[PATCH 2/5] iomap: add per-iomap_iter private data

[Christoph Hellwig <hch@lst.de>]

Allow the file system to keep state for all iterations.  For now only
wire it up for direct I/O as there is an immediate need for it there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/iomap/direct-io.c  | 8 ++++++++
 include/linux/iomap.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 15929690d89e3..355abe2eacc6a 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -520,6 +520,14 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 	dio->submit.waiter = current;
 	dio->submit.poll_bio = NULL;
 
+	/*
+	 * Transfer the private data that was passed by the caller to the
+	 * iomap_iter, and clear it in the iocb, as iocb->private will be
+	 * used for polled bio completion later.
+	 */
+	iomi.private = iocb->private;
+	WRITE_ONCE(iocb->private, NULL);
+
 	if (iov_iter_rw(iter) == READ) {
 		if (iomi.pos >= dio->i_size)
 			goto out_free_dio;
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index a5483020dad41..109c055865f73 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -188,6 +188,7 @@ struct iomap_iter {
 	unsigned flags;
 	struct iomap iomap;
 	struct iomap srcmap;
+	void *private;
 };
 
 int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops);
-- 
2.30.2