1 files changed, 13 insertions, 61 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index f807afd..04d1992 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -164,45 +164,15 @@ void delete_from_page_cache(struct page *page)
 }
 EXPORT_SYMBOL(delete_from_page_cache);
 
-static int sync_page(void *word)
+static int sleep_on_page(void *word)
 {
-	struct address_space *mapping;
-	struct page *page;
-
-	page = container_of((unsigned long *)word, struct page, flags);
-
-	/*
-	 * page_mapping() is being called without PG_locked held.
-	 * Some knowledge of the state and use of the page is used to
-	 * reduce the requirements down to a memory barrier.
-	 * The danger here is of a stale page_mapping() return value
-	 * indicating a struct address_space different from the one it's
-	 * associated with when it is associated with one.
-	 * After smp_mb(), it's either the correct page_mapping() for
-	 * the page, or an old page_mapping() and the page's own
-	 * page_mapping() has gone NULL.
-	 * The ->sync_page() address_space operation must tolerate
-	 * page_mapping() going NULL. By an amazing coincidence,
-	 * this comes about because none of the users of the page
-	 * in the ->sync_page() methods make essential use of the
-	 * page_mapping(), merely passing the page down to the backing
-	 * device's unplug functions when it's non-NULL, which in turn
-	 * ignore it for all cases but swap, where only page_private(page) is
-	 * of interest. When page_mapping() does go NULL, the entire
-	 * call stack gracefully ignores the page and returns.
-	 * -- wli
-	 */
-	smp_mb();
-	mapping = page_mapping(page);
-	if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
-		mapping->a_ops->sync_page(page);
 	io_schedule();
 	return 0;
 }
 
-static int sync_page_killable(void *word)
+static int sleep_on_page_killable(void *word)
 {
-	sync_page(word);
+	sleep_on_page(word);
 	return fatal_signal_pending(current) ? -EINTR : 0;
 }
 
@@ -558,12 +528,6 @@ struct page *__page_cache_alloc(gfp_t gfp)
 EXPORT_SYMBOL(__page_cache_alloc);
 #endif
 
-static int __sleep_on_page_lock(void *word)
-{
-	io_schedule();
-	return 0;
-}
-
 /*
  * In order to wait for pages to become available there must be
  * waitqueues associated with pages. By using a hash table of
@@ -591,7 +555,7 @@ void wait_on_page_bit(struct page *page, int bit_nr)
 	DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
 
 	if (test_bit(bit_nr, &page->flags))
-		__wait_on_bit(page_waitqueue(page), &wait, sync_page,
+		__wait_on_bit(page_waitqueue(page), &wait, sleep_on_page,
 							TASK_UNINTERRUPTIBLE);
 }
 EXPORT_SYMBOL(wait_on_page_bit);
@@ -655,17 +619,12 @@ EXPORT_SYMBOL(end_page_writeback);
 /**
  * __lock_page - get a lock on the page, assuming we need to sleep to get it
  * @page: the page to lock
- *
- * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary.  If some
- * random driver's requestfn sets TASK_RUNNING, we could busywait.  However
- * 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 __lock_page(struct page *page)
 {
 	DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
 
-	__wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
+	__wait_on_bit_lock(page_waitqueue(page), &wait, sleep_on_page,
 							TASK_UNINTERRUPTIBLE);
 }
 EXPORT_SYMBOL(__lock_page);
@@ -675,24 +634,10 @@ int __lock_page_killable(struct page *page)
 	DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
 
 	return __wait_on_bit_lock(page_waitqueue(page), &wait,
-					sync_page_killable, TASK_KILLABLE);
+					sleep_on_page_killable, TASK_KILLABLE);
 }
 EXPORT_SYMBOL_GPL(__lock_page_killable);
 
-/**
- * __lock_page_nosync - get a lock on the page, without calling sync_page()
- * @page: the page to lock
- *
- * Variant of lock_page that does not require the caller to hold a reference
- * on the page's mapping.
- */
-void __lock_page_nosync(struct page *page)
-{
-	DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
-	__wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
-							TASK_UNINTERRUPTIBLE);
-}
-
 int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 			 unsigned int flags)
 {
@@ -1407,12 +1352,15 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 	unsigned long seg = 0;
 	size_t count;
 	loff_t *ppos = &iocb->ki_pos;
+	struct blk_plug plug;
 
 	count = 0;
 	retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
 	if (retval)
 		return retval;
 
+	blk_start_plug(&plug);
+
 	/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
 	if (filp->f_flags & O_DIRECT) {
 		loff_t size;
@@ -1485,6 +1433,7 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 			break;
 	}
 out:
+	blk_finish_plug(&plug);
 	return retval;
 }
 EXPORT_SYMBOL(generic_file_aio_read);
@@ -2596,11 +2545,13 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
+	struct blk_plug plug;
 	ssize_t ret;
 
 	BUG_ON(iocb->ki_pos != pos);
 
 	mutex_lock(&inode->i_mutex);
+	blk_start_plug(&plug);
 	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 	mutex_unlock(&inode->i_mutex);
 
@@ -2611,6 +2562,7 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 		if (err < 0 && ret > 0)
 			ret = err;
 	}
+	blk_finish_plug(&plug);
 	return ret;
 }
 EXPORT_SYMBOL(generic_file_aio_write);