linux-kernel - [PATCH] zram: correct offset usage in zram_bio

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Date:	Tue, 22 Apr 2014 11:14:02 +0800
From:	Weijie Yang <weijie.yang@...sung.com>
To:	'Minchan Kim' <minchan@...nel.org>
Cc:	'Andrew Morton' <akpm@...ux-foundation.org>,
	'Nitin Gupta' <ngupta@...are.org>, iamjoonsoo.kim@....com,
	'Sergey Senozhatsky' <sergey.senozhatsky@...il.com>,
	'Bob Liu' <bob.liu@...cle.com>,
	'linux-kernel' <linux-kernel@...r.kernel.org>
Subject: [PATCH] zram: correct offset usage in zram_bio_discard

we want to skip the logical block which is partially covered by
the discard bio, so check the remaining size and subtract it if
there is a need to goto the next logical block.

This patch corrects the offset usage in zram_bio_discard.

Signed-off-by: Weijie Yang <weijie.yang@...sung.com>
---
 drivers/block/zram/zram_drv.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9849b52..48eccb3 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -572,10 +572,10 @@ static void zram_bio_discard(struct zram *zram, u32 index,
 	 * skipping this logical block is appropriate here.
 	 */
 	if (offset) {
-		if (n < offset)
+		if (n <= (PAGE_SIZE - offset))
 			return;
 
-		n -= offset;
+		n -= (PAGE_SIZE - offset);
 		index++;
 	}
 
-- 
1.7.10.4


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