Re: [PATCH 1/7] fs: Export generic_file_buffered_read()

[David Sterba <dsterba@suse.cz>]

On Fri, May 22, 2020 at 07:38:31AM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Export generic_file_buffered_read() to be used to
> supplement incomplete direct reads.
> 
> While we are at it, correct the comments and variable names.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>  include/linux/fs.h |  2 ++
>  mm/filemap.c       | 13 +++++++------
>  2 files changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 45cc10cdf6dd..366c533d30cd 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3124,6 +3124,8 @@ extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
>  extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
>  				    struct file *file_out, loff_t pos_out,
>  				    size_t *count, unsigned int flags);
> +extern ssize_t generic_file_buffered_read(struct kiocb *iocb,
> +		struct iov_iter *to, ssize_t already_read);
>  extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
>  extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
>  extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 23a051a7ef0f..27df1cf35eb4 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1979,7 +1979,7 @@ static void shrink_readahead_size_eio(struct file_ra_state *ra)
>   * generic_file_buffered_read - generic file read routine
>   * @iocb:	the iocb to read
>   * @iter:	data destination
> - * @written:	already copied
> + * @copied:	already copied
>   *
>   * This is a generic file read routine, and uses the
>   * mapping->a_ops->readpage() function for the actual low-level stuff.
> @@ -1988,11 +1988,11 @@ static void shrink_readahead_size_eio(struct file_ra_state *ra)
>   * of the logic when it comes to error handling etc.
>   *
>   * Return:
> - * * total number of bytes copied, including those the were already @written
> + * * total number of bytes copied, including those that were @copied
>   * * negative error code if nothing was copied
>   */
> -static ssize_t generic_file_buffered_read(struct kiocb *iocb,
> -		struct iov_iter *iter, ssize_t written)
> +ssize_t generic_file_buffered_read(struct kiocb *iocb,
> +		struct iov_iter *iter, ssize_t copied)
>  {
>  	struct file *filp = iocb->ki_filp;
>  	struct address_space *mapping = filp->f_mapping;
> @@ -2133,7 +2133,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
>  		prev_offset = offset;
>  
>  		put_page(page);
> -		written += ret;
> +		copied += ret;
>  		if (!iov_iter_count(iter))
>  			goto out;
>  		if (ret < nr) {
> @@ -2241,8 +2241,9 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
>  
>  	*ppos = ((loff_t)index << PAGE_SHIFT) + offset;
>  	file_accessed(filp);
> -	return written ? written : error;
> +	return copied ? copied : error;
>  }
> +EXPORT_SYMBOL_GPL(generic_file_buffered_read);

The renamed variable causes build issues with block tree so I've
s/copied/written/ back as we want only the function export.