Add initial version of renumber backend

Renumber is a way of renumbering container locks after the number
of locks available has changed.

For now, renumber only works with containers.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

1 files changed, 60 insertions, 0 deletions

diff --git a/libpod/runtime_renumber.go b/libpod/runtime_renumber.go
new file mode 100644
index 000000000..bc291156e
--- /dev/null
+++ b/libpod/runtime_renumber.go
@@ -0,0 +1,60 @@
+package libpod
+
+import (
+	"path/filepath"
+
+	"github.com/containers/storage"
+	"github.com/pkg/errors"
+)
+
+// RenumberLocks reassigns lock numbers for all containers, pods, and volumes in
+// the state.
+// It renders the runtime it is called on, and all container/pod/volume structs
+// from that runtime, unusable, and requires that a new runtime be initialized
+// after it is called.
+func (r *Runtime) RenumberLocks() error {
+	r.lock.Lock()
+	locked := true
+	defer func() {
+		if locked {
+			r.lock.Unlock()
+		}
+	}()
+
+	runtimeAliveLock := filepath.Join(r.config.TmpDir, "alive.lck")
+	aliveLock, err := storage.GetLockfile(runtimeAliveLock)
+	if err != nil {
+		return errors.Wrapf(err, "error acquiring runtime init lock")
+	}
+	aliveLock.Lock()
+	// It's OK to defer until Shutdown() has run, so no need to check locked
+	defer aliveLock.Unlock()
+
+	// Start off by deallocating all locks
+	if err := r.lockManager.FreeAllLocks(); err != nil {
+		return err
+	}
+
+	allCtrs, err := r.state.AllContainers()
+	if err != nil {
+		return err
+	}
+	for _, ctr := range allCtrs {
+		lock, err := r.lockManager.AllocateLock()
+		if err != nil {
+			return errors.Wrapf(err, "error allocating lock for container %s", ctr.ID())
+		}
+
+		ctr.config.LockID = lock.ID()
+
+		// Write the new lock ID
+		if err := r.state.RewriteContainerConfig(ctr, ctr.config); err != nil {
+			return err
+		}
+	}
+
+	r.lock.Unlock()
+	locked = false
+
+	return r.Shutdown(false)
+}