fix(squash): don't mount the mount points if already mounted

It is possible that user setup some early mount in the rootfs even
earlier, so just be more robust and cover that case too.

Signed-off-by: Kairui Song <kasong@redhat.com>

modules.d/99squash/init-squash.sh

@@ -1,12 +1,17 @@
 #!/bin/sh
 PATH=/bin:/sbin
 
-# Basic mounts for mounting a squash image
-mkdir /proc /sys /dev /run
-mount -t proc -o nosuid,noexec,nodev proc /proc
-mount -t sysfs -o nosuid,noexec,nodev sysfs /sys
-mount -t devtmpfs -o mode=755,noexec,nosuid,strictatime devtmpfs /dev
-mount -t tmpfs -o mode=755,nodev,nosuid,strictatime tmpfs /run
+[ -e /proc/self/mounts ] \
+    || (mkdir -p /proc && mount -t proc -o nosuid,noexec,nodev proc /proc)
+
+grep -q '^sysfs /sys sysfs' /proc/self/mounts \
+    || (mkdir -p /sys && mount -t sysfs -o nosuid,noexec,nodev sysfs /sys)
+
+grep -q '^devtmpfs /dev devtmpfs' /proc/self/mounts \
+    || (mkdir -p /dev && mount -t devtmpfs -o mode=755,noexec,nosuid,strictatime devtmpfs /dev)
+
+grep -q '^tmpfs /run tmpfs' /proc/self/mounts \
+    || (mkdir -p /run && mount -t tmpfs -o mode=755,noexec,nosuid,strictatime tmpfs /run)
 
 # Load required modules
 modprobe loop

modules.d/99squash/module-setup.sh

@@ -42,11 +42,11 @@ installpost() {
     # Install required modules and binaries for the squash image init script.
     if [[ $_busybox ]]; then
         inst "$_busybox" /usr/bin/busybox
-        for _i in sh echo mount modprobe mkdir switch_root; do
+        for _i in sh echo mount modprobe mkdir switch_root grep; do
             ln_r /usr/bin/busybox /usr/bin/$_i
         done
     else
-        DRACUT_RESOLVE_DEPS=1 inst_multiple sh mount modprobe mkdir switch_root
+        DRACUT_RESOLVE_DEPS=1 inst_multiple sh mount modprobe mkdir switch_root grep
     fi
 
     hostonly="" instmods "loop" "squashfs" "overlay"