Re: [PATCH] iomap: fix integer truncation issues in the zeroing and dirtying helpers

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

On Fri, Aug 11, 2017 at 05:18:05PM +0200, Christoph Hellwig wrote:
> Fix the min_t calls in the zeroing and dirtying helpers to perform the
> comparisms on 64-bit types, which prevents them from incorrectly
> being truncated, and larger zeroing operations being stuck in a never
> ending loop.
> 
> Special thanks to Markus Stockhausen for spotting the bug.
> 
> Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
> Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>

Looks fine to me,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

(Are you going to push this to Al yourself, or do you want me to drag it
through the xfs tree?)

> ---
>  fs/iomap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/iomap.c b/fs/iomap.c
> index 039266128b7f..59cc98ad7577 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -278,7 +278,7 @@ iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
>  		unsigned long bytes;	/* Bytes to write to page */
>  
>  		offset = (pos & (PAGE_SIZE - 1));
> -		bytes = min_t(unsigned long, PAGE_SIZE - offset, length);
> +		bytes = min_t(loff_t, PAGE_SIZE - offset, length);
>  
>  		rpage = __iomap_read_page(inode, pos);
>  		if (IS_ERR(rpage))
> @@ -373,7 +373,7 @@ iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
>  		unsigned offset, bytes;
>  
>  		offset = pos & (PAGE_SIZE - 1); /* Within page */
> -		bytes = min_t(unsigned, PAGE_SIZE - offset, count);
> +		bytes = min_t(loff_t, PAGE_SIZE - offset, count);
>  
>  		if (IS_DAX(inode))
>  			status = iomap_dax_zero(pos, offset, bytes, iomap);
> -- 
> 2.11.0
> 
> --
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