[PATCH 2/5] MM: export page_wakeup functions

NeilBrown
2014-09-24T02:03:25Z

This will allow NFS to wait for PG_private to be cleared and,
particularly, to send a wake-up when it is.

Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/pagemap.h | 10 ++++++++--
mm/filemap.c | 8 ++------
2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 87f9e4230d3a..2dca0cef3506 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -496,8 +496,8 @@ static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
}

/*
- * This is exported only for wait_on_page_locked/wait_on_page_writeback.
- * Never use this directly!
+ * This is exported only for wait_on_page_locked/wait_on_page_writeback,
+ * and for filesystems which need to wait on PG_private.
*/
extern void wait_on_page_bit(struct page *page, int bit_nr);

@@ -512,6 +512,12 @@ static inline int wait_on_page_locked_killable(struct page *page)
return 0;
}

+extern wait_queue_head_t *page_waitqueue(struct page *page);
+static inline void wake_up_page(struct page *page, int bit)
+{
+ __wake_up_bit(page_waitqueue(page), &page->flags, bit);
+}
+
/*
* Wait for a page to be unlocked.
*
diff --git a/mm/filemap.c b/mm/filemap.c
index 4a19c084bdb1..c9ba09f2ad3c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -670,17 +670,13 @@ EXPORT_SYMBOL(__page_cache_alloc);
* at a cost of "thundering herd" phenomena during rare hash
* collisions.
*/
-static wait_queue_head_t *page_waitqueue(struct page *page)
+wait_queue_head_t *page_waitqueue(struct page *page)
{
const struct zone *zone = page_zone(page);

return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
}
-
-static inline void wake_up_page(struct page *page, int bit)
-{
- __wake_up_bit(page_waitqueue(page), &page->flags, bit);
-}
+EXPORT_SYMBOL(page_waitqueue);

void wait_on_page_bit(struct page *page, int bit_nr)
{