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

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