zram: remove entry element member

Element is in the same anon union as handle and hence holds the same
value, which makes code below sort of confusing

    handle = zram_get_handle()
    if (!handle)
	element = zram_get_element()

Element doesn't really simplify the code, let's just remove it.  We
already re-purpose handle to store the block id a written back page.

Link: https://lkml.kernel.org/r/20241218063513.297475-3-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/block/zram/zram_drv.c

@@ -112,17 +112,6 @@ static void zram_clear_flag(struct zram *zram, u32 index,
 	zram->table[index].flags &= ~BIT(flag);
 }
 
-static inline void zram_set_element(struct zram *zram, u32 index,
-			unsigned long element)
-{
-	zram->table[index].element = element;
-}
-
-static unsigned long zram_get_element(struct zram *zram, u32 index)
-{
-	return zram->table[index].element;
-}
-
 static size_t zram_get_obj_size(struct zram *zram, u32 index)
 {
 	return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1);
@@ -879,7 +868,7 @@ static ssize_t writeback_store(struct device *dev,
 
 		zram_free_page(zram, index);
 		zram_set_flag(zram, index, ZRAM_WB);
-		zram_set_element(zram, index, blk_idx);
+		zram_set_handle(zram, index, blk_idx);
 		blk_idx = 0;
 		atomic64_inc(&zram->stats.pages_stored);
 		spin_lock(&zram->wb_limit_lock);
@@ -1505,7 +1494,7 @@ static void zram_free_page(struct zram *zram, size_t index)
 
 	if (zram_test_flag(zram, index, ZRAM_WB)) {
 		zram_clear_flag(zram, index, ZRAM_WB);
-		free_block_bdev(zram, zram_get_element(zram, index));
+		free_block_bdev(zram, zram_get_handle(zram, index));
 		goto out;
 	}
 
@@ -1549,12 +1538,10 @@ static int zram_read_from_zspool(struct zram *zram, struct page *page,
 
 	handle = zram_get_handle(zram, index);
 	if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) {
-		unsigned long value;
 		void *mem;
 
-		value = handle ? zram_get_element(zram, index) : 0;
 		mem = kmap_local_page(page);
-		zram_fill_page(mem, PAGE_SIZE, value);
+		zram_fill_page(mem, PAGE_SIZE, handle);
 		kunmap_local(mem);
 		return 0;
 	}
@@ -1600,7 +1587,7 @@ static int zram_read_page(struct zram *zram, struct page *page, u32 index,
 		 */
 		zram_slot_unlock(zram, index);
 
-		ret = read_from_bdev(zram, page, zram_get_element(zram, index),
+		ret = read_from_bdev(zram, page, zram_get_handle(zram, index),
 				     parent);
 	}
 
@@ -1751,7 +1738,7 @@ static int zram_write_page(struct zram *zram, struct page *page, u32 index)
 
 	if (flags) {
 		zram_set_flag(zram, index, flags);
-		zram_set_element(zram, index, element);
+		zram_set_handle(zram, index, element);
 	}  else {
 		zram_set_handle(zram, index, handle);
 		zram_set_obj_size(zram, index, comp_len);

drivers/block/zram/zram_drv.h

@@ -62,10 +62,7 @@ enum zram_pageflags {
 
 /* Allocated for each disk page */
 struct zram_table_entry {
-	union {
-		unsigned long handle;
-		unsigned long element;
-	};
+	unsigned long handle;
 	unsigned int flags;
 	spinlock_t lock;
 #ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME