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btrfs.go
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btrfs.go
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package driver
import (
"bytes"
"errors"
"fmt"
"os"
"os/exec"
"path/filepath"
"strings"
"code.cloudfoundry.org/lager"
)
type BtrFSDriver struct {
logger lager.Logger
btrfsBin string
}
func NewBtrFSDriver(
logger lager.Logger,
btrfsBin string,
) *BtrFSDriver {
return &BtrFSDriver{
logger: logger,
btrfsBin: btrfsBin,
}
}
func (driver *BtrFSDriver) CreateVolume(path string) error {
_, _, err := driver.run(driver.btrfsBin, "subvolume", "create", path)
if err != nil {
return err
}
_, _, err = driver.run(driver.btrfsBin, "quota", "enable", path)
if err != nil {
return err
}
return nil
}
func (driver *BtrFSDriver) DestroyVolume(path string) error {
volumePathsToDelete := []string{}
findSubvolumes := func(p string, f os.FileInfo, err error) error {
if err != nil {
return err
}
if !f.IsDir() {
return nil
}
isSub, err := isSubvolume(p)
if err != nil {
return fmt.Errorf("failed to check if %s is a subvolume: %s", p, err)
}
if isSub {
volumePathsToDelete = append(volumePathsToDelete, p)
}
return nil
}
if err := filepath.Walk(path, findSubvolumes); err != nil {
return fmt.Errorf("recursively walking subvolumes for %s failed: %v", path, err)
}
for i := len(volumePathsToDelete) - 1; i >= 0; i-- {
_, _, err := driver.run(driver.btrfsBin, "subvolume", "delete", volumePathsToDelete[i])
if err != nil {
return err
}
}
return nil
}
func (driver *BtrFSDriver) CreateCopyOnWriteLayer(path string, parent string) error {
_, _, err := driver.run(driver.btrfsBin, "subvolume", "snapshot", parent, path)
return err
}
func (driver *BtrFSDriver) GetVolumeSizeInBytes(path string) (int64, error) {
output, _, err := driver.run(driver.btrfsBin, "qgroup", "show", "-F", "--raw", path)
if err != nil {
return 0, err
}
qgroupsLines := strings.Split(strings.TrimSpace(output), "\n")
qgroupFields := strings.Fields(qgroupsLines[len(qgroupsLines)-1])
if len(qgroupFields) != 3 {
return 0, errors.New("unable-to-parse-btrfs-qgroup-show")
}
var exclusiveSize int64
_, err = fmt.Sscanf(qgroupFields[2], "%d", &exclusiveSize)
if err != nil {
return 0, err
}
return exclusiveSize, nil
}
func (driver *BtrFSDriver) run(command string, args ...string) (string, string, error) {
cmd := exec.Command(command, args...)
logger := driver.logger.Session("run-command", lager.Data{
"command": command,
"args": args,
})
stdout := &bytes.Buffer{}
stderr := &bytes.Buffer{}
cmd.Stdout = stdout
cmd.Stderr = stderr
err := cmd.Run()
loggerData := lager.Data{
"stdout": stdout.String(),
"stderr": stderr.String(),
}
if err != nil {
logger.Error("failed", err, loggerData)
return "", "", err
}
logger.Debug("ran", loggerData)
return stdout.String(), stderr.String(), nil
}