From cbbce82209490df8b68da9aec0d642451fe0a668 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Thu, 25 Sep 2014 13:55:19 +1000
Subject: SCHED: add some "wait..on_bit...timeout()" interfaces.

In commit c1221321b7c25b53204447cff9949a6d5a7ddddc
   sched: Allow wait_on_bit_action() functions to support a timeout

I suggested that a "wait_on_bit_timeout()" interface would not meet my
need.  This isn't true - I was just over-engineering.

Including a 'private' field in wait_bit_key instead of a focused
"timeout" field was just premature generalization.  If some other
use is ever found, it can be generalized or added later.

So this patch renames "private" to "timeout" with a meaning "stop
waiting when "jiffies" reaches or passes "timeout",
and adds two of the many possible wait..bit..timeout() interfaces:

wait_on_page_bit_killable_timeout(), which is the one I want to use,
and out_of_line_wait_on_bit_timeout() which is a reasonably general
example.  Others can be added as needed.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
 mm/filemap.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'mm')

diff --git a/mm/filemap.c b/mm/filemap.c
index 90effcdf948d..cbe5a9013f70 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -703,6 +703,19 @@ int wait_on_page_bit_killable(struct page *page, int bit_nr)
 			     bit_wait_io, TASK_KILLABLE);
 }
 
+int wait_on_page_bit_killable_timeout(struct page *page,
+				       int bit_nr, unsigned long timeout)
+{
+	DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
+
+	wait.key.timeout = jiffies + timeout;
+	if (!test_bit(bit_nr, &page->flags))
+		return 0;
+	return __wait_on_bit(page_waitqueue(page), &wait,
+			     bit_wait_io_timeout, TASK_KILLABLE);
+}
+EXPORT_SYMBOL_GPL(wait_on_page_bit_killable_timeout);
+
 /**
  * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
  * @page: Page defining the wait queue of interest
-- 
cgit v1.2.3


From a4796e37c12e177572b80864cbab9c907ea250b0 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Wed, 24 Sep 2014 11:28:32 +1000
Subject: MM: export page_wakeup functions

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>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
 include/linux/pagemap.h | 10 ++++++++--
 mm/filemap.c            |  8 ++------
 2 files changed, 10 insertions(+), 8 deletions(-)

(limited to 'mm')

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 cbe5a9013f70..b9b1413080be 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)
 {
-- 
cgit v1.2.3