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Message-Id: <1360959635-18922-3-git-send-email-konrad.wilk@oracle.com>
Date: Fri, 15 Feb 2013 15:20:26 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: dan.magenheimer@...cle.com, sjenning@...ux.vnet.ibm.com,
gregkh@...uxfoundation.org, akpm@...ux-foundation.org,
ngupta@...are.org, rcj@...ux.vnet.ibm.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
minchan@...nel.org
Cc: ric.masonn@...il.com, lliubbo@...il.com,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH 02/11] frontswap: Make frontswap_init use a pointer for the ops.
This simplifies the code in the frontswap - we can get rid
of the 'backend_registered' test and instead check against
frontswap_ops.
[v1: Rebase on top of 703ba7fe5e085f2c85eeb451c2ac13cf275c7cb2
(ramster->zcache move]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
drivers/staging/zcache/zcache-main.c | 8 ++++----
drivers/xen/tmem.c | 6 +++---
include/linux/frontswap.h | 2 +-
mm/frontswap.c | 38 +++++++++++++++++-------------------
4 files changed, 26 insertions(+), 28 deletions(-)
diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index 328898e..3365f59 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -1825,9 +1825,9 @@ static struct frontswap_ops zcache_frontswap_ops = {
.init = zcache_frontswap_init
};
-struct frontswap_ops zcache_frontswap_register_ops(void)
+struct frontswap_ops *zcache_frontswap_register_ops(void)
{
- struct frontswap_ops old_ops =
+ struct frontswap_ops *old_ops =
frontswap_register_ops(&zcache_frontswap_ops);
return old_ops;
@@ -1994,7 +1994,7 @@ static int __init zcache_init(void)
pr_warn("%s: cleancache_ops overridden\n", namestr);
}
if (zcache_enabled && !disable_frontswap) {
- struct frontswap_ops old_ops;
+ struct frontswap_ops *old_ops;
old_ops = zcache_frontswap_register_ops();
if (frontswap_has_exclusive_gets)
@@ -2006,7 +2006,7 @@ static int __init zcache_init(void)
namestr, frontswap_has_exclusive_gets,
!disable_frontswap_ignore_nonactive);
#endif
- if (old_ops.init != NULL)
+ if (old_ops != NULL)
pr_warn("%s: frontswap_ops overridden\n", namestr);
}
if (ramster_enabled)
diff --git a/drivers/xen/tmem.c b/drivers/xen/tmem.c
index 144564e..4b02c07 100644
--- a/drivers/xen/tmem.c
+++ b/drivers/xen/tmem.c
@@ -362,7 +362,7 @@ static int __init no_frontswap(char *s)
}
__setup("nofrontswap", no_frontswap);
-static struct frontswap_ops __initdata tmem_frontswap_ops = {
+static struct frontswap_ops tmem_frontswap_ops = {
.store = tmem_frontswap_store,
.load = tmem_frontswap_load,
.invalidate_page = tmem_frontswap_flush_page,
@@ -378,11 +378,11 @@ static int __init xen_tmem_init(void)
#ifdef CONFIG_FRONTSWAP
if (tmem_enabled && use_frontswap) {
char *s = "";
- struct frontswap_ops old_ops =
+ struct frontswap_ops *old_ops =
frontswap_register_ops(&tmem_frontswap_ops);
tmem_frontswap_poolid = -1;
- if (old_ops.init != NULL)
+ if (old_ops)
s = " (WARNING: frontswap_ops overridden)";
printk(KERN_INFO "frontswap enabled, RAM provided by "
"Xen Transcendent Memory\n");
diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h
index 3044254..d4f2987 100644
--- a/include/linux/frontswap.h
+++ b/include/linux/frontswap.h
@@ -14,7 +14,7 @@ struct frontswap_ops {
};
extern bool frontswap_enabled;
-extern struct frontswap_ops
+extern struct frontswap_ops *
frontswap_register_ops(struct frontswap_ops *ops);
extern void frontswap_shrink(unsigned long);
extern unsigned long frontswap_curr_pages(void);
diff --git a/mm/frontswap.c b/mm/frontswap.c
index c05a9db..b9b23b1 100644
--- a/mm/frontswap.c
+++ b/mm/frontswap.c
@@ -24,7 +24,7 @@
* frontswap_ops is set by frontswap_register_ops to contain the pointers
* to the frontswap "backend" implementation functions.
*/
-static struct frontswap_ops frontswap_ops __read_mostly;
+static struct frontswap_ops *frontswap_ops __read_mostly;
/*
* This global enablement flag reduces overhead on systems where frontswap_ops
@@ -108,41 +108,39 @@ static inline void inc_frontswap_invalidates(void) { }
*
* The time between the backend being registered and the swap file system
* calling the backend (via the frontswap_* functions) is indeterminate as
- * backend_registered is not atomic_t (or a value guarded by a spinlock).
