mdraid: wait for rd.md.uuid specified devices to be assembled

This patch uses wait_for_dev "/dev/disk/by-id/md-uuid-${uuid}" for the
specified uuids.

On timeout only md devices are force started which are specified by
uuid, or all, if rd.auto was specified.

Fixes https://github.com/dracutdevs/dracut/issues/227

modules.d/90mdraid/mdraid_start.sh

@@ -1,34 +1,68 @@
 #!/bin/sh
 
-type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
-_md_force_run() {
+type getargs >/dev/null 2>&1 || . /lib/dracut-lib.sh
+
+_md_start() {
     local _udevinfo
     local _path_s
     local _path_d
+    local _md="$1"
+    local _offroot="$2"
+
+    _udevinfo="$(udevadm info --query=env --name="${_md}")"
+    strstr "$_udevinfo" "MD_LEVEL=container" && continue
+    strstr "$_udevinfo" "DEVTYPE=partition" && continue
+
+    _path_s="/sys/$(udevadm info -q path -n "${_md}")/md/array_state"
+    [ ! -r "$_path_s" ] && continue
+
+    # inactive ?
+    [ "$(cat "$_path_s")" != "inactive" ] && continue
+
+    mdadm $_offroot -R "${_md}" 2>&1 | vinfo
+
+    # still inactive ?
+    [ "$(cat "$_path_s")" = "inactive" ] && continue
+
+    _path_d="${_path_s%/*}/degraded"
+    [ ! -r "$_path_d" ] && continue
+    > $hookdir/initqueue/work
+}
+
+_md_force_run() {
     local _offroot
+    local _md
+    local _UUID
+    local _MD_UUID=$(getargs rd.md.uuid -d rd_MD_UUID=)
+    [ -n "$_MD_UUID" ] || getargbool 0 rd.auto || return
+
     _offroot=$(strstr "$(mdadm --help-options 2>&1)" offroot && echo --offroot)
-    # try to force-run anything not running yet
-    for md in /dev/md[0-9_]*; do
-        [ -b "$md" ] || continue
-        _udevinfo="$(udevadm info --query=env --name="$md")"
-        strstr "$_udevinfo" "MD_LEVEL=container" && continue
-        strstr "$_udevinfo" "DEVTYPE=partition" && continue
 
-        _path_s="/sys/$(udevadm info -q path -n "$md")/md/array_state"
-        [ ! -r "$_path_s" ] && continue
+    if [ -n "$_MD_UUID" ]; then
+        for _md in /dev/md[0-9_]*; do
+            [ -b "$_md" ] || continue
+            _UUID=$(
+                /sbin/mdadm -D --export "$_md" \
+                    | while read line || [ -n "$line" ]; do
+                    str_starts "$line" "MD_UUID=" || continue
+                    printf "%s" "${line#MD_UUID=}"
+                done
+                )
 
-        # inactive ?
-        [ "$(cat "$_path_s")" != "inactive" ] && continue
+            [ -z "$_UUID" ] && continue
 
-        mdadm $_offroot -R "$md" 2>&1 | vinfo
+            # check if we should handle this device
+            strstr " $_MD_UUID " " $_UUID " || continue
 
-        # still inactive ?
-        [ "$(cat "$_path_s")" = "inactive" ] && continue
-
-        _path_d="${_path_s%/*}/degraded"
-        [ ! -r "$_path_d" ] && continue
-        > $hookdir/initqueue/work
-    done
+            _md_start "${_md}" "${_offroot}"
+        done
+    else
+        # try to force-run anything not running yet
+        for _md in /dev/md[0-9_]*; do
+            [ -b "$_md" ] || continue
+            _md_start "${_md}" "${_offroot}"
+        done
+    fi
 }
 
 _md_force_run

modules.d/90mdraid/parse-md.sh

@@ -25,6 +25,9 @@ else
             done < "${f}" > "${f}.new"
             mv "${f}.new" "$f"
         done
+        for uuid in $MD_UUID; do
+            wait_for_dev "/dev/disk/by-id/md-uuid-${uuid}"
+        done
     fi
 fi