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loopback: separate loop logic from devicemapper 

The loopback logic is not technically exclusive to the devicemapper
driver. This reorganizes the code such that the loopback code is usable
outside of the devicemapper package and driver.

Signed-off-by: Vincent Batts <vbatts@redhat.com>
This commit is contained in:
Vincent Batts 2015-12-14 17:16:34 -05:00
parent a292c04c01
commit af59752712
8 changed files with 208 additions and 172 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
daemon/graphdriver/devmapper/deviceset.go
View File

@ -24,6 +24,7 @@ import (
"github.com/docker/docker/daemon/graphdriver"
"github.com/docker/docker/pkg/devicemapper"
"github.com/docker/docker/pkg/idtools"
"github.com/docker/docker/pkg/loopback"
"github.com/docker/docker/pkg/mount"
"github.com/docker/docker/pkg/parsers"
"github.com/docker/go-units"
@ -1170,7 +1171,7 @@ func (devices *DeviceSet) ResizePool(size int64) error {
return fmt.Errorf("devmapper: Can't shrink file")
}
dataloopback := devicemapper.FindLoopDeviceFor(datafile)
dataloopback := loopback.FindLoopDeviceFor(datafile)
if dataloopback == nil {
return fmt.Errorf("devmapper: Unable to find loopback mount for: %s", datafilename)
}
@ -1182,7 +1183,7 @@ func (devices *DeviceSet) ResizePool(size int64) error {
}
defer metadatafile.Close()
metadataloopback := devicemapper.FindLoopDeviceFor(metadatafile)
metadataloopback := loopback.FindLoopDeviceFor(metadatafile)
if metadataloopback == nil {
return fmt.Errorf("devmapper: Unable to find loopback mount for: %s", metadatafilename)
}
@ -1194,8 +1195,8 @@ func (devices *DeviceSet) ResizePool(size int64) error {
}
// Reload size for loopback device
if err := devicemapper.LoopbackSetCapacity(dataloopback); err != nil {
return fmt.Errorf("devmapper: Unable to update loopback capacity: %s", err)
if err := loopback.SetCapacity(dataloopback); err != nil {
return fmt.Errorf("Unable to update loopback capacity: %s", err)
}
// Suspend the pool
@ -1414,7 +1415,7 @@ func getLoopFileDeviceMajMin(filename string) (string, uint64, uint64, error) {
}
defer file.Close()
loopbackDevice := devicemapper.FindLoopDeviceFor(file)
loopbackDevice := loopback.FindLoopDeviceFor(file)
if loopbackDevice == nil {
return "", 0, 0, fmt.Errorf("devmapper: Unable to find loopback mount for: %s", filename)
}
@ -1622,7 +1623,7 @@ func (devices *DeviceSet) initDevmapper(doInit bool) error {
return err
}
dataFile, err = devicemapper.AttachLoopDevice(data)
dataFile, err = loopback.AttachLoopDevice(data)
if err != nil {
return err
}
@ -1655,7 +1656,7 @@ func (devices *DeviceSet) initDevmapper(doInit bool) error {
return err
}
metadataFile, err = devicemapper.AttachLoopDevice(metadata)
metadataFile, err = loopback.AttachLoopDevice(metadata)
if err != nil {
return err
}

