Re: [PATCH v4 11/25] iomap: introduce iomap_fsverity_write() for writing fsverity metadata

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Mar 09, 2026 at 08:23:26PM +0100, Andrey Albershteyn wrote:
> This is just a wrapper around iomap_file_buffered_write() to create
> necessary iterator over metadata.
> 
> 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 31e39ab93a2e..88fe4723bb22 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -1259,6 +1259,31 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i,
>  }
>  EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
>  
> +ssize_t 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;

ret should be ssize_t.

> +	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;

Nit: If we're not returning the number of bytes written, then the return
type of this function ought to be int, not ssize_t.

Also ... if there's a short write, shouldn't we return some sort of
error instead of zero for success?

	ssize_t written = iomap_file_buffered_write(...);
	if (written < 0)
		return written;
	return ret == length ? 0 : -EIO;

--D

> +	return 0;
> +}
> +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 89e5a7abc012..844fc8414363 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -356,6 +356,9 @@ 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);
> +ssize_t 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
> 
>