zram: remove good and bad compress stats

Remove `good' and `bad' compressed sub-requests stats.  RW request may
cause a number of RW sub-requests.  zram used to account `good' compressed
sub-queries (with compressed size less than 50% of original size), `bad'
compressed sub-queries (with compressed size greater that 75% of original
size), leaving sub-requests with compression size between 50% and 75% of
original size not accounted and not reported.  zram already accounts each
sub-request's compression size so we can calculate real device compression
ratio.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit b7cccf8b4009bf74df61f3c9d86b95fabd807c11)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 3f98cf2..a09618c 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -292,7 +292,6 @@
 {
 	struct zram_meta *meta = zram->meta;
 	unsigned long handle = meta->table[index].handle;
-	u16 size = meta->table[index].size;
 
 	if (unlikely(!handle)) {
 		/*
@@ -306,14 +305,8 @@
 		return;
 	}
 
-	if (unlikely(size > max_zpage_size))
-		atomic_dec(&zram->stats.bad_compress);
-
 	zs_free(meta->mem_pool, handle);
 
-	if (size <= PAGE_SIZE / 2)
-		atomic_dec(&zram->stats.good_compress);
-
 	atomic64_sub(meta->table[index].size, &zram->stats.compr_size);
 	atomic_dec(&zram->stats.pages_stored);
 
@@ -477,7 +470,6 @@
 	}
 
 	if (unlikely(clen > max_zpage_size)) {
-		atomic_inc(&zram->stats.bad_compress);
 		clen = PAGE_SIZE;
 		src = NULL;
 		if (is_partial_io(bvec))
@@ -517,9 +509,6 @@
 	/* Update stats */
 	atomic64_add(clen, &zram->stats.compr_size);
 	atomic_inc(&zram->stats.pages_stored);
-	if (clen <= PAGE_SIZE / 2)
-		atomic_inc(&zram->stats.good_compress);
-
 out:
 	if (locked)
 		mutex_unlock(&meta->buffer_lock);
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index e81e9cd..2f173cb 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -78,8 +78,6 @@
 	atomic64_t notify_free;	/* no. of swap slot free notifications */
 	atomic_t pages_zero;		/* no. of zero filled pages */
 	atomic_t pages_stored;	/* no. of pages currently stored */
-	atomic_t good_compress;	/* % of pages with compression ratio<=50% */
-	atomic_t bad_compress;	/* % of pages with compression ratio>=75% */
 };
 
 struct zram_meta {