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Support copyup mount extension for tmpfs mounts 

If copyup is specified for a tmpfs mount, then the contents of the
underlying directory are copied into the tmpfs mounted over it.

Signed-off-by: Mrunal Patel <mrunalp@gmail.com>
This commit is contained in:
Mrunal Patel 2016-05-26 12:36:54 -07:00
parent 4356468f49
commit c7406f7075
1 changed files with 30 additions and 1 deletions
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31
libcontainer/rootfs_linux.go
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@ -16,6 +16,7 @@ import (
"github.com/docker/docker/pkg/mount" "github.com/docker/docker/pkg/mount"
"github.com/docker/docker/pkg/symlink" "github.com/docker/docker/pkg/symlink"
"github.com/mrunalp/fileutils"
"github.com/opencontainers/runc/libcontainer/cgroups" "github.com/opencontainers/runc/libcontainer/cgroups"
"github.com/opencontainers/runc/libcontainer/configs" "github.com/opencontainers/runc/libcontainer/configs"
"github.com/opencontainers/runc/libcontainer/label" "github.com/opencontainers/runc/libcontainer/label"
@ -152,15 +153,41 @@ func mountToRootfs(m *configs.Mount, rootfs, mountLabel string) error {
} }
return nil return nil
case "tmpfs": case "tmpfs":
copyUp := m.Extensions&configs.EXT_COPYUP == configs.EXT_COPYUP
tmpDir := ""
stat, err := os.Stat(dest) stat, err := os.Stat(dest)
if err != nil { if err != nil {
if err := os.MkdirAll(dest, 0755); err != nil { if err := os.MkdirAll(dest, 0755); err != nil {
return err return err
} }
} }
if copyUp {
tmpDir, err = ioutil.TempDir("/tmp", "runctmpdir")
if err != nil {
return newSystemErrorWithCause(err, "tmpcopyup: failed to create tmpdir")
}
defer os.RemoveAll(tmpDir)
m.Destination = tmpDir
}
if err := mountPropagate(m, rootfs, mountLabel); err != nil { if err := mountPropagate(m, rootfs, mountLabel); err != nil {
return err return err
} }
if copyUp {
if err := fileutils.CopyDirectory(dest, tmpDir); err != nil {
errMsg := fmt.Errorf("tmpcopyup: failed to copy %s to %s: %v", dest, tmpDir, err)
if err1 := syscall.Unmount(tmpDir, syscall.MNT_DETACH); err1 != nil {
return newSystemErrorWithCausef(err1, "tmpcopyup: %v: failed to unmount", errMsg)
}
return errMsg
}
if err := syscall.Mount(tmpDir, dest, "", syscall.MS_MOVE, ""); err != nil {
errMsg := fmt.Errorf("tmpcopyup: failed to move mount %s to %s: %v", tmpDir, dest, err)
if err1 := syscall.Unmount(tmpDir, syscall.MNT_DETACH); err1 != nil {
return newSystemErrorWithCausef(err1, "tmpcopyup: %v: failed to unmount", errMsg)
}
return errMsg
}
}
if stat != nil { if stat != nil {
if err = os.Chmod(dest, stat.Mode()); err != nil { if err = os.Chmod(dest, stat.Mode()); err != nil {
return err return err
@ -711,7 +738,9 @@ func mountPropagate(m *configs.Mount, rootfs string, mountLabel string) error {
if libcontainerUtils.CleanPath(dest) == "/dev" { if libcontainerUtils.CleanPath(dest) == "/dev" {
flags &= ^syscall.MS_RDONLY flags &= ^syscall.MS_RDONLY
} }
if !strings.HasPrefix(dest, rootfs) {
copyUp := m.Extensions&configs.EXT_COPYUP == configs.EXT_COPYUP
if !(copyUp || strings.HasPrefix(dest, rootfs)) {
dest = filepath.Join(rootfs, dest) dest = filepath.Join(rootfs, dest)
} }