4 files changed, 66 insertions, 8 deletions
diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
index fe7a4b7d30cf..668c6bf2554d 100644
--- a/drivers/block/zram/Kconfig
+++ b/drivers/block/zram/Kconfig
@@ -2,7 +2,7 @@
 config ZRAM
 	tristate "Compressed RAM block device support"
 	depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
-	select CRYPTO_LZO
+	depends on CRYPTO_LZO || CRYPTO_ZSTD || CRYPTO_LZ4 || CRYPTO_LZ4HC || CRYPTO_842
 	help
 	  Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
 	  Pages written to these disks are compressed and stored in memory
@@ -14,6 +14,46 @@ config ZRAM
 
 	  See Documentation/admin-guide/blockdev/zram.rst for more information.
 
+choice
+	prompt "Default zram compressor"
+	default ZRAM_DEF_COMP_LZORLE
+	depends on ZRAM
+
+config ZRAM_DEF_COMP_LZORLE
+	bool "lzo-rle"
+	depends on CRYPTO_LZO
+
+config ZRAM_DEF_COMP_ZSTD
+	bool "zstd"
+	depends on CRYPTO_ZSTD
+
+config ZRAM_DEF_COMP_LZ4
+	bool "lz4"
+	depends on CRYPTO_LZ4
+
+config ZRAM_DEF_COMP_LZO
+	bool "lzo"
+	depends on CRYPTO_LZO
+
+config ZRAM_DEF_COMP_LZ4HC
+	bool "lz4hc"
+	depends on CRYPTO_LZ4HC
+
+config ZRAM_DEF_COMP_842
+	bool "842"
+	depends on CRYPTO_842
+
+endchoice
+
+config ZRAM_DEF_COMP
+	string
+	default "lzo-rle" if ZRAM_DEF_COMP_LZORLE
+	default "zstd" if ZRAM_DEF_COMP_ZSTD
+	default "lz4" if ZRAM_DEF_COMP_LZ4
+	default "lzo" if ZRAM_DEF_COMP_LZO
+	default "lz4hc" if ZRAM_DEF_COMP_LZ4HC
+	default "842" if ZRAM_DEF_COMP_842
+
 config ZRAM_WRITEBACK
        bool "Write back incompressible or idle page to backing device"
        depends on ZRAM
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..66a33e418940 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -42,7 +42,7 @@ 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 = CONFIG_ZRAM_DEF_COMP;
 
 /* Module params (documentation at end) */
 static unsigned int num_devices = 1;
@@ -620,15 +620,19 @@ static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec,
 	return 1;
 }
 
+#define PAGE_WB_SIG "page_index="
+
+#define PAGE_WRITEBACK 0
 #define HUGE_WRITEBACK 1
 #define IDLE_WRITEBACK 2
 
+
 static ssize_t writeback_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct zram *zram = dev_to_zram(dev);
 	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
-	unsigned long index;
+	unsigned long index = 0;
 	struct bio bio;
 	struct bio_vec bio_vec;
 	struct page *page;
@@ -640,8 +644,17 @@ static ssize_t writeback_store(struct device *dev,
 		mode = IDLE_WRITEBACK;
 	else if (sysfs_streq(buf, "huge"))
 		mode = HUGE_WRITEBACK;
-	else
-		return -EINVAL;
+	else {
+		if (strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1))
+			return -EINVAL;
+
+		ret = kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index);
+		if (ret || index >= nr_pages)
+			return -EINVAL;
+
+		nr_pages = 1;
+		mode = PAGE_WRITEBACK;
+	}
 
 	down_read(&zram->init_lock);
 	if (!init_done(zram)) {
@@ -660,7 +673,7 @@ static ssize_t writeback_store(struct device *dev,
 		goto release_init_lock;
 	}
 
-	for (index = 0; index < nr_pages; index++) {
+	while (nr_pages--) {
 		struct bio_vec bvec;
 
 		bvec.bv_page = page;
@@ -1071,7 +1084,7 @@ static ssize_t mm_stat_show(struct device *dev,
 	max_used = atomic_long_read(&zram->stats.max_used_pages);
 
 	ret = scnprintf(buf, PAGE_SIZE,
-			"%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu\n",
+			"%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu %8llu\n",
 			orig_size << PAGE_SHIFT,
 			(u64)atomic64_read(&zram->stats.compr_data_size),
 			mem_used << PAGE_SHIFT,
@@ -1079,7 +1092,8 @@ static ssize_t mm_stat_show(struct device *dev,
 			max_used << PAGE_SHIFT,
 			(u64)atomic64_read(&zram->stats.same_pages),
 			pool_stats.pages_compacted,
-			(u64)atomic64_read(&zram->stats.huge_pages));
+			(u64)atomic64_read(&zram->stats.huge_pages),
+			(u64)atomic64_read(&zram->stats.huge_pages_since));
 	up_read(&zram->init_lock);
 
 	return ret;
@@ -1411,6 +1425,7 @@ out:
 	if (comp_len == PAGE_SIZE) {
 		zram_set_flag(zram, index, ZRAM_HUGE);
 		atomic64_inc(&zram->stats.huge_pages);
+		atomic64_inc(&zram->stats.huge_pages_since);
 	}
 
 	if (flags) {
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index f2fd46daa760..9cabcbb13fd9 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -78,6 +78,7 @@ struct zram_stats {
 	atomic64_t notify_free;	/* no. of swap slot free notifications */
 	atomic64_t same_pages;		/* no. of same element filled pages */
 	atomic64_t huge_pages;		/* no. of huge pages */
+	atomic64_t huge_pages_since;	/* no. of huge pages since zram set up */
 	atomic64_t pages_stored;	/* no. of pages currently stored */
 	atomic_long_t max_used_pages;	/* no. of maximum pages stored */
 	atomic64_t writestall;		/* no. of write slow paths */