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Subject[PATCH 07/12] lockdep: page lock hooks
rework the now complete page lock API to provide acquisition and release hooks.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/pagemap.h | 40 +++++++++++++++++++++++++++++++---------
mm/filemap.c | 13 +++++++------
2 files changed, 38 insertions(+), 15 deletions(-)
Index: linux-2.6/include/linux/pagemap.h
===================================================================
--- linux-2.6.orig/include/linux/pagemap.h
+++ linux-2.6/include/linux/pagemap.h
@@ -153,23 +153,45 @@ static inline pgoff_t linear_page_index(
return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
}

-extern void FASTCALL(__lock_page(struct page *page));
-extern void FASTCALL(__lock_page_nosync(struct page *page));
-extern void FASTCALL(unlock_page(struct page *page));
+extern void FASTCALL(__lock_page(struct page *page, unsigned long ip));
+extern void FASTCALL(__lock_page_nosync(struct page *page, unsigned long ip));
+extern void FASTCALL(unlock_page_nocheck(struct page *page));
+
+static inline void __lock_page_check(struct page *page, int try, unsigned long ip)
+{
+}
+
+static inline void __unlock_page_check(struct page *page, unsigned long ip)
+{
+}

/*
* lock_page may only be called if we have the page's inode pinned.
*/
+static inline int __trylock_page(struct page *page, int try)
+{
+ int ret = !TestSetPageLocked(page);
+ if (ret)
+ __lock_page_check(page, try, _RET_IP_);
+ return ret;
+}
+
+static inline int trylock_page(struct page *page)
+{
+ return __trylock_page(page, 1);
+}
+
static inline void lock_page(struct page *page)
{
might_sleep();
- if (TestSetPageLocked(page))
- __lock_page(page);
+ if (!__trylock_page(page, 0))
+ __lock_page(page, _RET_IP_);
}

-static inline int trylock_page(struct page *page)
+static inline void unlock_page(struct page *page)
{
- return !TestSetPageLocked(page);
+ __unlock_page_check(page, _RET_IP_);
+ unlock_page_nocheck(page);
}

/*
@@ -179,8 +201,8 @@ static inline int trylock_page(struct pa
static inline void lock_page_nosync(struct page *page)
{
might_sleep();
- if (TestSetPageLocked(page))
- __lock_page_nosync(page);
+ if (!__trylock_page(page, 0))
+ __lock_page_nosync(page, _RET_IP_);
}

/*
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -531,7 +531,7 @@ EXPORT_SYMBOL(wait_on_page_bit);
* the clear_bit and the read of the waitqueue (to avoid SMP races with a
* parallel wait_on_page_locked()).
*/
-void fastcall unlock_page(struct page *page)
+void fastcall unlock_page_nocheck(struct page *page)
{
smp_mb__before_clear_bit();
if (!TestClearPageLocked(page))
@@ -539,7 +539,7 @@ void fastcall unlock_page(struct page *p
smp_mb__after_clear_bit();
wake_up_page(page, PG_locked);
}
-EXPORT_SYMBOL(unlock_page);
+EXPORT_SYMBOL(unlock_page_nocheck);

/**
* end_page_writeback - end writeback against a page
@@ -565,12 +565,12 @@ EXPORT_SYMBOL(end_page_writeback);
* chances are that on the second loop, the block layer's plug list is empty,
* so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
*/
-void fastcall __lock_page(struct page *page)
+void fastcall __lock_page(struct page *page, unsigned long ip)
{
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
-
__wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
TASK_UNINTERRUPTIBLE);
+ __lock_page_check(page, 0, ip);
}
EXPORT_SYMBOL(__lock_page);

@@ -578,11 +578,12 @@ EXPORT_SYMBOL(__lock_page);
* Variant of lock_page that does not require the caller to hold a reference
* on the page's mapping.
*/
-void fastcall __lock_page_nosync(struct page *page)
+void fastcall __lock_page_nosync(struct page *page, unsigned long ip)
{
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
__wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
TASK_UNINTERRUPTIBLE);
+ __lock_page_check(page, 0, ip);
}

/**
@@ -628,7 +629,7 @@ repeat:
page_cache_get(page);
if (!trylock_page(page)) {
read_unlock_irq(&mapping->tree_lock);
- __lock_page(page);
+ __lock_page(page, _THIS_IP_);
read_lock_irq(&mapping->tree_lock);

/* Has the page been truncated while we slept? */
--

-
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