Fix bug

[can-eth-gw-linux.git] / mm / frontswap.c

diff --git a/mm/frontswap.c b/mm/frontswap.c
index 6b3e71a2cd483a70c845d33136719c43739a6c68..2890e67d602621f0aaf6b516905b5340c9ef7b2c 100644 (file)
--- a/mm/frontswap.c
+++ b/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);
@@ -263,6 +284,11 @@ static int __frontswap_unuse_pages(unsigned long total, unsigned long *unused,
        return ret;
 }
 
+/*
+ * Used to check if it's necessory and feasible to unuse pages.
+ * Return 1 when nothing to do, 0 when need to shink pages,
+ * error code when there is an error.
+ */
 static int __frontswap_shrink(unsigned long target_pages,
                                unsigned long *pages_to_unuse,
                                int *type)
@@ -275,7 +301,7 @@ static int __frontswap_shrink(unsigned long target_pages,
        if (total_pages <= target_pages) {
                /* Nothing to do */
                *pages_to_unuse = 0;
-               return 0;
+               return 1;
        }
        total_pages_to_unuse = total_pages - target_pages;
        return __frontswap_unuse_pages(total_pages_to_unuse, pages_to_unuse, type);
@@ -292,7 +318,7 @@ static int __frontswap_shrink(unsigned long target_pages,
 void frontswap_shrink(unsigned long target_pages)
 {
        unsigned long pages_to_unuse = 0;
-       int type, ret;
+       int uninitialized_var(type), ret;
 
        /*
         * we don't want to hold swap_lock while doing a very
@@ -302,7 +328,7 @@ void frontswap_shrink(unsigned long target_pages)
        spin_lock(&swap_lock);
        ret = __frontswap_shrink(target_pages, &pages_to_unuse, &type);
        spin_unlock(&swap_lock);
-       if (ret == 0 && pages_to_unuse)
+       if (ret == 0)
                try_to_unuse(type, true, pages_to_unuse);
        return;
 }