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Merge pull request #4765 from kolyshkin/criu-nits

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Refactor/improve prepareCriuRestoreMounts
This commit is contained in:
lfbzhm
2025-08-24 13:06:22 +08:00
committed by GitHub
parent 835591bab6 ce3cd4234c
commit d2e86c05c8
1 changed files with 34 additions and 58 deletions
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libcontainer/criu_linux.go
+34 -58
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@@ -523,34 +523,9 @@ func (c *Container) restoreNetwork(req *criurpc.CriuReq, criuOpts *CriuOpts) {
}
}
// makeCriuRestoreMountpoints makes the actual mountpoints for the
// restore using CRIU. This function is inspired from the code in
// rootfs_linux.go.
func (c *Container) makeCriuRestoreMountpoints(m *configs.Mount) error {
if m.Device == "cgroup" {
// No mount point(s) need to be created:
//
// * for v1, mount points are saved by CRIU because
// /sys/fs/cgroup is a tmpfs mount
//
// * for v2, /sys/fs/cgroup is a real mount, but
// the mountpoint appears as soon as /sys is mounted
return nil
}
// TODO: pass srcFD? Not sure if criu is impacted by issue #2484.
me := mountEntry{Mount: m}
// For all other filesystems, just make the target.
if _, err := createMountpoint(c.config.Rootfs, me); err != nil {
return fmt.Errorf("create criu restore mountpoint for %s mount: %w", me.Destination, err)
}
return nil
}
// isPathInPrefixList is a small function for CRIU restore to make sure
// mountpoints, which are on a tmpfs, are not created in the roofs.
func isPathInPrefixList(path string, prefix []string) bool {
for _, p := range prefix {
if strings.HasPrefix(path, p+"/") {
func isOnTmpfs(path string, mounts []*configs.Mount) bool {
for _, m := range mounts {
if m.Device == "tmpfs" && strings.HasPrefix(path, m.Destination+"/") {
return true
}
}
@@ -564,17 +539,6 @@ func isPathInPrefixList(path string, prefix []string) bool {
// This function also creates missing mountpoints as long as they
// are not on top of a tmpfs, as CRIU will restore tmpfs content anyway.
func (c *Container) prepareCriuRestoreMounts(mounts []*configs.Mount) error {
// First get a list of a all tmpfs mounts
tmpfs := []string{}
for _, m := range mounts {
switch m.Device {
case "tmpfs":
tmpfs = append(tmpfs, m.Destination)
}
}
// Now go through all mounts and create the mountpoints
// if the mountpoints are not on a tmpfs, as CRIU will
// restore the complete tmpfs content from its checkpoint.
umounts := []string{}
defer func() {
for _, u := range umounts {
@@ -590,28 +554,40 @@ func (c *Container) prepareCriuRestoreMounts(mounts []*configs.Mount) error {
})
}
}()
// Now go through all mounts and create the required mountpoints.
for _, m := range mounts {
if !isPathInPrefixList(m.Destination, tmpfs) {
if err := c.makeCriuRestoreMountpoints(m); err != nil {
// No cgroup mount point(s) need to be created:
// * for v1, mount points are saved by CRIU because
// /sys/fs/cgroup is a tmpfs mount;
// * for v2, /sys/fs/cgroup is a real mount, but
// the mountpoint appears as soon as /sys is mounted.
if m.Device == "cgroup" {
continue
}
// If the mountpoint is on a tmpfs, skip it as CRIU will
// restore the complete tmpfs content from its checkpoint.
if isOnTmpfs(m.Destination, mounts) {
continue
}
if _, err := createMountpoint(c.config.Rootfs, mountEntry{Mount: m}); err != nil {
return fmt.Errorf("create criu restore mountpoint for %s mount: %w", m.Destination, err)
}
// If the mount point is a bind mount, we need to mount
// it now so that runc can create the necessary mount
// points for mounts in bind mounts.
// This also happens during initial container creation.
// Without this CRIU restore will fail
// See: https://github.com/opencontainers/runc/issues/2748
// It is also not necessary to order the mount points
// because during initial container creation mounts are
// set up in the order they are configured.
if m.Device == "bind" {
if err := utils.WithProcfd(c.config.Rootfs, m.Destination, func(dstFd string) error {
return mountViaFds(m.Source, nil, m.Destination, dstFd, "", unix.MS_BIND|unix.MS_REC, "")
}); err != nil {
return err
}
// If the mount point is a bind mount, we need to mount
// it now so that runc can create the necessary mount
// points for mounts in bind mounts.
// This also happens during initial container creation.
// Without this CRIU restore will fail
// See: https://github.com/opencontainers/runc/issues/2748
// It is also not necessary to order the mount points
// because during initial container creation mounts are
// set up in the order they are configured.
if m.Device == "bind" {
if err := utils.WithProcfd(c.config.Rootfs, m.Destination, func(dstFd string) error {
return mountViaFds(m.Source, nil, m.Destination, dstFd, "", unix.MS_BIND|unix.MS_REC, "")
}); err != nil {
return err
}
umounts = append(umounts, m.Destination)
}
umounts = append(umounts, m.Destination)
}
}
return nil