fix(dracut.sh): check kernel zstd support early

Rather than checking late and falling back to "cat" if the kernel
doesn't support zstd decompression, do this early, and use the
fallback code path.

diff --git a/dracut.sh b/dracut.sh
index c6089ba63a2ef964fd974f519ce17894255dd77e..ce54a851950141779e7c63683101e0d283af5187 100755 (executable)
--- a/dracut.sh
+++ b/dracut.sh
@@ -2350,6 +2350,17 @@ if [[ $create_early_cpio == yes ]]; then
     fi
 fi
 
+if check_kernel_config CONFIG_RD_ZSTD; then
+    DRACUT_KERNEL_RD_ZSTD=yes
+else
+    DRACUT_KERNEL_RD_ZSTD=
+fi
+
+if [[ $compress == $DRACUT_COMPRESS_ZSTD* && ! $DRACUT_KERNEL_RD_ZSTD ]]; then
+    dwarn "dracut: kernel has no zstd support compiled in."
+    compress=
+fi
+
 if [[ $compress && $compress != cat ]]; then
     if ! command -v "${compress%% *}" &> /dev/null; then
         derror "dracut: cannot execute compression command '$compress', falling back to default"
@@ -2360,6 +2371,7 @@ fi
 if ! [[ $compress ]]; then
     # check all known compressors, if none specified
     for i in $DRACUT_COMPRESS_PIGZ $DRACUT_COMPRESS_GZIP $DRACUT_COMPRESS_LZ4 $DRACUT_COMPRESS_LZOP $DRACUT_COMPRESS_ZSTD $DRACUT_COMPRESS_LZMA $DRACUT_COMPRESS_XZ $DRACUT_COMPRESS_LBZIP2 $DRACUT_COMPRESS_BZIP2 $DRACUT_COMPRESS_CAT; do
+        [[ $i != "$DRACUT_COMPRESS_ZSTD" || $DRACUT_KERNEL_RD_ZSTD ]] || continue
         command -v "$i" &> /dev/null || continue
         compress="$i"
         break
@@ -2406,11 +2418,6 @@ case $compress in
         ;;
 esac
 
-if [[ $compress == $DRACUT_COMPRESS_ZSTD* ]] && ! check_kernel_config CONFIG_RD_ZSTD; then
-    dwarn "dracut: kernel has no zstd support compiled in."
-    compress="cat"
-fi
-
 if [[ -n $enhanced_cpio ]]; then
     if [[ $compress == "cat" ]]; then
         # dracut-cpio appends by default, so any ucode remains