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

[Rui Salvaterra <rsalvaterra@gmail.com>]

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@gmail.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