sys/fs/cgroup/blkio/blkio.bfq.weight_device"
+        is "${lines[1]}" "${lomajmin}\s\+123"
+    fi
+}