[PATCH v6 08/22] iomap: introduce iomap_fsverity_write() for writing fsverity metadata

[Andrey Albershteyn <aalbersh@kernel.org>]

This is just a wrapper around iomap_file_buffered_write() to create
necessary iterator over metadata.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
---
 fs/iomap/buffered-io.c | 25 +++++++++++++++++++++++++
 include/linux/iomap.h  |  3 +++
 2 files changed, 28 insertions(+)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 7ac319618f8e..0f89225dc3d7 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1287,6 +1287,31 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i,
 }
 EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
 
+int iomap_fsverity_write(struct file *file, loff_t pos, size_t length,
+		const void *buf, const struct iomap_ops *ops,
+		const struct iomap_write_ops *write_ops)
+{
+	int			ret;
+	struct iov_iter		iiter;
+	struct kvec		kvec = {
+		.iov_base	= (void *)buf,
+		.iov_len	= length,
+	};
+	struct kiocb		iocb = {
+		.ki_filp	= file,
+		.ki_ioprio	= get_current_ioprio(),
+		.ki_pos		= pos,
+	};
+
+	iov_iter_kvec(&iiter, WRITE, &kvec, 1, length);
+
+	ret = iomap_file_buffered_write(&iocb, &iiter, ops, write_ops, NULL);
+	if (ret < 0)
+		return ret;
+	return ret == length ? 0 : -EIO;
+}
+EXPORT_SYMBOL_GPL(iomap_fsverity_write);
+
 static void iomap_write_delalloc_ifs_punch(struct inode *inode,
 		struct folio *folio, loff_t start_byte, loff_t end_byte,
 		struct iomap *iomap, iomap_punch_t punch)
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 4d9202cae29f..83586f09f365 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -359,6 +359,9 @@ static inline bool iomap_want_unshare_iter(const struct iomap_iter *iter)
 ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
 		const struct iomap_ops *ops,
 		const struct iomap_write_ops *write_ops, void *private);
+int iomap_fsverity_write(struct file *file, loff_t pos, size_t length,
+		const void *buf, const struct iomap_ops *ops,
+		const struct iomap_write_ops *write_ops);
 void iomap_read_folio(const struct iomap_ops *ops,
 		struct iomap_read_folio_ctx *ctx, void *private);
 void iomap_readahead(const struct iomap_ops *ops,
-- 
2.51.2