wip

internal/devices/drivers.go

@@ -60,6 +60,7 @@ func InstallDrivers(ctx context.Context, vm *uvm.UtilityVM, share string) (close
 		share,
 		true,
 		vm.ID(),
+		"",
 		&scsi.MountConfig{},
 	)
 	if err != nil {

internal/hcsoci/resources_lcow.go

@@ -92,6 +92,7 @@ func allocateLinuxResources(ctx context.Context, coi *createOptionsInternal, r *
 					hostPath,
 					readOnly,
 					coi.HostingSystem.ID(),
+					"",
 					&scsi.MountConfig{Options: mount.Options, BlockDev: isBlockDev},
 				)
 				if err != nil {
@@ -114,6 +115,7 @@ func allocateLinuxResources(ctx context.Context, coi *createOptionsInternal, r *
 					hostPath,
 					readOnly,
 					coi.HostingSystem.ID(),
+					"",
 					&scsi.MountConfig{Options: mount.Options, BlockDev: isBlockDev},
 				)
 				if err != nil {

internal/hcsoci/resources_wcow.go

@@ -144,6 +144,7 @@ func setupMounts(ctx context.Context, coi *createOptionsInternal, r *resources.R
 						mount.Source,
 						readOnly,
 						coi.HostingSystem.ID(),
+						"",
 						&scsi.MountConfig{},
 					)
 				case MountTypeVirtualDisk:
@@ -153,6 +154,7 @@ func setupMounts(ctx context.Context, coi *createOptionsInternal, r *resources.R
 						mount.Source,
 						readOnly,
 						coi.HostingSystem.ID(),
+						"",
 						&scsi.MountConfig{},
 					)
 				case MountTypeExtensibleVirtualDisk:
@@ -161,6 +163,7 @@ func setupMounts(ctx context.Context, coi *createOptionsInternal, r *resources.R
 						ctx,
 						mount.Source,
 						readOnly,
+						"",
 						&scsi.MountConfig{},
 					)
 				}

internal/layers/lcow.go

@@ -14,7 +14,6 @@ import (
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 
-	"github.com/Microsoft/hcsshim/internal/guestpath"
 	"github.com/Microsoft/hcsshim/internal/log"
 	"github.com/Microsoft/hcsshim/internal/ospath"
 	"github.com/Microsoft/hcsshim/internal/resources"
@@ -136,6 +135,7 @@ func MountLCOWLayers(ctx context.Context, containerID string, layers *LCOWLayers
 		hostPath,
 		false,
 		vm.ID(),
+		guestRoot,
 		mConfig,
 	)
 	if err != nil {
@@ -155,7 +155,7 @@ func MountLCOWLayers(ctx context.Context, containerID string, layers *LCOWLayers
 		}
 	}()
 
-	rootfs := ospath.Join(vm.OS(), guestRoot, guestpath.RootfsPath)
+	rootfs := ospath.Join(vm.OS(), guestRoot, "rootfs")
 	err = vm.CombineLayersLCOW(ctx, containerID, lcowUvmLayerPaths, containerScratchPathInUVM, rootfs)
 	if err != nil {
 		return "", "", nil, err
@@ -194,6 +194,7 @@ func addLCOWLayer(ctx context.Context, vm *uvm.UtilityVM, layer *LCOWLayer) (uvm
 		layer.VHDPath,
 		true,
 		"",
+		"",
 		&scsi.MountConfig{
 			Partition: layer.Partition,
 			Options:   []string{"ro"},

internal/layers/wcow_mount.go

@@ -331,7 +331,7 @@ func mountHypervIsolatedWCIFSLayers(ctx context.Context, l *wcowWCIFSLayers, vm
 	hostPath := filepath.Join(l.scratchLayerPath, "sandbox.vhdx")
 	log.G(ctx).WithField("hostPath", hostPath).Debug("mounting scratch VHD")
 
-	scsiMount, err := vm.SCSIManager.AddVirtualDisk(ctx, hostPath, false, vm.ID(), &scsi.MountConfig{})
+	scsiMount, err := vm.SCSIManager.AddVirtualDisk(ctx, hostPath, false, vm.ID(), "", &scsi.MountConfig{})
 	if err != nil {
 		return nil, nil, fmt.Errorf("failed to add SCSI scratch VHD: %w", err)
 	}

internal/uvm/scsi/manager.go

@@ -141,6 +141,7 @@ func (m *Manager) AddVirtualDisk(
 	hostPath string,
 	readOnly bool,
 	vmID string,
+	guestPath string,
 	mc *MountConfig,
 ) (*Mount, error) {
 	if m == nil {
@@ -169,6 +170,7 @@ func (m *Manager) AddVirtualDisk(
 			readOnly: readOnly,
 			typ:      "VirtualDisk",
 		},
+		guestPath,
 		mcInternal)
 }
 
