Bug#848181: initramfs-tools-core: support mounting of more complex setups

[Tobias Schlemmer <keinstein@users.sf.net>]

Package: initramfs-tools-core
Version: 0.125
Severity: wishlist
Tags: patch

Hi,

I have the following antries in /etc/fstab:
/dev/mapper/tobias4-home /home           ext3    defaults        0       2
/home/usr /usr none bind 0 0

Currently /usr is not mounted automatically. However, with the attached patches
the mountfs function is able mount everything read-only. Tested manually with
the “kernel parameter” break=bottom.

Currently this script mounts only /usr, but not /usr/lib (if necessary) but
this can be easily added.




-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386, mingw64-amd64, mingw64-i386

Kernel: Linux 4.8.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=de_DE.utf8, LC_CTYPE=de_DE.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages initramfs-tools-core depends on:
ii  cpio         2.11+dfsg-6
ii  klibc-utils  2.0.4-9
ii  kmod         23-1
ii  udev         232-7

Versions of packages initramfs-tools-core recommends:
ii  busybox  1:1.22.0-19

Versions of packages initramfs-tools-core suggests:
ii  bash-completion  1:2.1-4.3

-- Configuration Files:
/etc/initramfs-tools/initramfs.conf changed:
MODULES=most
BUSYBOX=y
KEYMAP=n
COMPRESS=gzip
DEVICE=
NFSROOT=auto


-- no debconf information

--- functions	2016-12-14 20:32:54.256138631 +0100
+++ functions.ts	2016-12-14 22:29:53.295389926 +0100
@@ -420,6 +420,55 @@
 	done
 }
 
+# mount a directory in a subshell
+# this won't clobber the local variables
+# $1 mount point
+submountfs()
+{
+	echo submountfs "$*"
+	(
+		. ${rootmnt}/root/functions.ts
+		. ${rootmnt}/root/local.ts
+		mountfs "$1"
+	)
+}
+
+
+# find mountpoints for complicated setups.
+# this function tries to guess the mount point for directory
+# and recursively mounts the necessary super-dirs.
+# $1 mount point
+mountmount()
+{
+	echo mountmount "$*"
+	target="$1"
+	if [ -s "${target}" ]
+	then
+		newmount="$(readlink "${rootfs}${target}")"
+	else
+		newmount="${target}"
+	fi
+	for file in ${rootmnt}/etc/fstab; do
+		if [ -f "${file}" ]; then
+			while read fs dir garbage; do
+				case "${fs}" in 
+				""|\#*)
+					continue;
+					;;
+				esac
+				echo "checking ${newmount} in ${dir}"
+				case "${newmount}" in
+				${dir}/*)
+					mounting "${dir}"
+					submountfs "${dir}"
+					;;
+				esac
+			done < "${file}"
+		fi
+	done
+}
+
+
 # Mount a file system.  We parse the information from the fstab.  This
 # should be overridden by any boot script which can mount arbitrary
 # filesystems such as /usr.  This default implementation delegates to
@@ -429,9 +478,21 @@
 {
 	type=local
 	read_fstab_entry "$1"
-	if [ "${MNT_TYPE}" = "nfs" ] || [ "${MNT_TYPE}" = "nfs4" ]; then
+	echo "got fstab entry ${MNT_FSNAME} ${MNT_DIR} ${MNT_TYPE} ${MNT_OPTS}"
+	case "${MNT_TYPE}" in
+	nfs|nfs4)
+#	if [ "${MNT_TYPE}" = "nfs" ] || [ "${MNT_TYPE}" = "nfs4" ]; then
 		type=nfs
-	fi
+#	fi
+		;;
+	none)
+		mountmount "${MNT_FSNAME}"
+		MNT_FSNAME="${rootmnt}${MNT_FSNAME}"
+		mountmount "${MNT_DIR}"
+		;;		
+	"")
+		mountmount "$1"
+	esac
 
 	${type}_mount_fs "$1"
 }

--- local	2016-12-14 20:32:41.156138419 +0100
+++ local.ts	2016-12-14 22:24:23.683384595 +0100
@@ -163,7 +163,12 @@
 	fi
 
 	# FIXME This has no error checking
-	modprobe "${MNT_TYPE}"
+	if [ "${MNT_TYPE}" = "none" ]
+	then
+		MNT_FSNAME="${rootmnt}${MNT_FSNAME}"
+	else
+		modprobe "${MNT_TYPE}"
+	fi
 
 	if [ "$MNT_PASS" != 0 ]; then
 		checkfs "$MNT_FSNAME" "$MNT_DIR" "${MNT_TYPE}"