101
pkg/devicemapper/devmapper.go
View File

@ -47,32 +47,29 @@ const (
// List of errors returned when using devicemapper.
var (
ErrTaskRun = errors.New("dm_task_run failed")
ErrTaskSetName = errors.New("dm_task_set_name failed")
ErrTaskSetMessage = errors.New("dm_task_set_message failed")
ErrTaskSetAddNode = errors.New("dm_task_set_add_node failed")
ErrTaskSetRo = errors.New("dm_task_set_ro failed")
ErrTaskAddTarget = errors.New("dm_task_add_target failed")
ErrTaskSetSector = errors.New("dm_task_set_sector failed")
ErrTaskGetDeps = errors.New("dm_task_get_deps failed")
ErrTaskGetInfo = errors.New("dm_task_get_info failed")
ErrTaskGetDriverVersion = errors.New("dm_task_get_driver_version failed")
ErrTaskDeferredRemove = errors.New("dm_task_deferred_remove failed")
ErrTaskSetCookie = errors.New("dm_task_set_cookie failed")
ErrNilCookie = errors.New("cookie ptr can't be nil")
ErrAttachLoopbackDevice = errors.New("loopback mounting failed")
ErrGetBlockSize = errors.New("Can't get block size")
ErrUdevWait = errors.New("wait on udev cookie failed")
ErrSetDevDir = errors.New("dm_set_dev_dir failed")
ErrGetLibraryVersion = errors.New("dm_get_library_version failed")
ErrCreateRemoveTask = errors.New("Can't create task of type deviceRemove")
ErrRunRemoveDevice = errors.New("running RemoveDevice failed")
ErrInvalidAddNode = errors.New("Invalid AddNode type")
ErrGetLoopbackBackingFile = errors.New("Unable to get loopback backing file")
ErrLoopbackSetCapacity = errors.New("Unable set loopback capacity")
ErrBusy = errors.New("Device is Busy")
ErrDeviceIDExists = errors.New("Device Id Exists")
ErrEnxio = errors.New("No such device or address")
ErrTaskRun = errors.New("dm_task_run failed")
ErrTaskSetName = errors.New("dm_task_set_name failed")
ErrTaskSetMessage = errors.New("dm_task_set_message failed")
ErrTaskSetAddNode = errors.New("dm_task_set_add_node failed")
ErrTaskSetRo = errors.New("dm_task_set_ro failed")
ErrTaskAddTarget = errors.New("dm_task_add_target failed")
ErrTaskSetSector = errors.New("dm_task_set_sector failed")
ErrTaskGetDeps = errors.New("dm_task_get_deps failed")
ErrTaskGetInfo = errors.New("dm_task_get_info failed")
ErrTaskGetDriverVersion = errors.New("dm_task_get_driver_version failed")
ErrTaskDeferredRemove = errors.New("dm_task_deferred_remove failed")
ErrTaskSetCookie = errors.New("dm_task_set_cookie failed")
ErrNilCookie = errors.New("cookie ptr can't be nil")
ErrGetBlockSize = errors.New("Can't get block size")
ErrUdevWait = errors.New("wait on udev cookie failed")
ErrSetDevDir = errors.New("dm_set_dev_dir failed")
ErrGetLibraryVersion = errors.New("dm_get_library_version failed")
ErrCreateRemoveTask = errors.New("Can't create task of type deviceRemove")
ErrRunRemoveDevice = errors.New("running RemoveDevice failed")
ErrInvalidAddNode = errors.New("Invalid AddNode type")
ErrBusy = errors.New("Device is Busy")
ErrDeviceIDExists = errors.New("Device Id Exists")
ErrEnxio = errors.New("No such device or address")
)
var (
@ -257,58 +254,6 @@ func (t *Task) getNextTarget(next unsafe.Pointer) (nextPtr unsafe.Pointer, start
start, length, targetType, params
}
func getLoopbackBackingFile(file *os.File) (uint64, uint64, error) {
loopInfo, err := ioctlLoopGetStatus64(file.Fd())
if err != nil {
logrus.Errorf("devicemapper: Error get loopback backing file: %s", err)
return 0, 0, ErrGetLoopbackBackingFile
}
return loopInfo.loDevice, loopInfo.loInode, nil
}
// LoopbackSetCapacity reloads the size for the loopback device.
func LoopbackSetCapacity(file *os.File) error {
if err := ioctlLoopSetCapacity(file.Fd(), 0); err != nil {
logrus.Errorf("devicemapper: Error loopbackSetCapacity: %s", err)
return ErrLoopbackSetCapacity
}
return nil
}
// FindLoopDeviceFor returns a loopback device file for the specified file which
// is backing file of a loop back device.
func FindLoopDeviceFor(file *os.File) *os.File {
stat, err := file.Stat()
if err != nil {
return nil
}
targetInode := stat.Sys().(*syscall.Stat_t).Ino
targetDevice := stat.Sys().(*syscall.Stat_t).Dev
for i := 0; true; i++ {
path := fmt.Sprintf("/dev/loop%d", i)
file, err := os.OpenFile(path, os.O_RDWR, 0)
if err != nil {
if os.IsNotExist(err) {
return nil
}
// Ignore all errors until the first not-exist
// we want to continue looking for the file
continue
}
dev, inode, err := getLoopbackBackingFile(file)
if err == nil && dev == targetDevice && inode == targetInode {
return file
}
file.Close()
}
return nil
}
// UdevWait waits for any processes that are waiting for udev to complete the specified cookie.
func UdevWait(cookie *uint) error {
if res := DmUdevWait(*cookie); res != 1 {

