dracut: add --fstab, to ignore /proc/self/mountinfo

dracut

@@ -67,8 +67,9 @@ Creates initial ramdisk images for preloading modules
                          directory instead of the system-wide installed in
                          /usr/share/dracut/modules.d.
                          Useful when running dracut from a git checkout.
-  -H, --hostonly          Host-Only mode: Install only what is needed for
+  -H, --hostonly        Host-Only mode: Install only what is needed for
                          booting the local host instead of a generic host.
+  --fstab               Use /etc/fstab to determine the root device.
   -i, --include [SOURCE] [TARGET]
                         Include the files in the SOURCE directory into the
                          Target directory in the final initramfs.
@@ -107,6 +108,7 @@ while (($# > 0)); do
 	--confdir) confdir="$2"; shift;;
 	-l|--local) allowlocal="yes" ;;
 	-H|--hostonly) hostonly_l="yes" ;;
+	--fstab) use_fstab_l="yes" ;;
 	-i|--include) include_src="$2"; include_target="$3"; shift 2;;
 	-I|--install) install_items="$2"; shift;;
 	-*) printf "\nUnknown option: %s\n\n" "$1" >&2; usage; exit 1;;
@@ -161,6 +163,7 @@ fi
 [[ $fw_dir_l ]] && fw_dir=$fw_dir_l
 [[ $do_strip_l ]] && do_strip=$do_strip_l
 [[ $hostonly_l ]] && hostonly=$hostonly_l
+[[ $use_fstab_l ]] && use_fstab=$use_fstab_l
 [[ $mdadmconf_l ]] && mdadmconf=$mdadmconf_l
 [[ $lvmconf_l ]] && lvmconf=$lvmconf_l
 [[ $dracutbasedir ]] || dracutbasedir=/usr/share/dracut
@@ -236,7 +239,8 @@ chmod 755 "$initdir"
 
 export initdir hookdirs dracutbasedir dracutmodules drivers \
     fw_dir drivers_dir debug beverbose no_kernel kernel_only \
-    add_drivers mdadmconf lvmconf filesystems ignore_kmodules
+    add_drivers mdadmconf lvmconf filesystems ignore_kmodules \
+    use_fstab
 
 if [[ $kernel_only != yes ]]; then
     # Create some directory structure first

dracut-functions

@@ -94,6 +94,7 @@ print_vars() {
 }
 
 get_fs_env() {
+    [[ $1 ]] || return
     eval $(udevadm info --query=env --name=$1|egrep 'ID_FS_(TYPE|UUID)=')
     [[ $ID_FS_TYPE ]] && return
 
@@ -107,6 +108,13 @@ get_fs_env() {
 }
 
 get_fs_type() (
+    [[ $1 ]] || return
+    if [[ $1 != ${1#/dev/block/nfs:} ]] \
+	|| [[ $1 != ${1#/dev/block/nfs3:} ]] \
+	|| [[ $1 != ${1#/dev/block/nfs4:} ]]; then
+	echo "nfs"
+	return
+    fi
     get_fs_env $1 || return
     echo $ID_FS_TYPE
 )
@@ -118,10 +126,35 @@ get_fs_uuid() (
 
 # finds the major:minor of the block device backing the root filesystem.
 find_block_device() {
-    local majmin rootdev blkdev fs type opts misc
-    while read a b majmin c mpt opts d fs type opts misc; do
-	[[ $mpt = $1 ]] && { echo $majmin; break; } # we have a winner!
-    done < /proc/self/mountinfo
+    local x mpt majmin dev fs misc maj min
+    if [[ $use_fstab != yes ]]; then	
+	while read x x majmin x mpt x x fs misc; do
+            [[ $fs = nfs ]] && { echo $dev; return 0;}
+            [[ $fs = nfs3 ]] && { echo $dev; return 0;}
+            [[ $fs = nfs4 ]] && { echo $dev; return 0;}
+	    if [[ $mpt = $1 ]] && [[ ${majmin#0:} = $majmin ]]; then
+		echo $majmin; 
+		return 0 # we have a winner!
+	    fi
+	done < /proc/self/mountinfo       
+    fi
+    # fall back to /etc/fstab    
+    while read dev mpt fs misc; do
+	if [[ $mpt = $1 ]]; then
+            [[ $fs = nfs ]] && { echo $dev; return 0;}
+            [[ $fs = nfs3 ]] && { echo $dev; return 0;}
+            [[ $fs = nfs4 ]] && { echo $dev; return 0;}
+            [[ $dev != ${dev#UUID=} ]] && dev=/dev/disk/by-uuid/${dev#UUID=}
+            [[ $dev != ${dev#LABEL=} ]] && dev=/dev/disk/by-label/${dev#LABEL=}
+	    [[ -b $dev ]] || return 1 # oops, not a block device.
+	    ls -nLl "$dev" | { 
+		read x x x x maj min x;
+		maj=${maj//,/}; 
+		echo $maj:$min; 
+	    } && return 0
+	fi
+    done < /etc/fstab
+    return 1;
 }
 
 find_root_block_device() { find_block_device /; }