From a090301bbb10424ce4f99e40c97959f0e8664718 Mon Sep 17 00:00:00 2001 From: Valentin Rothberg Date: Tue, 2 Mar 2021 09:20:53 +0100 Subject: podman cp: support copying on tmpfs mounts Traditionally, the path resolution for containers has been resolved on the *host*; relative to the container's mount point or relative to specified bind mounts or volumes. While this works nicely for non-running containers, it poses a problem for running ones. In that case, certain kinds of mounts (e.g., tmpfs) will not resolve correctly. A tmpfs is held in memory and hence cannot be resolved relatively to the container's mount point. A copy operation will succeed but the data will not show up inside the container. To support these kinds of mounts, we need to join the *running* container's mount namespace (and PID namespace) when copying. Note that this change implies moving the copy and stat logic into `libpod` since we need to keep the container locked to avoid race conditions. The immediate benefit is that all logic is now inside `libpod`; the code isn't scattered anymore. Further note that Docker does not support copying to tmpfs mounts. Tests have been extended to cover *both* path resolutions for running and created containers. New tests have been added to exercise the tmpfs-mount case. For the record: Some tests could be improved by using `start -a` instead of a start-exec sequence. Unfortunately, `start -a` is flaky in the CI which forced me to use the more expensive start-exec option. Signed-off-by: Valentin Rothberg --- libpod/container_internal.go | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'libpod/container_internal.go') diff --git a/libpod/container_internal.go b/libpod/container_internal.go index 7e8226de4..a7da7f395 100644 --- a/libpod/container_internal.go +++ b/libpod/container_internal.go @@ -2086,6 +2086,10 @@ func (c *Container) setupOCIHooks(ctx context.Context, config *spec.Spec) (map[s // mount mounts the container's root filesystem func (c *Container) mount() (string, error) { + if c.state.State == define.ContainerStateRemoving { + return "", errors.Wrapf(define.ErrCtrStateInvalid, "cannot mount container %s as it is being removed", c.ID()) + } + mountPoint, err := c.runtime.storageService.MountContainerImage(c.ID()) if err != nil { return "", errors.Wrapf(err, "error mounting storage for container %s", c.ID()) -- cgit v1.2.3-54-g00ecf