zsmalloc: change return value unit of zs_get_total_size_bytes

zs_get_total_size_bytes returns a amount of memory zsmalloc consumed with
*byte unit* but zsmalloc operates *page unit* rather than byte unit so
let's change the API so benefit we could get is that reduce unnecessary
overhead (ie, change page unit with byte unit) in zsmalloc.

Since return type is pages, "zs_get_total_pages" is better than
"zs_get_total_size_bytes".

Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Dan Streetman <ddstreet@ieee.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: <juno.choi@lge.com>
Cc: <seungho1.park@lge.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: David Horner <ds2horner@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Conflicts:

	mm/zsmalloc.c

Change-Id: If5697d7b7f8ebaab3b58c1f9f84de747eb909ca3

3 files changed, 6 insertions, 8 deletions

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 2bb3f2c..803e7a2 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -111,10 +111,10 @@ static ssize_t mem_used_total_show(struct device *dev,
 
 	down_read(&zram->init_lock);
 	if (init_done(zram))
-		val = zs_get_total_size_bytes(meta->mem_pool);
+		val = zs_get_total_pages(meta->mem_pool);
 	up_read(&zram->init_lock);
 
-	return scnprintf(buf, PAGE_SIZE, "%llu\n", val);
+	return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
 }
 
 static ssize_t max_comp_streams_show(struct device *dev,
diff --git a/include/linux/zsmalloc.h b/include/linux/zsmalloc.h
index e44d634..05c2147 100644
--- a/include/linux/zsmalloc.h
+++ b/include/linux/zsmalloc.h
@@ -46,6 +46,6 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
 			enum zs_mapmode mm);
 void zs_unmap_object(struct zs_pool *pool, unsigned long handle);
 
-u64 zs_get_total_size_bytes(struct zs_pool *pool);
+unsigned long zs_get_total_pages(struct zs_pool *pool);
 
 #endif
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index e3b6909..8ac9230 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -239,7 +239,6 @@ struct mapping_area {
 	enum zs_mapmode vm_mm; /* mapping mode */
 };
 
-
 /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
 static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
 
@@ -1086,12 +1085,11 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
 }
 EXPORT_SYMBOL_GPL(zs_unmap_object);
 
-u64 zs_get_total_size_bytes(struct zs_pool *pool)
+unsigned long zs_get_total_pages(struct zs_pool *pool)
 {
-	u64 npages = atomic_long_read(&pool->pages_allocated);
-	return npages << PAGE_SHIFT;
+	return atomic_long_read(&pool->pages_allocated);
 }
-EXPORT_SYMBOL_GPL(zs_get_total_size_bytes);
+EXPORT_SYMBOL_GPL(zs_get_total_pages);
 
 module_init(zs_init);
 module_exit(zs_exit);