41
pkg/devicemapper/devmapper_wrapper.go
View File

@ -5,17 +5,8 @@ package devicemapper
/*
#cgo LDFLAGS: -L. -ldevmapper
#include <libdevmapper.h>
#include <linux/loop.h> // FIXME: present only for defines, maybe we can remove it?
#include <linux/fs.h> // FIXME: present only for BLKGETSIZE64, maybe we can remove it?
#ifndef LOOP_CTL_GET_FREE
#define LOOP_CTL_GET_FREE 0x4C82
#endif
#ifndef LO_FLAGS_PARTSCAN
#define LO_FLAGS_PARTSCAN 8
#endif
// FIXME: Can't we find a way to do the logging in pure Go?
extern void DevmapperLogCallback(int level, char *file, int line, int dm_errno_or_class, char *str);
@ -45,44 +36,12 @@ import (
type (
cdmTask C.struct_dm_task
loopInfo64 struct {
loDevice uint64 /* ioctl r/o */
loInode uint64 /* ioctl r/o */
loRdevice uint64 /* ioctl r/o */
loOffset uint64
loSizelimit uint64 /* bytes, 0 == max available */
loNumber uint32 /* ioctl r/o */
loEncryptType uint32
loEncryptKeySize uint32 /* ioctl w/o */
loFlags uint32 /* ioctl r/o */
loFileName [LoNameSize]uint8
loCryptName [LoNameSize]uint8
loEncryptKey [LoKeySize]uint8 /* ioctl w/o */
loInit [2]uint64
}
)
// IOCTL consts
const (
BlkGetSize64 = C.BLKGETSIZE64
BlkDiscard = C.BLKDISCARD
LoopSetFd = C.LOOP_SET_FD
LoopCtlGetFree = C.LOOP_CTL_GET_FREE
LoopGetStatus64 = C.LOOP_GET_STATUS64
LoopSetStatus64 = C.LOOP_SET_STATUS64
LoopClrFd = C.LOOP_CLR_FD
LoopSetCapacity = C.LOOP_SET_CAPACITY
)
// LOOP consts.
const (
LoFlagsAutoClear = C.LO_FLAGS_AUTOCLEAR
LoFlagsReadOnly = C.LO_FLAGS_READ_ONLY
LoFlagsPartScan = C.LO_FLAGS_PARTSCAN
LoKeySize = C.LO_KEY_SIZE
LoNameSize = C.LO_NAME_SIZE
)
// Devicemapper cookie flags.

45
pkg/devicemapper/ioctl.go
View File

@ -7,51 +7,6 @@ import (
"unsafe"
)
func ioctlLoopCtlGetFree(fd uintptr) (int, error) {
index, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, LoopCtlGetFree, 0)
if err != 0 {
return 0, err
}
return int(index), nil
}
func ioctlLoopSetFd(loopFd, sparseFd uintptr) error {
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopSetFd, sparseFd); err != 0 {
return err
}
return nil
}
func ioctlLoopSetStatus64(loopFd uintptr, loopInfo *loopInfo64) error {
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopSetStatus64, uintptr(unsafe.Pointer(loopInfo))); err != 0 {
return err
}
return nil
}
func ioctlLoopClrFd(loopFd uintptr) error {
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopClrFd, 0); err != 0 {
return err
}
return nil
}
func ioctlLoopGetStatus64(loopFd uintptr) (*loopInfo64, error) {
loopInfo := &loopInfo64{}
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopGetStatus64, uintptr(unsafe.Pointer(loopInfo))); err != 0 {
return nil, err
}
return loopInfo, nil
}
func ioctlLoopSetCapacity(loopFd uintptr, value int) error {
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopSetCapacity, uintptr(value)); err != 0 {
return err
}
return nil
}
func ioctlBlkGetSize64(fd uintptr) (int64, error) {
var size int64
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, BlkGetSize64, uintptr(unsafe.Pointer(&size))); err != 0 {

10
pkg/devicemapper/attach_loopback.go → pkg/loopback/attach_loopback.go
View File

@ -1,8 +1,9 @@
// +build linux
package devicemapper
package loopback
import (
"errors"
"fmt"
"os"
"syscall"
@ -10,6 +11,13 @@ import (
"github.com/Sirupsen/logrus"
)
// Loopback related errors
var (
ErrAttachLoopbackDevice = errors.New("loopback attach failed")
ErrGetLoopbackBackingFile = errors.New("Unable to get loopback backing file")
ErrSetCapacity = errors.New("Unable set loopback capacity")
)
func stringToLoopName(src string) [LoNameSize]uint8 {
var dst [LoNameSize]uint8
copy(dst[:], src[:])

