Re: [PATCH V11 15/19] block: enable multipage bvecs

[Ming Lei]

On Wed, Nov 21, 2018 at 05:12:06PM +0100, Christoph Hellwig wrote:
> On Wed, Nov 21, 2018 at 11:48:13PM +0800, Ming Lei wrote:
> > I guess the correct check should be:
> > 
> > 		end_addr = vec_addr + bv->bv_offset + bv->bv_len;
> > 		if (same_page &&
> > 		    (end_addr & PAGE_MASK) != (page_addr & PAGE_MASK))
> > 			return false;
> 
> Indeed.

The above is still not totally correct, and it should have been:

 		end_addr = vec_addr + bv->bv_offset + bv->bv_len - 1;
 		if (same_page && (end_addr & PAGE_MASK) != page_addr)
 			return false;

Also bv->bv_len should be guaranteed as being bigger than zero.

It also shows that it is quite easy to figure out the last page as
wrong, :-(


Thanks,
Ming