From 95e28a3f876b9efd9ab5f87788d59ca94a80386a Mon Sep 17 00:00:00 2001
From: Dan Magenheimer <dan.magenheimer@oracle.com>
Date: Thu, 20 Sep 2012 12:16:52 -0700
Subject: [PATCH] --- yaml --- r: 329133 b: refs/heads/master c:
 e3483a5f3a8ef448c229a2aceca9b2ad6a46b8ec h: refs/heads/master i:   329131:
 38489a2a2721ae0b45a8aab4eb1ea85dfc13a208 v: v3

---
 [refs]                          |  2 +-
 trunk/include/linux/frontswap.h |  2 ++
 trunk/mm/frontswap.c            | 23 ++++++++++++++++++++++-
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index b775a1de2212..93cec308c1bb 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a00bb1e9fc0925c0061e9d844523a3a47a7e2f7f
+refs/heads/master: e3483a5f3a8ef448c229a2aceca9b2ad6a46b8ec
diff --git a/trunk/include/linux/frontswap.h b/trunk/include/linux/frontswap.h
index 0e4e2eec5c1d..30442547b9e6 100644
--- a/trunk/include/linux/frontswap.h
+++ b/trunk/include/linux/frontswap.h
@@ -19,6 +19,8 @@ extern struct frontswap_ops
 extern void frontswap_shrink(unsigned long);
 extern unsigned long frontswap_curr_pages(void);
 extern void frontswap_writethrough(bool);
+#define FRONTSWAP_HAS_EXCLUSIVE_GETS
+extern void frontswap_tmem_exclusive_gets(bool);
 
 extern void __frontswap_init(unsigned type);
 extern int __frontswap_store(struct page *page);
diff --git a/trunk/mm/frontswap.c b/trunk/mm/frontswap.c
index 0547a35f798b..2890e67d6026 100644
--- a/trunk/mm/frontswap.c
+++ b/trunk/mm/frontswap.c
@@ -44,6 +44,13 @@ EXPORT_SYMBOL(frontswap_enabled);
  */
 static bool frontswap_writethrough_enabled __read_mostly;
 
+/*
+ * If enabled, the underlying tmem implementation is capable of doing
+ * exclusive gets, so frontswap_load, on a successful tmem_get must
+ * mark the page as no longer in frontswap AND mark it dirty.
+ */
+static bool frontswap_tmem_exclusive_gets_enabled __read_mostly;
+
 #ifdef CONFIG_DEBUG_FS
 /*
  * Counters available via /sys/kernel/debug/frontswap (if debugfs is
@@ -96,6 +103,15 @@ void frontswap_writethrough(bool enable)
 }
 EXPORT_SYMBOL(frontswap_writethrough);
 
+/*
+ * Enable/disable frontswap exclusive gets (see above).
+ */
+void frontswap_tmem_exclusive_gets(bool enable)
+{
+	frontswap_tmem_exclusive_gets_enabled = enable;
+}
+EXPORT_SYMBOL(frontswap_tmem_exclusive_gets);
+
 /*
  * Called when a swap device is swapon'd.
  */
@@ -174,8 +190,13 @@ int __frontswap_load(struct page *page)
 	BUG_ON(sis == NULL);
 	if (frontswap_test(sis, offset))
 		ret = frontswap_ops.load(type, offset, page);
-	if (ret == 0)
+	if (ret == 0) {
 		inc_frontswap_loads();
+		if (frontswap_tmem_exclusive_gets_enabled) {
+			SetPageDirty(page);
+			frontswap_clear(sis, offset);
+		}
+	}
 	return ret;
 }
 EXPORT_SYMBOL(__frontswap_load);