75 lines
1.6 KiB
Go
75 lines
1.6 KiB
Go
package btrfs
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import (
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"crypto/sha256"
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"fmt"
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"os"
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"path/filepath"
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"github.com/docker/containerd"
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"github.com/stevvooe/go-btrfs"
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)
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type Btrfs struct {
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device string // maybe we can resolve it with path?
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root string // root provides paths for internal storage.
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}
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func NewBtrfs(device, root string) (*Btrfs, error) {
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return &Btrfs{device: device, root: root}, nil
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}
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func (lm *Btrfs) Prepare(key, parent string) ([]containerd.Mount, error) {
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active := filepath.Join(lm.root, "active")
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if err := os.MkdirAll(active, 0755); err != nil {
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return nil, err
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}
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dir := filepath.Join(active, hash(key))
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if parent == "" {
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// create new subvolume
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// btrfs subvolume create /dir
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if err := btrfs.SubvolCreate(dir); err != nil {
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return nil, err
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}
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} else {
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// btrfs subvolume snapshot /parent /subvol
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if err := btrfs.SubvolSnapshot(dir, parent, false); err != nil {
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return nil, err
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}
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}
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// get the subvolume id back out for the mount
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info, err := btrfs.SubvolInfo(dir)
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if err != nil {
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return nil, err
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}
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return []containerd.Mount{
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{
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Type: "btrfs",
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Source: lm.device, // device?
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Target: key,
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// NOTE(stevvooe): While it would be nice to use to uuids for
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// mounts, they don't work reliably if the uuids are missing.
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Options: []string{fmt.Sprintf("subvolid=%d", info.ID)},
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},
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}, nil
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}
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func (lm *Btrfs) Commit(name, key string) error {
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dir := filepath.Join(lm.root, "active", hash(key))
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fmt.Println("commit to", name)
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if err := btrfs.SubvolSnapshot(name, dir, true); err != nil {
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return err
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}
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return btrfs.SubvolDelete(dir)
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}
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func hash(k string) string {
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return fmt.Sprintf("%x", sha256.Sum224([]byte(k)))
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}
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