daa1ea522b
Details about CimFs project are discussed in #8346 Signed-off-by: Amit Barve <ambarve@microsoft.com>
90 lines
2.9 KiB
Go
90 lines
2.9 KiB
Go
//go:build windows
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package cim
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import (
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"context"
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"fmt"
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"os"
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"sync"
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"github.com/Microsoft/go-winio/pkg/guid"
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hcsschema "github.com/Microsoft/hcsshim/internal/hcs/schema2"
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cimfs "github.com/Microsoft/hcsshim/pkg/cimfs"
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)
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// a cache of cim layer to its mounted volume - The mount manager plugin currently doesn't have an option of
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// querying a mounted cim to get the volume at which it is mounted, so we maintain a cache of that here
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var (
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cimMounts map[string]string = make(map[string]string)
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cimMountMapLock sync.Mutex
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// A random GUID used as a namespace for generating cim mount volume GUIDs: 6827367b-c388-4e9b-95ec-961c6d2c936c
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cimMountNamespace guid.GUID = guid.GUID{Data1: 0x6827367b, Data2: 0xc388, Data3: 0x4e9b, Data4: [8]byte{0x96, 0x1c, 0x6d, 0x2c, 0x93, 0x6c}}
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)
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// MountCimLayer mounts the cim at path `cimPath` and returns the mount location of that cim. This method
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// uses the `CimMountFlagCacheFiles` mount flag when mounting the cim. The containerID is used to generated
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// the volumeID for the volume at which this CIM is mounted. containerID is used so that if the shim process
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// crashes for any reason, the mounted cim can be correctly cleaned up during `shim delete` call.
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func MountCimLayer(ctx context.Context, cimPath, containerID string) (string, error) {
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volumeGUID, err := guid.NewV5(cimMountNamespace, []byte(containerID))
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if err != nil {
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return "", fmt.Errorf("generated cim mount GUID: %w", err)
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}
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vol, err := cimfs.Mount(cimPath, volumeGUID, hcsschema.CimMountFlagCacheFiles)
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if err != nil {
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return "", err
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}
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cimMountMapLock.Lock()
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defer cimMountMapLock.Unlock()
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cimMounts[fmt.Sprintf("%s_%s", containerID, cimPath)] = vol
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return vol, nil
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}
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// Unmount unmounts the cim at mounted for given container.
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func UnmountCimLayer(ctx context.Context, cimPath, containerID string) error {
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cimMountMapLock.Lock()
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defer cimMountMapLock.Unlock()
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if vol, ok := cimMounts[fmt.Sprintf("%s_%s", containerID, cimPath)]; !ok {
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return fmt.Errorf("cim %s not mounted", cimPath)
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} else {
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delete(cimMounts, fmt.Sprintf("%s_%s", containerID, cimPath))
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err := cimfs.Unmount(vol)
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if err != nil {
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return err
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}
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}
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return nil
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}
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// GetCimMountPath returns the volume at which a cim is mounted. If the cim is not mounted returns error
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func GetCimMountPath(cimPath, containerID string) (string, error) {
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cimMountMapLock.Lock()
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defer cimMountMapLock.Unlock()
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if vol, ok := cimMounts[fmt.Sprintf("%s_%s", containerID, cimPath)]; !ok {
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return "", fmt.Errorf("cim %s not mounted", cimPath)
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} else {
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return vol, nil
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}
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}
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func CleanupContainerMounts(containerID string) error {
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volumeGUID, err := guid.NewV5(cimMountNamespace, []byte(containerID))
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if err != nil {
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return fmt.Errorf("generated cim mount GUID: %w", err)
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}
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volPath := fmt.Sprintf("\\\\?\\Volume{%s}\\", volumeGUID.String())
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if _, err := os.Stat(volPath); err == nil {
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err = cimfs.Unmount(volPath)
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if err != nil {
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return err
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}
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}
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return nil
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}
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