+ * frontswap_ops is not atomic_t (or a value guarded by a spinlock).
* That is OK as we are comfortable missing some of these calls to the newly
* registered backend.
*
* Obviously the opposite (unloading the backend) must be done after all
* the frontswap_[store|load|invalidate_area|invalidate_page] start
- * ignorning or failing the requests - at which point backend_registered
+ * ignorning or failing the requests - at which point frontswap_ops
* would have to be made in some fashion atomic.
*/
static DECLARE_BITMAP(need_init, MAX_SWAPFILES);
-static bool backend_registered __read_mostly;
/*
* Register operations for frontswap, returning previous thus allowing
* detection of multiple backends and possible nesting.
*/
-struct frontswap_ops frontswap_register_ops(struct frontswap_ops *ops)
+struct frontswap_ops *frontswap_register_ops(struct frontswap_ops *ops)
{
- struct frontswap_ops old = frontswap_ops;
+ struct frontswap_ops *old = frontswap_ops;
int i;
- frontswap_ops = *ops;
frontswap_enabled = true;
for (i = 0; i < MAX_SWAPFILES; i++) {
if (test_and_clear_bit(i, need_init))
- (*frontswap_ops.init)(i);
+ ops->init(i);
}
/*
- * We MUST have backend_registered set _after_ the frontswap_init's
+ * We MUST have frontswap_ops set _after_ the frontswap_init's
* have been called. Otherwise __frontswap_store might fail. Hence
* the barrier to make sure compiler does not re-order us.
*/
barrier();
- backend_registered = true;
+ frontswap_ops = ops;
return old;
}
EXPORT_SYMBOL(frontswap_register_ops);
@@ -172,11 +170,11 @@ void __frontswap_init(unsigned type)
{
struct swap_info_struct *sis = swap_info[type];
- if (backend_registered) {
+ if (frontswap_ops) {
BUG_ON(sis == NULL);
if (sis->frontswap_map == NULL)
return;
- (*frontswap_ops.init)(type);
+ frontswap_ops->init(type);
}
else {
BUG_ON(type > MAX_SWAPFILES);
@@ -207,7 +205,7 @@ int __frontswap_store(struct page *page)
struct swap_info_struct *sis = swap_info[type];
pgoff_t offset = swp_offset(entry);
- if (!backend_registered) {
+ if (!frontswap_ops) {
inc_frontswap_failed_stores();
return ret;
}
@@ -216,7 +214,7 @@ int __frontswap_store(struct page *page)
BUG_ON(sis == NULL);
if (frontswap_test(sis, offset))
dup = 1;
- ret = frontswap_ops.store(type, offset, page);
+ ret = frontswap_ops->store(type, offset, page);
if (ret == 0) {
frontswap_set(sis, offset);
inc_frontswap_succ_stores();
@@ -251,13 +249,13 @@ int __frontswap_load(struct page *page)
struct swap_info_struct *sis = swap_info[type];
pgoff_t offset = swp_offset(entry);
- if (!backend_registered)
+ if (!frontswap_ops)
return ret;
BUG_ON(!PageLocked(page));
BUG_ON(sis == NULL);
if (frontswap_test(sis, offset))
- ret = frontswap_ops.load(type, offset, page);
+ ret = frontswap_ops->load(type, offset, page);
if (ret == 0) {
inc_frontswap_loads();
if (frontswap_tmem_exclusive_gets_enabled) {
@@ -277,12 +275,12 @@ void __frontswap_invalidate_page(unsigned type, pgoff_t offset)
{
struct swap_info_struct *sis = swap_info[type];
- if (!backend_registered)
+ if (!frontswap_ops)
return;
BUG_ON(sis == NULL);
if (frontswap_test(sis, offset)) {
- frontswap_ops.invalidate_page(type, offset);
+ frontswap_ops->invalidate_page(type, offset);
__frontswap_clear(sis, offset);
inc_frontswap_invalidates();
}
@@ -297,11 +295,11 @@ void __frontswap_invalidate_area(unsigned type)
{
struct swap_info_struct *sis = swap_info[type];
- if (backend_registered) {
+ if (frontswap_ops) {
BUG_ON(sis == NULL);
if (sis->frontswap_map == NULL)
return;
- (*frontswap_ops.invalidate_area)(type);
+ frontswap_ops->invalidate_area(type);
atomic_set(&sis->frontswap_pages, 0);
memset(sis->frontswap_map, 0, sis->max / sizeof(long));
}
--
1.8.0.2
--
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