53
pkg/loopback/ioctl.go Normal file
View File

@ -0,0 +1,53 @@
// +build linux
package loopback
import (
"syscall"
"unsafe"
)
func ioctlLoopCtlGetFree(fd uintptr) (int, error) {
index, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, LoopCtlGetFree, 0)
if err != 0 {
return 0, err
}
return int(index), nil
}
func ioctlLoopSetFd(loopFd, sparseFd uintptr) error {
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopSetFd, sparseFd); err != 0 {
return err
}
return nil
}
func ioctlLoopSetStatus64(loopFd uintptr, loopInfo *loopInfo64) error {
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopSetStatus64, uintptr(unsafe.Pointer(loopInfo))); err != 0 {
return err
}
return nil
}
func ioctlLoopClrFd(loopFd uintptr) error {
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopClrFd, 0); err != 0 {
return err
}
return nil
}
func ioctlLoopGetStatus64(loopFd uintptr) (*loopInfo64, error) {
loopInfo := &loopInfo64{}
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopGetStatus64, uintptr(unsafe.Pointer(loopInfo))); err != 0 {
return nil, err
}
return loopInfo, nil
}
func ioctlLoopSetCapacity(loopFd uintptr, value int) error {
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopSetCapacity, uintptr(value)); err != 0 {
return err
}
return nil
}

52
pkg/loopback/loop_wrapper.go Normal file
View File

@ -0,0 +1,52 @@
// +build linux
package loopback
/*
#include <linux/loop.h> // FIXME: present only for defines, maybe we can remove it?
#ifndef LOOP_CTL_GET_FREE
#define LOOP_CTL_GET_FREE 0x4C82
#endif
#ifndef LO_FLAGS_PARTSCAN
#define LO_FLAGS_PARTSCAN 8
#endif
*/
import "C"
type loopInfo64 struct {
loDevice uint64 /* ioctl r/o */
loInode uint64 /* ioctl r/o */
loRdevice uint64 /* ioctl r/o */
loOffset uint64
loSizelimit uint64 /* bytes, 0 == max available */
loNumber uint32 /* ioctl r/o */
loEncryptType uint32
loEncryptKeySize uint32 /* ioctl w/o */
loFlags uint32 /* ioctl r/o */
loFileName [LoNameSize]uint8
loCryptName [LoNameSize]uint8
loEncryptKey [LoKeySize]uint8 /* ioctl w/o */
loInit [2]uint64
}
// IOCTL consts
const (
LoopSetFd = C.LOOP_SET_FD
LoopCtlGetFree = C.LOOP_CTL_GET_FREE
LoopGetStatus64 = C.LOOP_GET_STATUS64
LoopSetStatus64 = C.LOOP_SET_STATUS64
LoopClrFd = C.LOOP_CLR_FD
LoopSetCapacity = C.LOOP_SET_CAPACITY
)
// LOOP consts.
const (
LoFlagsAutoClear = C.LO_FLAGS_AUTOCLEAR
LoFlagsReadOnly = C.LO_FLAGS_READ_ONLY
LoFlagsPartScan = C.LO_FLAGS_PARTSCAN
LoKeySize = C.LO_KEY_SIZE
LoNameSize = C.LO_NAME_SIZE
)

63
pkg/loopback/loopback.go Normal file
View File

@ -0,0 +1,63 @@
// +build linux
package loopback
import (
"fmt"
"os"
"syscall"
"github.com/Sirupsen/logrus"
)
func getLoopbackBackingFile(file *os.File) (uint64, uint64, error) {
loopInfo, err := ioctlLoopGetStatus64(file.Fd())
if err != nil {
logrus.Errorf("Error get loopback backing file: %s", err)
return 0, 0, ErrGetLoopbackBackingFile
}
return loopInfo.loDevice, loopInfo.loInode, nil
}
// SetCapacity reloads the size for the loopback device.
func SetCapacity(file *os.File) error {
if err := ioctlLoopSetCapacity(file.Fd(), 0); err != nil {
logrus.Errorf("Error loopbackSetCapacity: %s", err)
return ErrSetCapacity
}
return nil
}
// FindLoopDeviceFor returns a loopback device file for the specified file which
// is backing file of a loop back device.
func FindLoopDeviceFor(file *os.File) *os.File {
stat, err := file.Stat()
if err != nil {
return nil
}
targetInode := stat.Sys().(*syscall.Stat_t).Ino
targetDevice := stat.Sys().(*syscall.Stat_t).Dev
for i := 0; true; i++ {
path := fmt.Sprintf("/dev/loop%d", i)
file, err := os.OpenFile(path, os.O_RDWR, 0)
if err != nil {
if os.IsNotExist(err) {
return nil
}
// Ignore all errors until the first not-exist
// we want to continue looking for the file
continue
}
dev, inode, err := getLoopbackBackingFile(file)
if err == nil && dev == targetDevice && inode == targetInode {
return file
}
file.Close()
}
return nil
}