fs: make sb_init_dio_done_wq available outside of direct-io.c

We want to use the per-sb completion workqueue from the new iomap
direct I/O code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/direct-io.c

@@ -554,7 +554,7 @@ static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio)
  * filesystems that don't need it and also allows us to create the workqueue
  * late enough so the we can include s_id in the name of the workqueue.
  */
-static int sb_init_dio_done_wq(struct super_block *sb)
+int sb_init_dio_done_wq(struct super_block *sb)
 {
 	struct workqueue_struct *old;
 	struct workqueue_struct *wq = alloc_workqueue("dio/%s",

fs/internal.h

@@ -184,3 +184,6 @@ typedef loff_t (*iomap_actor_t)(struct inode *inode, loff_t pos, loff_t len,
 loff_t iomap_apply(struct inode *inode, loff_t pos, loff_t length,
 		unsigned flags, struct iomap_ops *ops, void *data,
 		iomap_actor_t actor);
+
+/* direct-io.c: */
+int sb_init_dio_done_wq(struct super_block *sb);