I don't think specutils should take a dependency on fsimpl/erofs for this == "erofs" check. specutils has very limited dependencies on the sentry. erofs pulls in a lot of stuff.

Similar to the duplication of the string "bind" above on line 503 and in

Use specutils.HasMountConf instead

Use specutils.HasMountConfig instead

Use specutils.HasMountConfig instead

I think what we really need is specutils.HasMountConfig(m).

// HasMountConfig returns true if the given mount has an associated GoferMountConf.
func HasMountConfig(m specs.Mount) bool {
	return IsGoferMount(m) || IsErofsMount(m)
}

The logic below handles the rest correctly by continuing if !mountConf.ShouldUseLisafs()

Use specutils.HasMountConfig instead

Use !specutils.HasMountConfig() instead

Update comment to say "Handle sub mounts."

EROFS mounts are not bind mounts.

No need for this. In c.createGoferFilestore(), if !goferConf.IsFilestorePresent(), then we return immediately.

Moreover, in the future, we may want to support EROFS+overlay, for which we will need to create filestore for the upper layer.

I think all these changes here are really complex and hard to follow.

The c.GoferMountConfs list is a subset of c.Spec.Mounts. It is difficult to iterate configs and track mount index. Everywhere else (as you can see in this PR), we iterate the mounts and track the config index. That approach also requires handling rootfs separately (outside the main loop), but that should be OK:

• rootfs often requires special handling, as you can see below, we need to handle rootfs differently in the if i==0 branch.
• It is consistent with the rest of the codebase.

So it should be something like:

switch {
    case c.GoferMountConfs[0].ShouldUseLisafs():
			refactored code to create socket pair and donate the gofer end and append the sandbox end
    case c.GoferMountConfs[0].ShouldUseErofs():
			f, err := os.Open(rootfsHint.Mount.Source)
			if err != nil {
				return nil, nil, nil, nil, fmt.Errorf("opening rootfs image %q: %v", rootfsHint.Mount.Source, err)
			}
			sandEnds = append(sandEnds, f)
}

cfgIdx := 1
for _, m := c.Spec.Mounts {
  if !specutils.HasMountConfig(m) {
    continue
  }
  switch {
    case c.GoferMountConfs[cfgIdx].ShouldUseLisafs():
			refactored code to create socket pair and donate the gofer end and append the sandbox end
    case c.GoferMountConfs[cfgIdx].ShouldUseErofs():
			f, err := os.Open(m.Source)
			if err != nil {
				return nil, nil, nil, nil, fmt.Errorf("opening EROFS image %q: %v", m.Source, err)
			}
			sandEnds = append(sandEnds, f)
  }
  cfgIdx++
}