From 946f6b5c2e2ac5af79b87e10ef67cad5829f206f Mon Sep 17 00:00:00 2001
From: Jordan Yates <jordan@embeint.com>
Date: Sun, 12 Jan 2025 14:46:33 +1000
Subject: [PATCH] fs: allow enabling filesystems with `FILE_SYSTEM_LIB_LINK`

Update the Kconfig configuration to allow enabling the underlying
filesystems (e.g. exFAT), with only `FILE_SYSTEM_LIB_LINK` enabled.

Signed-off-by: Jordan Yates <jordan@embeint.com>
---
 subsys/fs/Kconfig             | 31 ++++++++++++++++++-------------
 subsys/fs/Kconfig.fatfs       |  2 +-
 subsys/fs/Kconfig.littlefs    |  2 +-
 subsys/fs/ext2/CMakeLists.txt |  2 +-
 subsys/fs/ext2/Kconfig        |  2 +-
 5 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/subsys/fs/Kconfig b/subsys/fs/Kconfig
index ed3ead2f841..bf6933f13aa 100644
--- a/subsys/fs/Kconfig
+++ b/subsys/fs/Kconfig
@@ -22,18 +22,6 @@ config FILE_SYSTEM
 
 if FILE_SYSTEM
 
-module = FS
-module-str = fs
-source "subsys/logging/Kconfig.template.log_config"
-
-config APP_LINK_WITH_FS
-	bool "Link 'app' with FS"
-	default y
-	help
-	  Add FS header files to the 'app' include path. It may be
-	  disabled if the include paths for FS are causing aliasing
-	  issues for 'app'.
-
 config FILE_SYSTEM_MAX_TYPES
 	int "Maximum number of distinct file system types allowed"
 	default 2
@@ -110,11 +98,28 @@ config FUSE_FS_ACCESS
 	help
 	  Expose file system partitions to the host system through FUSE.
 
+endif # FILE_SYSTEM
+
+if FILE_SYSTEM_LIB_LINK
+
+config APP_LINK_WITH_FS
+	bool "Link 'app' with FS"
+	default y
+	help
+	  Add FS header files to the 'app' include path. It may be
+	  disabled if the include paths for FS are causing aliasing
+	  issues for 'app'.
+
+# Logging defined here as modules/fs/littlefs/lfs.c expects CONFIG_FS_LOG_LEVEL
+module = FS
+module-str = fs
+source "subsys/logging/Kconfig.template.log_config"
+
 rsource "Kconfig.fatfs"
 rsource "Kconfig.littlefs"
 rsource "ext2/Kconfig"
 
-endif # FILE_SYSTEM
+endif # FILE_SYSTEM_LIB_LINK
 
 rsource "fcb/Kconfig"
 rsource "nvs/Kconfig"
diff --git a/subsys/fs/Kconfig.fatfs b/subsys/fs/Kconfig.fatfs
index 59bf3f7aa2d..e91cd71c7dd 100644
--- a/subsys/fs/Kconfig.fatfs
+++ b/subsys/fs/Kconfig.fatfs
@@ -5,7 +5,7 @@
 
 config FAT_FILESYSTEM_ELM
 	bool "ELM FAT file system support"
-	depends on FILE_SYSTEM
+	depends on FILE_SYSTEM_LIB_LINK
 	select DISK_ACCESS
 	help
 	  Use the ELM FAT File system implementation.
diff --git a/subsys/fs/Kconfig.littlefs b/subsys/fs/Kconfig.littlefs
index 048e921f62b..b7e1c4bf8d4 100644
--- a/subsys/fs/Kconfig.littlefs
+++ b/subsys/fs/Kconfig.littlefs
@@ -5,7 +5,7 @@
 
 config FILE_SYSTEM_LITTLEFS
 	bool "LittleFS support"
-	depends on FILE_SYSTEM
+	depends on FILE_SYSTEM_LIB_LINK
 	depends on ZEPHYR_LITTLEFS_MODULE
 	help
 	  Enables LittleFS file system support.
diff --git a/subsys/fs/ext2/CMakeLists.txt b/subsys/fs/ext2/CMakeLists.txt
index e66c8895a4c..8bb69eb2e13 100644
--- a/subsys/fs/ext2/CMakeLists.txt
+++ b/subsys/fs/ext2/CMakeLists.txt
@@ -6,12 +6,12 @@ target_include_directories(EXT2 INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
 
 zephyr_library()
 zephyr_library_sources(
-  ext2_ops.c
   ext2_impl.c
   ext2_disk_access.c
   ext2_bitmap.c
   ext2_diskops.c
 )
+zephyr_library_sources_ifdef(CONFIG_FILE_SYSTEM ext2_ops.c)
 zephyr_library_sources_ifdef(CONFIG_FILE_SYSTEM_MKFS ext2_format.c)
 
 zephyr_library_link_libraries(EXT2)
diff --git a/subsys/fs/ext2/Kconfig b/subsys/fs/ext2/Kconfig
index a4f3f919a10..83ebd62f9a7 100644
--- a/subsys/fs/ext2/Kconfig
+++ b/subsys/fs/ext2/Kconfig
@@ -5,7 +5,7 @@
 
 config FILE_SYSTEM_EXT2
 	bool "Ext2 file system support"
-	depends on FILE_SYSTEM
+	depends on FILE_SYSTEM_LIB_LINK
 	help
 	  Enable Ext2 file system support.