[PATCH] block: fix mp_bvec_for_each_page

[PATCH] block: fix mp_bvec_for_each_page

[Ming Lei]

mp_bvec_for_each_page() may miss the 1st page in case that the bvec
ends before last byte of the 1st PAGE.

So fix it by checking against the last page.

Fixes: 05d5585e42a399700 ("block: introduce mp_bvec_for_each_page() for iterating over page")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 include/linux/bvec.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index 98a140fa4dac..85894d5000a1 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -197,7 +197,7 @@ static inline void mp_bvec_last_segment(const struct bio_vec *bvec,
 
 #define mp_bvec_for_each_page(pg, bv, i)				\
 	for (i = (bv)->bv_offset / PAGE_SIZE;				\
-		(i < (((bv)->bv_offset + (bv)->bv_len) / PAGE_SIZE)) && \
+		(i <= (((bv)->bv_offset + (bv)->bv_len - 1) / PAGE_SIZE)) && \
 		(pg = bvec_nth_page((bv)->bv_page, i)); i += 1)
 
 #endif /* __LINUX_BVEC_ITER_H */
-- 
2.9.5

Re: [PATCH] block: fix mp_bvec_for_each_page

[Jens Axboe]

On 2/28/19 5:29 AM, Ming Lei wrote:
> mp_bvec_for_each_page() may miss the 1st page in case that the bvec
> ends before last byte of the 1st PAGE.
> 
> So fix it by checking against the last page.

Thanks, I just folded this in.

-- 
Jens Axboe