Add all btrfs devices

We have to find them with "btrfs usage", which is cumbersome.

dracut-functions.sh

@@ -31,6 +31,10 @@ strstr() { [[ $1 = *"$2"* ]]; }
 strglobin() { [[ $1 = *$2* ]]; }
 # Generic glob matching function. If glob pattern $2 matches all of $1, OK
 strglob() { [[ $1 = $2 ]]; }
+# returns OK if $1 contains literal string $2 at the beginning, and isn't empty
+str_starts() { [ "${1#"$2"*}" != "$1" ]; }
+# returns OK if $1 contains literal string $2 at the end, and isn't empty
+str_ends() { [ "${1%*"$2"}" != "$1" ]; }
 
 # helper function for check() in module-setup.sh
 # to check for required installed binaries
@@ -1815,3 +1819,12 @@ lvm_internal_dev() {
     [[ ${DM_LV_LAYER} ]] || [[ ! -L /dev/${DM_VG_NAME}/${DM_LV_NAME} ]]
 }
 
+btrfs_devs() {
+    local _mp="$1"
+    btrfs device usage "$_mp" \
+        | while read _dev _rest; do
+        str_starts "$_dev" "/" || continue
+        _dev=${_dev%,}
+        printf -- "%s\n" "$_dev"
+        done
+}

dracut.sh

@@ -1146,6 +1146,11 @@ for line in "${fstab_lines[@]}"; do
             ;;
     esac
     [ -z "$dev" ] && dwarn "Bad fstab entry $@" && continue
+    if [[ "$3" == btrfs ]]; then
+        for i in $(btrfs_devs "$2"); do
+            push_host_devs "$i"
+        done
+    fi
     push_host_devs "$dev"
     host_fs_types["$dev"]="$3"
 done
@@ -1194,8 +1199,14 @@ if [[ $hostonly ]]; then
         _bdev=$(readlink -f "/dev/block/$_dev")
         [[ -b $_bdev ]] && _dev=$_bdev
         push_host_devs $_dev
-        [[ "$mp" == "/" ]] && root_dev="$_dev"
+        [[ "$mp" == "/" ]] && push root_devs "$_dev"
         push_host_devs "$_dev"
+        if [[ $(find_mp_fstype "$mp") == btrfs ]]; then
+            for i in $(btrfs_devs "$mp"); do
+                [[ "$mp" == "/" ]] && push root_devs "$i"
+                push_host_devs "$i"
+            done
+        fi
     done
 
     if [[ -f /proc/swaps ]] && [[ -f /etc/fstab ]]; then
@@ -1240,7 +1251,14 @@ if [[ $hostonly ]]; then
             [[ "$_o" != *x-initrd.mount* ]] && continue
             _dev=$(expand_persistent_dev "$_d")
             _dev="$(readlink -f "$_dev")"
-            [[ -b $_dev ]] && push_host_devs "$_dev"
+            [[ -b $_dev ]] || continue
+
+            push_host_devs "$_dev"
+            if [[ "$_t" == btrfs ]]; then
+                for i in $(find_btrfs_devs "$_m"); do
+                    push_host_devs "$i"
+                done
+            fi
         done < /etc/fstab
     fi
 

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

@@ -102,7 +102,9 @@ install() {
                 . "$moddir/dracut-lib.sh"
 
                 for _dev in ${host_devs[@]}; do
-                    [[ "$_dev" == "$root_dev" ]] && continue
+                    for _dev2 in ${root_devs[@]}; do
+                        [[ "$_dev" == "$_dev2" ]] && continue 2
+                    done
 
                     # We only actually wait for real devs - swap is only needed
                     # for resume and udev rules generated when parsing resume=