[PATCHv4 13/21] zram: add support for dict comp config

[Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>]

Handle dict=path param so that we can read a pre-trained
compression algorithm dictionary which we then pass to the
backend configuration.

Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
 drivers/block/zram/zram_drv.c | 54 ++++++++++++++++++++++++++++-------
 1 file changed, 43 insertions(+), 11 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 91706889b63f..216686a5f3f0 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -33,6 +33,7 @@
 #include <linux/debugfs.h>
 #include <linux/cpuhotplug.h>
 #include <linux/part_stat.h>
+#include <linux/kernel_read_file.h>
 
 #include "zram_drv.h"
 
@@ -998,9 +999,35 @@ static int __comp_algorithm_store(struct zram *zram, u32 prio, const char *buf)
 	return 0;
 }
 
-static int comp_config_store(struct zram *zram, u32 prio, s32 level)
+static void __reset_comp_config(struct zram *zram, u32 prio)
 {
+	struct zcomp_config *config = &zram->configs[prio];
+
+	vfree(config->dict);
+	config->level = ZCOMP_CONFIG_NO_LEVEL;
+	config->dict_sz = 0;
+	config->dict = NULL;
+}
+
+static int comp_config_store(struct zram *zram, u32 prio, s32 level,
+			     const char *dict_path)
+{
+	ssize_t sz = 0;
+
+	__reset_comp_config(zram, prio);
+
+	if (dict_path) {
+		sz = kernel_read_file_from_path(dict_path, 0,
+						&zram->configs[prio].dict,
+						INT_MAX,
+						NULL,
+						READING_POLICY);
+		if (sz < 0)
+			return -EINVAL;
+	}
+
 	zram->configs[prio].level = level;
+	zram->configs[prio].dict_sz = sz;
 	return 0;
 }
 
@@ -1020,7 +1047,7 @@ static ssize_t comp_algorithm_store(struct device *dev,
 {
 	struct zram *zram = dev_to_zram(dev);
 	char *args, *param, *val;
-	char *alg = NULL;
+	char *alg = NULL, *dict_path = NULL;
 	s32 level = ZCOMP_CONFIG_NO_LEVEL;
 	int ret;
 
@@ -1048,12 +1075,17 @@ static ssize_t comp_algorithm_store(struct device *dev,
 				return ret;
 			continue;
 		}
+
+		if (!strcmp(param, "dict")) {
+			dict_path = val;
+			continue;
+		}
 	}
 
 	if (!alg)
 		return -EINVAL;
 
-	ret = comp_config_store(zram, ZRAM_PRIMARY_COMP, level);
+	ret = comp_config_store(zram, ZRAM_PRIMARY_COMP, level, dict_path);
 	if (!ret)
 		ret = __comp_algorithm_store(zram, ZRAM_PRIMARY_COMP, alg);
 	return ret ? ret : len;
@@ -1087,7 +1119,7 @@ static ssize_t recomp_algorithm_store(struct device *dev,
 	struct zram *zram = dev_to_zram(dev);
 	int prio = ZRAM_SECONDARY_COMP;
 	char *args, *param, *val;
-	char *alg = NULL;
+	char *alg = NULL, *dict_path = NULL;
 	s32 level = ZCOMP_CONFIG_NO_LEVEL;
 	int ret;
 
@@ -1116,6 +1148,11 @@ static ssize_t recomp_algorithm_store(struct device *dev,
 				return ret;
 			continue;
 		}
+
+		if (!strcmp(param, "dict")) {
+			dict_path = val;
+			continue;
+		}
 	}
 
 	if (!alg)
@@ -1124,7 +1161,7 @@ static ssize_t recomp_algorithm_store(struct device *dev,
 	if (prio < ZRAM_SECONDARY_COMP || prio >= ZRAM_MAX_COMPS)
 		return -EINVAL;
 
-	ret = comp_config_store(zram, prio, level);
+	ret = comp_config_store(zram, prio, level, dict_path);
 	if (!ret)
 		ret = __comp_algorithm_store(zram, prio, alg);
 	return ret ? ret : len;
@@ -2034,12 +2071,7 @@ static void zram_reset_comp_configs(struct zram *zram)
 	u32 prio;
 
 	for (prio = 0; prio < ZRAM_MAX_COMPS; prio++) {
-		struct zcomp_config *config = &zram->configs[prio];
-
-		vfree(config->dict);
-		config->level = ZCOMP_CONFIG_NO_LEVEL;
-		config->dict_sz = 0;
-		config->dict = NULL;
+		__reset_comp_config(zram, prio);
 	}
 }
 
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog