linux-kernel - [PATCH 2/2] zram: do not count duplicated pages as compressed

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1494834068-27004-2-git-send-email-minchan@kernel.org>
Date:   Mon, 15 May 2017 16:41:08 +0900
From:   Minchan Kim <minchan@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     <linux-kernel@...r.kernel.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        kernel-team <kernel-team@....com>,
        Minchan Kim <minchan@...nel.org>
Subject: [PATCH 2/2] zram: do not count duplicated pages as compressed

it's not same compressed pages and deduplicated pages
so we shouldn't count duplicated pages as compressed pages.

Signed-off-by: Minchan Kim <minchan@...nel.org>
---
 drivers/block/zram/zram_dedup.c |  4 ----
 drivers/block/zram/zram_drv.c   | 24 +++++++++++++++++++-----
 drivers/block/zram/zram_drv.h   |  1 +
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/drivers/block/zram/zram_dedup.c b/drivers/block/zram/zram_dedup.c
index 14c4988f8ff7..c15848cc1b31 100644
--- a/drivers/block/zram/zram_dedup.c
+++ b/drivers/block/zram/zram_dedup.c
@@ -101,9 +101,6 @@ static unsigned long zram_dedup_put(struct zram *zram,
 	entry->refcount--;
 	if (!entry->refcount)
 		rb_erase(&entry->rb_node, &hash->rb_root);
-	else
-		atomic64_sub(entry->len, &zram->stats.dup_data_size);
-
 	spin_unlock(&hash->lock);
 
 	return entry->refcount;
@@ -127,7 +124,6 @@ static struct zram_entry *__zram_dedup_get(struct zram *zram,
 
 again:
 	entry->refcount++;
-	atomic64_add(entry->len, &zram->stats.dup_data_size);
 	spin_unlock(&hash->lock);
 
 	if (prev)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index b885356551e9..8152e405117b 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -624,15 +624,22 @@ static void zram_free_page(struct zram *zram, size_t index)
 		return;
 	}
 
+	if (zram_dedup_enabled(zram) &&
+			zram_test_flag(zram, index, ZRAM_DUP)) {
+		zram_clear_flag(zram, index, ZRAM_DUP);
+		atomic64_sub(entry->len, &zram->stats.dup_data_size);
+		goto out;
+	}
+
 	if (!entry)
 		return;
 
-	zram_entry_free(zram, entry);
-
 	atomic64_sub(zram_get_obj_size(zram, index),
 			&zram->stats.compr_data_size);
-	atomic64_dec(&zram->stats.pages_stored);
+out:
+	zram_entry_free(zram, entry);
 
+	atomic64_dec(&zram->stats.pages_stored);
 	zram_set_entry(zram, index, NULL);
 	zram_set_obj_size(zram, index, 0);
 }
@@ -794,7 +801,15 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index)
 	entry = zram_dedup_find(zram, page, &checksum);
 	if (entry) {
 		comp_len = entry->len;
-		goto found_dup;
+		zram_slot_lock(zram, index);
+		zram_free_page(zram, index);
+		zram_set_flag(zram, index, ZRAM_DUP);
+		zram_set_entry(zram, index, entry);
+		zram_set_obj_size(zram, index, comp_len);
+		zram_slot_unlock(zram, index);
+		atomic64_add(comp_len, &zram->stats.dup_data_size);
+		atomic64_inc(&zram->stats.pages_stored);
+		return 0;
 	}
 
 	zstrm = zcomp_stream_get(zram->comp);
@@ -818,7 +833,6 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index)
 	zs_unmap_object(zram->mem_pool, zram_entry_handle(zram, entry));
 	zram_dedup_insert(zram, entry, checksum);
 
-found_dup:
 	/*
 	 * Free memory associated with this sector
 	 * before overwriting unused sectors.
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 0091e23873c1..8ccfdcd8f674 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -64,6 +64,7 @@ static const size_t max_zpage_size = PAGE_SIZE / 4 * 3;
 enum zram_pageflags {
 	/* Page consists entirely of zeros */
 	ZRAM_SAME = ZRAM_FLAG_SHIFT,
+	ZRAM_DUP,
 	ZRAM_ACCESS,	/* page is now accessed */
 
 	__NR_ZRAM_PAGEFLAGS,
-- 
2.7.4