Re: [PATCH 16/27] iomap: switch iomap_bmap to use iomap_iter

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

On Mon, Jul 19, 2021 at 12:35:09PM +0200, Christoph Hellwig wrote:
> Rewrite the ->bmap implementation based on iomap_iter.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/iomap/fiemap.c | 31 +++++++++++++------------------
>  1 file changed, 13 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/iomap/fiemap.c b/fs/iomap/fiemap.c
> index acad09a8c188df..60daadba16c149 100644
> --- a/fs/iomap/fiemap.c
> +++ b/fs/iomap/fiemap.c
> @@ -92,35 +92,30 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
>  }
>  EXPORT_SYMBOL_GPL(iomap_fiemap);
>  
> -static loff_t
> -iomap_bmap_actor(struct inode *inode, loff_t pos, loff_t length,
> -		void *data, struct iomap *iomap, struct iomap *srcmap)
> -{
> -	sector_t *bno = data, addr;
> -
> -	if (iomap->type == IOMAP_MAPPED) {
> -		addr = (pos - iomap->offset + iomap->addr) >> inode->i_blkbits;
> -		*bno = addr;
> -	}
> -	return 0;
> -}
> -
>  /* legacy ->bmap interface.  0 is the error return (!) */
>  sector_t
>  iomap_bmap(struct address_space *mapping, sector_t bno,
>  		const struct iomap_ops *ops)
>  {
> -	struct inode *inode = mapping->host;
> -	loff_t pos = bno << inode->i_blkbits;
> -	unsigned blocksize = i_blocksize(inode);
> +	struct iomap_iter iter = {
> +		.inode	= mapping->host,
> +		.pos	= (loff_t)bno << mapping->host->i_blkbits,
> +		.len	= i_blocksize(mapping->host),
> +		.flags	= IOMAP_REPORT,
> +	};
>  	int ret;
>  
>  	if (filemap_write_and_wait(mapping))
>  		return 0;
>  
>  	bno = 0;
> -	ret = iomap_apply(inode, pos, blocksize, 0, ops, &bno,
> -			  iomap_bmap_actor);
> +	while ((ret = iomap_iter(&iter, ops)) > 0) {
> +		if (iter.iomap.type != IOMAP_MAPPED)
> +			continue;

There isn't a mapped extent, so return 0 here, right?

--D

> +		bno = (iter.pos - iter.iomap.offset + iter.iomap.addr) >>
> +				mapping->host->i_blkbits;
> +	}
> +
>  	if (ret)
>  		return 0;
>  	return bno;
> -- 
> 2.30.2
>