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
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
// +build linux,amd64
package btrfs
/*
#include <stdlib.h>
#include <dirent.h>
#include <btrfs/ioctl.h>
*/
import "C"
import (
"fmt"
"github.com/dotcloud/docker/runtime/graphdriver"
"os"
"path"
"syscall"
"unsafe"
)
func init() {
graphdriver.Register("btrfs", Init)
}
func Init(home string) (graphdriver.Driver, error) {
rootdir := path.Dir(home)
var buf syscall.Statfs_t
if err := syscall.Statfs(rootdir, &buf); err != nil {
return nil, err
}
if buf.Type != 0x9123683E {
return nil, fmt.Errorf("%s is not a btrfs filesystem", rootdir)
}
return &Driver{
home: home,
}, nil
}
type Driver struct {
home string
}
func (d *Driver) String() string {
return "btrfs"
}
func (d *Driver) Status() [][2]string {
return nil
}
func (d *Driver) Cleanup() error {
return nil
}
func free(p *C.char) {
C.free(unsafe.Pointer(p))
}
func openDir(path string) (*C.DIR, error) {
Cpath := C.CString(path)
defer free(Cpath)
dir := C.opendir(Cpath)
if dir == nil {
return nil, fmt.Errorf("Can't open dir")
}
return dir, nil
}
func closeDir(dir *C.DIR) {
if dir != nil {
C.closedir(dir)
}
}
func getDirFd(dir *C.DIR) uintptr {
return uintptr(C.dirfd(dir))
}
func subvolCreate(path, name string, mountLabel string) error {
dir, err := openDir(path)
if err != nil {
return err
}
defer closeDir(dir)
var args C.struct_btrfs_ioctl_vol_args
for i, c := range []byte(name) {
args.name[i] = C.char(c)
}
_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_SUBVOL_CREATE,
uintptr(unsafe.Pointer(&args)))
if errno != 0 {
return fmt.Errorf("Failed to create btrfs subvolume: %v", errno.Error())
}
return nil
}
func subvolSnapshot(src, dest, name string) error {
srcDir, err := openDir(src)
if err != nil {
return err
}
defer closeDir(srcDir)
destDir, err := openDir(dest)
if err != nil {
return err
}
defer closeDir(destDir)
var args C.struct_btrfs_ioctl_vol_args_v2
args.fd = C.__s64(getDirFd(srcDir))
for i, c := range []byte(name) {
args.name[i] = C.char(c)
}
_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(destDir), C.BTRFS_IOC_SNAP_CREATE_V2,
uintptr(unsafe.Pointer(&args)))
if errno != 0 {
return fmt.Errorf("Failed to create btrfs snapshot: %v", errno.Error())
}
return nil
}
func subvolDelete(path, name string) error {
dir, err := openDir(path)
if err != nil {
return err
}
defer closeDir(dir)
var args C.struct_btrfs_ioctl_vol_args
for i, c := range []byte(name) {
args.name[i] = C.char(c)
}
_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_SNAP_DESTROY,
uintptr(unsafe.Pointer(&args)))
if errno != 0 {
return fmt.Errorf("Failed to destroy btrfs snapshot: %v", errno.Error())
}
return nil
}
func (d *Driver) subvolumesDir() string {
return path.Join(d.home, "subvolumes")
}
func (d *Driver) subvolumesDirId(id string) string {
return path.Join(d.subvolumesDir(), id)
}
func (d *Driver) Create(id string, parent string, mountLabel string) error {
subvolumes := path.Join(d.home, "subvolumes")
if err := os.MkdirAll(subvolumes, 0700); err != nil {
return err
}
if parent == "" {
if err := subvolCreate(subvolumes, id, mountLabel); err != nil {
return err
}
} else {
parentDir, err := d.Get(parent)
if err != nil {
return err
}
if err := subvolSnapshot(parentDir, subvolumes, id); err != nil {
return err
}
}
return nil
}
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
}
return os.RemoveAll(dir)
}
func (d *Driver) Get(id 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
}
func (d *Driver) Put(id string) {
// Get() creates no runtime resources (like e.g. mounts)
// so this doesn't need to do anything.
}
func (d *Driver) Exists(id string) bool {
dir := d.subvolumesDirId(id)
_, err := os.Stat(dir)
return err == nil
}
|
