linux-kernel - [PATCH] frontswap: enable call to invalidate area on swapoff

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Date:	Mon, 07 Oct 2013 17:25:41 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	linux-kernel@...r.kernel.org
Cc:	Shaohua Li <shli@...ionio.com>, Minchan Kim <minchan@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Subject: [PATCH] frontswap: enable call to invalidate area on swapoff

During swapoff the frontswap_map was NULL-ified before calling
frontswap_invalidate_area(). However the frontswap_invalidate_area()
exits early if frontswap_map is NULL. Invalidate was never called during
swapoff.

This patch moves frontswap_map_set() in swapoff just after calling
frontswap_invalidate_area() so outside of locks
(swap_lock and swap_info_struct->lock). This shouldn't be a problem as
during swapon the frontswap_map_set() is called also outside of any
locks.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
---
 mm/swapfile.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 3963fc2..3a4896b 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1922,10 +1922,10 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	p->cluster_info = NULL;
 	p->flags = 0;
 	frontswap_map = frontswap_map_get(p);
-	frontswap_map_set(p, NULL);
 	spin_unlock(&p->lock);
 	spin_unlock(&swap_lock);
 	frontswap_invalidate_area(type);
+	frontswap_map_set(p, NULL);
 	mutex_unlock(&swapon_mutex);
 	free_percpu(p->percpu_cluster);
 	p->percpu_cluster = NULL;
-- 
1.7.9.5

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