iomap: factor out a iomap_dio_done helper

Split out the struct iomap-dio level final completion from
iomap_dio_bio_end_io into a helper to clean up the code and make it
reusable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-7-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: Christoph Hellwig

fs/iomap/direct-io.c

@@ -165,43 +165,31 @@ static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
 	cmpxchg(&dio->error, 0, ret);
 }
 
-void iomap_dio_bio_end_io(struct bio *bio)
+/*
+ * Called when dio->ref reaches zero from an I/O completion.
+ */
+static void iomap_dio_done(struct iomap_dio *dio)
 {
-	struct iomap_dio *dio = bio->bi_private;
-	bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
 	struct kiocb *iocb = dio->iocb;
 
-	if (bio->bi_status)
-		iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
-	if (!atomic_dec_and_test(&dio->ref))
-		goto release_bio;
-
-	/*
-	 * Synchronous dio, task itself will handle any completion work
-	 * that needs after IO. All we need to do is wake the task.
-	 */
 	if (dio->wait_for_completion) {
+		/*
+		 * Synchronous I/O, task itself will handle any completion work
+		 * that needs after IO. All we need to do is wake the task.
+		 */
 		struct task_struct *waiter = dio->submit.waiter;
 
 		WRITE_ONCE(dio->submit.waiter, NULL);
 		blk_wake_io_task(waiter);
-		goto release_bio;
-	}
-
-	/*
-	 * Flagged with IOMAP_DIO_INLINE_COMP, we can complete it inline
-	 */
-	if (dio->flags & IOMAP_DIO_INLINE_COMP) {
+	} else if (dio->flags & IOMAP_DIO_INLINE_COMP) {
 		WRITE_ONCE(iocb->private, NULL);
 		iomap_dio_complete_work(&dio->aio.work);
-		goto release_bio;
-	}
-
-	/*
-	 * If this dio is flagged with IOMAP_DIO_CALLER_COMP, then schedule
-	 * our completion that way to avoid an async punt to a workqueue.
-	 */
-	if (dio->flags & IOMAP_DIO_CALLER_COMP) {
+	} else if (dio->flags & IOMAP_DIO_CALLER_COMP) {
+		/*
+		 * If this dio is flagged with IOMAP_DIO_CALLER_COMP, then
+		 * schedule our completion that way to avoid an async punt to a
+		 * workqueue.
+		 */
 		/* only polled IO cares about private cleared */
 		iocb->private = dio;
 		iocb->dio_complete = iomap_dio_deferred_complete;
@@ -219,19 +207,31 @@ void iomap_dio_bio_end_io(struct bio *bio)
 		 * issuer.
 		 */
 		iocb->ki_complete(iocb, 0);
-		goto release_bio;
+	} else {
+		struct inode *inode = file_inode(iocb->ki_filp);
+
+		/*
+		 * Async DIO completion that requires filesystem level
+		 * completion work gets punted to a work queue to complete as
+		 * the operation may require more IO to be issued to finalise
+		 * filesystem metadata changes or guarantee data integrity.
+		 */
+		INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
+		queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
 	}
+}
+
+void iomap_dio_bio_end_io(struct bio *bio)
+{
+	struct iomap_dio *dio = bio->bi_private;
+	bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
+
+	if (bio->bi_status)
+		iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
+
+	if (atomic_dec_and_test(&dio->ref))
+		iomap_dio_done(dio);
 
-	/*
-	 * Async DIO completion that requires filesystem level completion work
-	 * gets punted to a work queue to complete as the operation may require
-	 * more IO to be issued to finalise filesystem metadata changes or
-	 * guarantee data integrity.
-	 */
-	INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
-	queue_work(file_inode(iocb->ki_filp)->i_sb->s_dio_done_wq,
-			&dio->aio.work);
-release_bio:
 	if (should_dirty) {
 		bio_check_pages_dirty(bio);
 	} else {