[PATCH v3] f2fs: compress: Allow modular (de)compression algorithms

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Randy Dunlap <rdunlap@infradead.org>
Cc: linux-f2fs-devel@lists.sourceforge.net,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	Geert Uytterhoeven <geert@linux-m68k.org>
Subject: [PATCH v3] f2fs: compress: Allow modular (de)compression algorithms
Date: Fri, 26 Feb 2021 16:51:42 +0100	[thread overview]
Message-ID: <20210226155142.2909545-1-geert@linux-m68k.org> (raw)

If F2FS_FS is modular, enabling the compressions options
F2FS_FS_{LZ4,LZ4HZ,LZO,LZORLE,ZSTD} will make the (de)compression
algorithms {LZ4,LZ4HC,LZO,ZSTD}_{,DE}COMPRESS builtin instead of
modular, as the former depend on an intermediate boolean
F2FS_FS_COMPRESSION, which in-turn depends on tristate F2FS_FS.

Indeed, if a boolean symbol A depends directly on a tristate symbol B
and selects another tristate symbol C:

    tristate B

    tristate C

    bool A
      depends on B
      select C

and B is modular, then C will also be modular.

However, if there is an intermediate boolean D in the dependency chain
between A and B:

    tristate B

    tristate C

    bool D
      depends on B

    bool A
      depends on D
      select C

then the modular state won't propagate from B to C, and C will be
builtin instead of modular.

As modular dependency propagation through intermediate symbols is
obscure, fix this in a robust way by moving the selection of tristate
(de)compression algorithms from the boolean compression options to the
tristate main F2FS_FS option.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v3:
  - Drop redundant selects (F2FS_FS_LZORLE depends on F2FS_FS_LZO),

v2:
  - Move the selects to F2FS_FS instead of adding direct dependencies
    on F2FS_FS.
---
 fs/f2fs/Kconfig | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/fs/f2fs/Kconfig b/fs/f2fs/Kconfig
index 62e638a49bbf089a..7669de7b49cea189 100644
--- a/fs/f2fs/Kconfig
+++ b/fs/f2fs/Kconfig
@@ -7,6 +7,13 @@ config F2FS_FS
 	select CRYPTO_CRC32
 	select F2FS_FS_XATTR if FS_ENCRYPTION
 	select FS_ENCRYPTION_ALGS if FS_ENCRYPTION
+	select LZ4_COMPRESS if F2FS_FS_LZ4
+	select LZ4_DECOMPRESS if F2FS_FS_LZ4
+	select LZ4HC_COMPRESS if F2FS_FS_LZ4HC
+	select LZO_COMPRESS if F2FS_FS_LZO
+	select LZO_DECOMPRESS if F2FS_FS_LZO
+	select ZSTD_COMPRESS if F2FS_FS_ZSTD
+	select ZSTD_DECOMPRESS if F2FS_FS_ZSTD
 	help
 	  F2FS is based on Log-structured File System (LFS), which supports
 	  versatile "flash-friendly" features. The design has been focused on
@@ -94,8 +101,6 @@ config F2FS_FS_COMPRESSION
 config F2FS_FS_LZO
 	bool "LZO compression support"
 	depends on F2FS_FS_COMPRESSION
-	select LZO_COMPRESS
-	select LZO_DECOMPRESS
 	default y
 	help
 	  Support LZO compress algorithm, if unsure, say Y.
@@ -103,8 +108,6 @@ config F2FS_FS_LZO
 config F2FS_FS_LZ4
 	bool "LZ4 compression support"
 	depends on F2FS_FS_COMPRESSION
-	select LZ4_COMPRESS
-	select LZ4_DECOMPRESS
 	default y
 	help
 	  Support LZ4 compress algorithm, if unsure, say Y.
@@ -113,7 +116,6 @@ config F2FS_FS_LZ4HC
 	bool "LZ4HC compression support"
 	depends on F2FS_FS_COMPRESSION
 	depends on F2FS_FS_LZ4
-	select LZ4HC_COMPRESS
 	default y
 	help
 	  Support LZ4HC compress algorithm, LZ4HC has compatible on-disk
@@ -122,8 +124,6 @@ config F2FS_FS_LZ4HC
 config F2FS_FS_ZSTD
 	bool "ZSTD compression support"
 	depends on F2FS_FS_COMPRESSION
-	select ZSTD_COMPRESS
-	select ZSTD_DECOMPRESS
 	default y
 	help
 	  Support ZSTD compress algorithm, if unsure, say Y.
@@ -132,8 +132,6 @@ config F2FS_FS_LZORLE
 	bool "LZO-RLE compression support"
 	depends on F2FS_FS_COMPRESSION
 	depends on F2FS_FS_LZO
-	select LZO_COMPRESS
-	select LZO_DECOMPRESS
 	default y
 	help
 	  Support LZO-RLE compress algorithm, if unsure, say Y.
-- 
2.25.1

