On Tue, Apr 26, 2022 at 10:40 AM Federico Vaga <federico.vaga@xxxxxxx> wrote:
>
> On Fri, Apr 22, 2022 at 01:04:45PM +0200, German Maglione wrote:
> >On Wed, Apr 20, 2022 at 9:17 AM Federico Vaga <federico.vaga@xxxxxxx> wrote:
> >>
> >> The dmsquash-live module assumes that `overlay` is always a module.
> >> Therefore, when `overlay` is built-in the kernel, this module will fail
> >> to detect the presence of such a feature.
> >>
> >> This patch adds a fallback mechanism to check also `/proc/filesystem`.
> >> This is also what happens with the dracut NSF module when loading the
> >> kernel module `rpc_pipefs`.
> >>
> >> Signed-off-by: Federico Vaga <federico.vaga@xxxxxxx>
> >> ---
> >> modules.d/90dmsquash-live/dmsquash-live-root.sh | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/modules.d/90dmsquash-live/dmsquash-live-root.sh b/modules.d/90dmsquash-live/dmsquash-live-root.sh
> >> index fd8a858a..b4a44e92 100755
> >> --- a/modules.d/90dmsquash-live/dmsquash-live-root.sh
> >> +++ b/modules.d/90dmsquash-live/dmsquash-live-root.sh
> >> @@ -170,7 +170,7 @@ do_live_overlay() {
> >> fi
> >> fi
> >> if [ -n "$overlayfs" ]; then
> >> - if ! modprobe overlay; then
> >> + if ! (modprobe overlay || strstr "$(cat /proc/filesystems)" overlay); then
> >
> >if ! { modprobe overlay || strstr "$(cat /proc/filesystems)" overlay; }; then
> >
> >I recently made the same mistake of using a subshell.
>
> For my understanding:
>
> Why do you think it's a mistake to use a subshell?
>
> Are you thinking about execution performance, or some locale variable
> that do not get exported to the subshell?
Well, maybe "mistake" was not the best word to use in this case,
the subshell here it's simply unnecessary
> Then, why curly brackets and not double square brackets?
do you mean like:
if ! [[ modprobe overlay; ]]; then
this is a mistake, you cannot wrap commands in [[ ]] (or []), try this:
[[ false ]] && echo "you should not see this"
> I see the latter is far more used among modules; even if it is
> enforcing a dependency on bash (or whatever supports `[[`)
That the hooks be posix compliant (as you said [[ can be considered as
a bashism)
is explicitly required In the dracut docs, although it is true that
there are some hooks
that use [[, but mostly setup scripts.
>
> Thanks in advance for the clarifications :)
>
> >> if [ "$overlayfs" = required ]; then
> >> die "OverlayFS is required but not available."
> >> exit 1
> >> --
> >> 2.27.0
> >>
> >
> >
> >--
> >German
> >
>
--
German
