Merge tag 'stable/for-linus-3.7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm
Pull frontswap update from Konrad Rzeszutek Wilk:
"Features:
- Support exlusive get if backend is capable.
Bug-fixes:
- Fix compile warnings
- Add comments/cleanup doc
- Fix wrong if condition"
* tag 'stable/for-linus-3.7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm:
frontswap: support exclusive gets if tmem backend is capable
mm: frontswap: fix a wrong if condition in frontswap_shrink
mm/frontswap: fix uninit'ed variable warning
mm/frontswap: cleanup doc and comment error
mm: frontswap: remove unneeded headers
diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h
index 0e4e2ee..3044254 100644
--- a/include/linux/frontswap.h
+++ b/include/linux/frontswap.h
@@ -19,6 +19,8 @@
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/mm/frontswap.c b/mm/frontswap.c
index 6b3e71a..2890e67 100644
--- a/mm/frontswap.c
+++ b/mm/frontswap.c
@@ -44,6 +44,13 @@
*/
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
@@ -97,6 +104,15 @@
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.
*/
void __frontswap_init(unsigned type)
@@ -174,8 +190,13 @@
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 @@
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 @@
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 @@
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 @@
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;
}