linux-kernel - [PATCH v1 1/9] zram: clean up duplicated codes in __zram_bvec

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Date:   Mon, 26 Jun 2017 15:52:59 +0900
From:   Minchan Kim <minchan@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, Juneho Choi <juno.choi@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        kernel-team <kernel-team@....com>,
        Minchan Kim <minchan@...nel.org>
Subject: [PATCH v1 1/9] zram: clean up duplicated codes in __zram_bvec_write

__zram_bvec_write has some of duplicated logic for zram meta data
handling of same_page|compressed_page.  This patch aims to clean it up
without behavior change.

Link: http://lkml.kernel.org/r/1496019048-27016-1-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@...nel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
---
 drivers/block/zram/zram_drv.c | 55 +++++++++++++++++--------------------------
 1 file changed, 22 insertions(+), 33 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index d3e3af2..5d3ea405 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -453,30 +453,6 @@ static bool zram_same_page_read(struct zram *zram, u32 index,
 	return false;
 }
 
-static bool zram_same_page_write(struct zram *zram, u32 index,
-					struct page *page)
-{
-	unsigned long element;
-	void *mem = kmap_atomic(page);
-
-	if (page_same_filled(mem, &element)) {
-		kunmap_atomic(mem);
-		/* Free memory associated with this sector now. */
-		zram_slot_lock(zram, index);
-		zram_free_page(zram, index);
-		zram_set_flag(zram, index, ZRAM_SAME);
-		zram_set_element(zram, index, element);
-		zram_slot_unlock(zram, index);
-
-		atomic64_inc(&zram->stats.same_pages);
-		atomic64_inc(&zram->stats.pages_stored);
-		return true;
-	}
-	kunmap_atomic(mem);
-
-	return false;
-}
-
 static void zram_meta_free(struct zram *zram, u64 disksize)
 {
 	size_t num_pages = disksize >> PAGE_SHIFT;
@@ -685,14 +661,23 @@ static int zram_compress(struct zram *zram, struct zcomp_strm **zstrm,
 static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index)
 {
 	int ret;
-	unsigned long handle;
-	unsigned int comp_len;
-	void *src, *dst;
+	unsigned long handle = 0;
+	unsigned int comp_len = 0;
+	void *src, *dst, *mem;
 	struct zcomp_strm *zstrm;
 	struct page *page = bvec->bv_page;
+	unsigned long element = 0;
+	enum zram_pageflags flags = 0;
 
-	if (zram_same_page_write(zram, index, page))
-		return 0;
+	mem = kmap_atomic(page);
+	if (page_same_filled(mem, &element)) {
+		kunmap_atomic(mem);
+		/* Free memory associated with this sector now */
+		atomic64_inc(&zram->stats.same_pages);
+		flags = ZRAM_SAME;
+		goto out;
+	}
+	kunmap_atomic(mem);
 
 	zstrm = zcomp_stream_get(zram->comp);
 	ret = zram_compress(zram, &zstrm, page, &handle, &comp_len);
@@ -712,19 +697,23 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index)
 
 	zcomp_stream_put(zram->comp);
 	zs_unmap_object(zram->mem_pool, handle);
-
+out:
 	/*
 	 * Free memory associated with this sector
 	 * before overwriting unused sectors.
 	 */
 	zram_slot_lock(zram, index);
 	zram_free_page(zram, index);
-	zram_set_handle(zram, index, handle);
-	zram_set_obj_size(zram, index, comp_len);
+	if (flags == ZRAM_SAME) {
+		zram_set_flag(zram, index, ZRAM_SAME);
+		zram_set_element(zram, index, element);
+	} else {
+		zram_set_handle(zram, index, handle);
+		zram_set_obj_size(zram, index, comp_len);
+	}
 	zram_slot_unlock(zram, index);
 
 	/* Update stats */
-	atomic64_add(comp_len, &zram->stats.compr_data_size);
 	atomic64_inc(&zram->stats.pages_stored);
 	return 0;
 }
-- 
2.7.4