[PATCH 09/10] iomap: add a IOMAP_DIO_NOALLOC flag

[Christoph Hellwig <hch@lst.de>]

Add a flag to request that the iomap instances do not allocate blocks
by translating it to another new IOMAP_NOALLOC flag.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/iomap/direct-io.c  | 2 ++
 include/linux/iomap.h | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 96dc72debc4b79..a01f1d182685b4 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -436,6 +436,8 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 
 	if (is_sync_kiocb(iocb))
 		dio_flags |= IOMAP_DIO_FORCE_WAIT;
+	if (dio_flags & IOMAP_DIO_NOALLOC)
+		flags |= IOMAP_NOALLOC;
 
 	dio = kmalloc(sizeof(*dio), GFP_KERNEL);
 	if (!dio)
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index e7865654dd0dca..a92890d5dc6799 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -122,6 +122,7 @@ struct iomap_page_ops {
 #define IOMAP_FAULT		(1 << 3) /* mapping for page fault */
 #define IOMAP_DIRECT		(1 << 4) /* direct I/O */
 #define IOMAP_NOWAIT		(1 << 5) /* do not block */
+#define IOMAP_NOALLOC		(1 << 6) /* do not allocate blocks */
 
 struct iomap_ops {
 	/*
@@ -257,6 +258,7 @@ struct iomap_dio_ops {
 };
 
 #define IOMAP_DIO_FORCE_WAIT	(1 << 0)	/* force waiting for I/O */
+#define IOMAP_DIO_NOALLOC	(1 << 1)	/* do not allocate blocks */
 
 ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
-- 
2.29.2