521 lines
12 KiB
Go
521 lines
12 KiB
Go
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// +build linux
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package btrfs
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/*
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#include <stdlib.h>
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#include <dirent.h>
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#include <btrfs/ioctl.h>
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#include <btrfs/ctree.h>
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static void set_name_btrfs_ioctl_vol_args_v2(struct btrfs_ioctl_vol_args_v2* btrfs_struct, const char* value) {
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snprintf(btrfs_struct->name, BTRFS_SUBVOL_NAME_MAX, "%s", value);
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}
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*/
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import "C"
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import (
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"fmt"
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"os"
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"path"
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"path/filepath"
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"strings"
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"syscall"
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"unsafe"
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"github.com/containers/storage/drivers"
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"github.com/containers/storage/pkg/idtools"
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"github.com/containers/storage/pkg/mount"
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"github.com/containers/storage/pkg/parsers"
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"github.com/docker/go-units"
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"github.com/opencontainers/runc/libcontainer/label"
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)
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func init() {
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graphdriver.Register("btrfs", Init)
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}
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var (
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quotaEnabled = false
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userDiskQuota = false
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)
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type btrfsOptions struct {
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minSpace uint64
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size uint64
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}
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// Init returns a new BTRFS driver.
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// An error is returned if BTRFS is not supported.
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func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (graphdriver.Driver, error) {
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fsMagic, err := graphdriver.GetFSMagic(home)
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if err != nil {
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return nil, err
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}
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if fsMagic != graphdriver.FsMagicBtrfs {
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return nil, graphdriver.ErrPrerequisites
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}
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rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps)
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if err != nil {
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return nil, err
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}
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if err := idtools.MkdirAllAs(home, 0700, rootUID, rootGID); err != nil {
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return nil, err
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}
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if err := mount.MakePrivate(home); err != nil {
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return nil, err
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}
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opt, err := parseOptions(options)
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if err != nil {
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return nil, err
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}
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if userDiskQuota {
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if err := subvolEnableQuota(home); err != nil {
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return nil, err
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}
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quotaEnabled = true
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}
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driver := &Driver{
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home: home,
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uidMaps: uidMaps,
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gidMaps: gidMaps,
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options: opt,
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}
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return graphdriver.NewNaiveDiffDriver(driver, uidMaps, gidMaps), nil
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}
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func parseOptions(opt []string) (btrfsOptions, error) {
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var options btrfsOptions
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for _, option := range opt {
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key, val, err := parsers.ParseKeyValueOpt(option)
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if err != nil {
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return options, err
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}
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key = strings.ToLower(key)
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switch key {
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case "btrfs.min_space":
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minSpace, err := units.RAMInBytes(val)
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if err != nil {
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return options, err
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}
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userDiskQuota = true
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options.minSpace = uint64(minSpace)
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default:
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return options, fmt.Errorf("Unknown option %s", key)
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}
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}
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return options, nil
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}
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// Driver contains information about the filesystem mounted.
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type Driver struct {
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//root of the file system
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home string
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uidMaps []idtools.IDMap
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gidMaps []idtools.IDMap
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options btrfsOptions
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}
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// String prints the name of the driver (btrfs).
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func (d *Driver) String() string {
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return "btrfs"
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}
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// Status returns current driver information in a two dimensional string array.
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// Output contains "Build Version" and "Library Version" of the btrfs libraries used.
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// Version information can be used to check compatibility with your kernel.
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func (d *Driver) Status() [][2]string {
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status := [][2]string{}
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if bv := btrfsBuildVersion(); bv != "-" {
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status = append(status, [2]string{"Build Version", bv})
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}
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if lv := btrfsLibVersion(); lv != -1 {
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status = append(status, [2]string{"Library Version", fmt.Sprintf("%d", lv)})
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}
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return status
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}
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// GetMetadata returns empty metadata for this driver.
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func (d *Driver) GetMetadata(id string) (map[string]string, error) {
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return nil, nil
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}
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// Cleanup unmounts the home directory.
