linux-kernel - [PATCH v3] zram: break the strict dependency from lzo

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Date:   Mon, 26 Oct 2020 08:51:41 +0000
From:   Rui Salvaterra <rsalvaterra@...il.com>
To:     minchan@...nel.org, ngupta@...are.org,
        sergey.senozhatsky.work@...il.com
Cc:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        Rui Salvaterra <rsalvaterra@...il.com>
Subject: [PATCH v3] zram: break the strict dependency from lzo

There's nothing special about zram and lzo. It works just fine without it, so
as long as at least one of the other supported compression algorithms is
selected.

Signed-off-by: Rui Salvaterra <rsalvaterra@...il.com>
---
v3: fix the default selection when lzo isn't present. Rebase against 5.10-rc1.
v2: fix the dependency on CRYPTO.

 drivers/block/zram/Kconfig    |  6 +++++-
 drivers/block/zram/zcomp.c    |  2 ++
 drivers/block/zram/zram_drv.c | 14 +++++++++++++-
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
index fe7a4b7d30cf..14b2b098d662 100644
--- a/drivers/block/zram/Kconfig
+++ b/drivers/block/zram/Kconfig
@@ -2,7 +2,6 @@
 config ZRAM
 	tristate "Compressed RAM block device support"
 	depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
-	select CRYPTO_LZO
 	help
 	  Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
 	  Pages written to these disks are compressed and stored in memory
@@ -37,3 +36,8 @@ config ZRAM_MEMORY_TRACKING
 	  /sys/kernel/debug/zram/zramX/block_state.
 
 	  See Documentation/admin-guide/blockdev/zram.rst for more information.
+
+config ZRAM_AUTOSEL_ALGO
+	def_bool y
+	depends on ZRAM && !(CRYPTO_LZ4 || CRYPTO_LZ4HC || CRYPTO_842 || CRYPTO_ZSTD)
+	select CRYPTO_LZO
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 33e3b76c4fa9..052aa3f65514 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -15,8 +15,10 @@
 #include "zcomp.h"
 
 static const char * const backends[] = {
+#if IS_ENABLED(CONFIG_CRYPTO_LZO)
 	"lzo",
 	"lzo-rle",
+#endif
 #if IS_ENABLED(CONFIG_CRYPTO_LZ4)
 	"lz4",
 #endif
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 1b697208d661..2ae09561ba79 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -42,7 +42,19 @@ static DEFINE_IDR(zram_index_idr);
 static DEFINE_MUTEX(zram_index_mutex);
 
 static int zram_major;
-static const char *default_compressor = "lzo-rle";
+
+static const char *default_compressor =
+#if IS_ENABLED(CONFIG_CRYPTO_LZO)
+	"lzo-rle";
+#elif IS_ENABLED(CONFIG_CRYPTO_LZ4)
+	"lz4";
+#elif IS_ENABLED(CONFIG_CRYPTO_LZ4HC)
+	"lz4hc";
+#elif IS_ENABLED(CONFIG_CRYPTO_842)
+	"842";
+#elif IS_ENABLED(CONFIG_CRYPTO_ZSTD)
+	"zstd";
+#endif
 
 /* Module params (documentation at end) */
 static unsigned int num_devices = 1;
-- 
2.28.0