linux-kernel - [PATCH] zram: use writer semaphores in device attributes store

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Date:	Fri, 17 Jun 2016 11:31:29 +0800
From:	Geliang Tang <geliangtang@...il.com>
To:	Minchan Kim <minchan@...nel.org>, Nitin Gupta <ngupta@...are.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	Geliang Tang <geliangtang@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] zram: use writer semaphores in device attributes store

Since the device attributes store provides write access. This patch uses
down_write()/up_write() instead of down_read()/up_read() in
mem_used_max_store() and compact_store().

Signed-off-by: Geliang Tang <geliangtang@...il.com>
---
 drivers/block/zram/zram_drv.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 7454cf1..cfed743 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -293,13 +293,13 @@ static ssize_t mem_used_max_store(struct device *dev,
 	if (err || val != 0)
 		return -EINVAL;
 
-	down_read(&zram->init_lock);
+	down_write(&zram->init_lock);
 	if (init_done(zram)) {
 		struct zram_meta *meta = zram->meta;
 		atomic_long_set(&zram->stats.max_used_pages,
 				zs_get_total_pages(meta->mem_pool));
 	}
-	up_read(&zram->init_lock);
+	up_write(&zram->init_lock);
 
 	return len;
 }
@@ -372,15 +372,15 @@ static ssize_t compact_store(struct device *dev,
 	struct zram *zram = dev_to_zram(dev);
 	struct zram_meta *meta;
 
-	down_read(&zram->init_lock);
+	down_write(&zram->init_lock);
 	if (!init_done(zram)) {
-		up_read(&zram->init_lock);
+		up_write(&zram->init_lock);
 		return -EINVAL;
 	}
 
 	meta = zram->meta;
 	zs_compact(meta->mem_pool);
-	up_read(&zram->init_lock);
+	up_write(&zram->init_lock);
 
 	return len;
 }
-- 
1.9.1