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func (d *Driver) Cleanup() error {
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if quotaEnabled {
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if err := subvolDisableQuota(d.home); err != nil {
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return err
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}
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}
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return mount.Unmount(d.home)
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}
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func free(p *C.char) {
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C.free(unsafe.Pointer(p))
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}
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func openDir(path string) (*C.DIR, error) {
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Cpath := C.CString(path)
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defer free(Cpath)
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dir := C.opendir(Cpath)
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if dir == nil {
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return nil, fmt.Errorf("Can't open dir")
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}
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return dir, nil
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}
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func closeDir(dir *C.DIR) {
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if dir != nil {
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C.closedir(dir)
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}
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}
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func getDirFd(dir *C.DIR) uintptr {
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return uintptr(C.dirfd(dir))
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}
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func subvolCreate(path, name string) error {
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dir, err := openDir(path)
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if err != nil {
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return err
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}
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defer closeDir(dir)
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var args C.struct_btrfs_ioctl_vol_args
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for i, c := range []byte(name) {
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args.name[i] = C.char(c)
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}
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_SUBVOL_CREATE,
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uintptr(unsafe.Pointer(&args)))
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if errno != 0 {
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return fmt.Errorf("Failed to create btrfs subvolume: %v", errno.Error())
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}
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return nil
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}
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func subvolSnapshot(src, dest, name string) error {
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srcDir, err := openDir(src)
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if err != nil {
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return err
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}
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defer closeDir(srcDir)
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destDir, err := openDir(dest)
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if err != nil {
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return err
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}
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defer closeDir(destDir)
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var args C.struct_btrfs_ioctl_vol_args_v2
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args.fd = C.__s64(getDirFd(srcDir))
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var cs = C.CString(name)
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C.set_name_btrfs_ioctl_vol_args_v2(&args, cs)
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C.free(unsafe.Pointer(cs))
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(destDir), C.BTRFS_IOC_SNAP_CREATE_V2,
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uintptr(unsafe.Pointer(&args)))
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if errno != 0 {
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return fmt.Errorf("Failed to create btrfs snapshot: %v", errno.Error())
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}
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return nil
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}
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func isSubvolume(p string) (bool, error) {
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var bufStat syscall.Stat_t
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if err := syscall.Lstat(p, &bufStat); err != nil {
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return false, err
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}
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// return true if it is a btrfs subvolume
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return bufStat.Ino == C.BTRFS_FIRST_FREE_OBJECTID, nil
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}
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func subvolDelete(dirpath, name string) error {
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dir, err := openDir(dirpath)
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if err != nil {
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return err
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}
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defer closeDir(dir)
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fullPath := path.Join(dirpath, name)
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var args C.struct_btrfs_ioctl_vol_args
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// walk the btrfs subvolumes
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walkSubvolumes := func(p string, f os.FileInfo, err error) error {
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if err != nil {
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if os.IsNotExist(err) && p != fullPath {
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// missing most likely because the path was a subvolume that got removed in the previous iteration
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// since it's gone anyway, we don't care
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return nil
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}
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return fmt.Errorf("error walking subvolumes: %v", err)
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}
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// we want to check children only so skip itself
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// it will be removed after the filepath walk anyways
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if f.IsDir() && p != fullPath {
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sv, err := isSubvolume(p)
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if err != nil {
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return fmt.Errorf("Failed to test if %s is a btrfs subvolume: %v", p, err)
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}
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if sv {
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if err := subvolDelete(path.Dir(p), f.Name()); err != nil {
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return fmt.Errorf("Failed to destroy btrfs child subvolume (%s) of parent (%s): %v", p, dirpath, err)
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}
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}
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}
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return nil
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}
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if err := filepath.Walk(path.Join(dirpath, name), walkSubvolumes); err != nil {
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return fmt.Errorf("Recursively walking subvolumes for %s failed: %v", dirpath, err)
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}
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// all subvolumes have been removed
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// now remove the one originally passed in
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for i, c := range []byte(name) {
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args.name[i] = C.char(c)
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}
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_SNAP_DESTROY,
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uintptr(unsafe.Pointer(&args)))
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if errno != 0 {
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return fmt.Errorf("Failed to destroy btrfs snapshot %s for %s: %v", dirpath, name, errno.Error())
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}
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return nil
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}
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func subvolEnableQuota(path string) error {
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dir, err := openDir(path)
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if err != nil {
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return err
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}
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defer closeDir(dir)
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var args C.struct_btrfs_ioctl_quota_ctl_args
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args.cmd = C.BTRFS_QUOTA_CTL_ENABLE
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_QUOTA_CTL,
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uintptr(unsafe.Pointer(&args)))
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if errno != 0 {
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return fmt.Errorf("Failed to enable btrfs quota for %s: %v", dir, errno.Error())
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}
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return nil
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}
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func subvolDisableQuota(path string) error {
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dir, err := openDir(path)
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if err != nil {
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return err
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}
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defer closeDir(dir)
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var args C.struct_btrfs_ioctl_quota_ctl_args
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args.cmd = C.BTRFS_QUOTA_CTL_DISABLE
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_QUOTA_CTL,
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uintptr(unsafe.Pointer(&args)))
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if errno != 0 {
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return fmt.Errorf("Failed to disable btrfs quota for %s: %v", dir, errno.Error())
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}
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return nil
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}
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func subvolRescanQuota(path string) error {
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dir, err := openDir(path)
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if err != nil {
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return err
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}
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defer closeDir(dir)
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var args C.struct_btrfs_ioctl_quota_rescan_args
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_QUOTA_RESCAN_WAIT,
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uintptr(unsafe.Pointer(&args)))
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if errno != 0 {
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return fmt.Errorf("Failed to rescan btrfs quota for %s: %v", dir, errno.Error())
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}
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return nil
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}
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func subvolLimitQgroup(path string, size uint64) error {
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dir, err := openDir(path)
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if err != nil {
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return err
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}
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defer closeDir(dir)
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var args C.struct_btrfs_ioctl_qgroup_limit_args
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args.lim.max_referenced = C.__u64(size)
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args.lim.flags = C.BTRFS_QGROUP_LIMIT_MAX_RFER
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_QGROUP_LIMIT,
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uintptr(unsafe.Pointer(&args)))
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if errno != 0 {
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return fmt.Errorf("Failed to limit qgroup for %s: %v", dir, errno.Error())
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}
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return nil
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}
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func (d *Driver) subvolumesDir() string {
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return path.Join(d.home, "subvolumes")
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}
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func (d *Driver) subvolumesDirID(id string) string {
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return path.Join(d.subvolumesDir(), id)
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}
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// CreateReadWrite creates a layer that is writable for use as a container
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// file system.
