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loopback: separate loop logic from devicemapper

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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 c28b794f70
commit 74e35aace0
7 changed files with 200 additions and 165 deletions
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101
devicemapper/devmapper.go
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@ -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 {