From 735d3518896827c86481b53182bb47a507e38681 Mon Sep 17 00:00:00 2001
From: Antonio Alvarez Feijoo <antonio.feijoo@suse.com>
Date: Wed, 8 Apr 2026 10:46:02 +0200
Subject: [PATCH] perf(dracut-functions): optimize inst_libdir_file()

Let's start analyzing the output of a non-hostonly build, focusing on the
`inst_libdir_file()` calls:

```
$ dracut -f -N --debug testn.img 2>&1 &> testn.txt
$ grep -r -c "(inst_libdir_file): inst_multiple" testn.txt
17
$ grep -r "(inst_libdir_file): inst_multiple" testn.txt | awk -F"inst_multiple " '{ print $2 }' | tr ' ' '\n' | sort | wc -l
295
$ grep -r "(inst_libdir_file): inst_multiple" testn.txt | awk -F"inst_multiple " '{ print $2 }' | tr ' ' '\n' | sort -u | wc -l
201
```

There are 94 files that are attempted to be installed multiple times. After
adding a simple cache:

```
$ grep -r -c "(inst_libdir_file): inst_multiple" testn2.txt
13
$ grep -r "(inst_libdir_file): inst_multiple" testn2.txt | awk -F"inst_multiple " '{ print $2 }' | tr ' ' '\n' | sort | wc -l
201
```
---
 dracut-functions.sh | 19 +++++++++++++++++--
 test/test-functions |  4 ++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/dracut-functions.sh b/dracut-functions.sh
index 8d4785ddae..36ca5e6633 100755
--- a/dracut-functions.sh
+++ b/dracut-functions.sh
@@ -1336,6 +1336,13 @@ inst_libdir_dir() {
 # -n <pattern> install matching files
 inst_libdir_file() {
     local -a _files=()
+    local _path
+
+    # cache installed libdir files
+    if ! declare -p _libdir_file_cache 2> /dev/null | grep -q "declare -A"; then
+        declare -gxA _libdir_file_cache=()
+    fi
+
     if [[ $1 == "-n" ]]; then
         local _pattern=$2
         shift 2
@@ -1343,7 +1350,11 @@ inst_libdir_file() {
             for _i in "$@"; do
                 for _f in "${dracutsysrootdir-}$_dir"/$_i; do
                     [[ ${_f#"${dracutsysrootdir-}"} =~ $_pattern ]] || continue
-                    [[ -e $_f ]] && _files+=("${_f#"${dracutsysrootdir-}"}")
+                    _path="${_f#"${dracutsysrootdir-}"}"
+                    if [[ -e $_f ]] && [[ ${_libdir_file_cache[$_path]:-} != 1 ]]; then
+                        _files+=("$_path")
+                        _libdir_file_cache[$_path]=1
+                    fi
                 done
             done
         done
@@ -1351,7 +1362,11 @@ inst_libdir_file() {
         for _dir in $libdirs; do
             for _i in "$@"; do
                 for _f in "${dracutsysrootdir-}$_dir"/$_i; do
-                    [[ -e $_f ]] && _files+=("${_f#"${dracutsysrootdir-}"}")
+                    _path="${_f#"${dracutsysrootdir-}"}"
+                    if [[ -e $_f ]] && [[ ${_libdir_file_cache[$_path]:-} != 1 ]]; then
+                        _files+=("$_path")
+                        _libdir_file_cache[$_path]=1
+                    fi
                 done
             done
         done
diff --git a/test/test-functions b/test/test-functions
index 8b76dc649a..a84c026f34 100644
--- a/test/test-functions
+++ b/test/test-functions
@@ -93,6 +93,10 @@ build_rootfs_base() {
     # Include os-release to make systemd's initrd-switch-root.service happy
     cp /usr/lib/os-release "$rootdir/usr/lib/os-release"
 
+    # Unset cache variables, otherwise successive calls to build_rootfs_base()
+    # to generate another initrd would not install the required files
+    unset _libdir_file_cache
+
     if [[ "$(type -t inst_multiple 2> /dev/null)" != "function" ]]; then
         # shellcheck source=./dracut-functions.sh
         . "$PKGLIBDIR/dracut-functions.sh"