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func (d *Driver) CreateReadWrite(id, parent, mountLabel string, storageOpt map[string]string) error {
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return d.Create(id, parent, mountLabel, storageOpt)
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}
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// Create the filesystem with given id.
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func (d *Driver) Create(id, parent, mountLabel string, storageOpt map[string]string) error {
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|
subvolumes := path.Join(d.home, "subvolumes")
|
||
|
|
rootUID, rootGID, err := idtools.GetRootUIDGID(d.uidMaps, d.gidMaps)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if err := idtools.MkdirAllAs(subvolumes, 0700, rootUID, rootGID); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if parent == "" {
|
||
|
|
if err := subvolCreate(subvolumes, id); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
parentDir := d.subvolumesDirID(parent)
|
||
|
|
st, err := os.Stat(parentDir)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if !st.IsDir() {
|
||
|
|
return fmt.Errorf("%s: not a directory", parentDir)
|
||
|
|
}
|
||
|
|
if err := subvolSnapshot(parentDir, subvolumes, id); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if _, ok := storageOpt["size"]; ok {
|
||
|
|
driver := &Driver{}
|
||
|
|
if err := d.parseStorageOpt(storageOpt, driver); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if err := d.setStorageSize(path.Join(subvolumes, id), driver); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// if we have a remapped root (user namespaces enabled), change the created snapshot
|
||
|
|
// dir ownership to match
|
||
|
|
if rootUID != 0 || rootGID != 0 {
|
||
|
|
if err := os.Chown(path.Join(subvolumes, id), rootUID, rootGID); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return label.Relabel(path.Join(subvolumes, id), mountLabel, false)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Parse btrfs storage options
|
||
|
|
func (d *Driver) parseStorageOpt(storageOpt map[string]string, driver *Driver) error {
|
||
|
|
// Read size to change the subvolume disk quota per container
|
||
|
|
for key, val := range storageOpt {
|
||
|
|
key := strings.ToLower(key)
|
||
|
|
switch key {
|
||
|
|
case "size":
|
||
|
|
size, err := units.RAMInBytes(val)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
driver.options.size = uint64(size)
|
||
|
|
default:
|
||
|
|
return fmt.Errorf("Unknown option %s", key)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Set btrfs storage size
|
||
|
|
func (d *Driver) setStorageSize(dir string, driver *Driver) error {
|
||
|
|
if driver.options.size <= 0 {
|
||
|
|
return fmt.Errorf("btrfs: invalid storage size: %s", units.HumanSize(float64(driver.options.size)))
|
||
|
|
}
|
||
|
|
if d.options.minSpace > 0 && driver.options.size < d.options.minSpace {
|
||
|
|
return fmt.Errorf("btrfs: storage size cannot be less than %s", units.HumanSize(float64(d.options.minSpace)))
|
||
|
|
}
|
||
|
|
|
||
|
|
if !quotaEnabled {
|
||
|
|
if err := subvolEnableQuota(d.home); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
quotaEnabled = true
|
||
|
|
}
|
||
|
|
|
||
|
|
if err := subvolLimitQgroup(dir, driver.options.size); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Remove the filesystem with given id.
|
||
|
|
func (d *Driver) Remove(id string) error {
|
||
|
|
dir := d.subvolumesDirID(id)
|
||
|
|
if _, err := os.Stat(dir); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if err := subvolDelete(d.subvolumesDir(), id); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if err := os.RemoveAll(dir); err != nil && !os.IsNotExist(err) {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if err := subvolRescanQuota(d.home); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Get the requested filesystem id.
|
||
|
|
func (d *Driver) Get(id, mountLabel string) (string, error) {
|
||
|
|
dir := d.subvolumesDirID(id)
|
||
|
|
st, err := os.Stat(dir)
|
||
|
|
if err != nil {
|
||
|
|
return "", err
|
||
|
|
}
|
||
|
|
|
||
|
|
if !st.IsDir() {
|
||
|
|
return "", fmt.Errorf("%s: not a directory", dir)
|
||
|
|
}
|
||
|
|
|
||
|
|
return dir, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Put is not implemented for BTRFS as there is no cleanup required for the id.
|
||
|
|
func (d *Driver) Put(id string) error {
|
||
|
|
// Get() creates no runtime resources (like e.g. mounts)
|
||
|
|
// so this doesn't need to do anything.
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Exists checks if the id exists in the filesystem.
|
||
|
|
func (d *Driver) Exists(id string) bool {
|
||
|
|
dir := d.subvolumesDirID(id)
|
||
|
|
_, err := os.Stat(dir)
|
||
|
|
return err == nil
|
||
|
|
}
|