Re: [PATCH] iomap: iomap_bmap should accept unwritten maps

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Tue, May 05, 2020 at 07:36:08PM +0100, Yuxuan Shui wrote:
> commit ac58e4fb03f9d111d733a4ad379d06eef3a24705 moved ext4_bmap from
> generic_block_bmap to iomap_bmap, this introduced a regression which
> prevents some user from using previously working swapfiles. The kernel
> will complain about holes while there is none.
> 
> What is happening here is that the swapfile has unwritten mappings,
> which is rejected by iomap_bmap, but was accepted by ext4_get_block.

...which is why ext4 ought to use iomap_swapfile_activate.

--D

> This commit makes sure iomap_bmap would accept unwritten mappings as
> well.
> 
> Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
> ---
>  fs/iomap/fiemap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/iomap/fiemap.c b/fs/iomap/fiemap.c
> index d55e8f491a5e..fb488dcfa8c7 100644
> --- a/fs/iomap/fiemap.c
> +++ b/fs/iomap/fiemap.c
> @@ -115,7 +115,7 @@ iomap_bmap_actor(struct inode *inode, loff_t pos, loff_t length,
>  {
>  	sector_t *bno = data, addr;
>  
> -	if (iomap->type == IOMAP_MAPPED) {
> +	if (iomap->type == IOMAP_MAPPED || iomap->type == IOMAP_UNWRITTEN) {
>  		addr = (pos - iomap->offset + iomap->addr) >> inode->i_blkbits;
>  		*bno = addr;
>  	}
> -- 
> 2.26.2
>