[PATCH 4/5] mm: introduce wait_on_page_locked_killable

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

commit 2687a356 (Add lock_page_killable) introduced killable
lock_page(). Similarly this patch introdues killable
wait_on_page_locked().

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
 include/linux/pagemap.h |    9 +++++++++
 mm/filemap.c            |   11 +++++++++++
 2 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e407601..49f9315 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -369,6 +369,15 @@ static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
  */
 extern void wait_on_page_bit(struct page *page, int bit_nr);
 
+extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
+
+static inline int wait_on_page_locked_killable(struct page *page)
+{
+	if (PageLocked(page))
+		return wait_on_page_bit_killable(page, PG_locked);
+	return 0;
+}
+
 /* 
  * Wait for a page to be unlocked.
  *
diff --git a/mm/filemap.c b/mm/filemap.c
index a6cfecf..f5f9ac2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -608,6 +608,17 @@ void wait_on_page_bit(struct page *page, int bit_nr)
 }
 EXPORT_SYMBOL(wait_on_page_bit);
 
+int wait_on_page_bit_killable(struct page *page, int bit_nr)
+{
+	DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
+
+	if (!test_bit(bit_nr, &page->flags))
+		return 0;
+
+	return __wait_on_bit(page_waitqueue(page), &wait, sync_page_killable,
+							TASK_KILLABLE);
+}
+
 /**
  * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
  * @page: Page defining the wait queue of interest
-- 
1.6.5.2