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snapshot/overlay: use readonly bindmount for single parent view 

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
This commit is contained in:
Derek McGowan 2017-02-27 13:21:20 -08:00
parent 1723444ba2
commit eeb88554ac
2 changed files with 49 additions and 3 deletions
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11
snapshot/overlay/overlay.go
View File

@ -330,6 +330,17 @@ func (a *activeDir) mounts(c *cache) ([]containerd.Mount, error) {
)
} else if !os.IsNotExist(err) {
return nil, err
} else if len(parents) == 1 {
return []containerd.Mount{
{
Source: parents[0],
Type: "bind",
Options: []string{
"ro",
"rbind",
},
},
}, nil
}
options = append(options, fmt.Sprintf("lowerdir=%s", strings.Join(parents, ":")))

41
snapshot/overlay/overlay_test.go
View File

@ -209,7 +209,7 @@ func TestOverlayView(t *testing.T) {
if err != nil {
t.Fatal(err)
}
key := "/tmp/test"
key := "/tmp/base"
mounts, err := o.Prepare(ctx, key, "")
if err != nil {
t.Fatal(err)
@ -221,7 +221,42 @@ func TestOverlayView(t *testing.T) {
if err := o.Commit(ctx, "base", key); err != nil {
t.Fatal(err)
}
mounts, err = o.View(ctx, "/tmp/test2", "base")
key = "/tmp/top"
_, err = o.Prepare(ctx, key, "base")
if err != nil {
t.Fatal(err)
}
if err := ioutil.WriteFile(filepath.Join(root, "active", hash(key), "fs", "foo"), []byte("hi, again"), 0660); err != nil {
t.Fatal(err)
}
if err := o.Commit(ctx, "top", key); err != nil {
t.Fatal(err)
}
mounts, err = o.View(ctx, "/tmp/view1", "base")
if err != nil {
t.Fatal(err)
}
if len(mounts) != 1 {
t.Fatalf("should only have 1 mount but received %d", len(mounts))
}
m = mounts[0]
if m.Type != "bind" {
t.Errorf("mount type should be bind but received %q", m.Type)
}
expected := filepath.Join(root, "committed", hash("base"), "fs")
if m.Source != expected {
t.Errorf("expected source %q but received %q", expected, m.Source)
}
if m.Options[0] != "ro" {
t.Errorf("expected mount option ro but received %q", m.Options[0])
}
if m.Options[1] != "rbind" {
t.Errorf("expected mount option rbind but received %q", m.Options[1])
}
mounts, err = o.View(ctx, "/tmp/view2", "top")
if err != nil {
t.Fatal(err)
}
@ -238,7 +273,7 @@ func TestOverlayView(t *testing.T) {
if len(m.Options) != 1 {
t.Errorf("expected 1 mount option but got %d", len(m.Options))
}
expected := fmt.Sprintf("lowerdir=%s", filepath.Join(root, "committed", hash("base"), "fs"))
expected = fmt.Sprintf("lowerdir=%s:%s", filepath.Join(root, "committed", hash("top"), "fs"), filepath.Join(root, "committed", hash("base"), "fs"))
if m.Options[0] != expected {
t.Errorf("expected option %q but received %q", expected, m.Options[0])
}