1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
|
// +build linux,cgo
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 == uint64(targetDevice) && inode == targetInode {
return file
}
file.Close()
}
return nil
}
|