@@ -187,6 +189,7 @@ func (m *Manager) AddPhysicalDisk(
 	hostPath string,
 	readOnly bool,
 	vmID string,
+	guestPath string,
 	mc *MountConfig,
 ) (*Mount, error) {
 	if m == nil {
@@ -215,6 +218,7 @@ func (m *Manager) AddPhysicalDisk(
 			readOnly: readOnly,
 			typ:      "PassThru",
 		},
+		guestPath,
 		mcInternal)
 }
 
@@ -233,6 +237,7 @@ func (m *Manager) AddExtensibleVirtualDisk(
 	ctx context.Context,
 	hostPath string,
 	readOnly bool,
+	guestPath string,
 	mc *MountConfig,
 ) (*Mount, error) {
 	if m == nil {
@@ -260,10 +265,11 @@ func (m *Manager) AddExtensibleVirtualDisk(
 			typ:      "ExtensibleVirtualDisk",
 			evdType:  evdType,
 		},
+		guestPath,
 		mcInternal)
 }
 
-func (m *Manager) add(ctx context.Context, attachConfig *attachConfig, mountConfig *mountConfig) (_ *Mount, err error) {
+func (m *Manager) add(ctx context.Context, attachConfig *attachConfig, guestPath string, mountConfig *mountConfig) (_ *Mount, err error) {
 	controller, lun, err := m.attachManager.attach(ctx, attachConfig)
 	if err != nil {
 		return nil, err
@@ -274,9 +280,8 @@ func (m *Manager) add(ctx context.Context, attachConfig *attachConfig, mountConf
 		}
 	}()
 
-	var guestPath string
 	if mountConfig != nil {
-		guestPath, err = m.mountManager.mount(ctx, controller, lun, mountConfig)
+		guestPath, err = m.mountManager.mount(ctx, controller, lun, guestPath, mountConfig)
 		if err != nil {
 			return nil, err
 		}
@@ -287,14 +292,9 @@ func (m *Manager) add(ctx context.Context, attachConfig *attachConfig, mountConf
 
 func (m *Manager) remove(ctx context.Context, controller, lun uint, guestPath string) error {
 	if guestPath != "" {
-		removed, err := m.mountManager.unmount(ctx, guestPath)
-		if err != nil {
+		if err := m.mountManager.unmount(ctx, guestPath); err != nil {
 			return err
 		}
-
-		if !removed {
-			return nil
-		}
 	}
 
 	if _, err := m.attachManager.detach(ctx, controller, lun); err != nil {

internal/uvm/scsi/mount.go

@@ -5,36 +5,31 @@ package scsi
 import (
 	"context"
 	"fmt"
-	"reflect"
-	"sort"
 	"sync"
+	"sync/atomic"
 )
 
 type mountManager struct {
-	m       sync.Mutex
-	mounter mounter
-	// Tracks current mounts. Entries will be nil if the mount was unmounted, meaning the index is
-	// available for use.
-	mounts   []*mount
-	mountFmt string
+	mounter       mounter
+	mounts        map[string]*mount // Guest path -> mount struct. Tracks current mounts.
+	m             sync.Mutex        // Guards access to the mounts map.
+	guestMountFmt string
+	mountIndex    atomic.Uint64
 }
 
-func newMountManager(mounter mounter, mountFmt string) *mountManager {
+func newMountManager(mounter mounter, guestMountFmt string) *mountManager {
 	return &mountManager{
-		mounter:  mounter,
-		mountFmt: mountFmt,
+		mounter:       mounter,
+		mounts:        make(map[string]*mount),
+		guestMountFmt: guestMountFmt,
 	}
 }
 
 type mount struct {
 	path       string
-	index      int
 	controller uint
 	lun        uint
 	config     *mountConfig
-	waitErr    error
-	waitCh     chan struct{}
-	refCount   uint
 }
 
 type mountConfig struct {
@@ -47,107 +42,54 @@ type mountConfig struct {
 	filesystem       string
 }
 
