Add FSTYPE config parameter to allow overriding filesystem type detection

This is needed for testing, and should also be useful for building
more generic initramfs images.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

conf/initramfs.conf

@@ -66,3 +66,12 @@ NFSROOT=auto
 #
 
 RUNSIZE=10%
+
+#
+# FSTYPE: ...
+#
+# The filesytem type(s) to support, or "auto" to use the current root
+# filesystem type
+#
+
+FSTYPE=auto

hooks/fsck

@@ -64,8 +64,18 @@ get_fsck_type_fstab () {
 }
 
 get_fsck_types() {
-	get_fsck_type_fstab /    root
-	get_fsck_type_fstab /usr /usr
+	if [ "${FSTYPE:-auto}" = auto ]; then
+		get_fsck_type_fstab /    root
+		get_fsck_type_fstab /usr usr
+	else
+		local IFS=,
+		local fstype
+		set -f
+		for fstype in $FSTYPE; do
+			echo "$fstype"
+		done
+		set +f
+	fi
 }
 
 case $1 in

initramfs.conf.5

@@ -93,6 +93,12 @@ or is set to \fIauto\fP,
 will automatically select the largest available swap partition.
 Set it to \fInone\fP to disable resume from disk.
 
+.TP
+\fB FSTYPE
+Specifies the filesystem type(s) to support, separated by commas.  If
+this is not defined or is set to \fIauto\fP, \fBmkinitramfs\fP will
+automatically detect the current root and \fI/usr\fP filesystem types.
+
 .SH VARIABLES FOR NFS BOOT
 .TP
 \fB DEVICE

mkinitramfs

@@ -247,6 +247,7 @@ export KEYMAP
 export MODULES
 export BUSYBOX
 export RESUME
+export FSTYPE
 
 # Private, used by 'catenate_cpiogz'.
 export __TMPCPIOGZ