iomap: Separate out generic_write_sync() from iomap_dio_complete()

This introduces a separate function __iomap_dio_complte() which
completes the Direct I/O without performing the write sync.

Filesystems such as btrfs which require an inode_lock for sync can call
__iomap_dio_complete() and must perform sync on their own after unlock.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

fs/iomap/direct-io.c

@@ -76,7 +76,7 @@ static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap,
 		dio->submit.cookie = submit_bio(bio);
 }
 
-ssize_t iomap_dio_complete(struct iomap_dio *dio)
+ssize_t __iomap_dio_complete(struct iomap_dio *dio)
 {
 	const struct iomap_dio_ops *dops = dio->dops;
 	struct kiocb *iocb = dio->iocb;
@@ -119,18 +119,28 @@ ssize_t iomap_dio_complete(struct iomap_dio *dio)
 	}
 
 	inode_dio_end(file_inode(iocb->ki_filp));
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__iomap_dio_complete);
+
+ssize_t iomap_dio_complete(struct iomap_dio *dio)
+{
+	ssize_t ret;
+
+	ret = __iomap_dio_complete(dio);
 	/*
 	 * If this is a DSYNC write, make sure we push it to stable storage now
 	 * that we've written data.
 	 */
 	if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
-		ret = generic_write_sync(iocb, ret);
+		ret = generic_write_sync(dio->iocb, ret);
 
 	kfree(dio);
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(iomap_dio_complete);
+
 
 static void iomap_dio_complete_work(struct work_struct *work)
 {

include/linux/iomap.h

@@ -262,7 +262,7 @@ ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 struct iomap_dio *__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
 		bool wait_for_completion);
-ssize_t iomap_dio_complete(struct iomap_dio *dio);
+ssize_t __iomap_dio_complete(struct iomap_dio *dio);
 int iomap_dio_iopoll(struct kiocb *kiocb, bool spin);
 
 #ifdef CONFIG_SWAP