zram: reset per-priority params when changing algorithm before init

Parameters validated against one algorithm may be invalid for another
(e.g. lz4 accepts level=65535 but zstd does not).  Although algorithm
changes are blocked after disksize is set, they are allowed before
device initialization.  Reset per-priority params on algorithm change
so that stale parameters do not silently carry over.

Signed-off-by: Haoqin Huang <haoqinhuang@tencent.com>
Reviewed-by: Rongwei Wang <zigiwang@tencent.com>

Author: Haoqin Huang

drivers/block/zram/zram_drv.c

@@ -57,6 +57,7 @@ static size_t huge_class_size;
 static const struct block_device_operations zram_devops;
 
 static void slot_free(struct zram *zram, u32 index);
+static void comp_params_reset(struct zram *zram, u32 prio);
 #define slot_dep_map(zram, index) (&(zram)->table[(index)].dep_map)
 
 static void slot_lock_init(struct zram *zram, u32 index)
@@ -1681,6 +1682,7 @@ static int __comp_algorithm_store(struct zram *zram, u32 prio, const char *buf)
 	}
 
 	comp_algorithm_set(zram, prio, alg);
+	comp_params_reset(zram, prio);
 	return 0;
 }