containerd/mount/mount_linux.go
Ian Campbell d42cb88ba2 Loop umount'ing rootfs until there are no more mounts
This is simpler than trying to count how many successful mounts we made.

Signed-off-by: Ian Campbell <ian.campbell@docker.com>
2017-07-20 10:50:08 +01:00

90 lines
2.6 KiB
Go

package mount
import (
"strings"
"golang.org/x/sys/unix"
)
func (m *Mount) Mount(target string) error {
flags, data := parseMountOptions(m.Options)
return unix.Mount(m.Source, target, m.Type, uintptr(flags), data)
}
func Unmount(mount string, flags int) error {
return unix.Unmount(mount, flags)
}
// UnmountAll repeatedly unmounts the given mount point until there
// are no mounts remaining (EINVAL is returned by mount), which is
// useful for undoing a stack of mounts on the same mount point.
func UnmountAll(mount string, flags int) error {
for {
if err := Unmount(mount, flags); err != nil {
// EINVAL is returned if the target is not a
// mount point, indicating that we are
// done. It can also indicate a few other
// things (such as invalid flags) which we
// unfortunately end up squelching here too.
if err == unix.EINVAL {
return nil
}
return err
}
}
}
// parseMountOptions takes fstab style mount options and parses them for
// use with a standard mount() syscall
func parseMountOptions(options []string) (int, string) {
var (
flag int
data []string
)
flags := map[string]struct {
clear bool
flag int
}{
"async": {true, unix.MS_SYNCHRONOUS},
"atime": {true, unix.MS_NOATIME},
"bind": {false, unix.MS_BIND},
"defaults": {false, 0},
"dev": {true, unix.MS_NODEV},
"diratime": {true, unix.MS_NODIRATIME},
"dirsync": {false, unix.MS_DIRSYNC},
"exec": {true, unix.MS_NOEXEC},
"mand": {false, unix.MS_MANDLOCK},
"noatime": {false, unix.MS_NOATIME},
"nodev": {false, unix.MS_NODEV},
"nodiratime": {false, unix.MS_NODIRATIME},
"noexec": {false, unix.MS_NOEXEC},
"nomand": {true, unix.MS_MANDLOCK},
"norelatime": {true, unix.MS_RELATIME},
"nostrictatime": {true, unix.MS_STRICTATIME},
"nosuid": {false, unix.MS_NOSUID},
"rbind": {false, unix.MS_BIND | unix.MS_REC},
"relatime": {false, unix.MS_RELATIME},
"remount": {false, unix.MS_REMOUNT},
"ro": {false, unix.MS_RDONLY},
"rw": {true, unix.MS_RDONLY},
"strictatime": {false, unix.MS_STRICTATIME},
"suid": {true, unix.MS_NOSUID},
"sync": {false, unix.MS_SYNCHRONOUS},
}
for _, o := range options {
// If the option does not exist in the flags table or the flag
// is not supported on the platform,
// then it is a data value for a specific fs type
if f, exists := flags[o]; exists && f.flag != 0 {
if f.clear {
flag &^= f.flag
} else {
flag |= f.flag
}
} else {
data = append(data, o)
}
}
return flag, strings.Join(data, ",")
}