iomap: add IOMAP_DIO_INLINE_COMP

Rather than gate whether or not we need to punt a dio completion to a
workqueue on whether the IO is a write or not, add an explicit flag for
it. For now we treat them the same, reads always set the flags and async
writes do not.

No functional changes in this patch.
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/iomap/direct-io.c

@@ -20,6 +20,7 @@
  * Private flags for iomap_dio, must not overlap with the public ones in
  * iomap.h:
  */
+#define IOMAP_DIO_INLINE_COMP	(1U << 27)
 #define IOMAP_DIO_WRITE_THROUGH	(1U << 28)
 #define IOMAP_DIO_NEED_SYNC	(1U << 29)
 #define IOMAP_DIO_WRITE		(1U << 30)
@@ -172,8 +173,10 @@ void iomap_dio_bio_end_io(struct bio *bio)
 		goto release_bio;
 	}
 
-	/* Read completion can always complete inline. */
-	if (!(dio->flags & IOMAP_DIO_WRITE)) {
+	/*
+	 * Flagged with IOMAP_DIO_INLINE_COMP, we can complete it inline
+	 */
+	if (dio->flags & IOMAP_DIO_INLINE_COMP) {
 		WRITE_ONCE(iocb->private, NULL);
 		iomap_dio_complete_work(&dio->aio.work);
 		goto release_bio;
@@ -528,6 +531,9 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		iomi.flags |= IOMAP_NOWAIT;
 
 	if (iov_iter_rw(iter) == READ) {
+		/* reads can always complete inline */
+		dio->flags |= IOMAP_DIO_INLINE_COMP;
+
 		if (iomi.pos >= dio->i_size)
 			goto out_free_dio;