Merge pull request #18686 from cpuguy83/fix_btrfs_subvol_delete_panic

Fix btrfs recursive btrfs subvol delete

daemon/graphdriver/btrfs/btrfs.go

@@ -188,20 +188,29 @@ func subvolDelete(dirpath, name string) error {
 		return err
 	}
 	defer closeDir(dir)
+	fullPath := path.Join(dirpath, name)
 
 	var args C.struct_btrfs_ioctl_vol_args
 
 	// walk the btrfs subvolumes
 	walkSubvolumes := func(p string, f os.FileInfo, err error) error {
+		if err != nil {
+			if os.IsNotExist(err) && p != fullPath {
+				// missing most likely because the path was a subvolume that got removed in the previous iteration
+				// since it's gone anyway, we don't care
+				return nil
+			}
+			return fmt.Errorf("error walking subvolumes: %v", err)
+		}
 		// we want to check children only so skip itself
 		// it will be removed after the filepath walk anyways
-		if f.IsDir() && p != path.Join(dirpath, name) {
+		if f.IsDir() && p != fullPath {
 			sv, err := isSubvolume(p)
 			if err != nil {
 				return fmt.Errorf("Failed to test if %s is a btrfs subvolume: %v", p, err)
 			}
 			if sv {
-				if err := subvolDelete(p, f.Name()); err != nil {
+				if err := subvolDelete(path.Dir(p), f.Name()); err != nil {
 					return fmt.Errorf("Failed to destroy btrfs child subvolume (%s) of parent (%s): %v", p, dirpath, err)
 				}
 			}

daemon/graphdriver/btrfs/btrfs_test.go

@@ -3,6 +3,8 @@
 package btrfs
 
 import (
+	"os"
+	"path"
 	"testing"
 
 	"github.com/docker/docker/daemon/graphdriver/graphtest"
@@ -26,6 +28,36 @@ func TestBtrfsCreateSnap(t *testing.T) {
 	graphtest.DriverTestCreateSnap(t, "btrfs")
 }
 
+func TestBtrfsSubvolDelete(t *testing.T) {
+	d := graphtest.GetDriver(t, "btrfs")
+	if err := d.Create("test", "", ""); err != nil {
+		t.Fatal(err)
+	}
+	defer graphtest.PutDriver(t)
+
+	dir, err := d.Get("test", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer d.Put("test")
+
+	if err := subvolCreate(dir, "subvoltest"); err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := os.Stat(path.Join(dir, "subvoltest")); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := d.Remove("test"); err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := os.Stat(path.Join(dir, "subvoltest")); !os.IsNotExist(err) {
+		t.Fatalf("expected not exist error on nested subvol, got: %v", err)
+	}
+}
+
 func TestBtrfsTeardown(t *testing.T) {
 	graphtest.PutDriver(t)
 }