-func (mm *mountManager) mount(ctx context.Context, controller, lun uint, c *mountConfig) (_ string, err error) {
-	// Normalize the mount config for comparison.
-	// Config equality relies on the options slices being compared element-wise. Sort the options
-	// slice first so that two slices with different ordering compare as equal. We assume that
-	// order will never matter for mount options.
-	sort.Strings(c.options)
+func (mm *mountManager) mount(ctx context.Context, controller, lun uint, path string, c *mountConfig) (_ string, err error) {
+	if path == "" {
+		path = fmt.Sprintf(mm.guestMountFmt, mm.mountIndex.Add(1))
+	}
+	mount := &mount{
+		path:       path,
+		controller: controller,
+		lun:        lun,
+		config:     c,
+	}
+	if err := func() error {
+		mm.m.Lock()
+		defer mm.m.Unlock()
 
-	mount, existed := mm.trackMount(controller, lun, c)
-	if existed {
-		select {
-		case <-ctx.Done():
-			return "", ctx.Err()
-		case <-mount.waitCh:
-			if mount.waitErr != nil {
-				return "", mount.waitErr
-			}
+		if _, ok := mm.mounts[path]; ok {
+			return fmt.Errorf("another mount is already present at %s", path)
 		}
-		return mount.path, nil
+
+		mm.mounts[path] = mount
+		return nil
+	}(); err != nil {
+		return "", err
 	}
 
 	defer func() {
 		if err != nil {
 			mm.m.Lock()
-			mm.untrackMount(mount)
+			delete(mm.mounts, path)
 			mm.m.Unlock()
 		}
-
-		mount.waitErr = err
-		close(mount.waitCh)
 	}()
 
 	if err := mm.mounter.mount(ctx, controller, lun, mount.path, c); err != nil {
 		return "", fmt.Errorf("mount scsi controller %d lun %d at %s: %w", controller, lun, mount.path, err)
 	}
-	return mount.path, nil
+	return path, nil
 }
 
-func (mm *mountManager) unmount(ctx context.Context, path string) (bool, error) {
+func (mm *mountManager) unmount(ctx context.Context, path string) error {
 	mm.m.Lock()
 	defer mm.m.Unlock()
 
-	var mount *mount
-	for _, mount = range mm.mounts {
-		if mount != nil && mount.path == path {
-			break
-		}
-	}
-
-	mount.refCount--
-	if mount.refCount > 0 {
-		return false, nil
-	}
-
+	mount := mm.mounts[path]
 	if err := mm.mounter.unmount(ctx, mount.controller, mount.lun, mount.path, mount.config); err != nil {
-		return false, fmt.Errorf("unmount scsi controller %d lun %d at path %s: %w", mount.controller, mount.lun, mount.path, err)
+		return fmt.Errorf("unmount scsi controller %d lun %d at path %s: %w", mount.controller, mount.lun, mount.path, err)
 	}
-	mm.untrackMount(mount)
-
-	return true, nil
-}
 
-func (mm *mountManager) trackMount(controller, lun uint, c *mountConfig) (*mount, bool) {
-	mm.m.Lock()
-	defer mm.m.Unlock()
-
-	var freeIndex int = -1
-	for i, mount := range mm.mounts {
-		if mount == nil {
-			if freeIndex == -1 {
-				freeIndex = i
-			}
-		} else if controller == mount.controller &&
-			lun == mount.lun &&
-			reflect.DeepEqual(c, mount.config) {
-
-			mount.refCount++
-			return mount, true
-		}
-	}
-
-	// New mount.
-	mount := &mount{
-		controller: controller,
-		lun:        lun,
-		config:     c,
-		refCount:   1,
-		waitCh:     make(chan struct{}),
-	}
-	if freeIndex == -1 {
-		mount.index = len(mm.mounts)
-		mm.mounts = append(mm.mounts, mount)
-	} else {
-		mount.index = freeIndex
-		mm.mounts[freeIndex] = mount
-	}
-	// Use the mount index to produce a unique guest path.
-	mount.path = fmt.Sprintf(mm.mountFmt, mount.index)
-	return mount, false
-}
+	delete(mm.mounts, path)
 
-// Caller must be holding mm.m.
-func (mm *mountManager) untrackMount(mount *mount) {
-	mm.mounts[mount.index] = nil
+	return nil
 }