From 5f2a105d5e33a038a717995d2738434f9c25aed2 Mon Sep 17 00:00:00 2001
From: Andrew Morton <akpm@osdl.org>
Date: Fri, 22 Dec 2006 01:04:48 -0800
Subject: [PATCH] truncate: dirty memory accounting fix

Only (un)account for IO and page-dirtying for devices which have real backing
store (ie: not tmpfs or ramdisks).

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 mm/truncate.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/truncate.c b/mm/truncate.c
index 89a5c359b6e..4a38dd1a4ce 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -60,7 +60,8 @@ void cancel_dirty_page(struct page *page, unsigned int account_size)
 		WARN_ON(++warncount < 5);
 	}
 		
-	if (TestClearPageDirty(page) && account_size) {
+	if (TestClearPageDirty(page) && account_size &&
+			mapping_cap_account_dirty(page->mapping)) {
 		dec_zone_page_state(page, NR_FILE_DIRTY);
 		task_io_account_cancelled_write(account_size);
 	}
-- 
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