block: move bdi/address_space unplug functions to backing-dev.h

There's nothing block related about them, the backing device
is used by things like NFS etc as well. This gets rid of the
need to protect such calls by CONFIG_BLOCK.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

fs/aio.c

@@ -15,6 +15,7 @@
 #include <linux/aio_abi.h>
 #include <linux/module.h>
 #include <linux/syscalls.h>
+#include <linux/backing-dev.h>
 #include <linux/uio.h>
 
 #define DEBUG 0

include/linux/backing-dev.h

@@ -331,4 +331,17 @@ static inline int bdi_sched_wait(void *word)
 	return 0;
 }
 
+static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
+				       struct page *page)
+{
+	if (bdi && bdi->unplug_io_fn)
+		bdi->unplug_io_fn(bdi, page);
+}
+
+static inline void blk_run_address_space(struct address_space *mapping)
+{
+	if (mapping)
+		blk_run_backing_dev(mapping->backing_dev_info, NULL);
+}
+
 #endif		/* _LINUX_BACKING_DEV_H */

include/linux/blkdev.h

@@ -823,19 +823,6 @@ static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 	return bdev->bd_disk->queue;
 }
 
-static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
-				       struct page *page)
-{
-	if (bdi && bdi->unplug_io_fn)
-		bdi->unplug_io_fn(bdi, page);
-}
-
-static inline void blk_run_address_space(struct address_space *mapping)
-{
-	if (mapping)
-		blk_run_backing_dev(mapping->backing_dev_info, NULL);
-}
-
 /*
  * blk_rq_pos()			: the current sector
  * blk_rq_bytes()		: bytes left in the entire request